Original subtitles

we will get started very soon

on this third webinar on traditional

construction

and earthquakes

okay it's 9am let's get started

hello everyone and welcome to this third

and final escarsa webinar

on earthquakes and traditional

construction

my name is timmy hills and i am a

structural engineer at old structures

engineering in new york and an adjunct

professor at columbia university

today's webinar is brought to you by

ikomos escarsa or the international

scientific committee on the analysis and

restoration of structures of

architectural heritage

while more people still join i will

briefly introduce our scientific

committee we are an international group

of engineers architects

scientists and educators dedicated to

the restoration and care of build

heritage

we mostly focus on the structural and

technical aspects of conservation of

architectural heritage

we have an elected board our president

is gurun arun

our secretary is tom warson we also have

a webinar chair

steve kelly and it's his birthday today

happy birthday steve

the goals of viscarsa are amongst others

to disseminate knowledge promote

international

cooperation and organize international

training systems

another goal is to collaborate with

other scientific committees

and we are happy to welcome members from

a wide variety of icomos committees

attending today again

in the past years iskarsa has published

principles for the analysis

of conservation and structural

restoration of architectural heritage

and then aside from organizing webinars

we publish

newsletters we are currently developing

guidelines escarsa guidelines

pre-pandemic we were also organizing

workshops um the last ones were in korea

and then turkey and iran

um you can reach us at iskarsa

gmail.com follow us on facebook find our

webinars on youtube

or you can find our website

that's it for the iscarsa introduction

it brings us to our third webinar

on traditional construction and

earthquakes which is also a good moment

to look back at what we've brought to

you

thus far we've had speakers from north

and south america

africa europe various regions in asia

and today we will be revisiting iran and

nepal

talk about greece and finally we will

have randolph present his observations

from around the world

throughout this webinar series we've had

we have been highlighting traditional

structures from wood

masonry earth and several mixed-use

systems of those materials

we have seen parallels between the

construction techniques across the

himalaya

and have been able to compare them to

approaches in the maghreb peru

and persia amongst others as we circle

through these areas it has been clear

that in order to come up with

appropriate intervention strategies

we foremost need to understand

traditional construction

we need to discuss its strengths and

weaknesses in order to design

proper interventions over the course of

these webinars we have been very

fortunate to have heard from a large

number of you

via the chat via email over facebook and

so on

and also today we really hope to hear

from you we look forward to

taking your questions after the

presentations and please feel free to

post in the chat and the

q a at any time we also would like you

to know that we have a special escarsa

webinar

on authenticity and reconstruction

scheduled at the end of the month

which will be hosted by chola akintunde

before handing over the floor to our

speakers i would like to thank evan

spare and

tom morrison who are again my co-host

today i would also like to thank the

other members of the organizing webinar

committee steve kelly kai waiso garun

arun guiger anjali yu

chula akintunde stacey wallace and maya

segarra lagunas

finally i would really like to thank all

of our distinguished speakers for today

for agreeing to share their work with us

and so with that i would like to move on

to our first speaker

eugenie kriti she has recorded her

presentation

so we will play a video she is a civil

engineer and researcher at cathay

laboratory

architecture environment and building

cultures

research unit of the school of

architecture of grenoble

she studied at the ecole central de

paris and at qatar in grenoble

she recorded a presentation for us

titled understanding traditional

anti-seismic strategies

in yast kahar architecture

in iran

let me get that video up

there we go

hello everyone my name is eugenie crete

and

i'm a french engineer working as a

researcher

at carter laboratory at the school of

architecture of grenoble

you may be you may be a bit surprised

by the picture i choose to illustrate my

presentation

that is not a post

earthquake damaged building

and by the case study we selected

yes that

as those who are familiar with iran may

know

is not in a highly safe maker area

and this discrepancy is precisely the

object

of my presentation

we all know that in

disaster prone areas inhabitants usually

developed

local building cultures to cope

with the risks they face the works of

ferruccio ferrini highlighted the

development of

local seismic cultures with different

approaches

prevention or repairs depending on two

parameters the intensity

of local specific activity

and its frequency

these local seismic cultures

often disseminated

because of continuous exchanges

between builders and it may be

i hear the video quality is poor let me

switch wifi networks

which would make things better give me

a dissemination that is highly connected

to technical reasons between territories

that have

similar seismic activities

but what is less often considered

is that these local seismic cultures

are also embedded in building cultures

that

encompass other aspects

and that also disseminate in

less seismic career

areas because of not because of

technical reasons but because of

political or cultural reasons

and in that case technical seismic

elements can still be read

but have often faced important

distortions

so the methodology i'm going to

introduce

here is based on this

hypothesis and aims at taking advantage

of

this dissemination territories with

rather low seismic activities

to overcome the huge difficulties

we face when trying to assess

traditional seismic techniques

in fact the efficiency of a traditional

seismic technique used to be

assessed by post-earthquake observation

but this kind of analyses that were part

of builders capacity building in most

seismic careers until the end of the

19th century

it was neglected ever since in favor

of calculation and digital

analysis post earthquake observations

and institute assessments

are nowadays facing two main interlocked

hindrances that are

the post-earthquake quick destruction of

vernacular heritage by the institutions

in starch

in charge of securing the sites or

rebuilding

and earthquake damage due to

unsuitable previous maintenance of build

heritage

and the distortion of traditional

techniques

induced by previous loss of knowledge

so to overcome these difficulties we

suggest a three-step

methodology first step

consists in broadening the scope

of observations at two levels

first geographical broadening

by studying heritage buildings in

broader areas including territories

that are closely connected to high

seismic areas

but that have rather low seismic

activities

and second technical broadening by

analyzing analyzing local architecture

with a grid of analysis that goes beyond

the usual seismic strengthening

strategies that are connected to modern

materials

second step consists in elaborating

technical hypotheses based on these

observations

and third step consists

in consolidating these hypotheses

through different methods designed on a

case-by-case basis

and illustrated in this presentation

by both institute observations

and experimental works

so i'm going to illustrate this approach

with the case study focusing on

iranian casual architecture

kajar parry rod was a razor prosperous

in the central part of

iran and many cities and buildings of

this rio were heavily modified at that

time

that is end of 18th century and 19th

centuries the architectural

vocabularies developed at that time is

still very commonly observed

in yest that is

a city in the desert

part of iran that is very famous for

its well-preserved historic

city center and as you can notice

on this map seismic

activity in nest is not

as important as in the surrounding areas

but building cultures

iniest were fed by those of

the surrounding areas that face earth

that face earthquake of higher

intensities

with possibilities of distortions that

must be

kept in mind while conducting the

analysis

[Music]

yes the historic uh

city center is a dense area where

traditional buildings are mainly made

out of adobes

these buildings are closely interlocked

because lateral thrusts that

result from volts and domes are

balanced on scale that range from

inside a single house

to inside the urban block

and even uh up to

in between blocks thanks to

arches and the vaults that cross

the streets

local historic buildings look uh

similar to historic buildings of this

wide part of iran and they usually have

one or two levels above the ground and

up to

three underground levels their global

shape mass and rigidity distribution

[Music]

are in line with usual recommendations

regarding masonry buildings in

seismic ureas and what

makes yazda historic city center very

instructive

is first its high number of

historic buildings and second there are

various

conditions of conservation because it is

very instructive

to analyze houses at the different

stages of

collapse to understand their structural

pattern and see beyond plasters

the second broadening we suggest is a

technical one

because engineers usually face

two major difficulties when studying

traditional seismic strategies the first

one is due to the distortions

as these techniques may have suffered

and that prevent from

identifying and understanding them

easily but the second one the second one

second difficulty is due

to the distortion of our

brains that are educated to

recognize only a few seismic devices

those in line with modern seismic

strategies

that are almost exclusively

based on strengthening strategies

and not on energy dissipation

at connections or

structures flexibility or the

integration of

fuse elements that are widely

represented in

traditional seismic strategies it is

this is why it's necessary to get

familiar

with the wide scope of traditional

seismic techniques

and practices that developed in

various locations to be able to identify

and understand architectural elements

that

may not appear as seismic features

at first glance

so qatar published a booklet

that can help in getting this

wider understanding of seismic

strategies

through the study of traditional

monumental and vernacular architecture

from more than 40 countries

all over the world in this collection of

examples

includes 80 practices

and technical solutions to improve

inhabitants resilience regarding

floods earthquakes cyclones

landslides and the idea being

to help developing comparative

analyses of similar practices that are

found

in different locations and

help in building first

our understanding of these techniques

and second

our advocacy work

you can download this publication from

qatar

qatar's website i just indicated the

link

just here

so going back to our case study

to illustrate step two

that is the elaboration of a technical

hypothesis the idea

being to go beyond usual considerations

regarding the shape of the building

and of its walls two deeper study

architectural elements that are nowadays

not considered as stays make good

practices

often because they also offer other

advantages but that may have seismic

origin

i will illustrate with a few of them

so first example relates to the smaller

volts that are built above the

branches of uh of many volts

we know that during an earthquake a volt

stability is compromised

mainly by the inertial forces that

induce

deformations that are efficiently

reduced

thanks to the feelings that are above

hunches of the world but these feelings

increase the weight of the roofing which

should be avoided and in esd

architecture

the hunches of the votes are often not

strengthened by

feelings but my smaller votes

named canepus that are

either perpendicular or um

with the same axis as the main board

and these smaller volts are usually

explained by their

thermal advantages and because of their

efficiency to get flat roofs

but they are also probably highly

efficient to increase

the resistance of the main volt towards

earthquake without burdening

it

a second example relates to the wooden

and glass

facade that often closes winter

living spaces in traditional houses

this kind of clothing is not only

allowing for large amounts of light

to enter

we know that gobble and walls are often

the first to collapse

in case of an earthquake so closing

these gables and walls

have turned disastrous during bam

earthquake

so closing those spaces with a light and

flexible

item also contributes to avoiding the

collapse

of heavy walls in case of out of plane

out of pancake

and deeper research on

the timber elements geometry and their

connections with

glass elements would confirm this

hypothesis the third example

relates to the layout of masonry

that is often declined in very beautiful

pattern

but is it only for aesthetic reasons

this infill panel you can see on the

left

seems to be a variation of a well-known

seismic principle

of framed structure that is that

masonry in-field walls should be weaker

than the load-bearing structure

as it should fail first in case of too

high

solid stations

so these in-field panels

that are built with specific layouts

they have an obvious aesthetic aim

but they are also probably less rigid

than common masonry layout

and moreover cracks can propagate easily

through the pattern but by

dividing the panel in sorry

by dividing the panel in elements that

keep

that keep interlocked thanks to their

geometry

a slightly different example is

interesting

that is the layout of the shaking

minerate of

karanak or jazzed city world

as these two buildings are by

their very functions built to resist

vibrations the city walls because of

military reasons

and the minaret because it is a

traditional performance to make it

oscillate with the mere

swinging movement of a person located

in the upper part of the minaret

this specific layout allows for

weaker interfaces

where cracks appear first

circled in orange

on the picture and by cracking

it dissipates energy without endangering

the world structure

as the disconnected elements uh

like for example the one circled in red

on the picture

keep interlocked thanks to their shapes

so these masonry layouts should not be

reduced to aesthetical purposes

which is often the case and induce huge

problems when stronger mortar is used

during restoration works for example as

the cracks

appear in adobe's razor

than appearing in the mortar itself

[Music]

another example relates to mukharna

capitals that were traditionally built

using dozens of timber elements and that

may have developed as dissipative

capitals

before being reduced to aesthetic

functions and distorted when

simplifying their making and conserving

just

the way they look

i selected the last example to

illustrate the third step of the

methodology that is the insertion of

vague bricks in adobe vaults

rows of baked bricks

are often inserted into adobe vaults

approximately every 50 centimeter

which may be part of a strategy to

improve the global stability

of adobe vaults as

this technique can be understood as a

way to create

fuse interfaces and facilitate the

creation of sectional cracks

during the quake

and dividing the vault in arches

that keep stable instead of having

diagonal cracks that would endanger the

structure

this insertion of the baked brakes in

adobe vaults

is hardly visible when the vaults are

plastered

but we could observe it in several

houses

where plaster was partially removed

and most importantly we observed it in a

house with

bad condition allowed for a deeper

observation of the formation

of cracks in these walls

this house suffered from improper

maintenance and it was especially

interesting as it includes uh

five collapsing or badly cracked

vault built using adobes

and baked bricks and wherever visible

it was noticed that main cracks and

partial collapses

systematically occurred at the baked

breed bricks

rose insertions

this observation campaign of

collapsing houses that are not

post earthquake collapse

is unusual to study seismic elements but

it turned out to be very instructive

in order to better understand the

medicines lessons

know how that relates to these

observations we tested different brick

mud mortar break sandwiches

to compare their sheer resistances

we aimed at understanding

if masons were preparing adobes

and baked bricks differently before

applying

mortar that is by

wetting them or not and we measured

that when bricks are wet before

mortar application the shear stress

values for both baked and adobe bricks

were similar

but when samples were prepared without

wetting the bricks before the

application of marta

the shear resistance decreased a lot

which may be explained by an improper

bond development due to a two-phase

moisture flow between the bricks and

mortar

so it could be a way

that masons used to

to create these fuse

interfaces in adobe rules

but this example of experimental work

is very interesting because it is

very simple to set up as it requires

basic lab equipment

and one can even perform comparative

tests

of shear resistance with a

bucket and nylon belts

i will quickly speak about another

example of

experimental works we conducted that can

be considered

as the other extremity of the ladder as

it

required very important lab

equipment these examples relate

to horizontal zipper insertions

i'm sure you are all quite familiar with

these

elements that can be found in many

seismic areas for example those circled

in black

on this map

to consolidate our hypothesis about

these timber insertions and the effects

of the different

variations we had observed

we built different models

of houses and analyzed their behavior

when submitted to vibrations

simulating an earthquake so we are

currently analyzing

the differences between the models

regarding the mercenary displacement

acceleration

the propagation of cracks

and the modification of fundamental

frequencies and model

stiffness this work was conducted

as a part as part of the phd of

santosh yadav

that is a nepalese student

working at the tricera 3sr

laboratory in grenoble

this work is an interesting example

as it does not only help understanding

the traditional strategies

and but also aims at

improving reconstruction at a larger

scale

including new buildings um

by better understanding how to get the

best from

local resources for example in that

case by conducting a comparative

analysis of

timber concrete and bamboo insertions

i would like to insist on the fact that

this methodology does not

necessarily imply having access to

important equipment in this example we

used a

laboratory shaking table of important

dimensions that is not so common

we use this equipment because we also

wanted to

this work to feed research on digital

modeling

but interesting work is also possible

with a low cost shaking table

for comparative analysis

[Music]

for example these pictures

relate to a research project we work on

with yaz

university in which we use a shaking

table

built with a basic motor

that is very efficient for comparative

analysis

for example here with two vaulted

[Music]

models one wheeze and one without a

gel grid or with different

masonry wallets we had also

built a makeshift

shaking table of smaller dimensions

without motor

only strong springs

that did not allow for the testing of

such big models but did allow for

a comparative analysis of smaller

elements

so to conclude i will insist on the fact

that

a deep understanding of these features

is not it's of

major importance to develop proper

maintenance

of historic buildings we are currently

working with jazz

to develop pedagogical materials to

disseminate

guidelines amongst institutions and

inhabitants to tackle the important

issues induced by improper maintenance

this methodology aims at illustrating

how

engineers may contribute to

rediscovering

understanding and validating

traditional practices in another ways

and

numerical modeling because numerical

models

are out of reach of many professionals

and their current limits are known these

models are often very complex

and fail taking into account the

material variabilities

the interface behavior the

side effects including for example

the connections between buildings and

they request

highly qualified professionals to select

the adequate

simplifications and analyze the results

but it is still very difficult to

discuss with technical

authorities if works are not based on

numerical modelling

i will end this presentation with two

pictures of a market

we built a few years ago in arabic

near yest as it is an example of a

project in which we managed to convince

technical authorities to validate

projects not by performing numerical

modelling but

performing very simple experimental

works and these works highlighted the

efficiency of

traditional materials and shapes when

properly built

and of a few basic modern

reinforcements like for example the pvc

tubes you can see on this picture that

were

vertically inserted in the adobe mastery

so thank you very much for your

attention and uh

don't hesitate to send me your comments

or questions by email i

wish you all a nice webinar

okay so that was our first presentation

from eugenie as she said she could not

join us today but you can reach out to

her

directly our next presentation will be

by

evan speer evan is a professional

engineer currently based in seattle usa

he is currently affiliated with

consulting firm swenson say faget

structural engineers

he works on a variety of building

designs and renovation projects

with a focus on historic preservation

and adaptive reuse

he has been involved with preservation

efforts in the u.s europe and

asia and evan has been involved with

heritage preservation efforts in nepal

since 2015

largely in support of the kathmandu

valley preservation trust

he holds a bachelor of civil engineering

from the university of vermont in the us

and in advanced masters in structural

analysis of monuments and historical

constructions

the famous sac program uh that's coming

out of the university of menio

and the czech technical university in

prague amongst others

evan is also an associate member of

iskarsa welcome evan

hi tim hi everybody thank you for the

introduction

um i will get my screen shared here

um tim can you confirm that you can see

everything

yes i can see it alrighty so

um as we discussed a little bit earlier

i'm just

going to um try to keep this brief

uh so that we can have a good discussion

at the end my name is evan speer

i have been involved in preservation

efforts in

in nepal and largely the patent durbar

square

unesco world heritage site since the

gorka earthquake

2015.

so a little bit of background on the

kathmandu valley what what area am i

talking about

we've had we've been lucky to have at

least

one presentation about nepal and

nepalese architecture

in each of these webinars so i won't go

too in depth but

the kathmandu valley is a microcosm of

cultural heritage in within the larger

area of nepal largely due to the local

nawar population

there were three former city-states

kathmandu patan and bhaktapur each of

these

have what are called durbar squares a

large town square

where there was a palace for the

local reigning monarchs and a series of

various temples

that were created for the local

communities

it is one of the highest density areas

of unesco world heritage sites

in the world with seven sites um

in a very close proximity um

why was i over there i was there with

the

kathmandu valley preservation trust

which was uh founded in 1991

uh it's the only nepal based non-profit

solely devoted to historic preservation

they have been working on seismic

strengthening projects

and preservation work since long before

the earthquake

learned a lot of uh lessons along the

way uh through

various projects with nawar architecture

uh they are patent-based mainly mainly

working in the patent durbar square

and uh have the mission to facilitate

cooperation between western and local

professionals and craftsmen uh

stimulating cross-cultural education

preservation of these monuments but uh

also

jobs and training for local craftsmen in

these types of trades which in a lot of

areas of the world

stone masonry brick masonry roof tile

laying

timber construction and also wood

carving

a lot of those art forms are being lost

so what is of our square this is a look

before the earthquake

of uh some traditional nepali

uh tiered temples uh which will

be the focus of my presentation here um

charon ryan on the left

and this far on the right um

a few historic photos showing

just how it seems like you are stepping

back in time

these these temples are

in very close proximity to one another

um in the historic

city core um as you can see here in this

plan

uh what is outlined in blue is uh the

traditional palace with various

courtyard

structures and smaller tiered temples

coming off

the top of those and the various

assortment of smaller structures to

the left are the various temples

throughout the square the temples

shown in red were completely collapsed

after the

2015 earthquake

here is an elevation of the main palace

i will not go into detail

here for the sake of time

but you can just see the intricacy

of the the architecture here it's

masonry bearing walls with timber

portals uh

around all of the doors and windows

carved timber struts holding overhanging

roofs

and several tier tiered roof structures

within this so um i am going to give a

couple

uh brief introductions of the

traditional temple typologies

uh that we've got and then i will go

into

a typical failure mechanisms and

what we have learned from the

earthquakes

and how we can address some of these

failure

criteria so the char narayan temple

is a two-tiered structure dating back to

1565. it was completely lost

in the 2015 earthquake but

interestingly enough due to various

energy

dissipation elements

as eugenie had mentioned earlier

the lack of

strong connections between building

materials and the

mud mortar in the masonry allowed

the building to basically just fall

apart

and a lot was able to be salvaged these

are not inhabited buildings

so while this building was lost due to

a number of failure mechanisms a lot of

historic material was able to be

salvaged you can see here

the two tiered structure

has in a series of core walls an inner

core that goes

full height and an outer core wall um

that is from the exterior appears to be

a brick masonry bearing wall but largely

is a timber frame due to that portal

that is doing a lot of the load bearing

for the upper structure

a similar typology of another tiered

temple

consists of an outer timber ambulatory

on the ground floor and as you can see

here all of

these temples are raised up on plinths

multi-tiered plinths this temple

actually

experienced this significant amount of

torsion

in the earthquake but was was able to

withstand

the ground motion and

was able to redistribute the load pass

and

come back to place approximately uh

over the first floor it was

approximately eight centimeters out of

plum um so it did have some racking

going around on the ground floor

but it it was able to redistribute those

loads

here we see this section and plan as

well

we've got the same two-tiered

two-tiered temple with the inner and

outer cores

um and the exterior core on the ground

floor

has a series of large timber columns all

the timber here

is a local material called saul which

is an old growth kind of teak it's a

very hard wood

that blends well to carving

the architectural elements are made out

of salt

and a lot of the structural hidden

elements are made out of a

kind of local pine you can see here in

this isometric

this vespara has a

very significant timber frame so from

the exterior

in some of the photos that you see there

it looks largely like it's a masonry

bearing structure

but when you look deeper look through

the weeds of this

there's a traditional

large amount of timber here that is

allowing this building to be more

ductile than you would

um originally understand just

just looking at it so the significant

amount of timber here there are some

weaker connections but

it was observed through post-earthquake

forensics on this

on this uh construction that it had

significantly more

timber than other structures in the

in the square so that this was a later

structure built in 1627

so in that in that 80 years they

added more timber for one reason or

another

but the more significant timber frame

led to a more

ductile structure which was able to

dissipate more of the seismic energy and

stay withstanding during the earthquake

now there are a lot of other factors at

play here

but that was one of the

factors that we we noticed uh and

through our forensic observations uh

led to the success uh of this

structure in the earthquake um you can

see here this is an elevation

of the ground floor inner core uh the

opening to the sanctum

um and all of this darker area

intricately carved wood um actually

provides a

pretty substantial frame

for bearing the masonry

walls above it so there are small areas

of brick infill but it is largely for

infill and the main structure is

timber here you see that same elevation

where we have the masonry infill there

another smaller typology

which i will not go into uh as deeply

um this is not a temple these are small

what they call

pati structures um the one on the left

was actually used

for the coronation of the kings there's

a throne in the

stone thrown in the center portion of it

but

i like to think of these as um

early 1700s era bus stops

everybody you walk through the main

square which is which is

lively with local and and tourist

populations

and in any part of the day there are

people

sitting in these structures

hanging out having having their coffee

having their tea

sometimes selling vegetables very lively

structures in the local community

but as you can tell they were not very

well suited

for the for the seismic motion that they

saw they are located right next to a

large step well

um but largely um

the structure is a significant

um it's about three meters by

six meters um

and it's an open timber arcade

supporting uh

brick masonry walls uh bearing walls

with a

heavy earthen roof and clay tiles

so looking at these types of structures

what type of typical seismic failure

mechanisms were we seeing

and um what types of energy dissipative

or seismic connections were we seeing in

the traditional

constructions so one of the largest most

important

failure mechanisms that we were noticing

is the independent foundations

so these tiered temples um when you

actually dig into the plinth

the exterior and

interior core walls are basically

sitting on

brick masonry strip foundations that are

going deep into the ground

so the uh outer and inner wall

foundations are not tied together they

just have

infill of mud and some rick rubble

and there's no structural connection

between those

foundations so we were seeing

independent movement of

the foundations

during the seismic events and the

plinths as well

uh the edge the perimeter walls of the

plinths were not connected

um to the walls

of the structure itself so the structure

being tied at higher portions

of the building at the tops of the

the walls and at the floor levels

were not actually connected in the

ground itself

as you can see here we did a lot of

digging

to try to identify how deep these

foundations went

uh and also to find any ties there were

some

small ties between plinth levels

but between the interior and exterior

walls

we got down deep enough where we needed

to put shoring between and

we went down about six meters before uh

deciding to get out um just giving

shoring restraints

um so what do we do here uh

we didn't want to change

uh too much significant in terms of

the traditional layout of these

foundations but um it was identified as

a

substantial threat to the

seismic behavior of these so what we did

was we

infilled these plinths

with a separate brick masonry

largely just in a typical mud mortar

below the ground

and above the ground in certain areas

using lime

mortar within this masonry so that we

could

we could connect all of the plants and

and provide a more stable base

on which to either rebuild or um

repair some of these structures um

another failure component that we saw

was uh masonry composition as i saw in

the chat earlier

um it is not just about intent it is

about

execution uh of

traditional methods uh and also

the uh maintenance of these methods so

um

traditional mortars in these brick

masonry walls that we're seeing

is derived from a specific strata of

clay about three to five meters below

the ground surface in the kathmandu

valley

um but it lacks any true cementitious

binder as a lot of areas around the

world see with their

brick masonry so this is a more ductile

type of brick masonry

mortar tends to dry out if it is not

mixed properly

it dries out faster if it is not the

right clay it dries out faster

and then it turns to a sand like medium

so the bricks will start rubbing

against each other because they lack the

proper cohesion to

maintain their uh their masonry behavior

so in seismic event the bricks can unzip

either in a local failure for these

infill areas or as a load-bearing

failure

for the walls themselves and as you can

see here

traditional face bricks that were fired

differently

are tapered on the inside so that you

can get a very thin bead

for the mortar joints but this tends to

erode with

with water infiltration in a lot of

these buildings uh

water would come through erode this the

clay layer behind it and these

bricks would just kind of bow together

um

and so that also led to a lot of outer

plane failure

and a lot of just defacing of the brick

and this could also be

adapted by uh just a more sound

uh sound construction of the brick

masonry itself

as you can see at the base there's a

couple different ways to

relay the masonry with the same type of

mortar but in

just a

more diligent fashion

also a large component of

failure in these structures is the weak

connections um the

basic understanding of seismic design is

seen in a lot of the connections here

mortise and tenon style joints between

the columns

and the base stones that are beneath

them

and also wall ties have little pegs

called chuckles that

are tapered to hold the

timber frame to the the walls

which you see in a lot of similar areas

of the world which i've seen

in a lot of these presentations as well

but

these are not maintained they're meant

to every

two years or so meant to be hammered

down a little bit more to maintain

a strong connection that was not often

done

and also the tendons are very small

with regards to the displacements that

we see in the earthquakes that hit nepal

there's a lot of ground movement and

there's only about a few centimeters

three-quarters to an inch of

depth on a lot of these tenons you can

see here this is the lower

floor of one of the tiered temples with

the outer ambulatory this one actually

collapsed in the earthquake

you can see up on the top left one of

the columns after the fact the tendon is

still

in place it's a very small tenon but it

had dislodged from the base stone

scene to the right

in the vertical motion induced by

the earthquake and that dislodged and

since the

stone the base stone was not connected

to the surrounding stones

it also dislodged and that was one of

the failure mechanisms that

lost load bearing at the corner here

and the struts also lost their bearing

and

led to collapse the roof

also you can see here on the temple i

showed earlier that

went into torsion but was able to

withstand the

tendon dislodged from its base stone but

the base stone stayed in its place

now what do we do with this type of

of connection we don't want to change

the load path

we don't want to um make things too

stiff uh we just want to give it a bit

extra room to move in this earthquake

give it a little bit more

strength and flexibility to to displace

more than just the three-quarters of an

inch that

it was allowed to before before failing

as a connection

so we kept these same layouts

and even in new columns that we needed

to make

we just inserted a some stainless steel

dowels

down into the base stones and connected

the base stones

this was the similar

methodology with a lot of smaller

connections

struts supporting the roofs didn't have

a positive connection

adding a positive connection back to

timber

adding more wood in

within the timber frame of walls that

were reconstructed

in accordance with similar

structures of uh similar nature are

seen around the uh kathmandu valley all

had precedence

um so just to try to strengthen these

smaller connections

around the structure roof struts as you

can see here

were not necessarily positively

connected back to the wall

at the base so in these earthquakes

they were often dislodged from their

bearing

what to do here we can uh reinforce

these

peg connections just to give them a

little bit added strength

um so that they don't either dislodge or

sheer off during an earthquake not

necessarily overly stiffening

anything but allowing those connections

to maintain themselves

to hold the structure together

so looking at these just typical

interventions that we were looking at

we're not looking at

a seismic retrofit in the typical sense

but we're looking at more of a

addressing deficiencies to try to

maintain this

ductal nature of these traditional

constructions

not making it overly stiff like a lot of

approaches

uh could think coming from new

construction

throw in some brace steel brace frames

throw in some

uh steel moment frames but that is not

appropriate in these types of situations

of course

because it is a new type of material it

is a

different methodology of of dealing with

the energy from the seismic event

so it will make this building way too

stiff and then that will

induce stresses into the structure that

it cannot withstand

so we're staying with this uh ductal

nature

um but we want to have it shaking on a

solid base so we're connecting the

plinth foundation walls with brick

masonry so that

it is more of a homogeneous uh

foundation underneath and then providing

some added connection to the

base layer of threshold stones

around the bottom the connection of the

superstructure

to the foundations via either a ring

beam

or a slab between the stones that we can

just connect to make the base a more

homogeneous

uh connection

this connection and this foundation

consolidation will limit the independent

movement of

these uh foundation walls

so that it will help the superstructure

kind of maintain and shake as as one

unit

typical superstructure interventions as

discussed before

strengthening these timber connections

allowing them to

absorb a little bit of of energy and not

to um not to dislodge so providing

positive connections where there

sometimes

were missing but not intending to overly

strengthen or stiffen the structure so

that we still

are able to get that energy dissipative

uh nature of these types of structures

that we were able to see in the ones

that survived the earthquakes

also introduced diaphragms were

appropriate you can see

in the upper floors which are

often not accessible to the public

um we were either able to put diagonal

planking

using the same types of planks uh

that were used for these floors

thickening the floor assembly a little

bit

to provide a

better diaphragm action to also connect

at this level the inner and outer cores

to limit that in independent movement

and then also tie the foundation to the

superstructure

now that was very quick uh summary of

some of the some of the typologies

structures that we saw and

and the interventions that we're looking

at but um what what does

a lot of this come down to as i've

mentioned uh multiple times is

um the importance of regular maintenance

a lot of the traditional structure uh

structural connections and components

um had the had the intent

had the uh possibility of um

seismic resistance but um due to

irregular like deferred maintenance and

several decades centuries of um

not cleaning out the upper floors from

pigeon droppings or different things led

to wood rot and then the wood

connections of course lost their

strength so

it wasn't necessarily in areas of

failed structures not necessarily a

failure of the traditional construction

but often times of maintenance how

exactly

do we define minimal intervention this

is something we've come back to several

times and

i hope to discuss in the discussion

today

what is minimal we can't really put a

specific number to minimal

coming from the structural side of it we

want to improve life safety of course

and what level do what bar do we hold

what level do we look at for this

what we got to in

in pattan was uh the concept of seismic

improvement

versus a seismic retrofit so um

instead of trying to apply these code

level forces

um to these massive heavy structures uh

which would require some sort of new

lateral element

new frame in there just to resolve these

forces

that goes against the energy dissipative

uh

nature of these structures so if we just

use a lot of small scale

interventions a lot of small scale

improvements

or just being true to the traditional

construction

and

resolving the brick masonry wall

composition

in a little bit more uh diligent way

um then was often seen in say the 1934

rebuilds after the

previous uh large earthquake where

a lot of reconstruction was rushed due

to

due to various constraints at that time

if we combine all of these small-scale

interventions this ultimately leads to

an improved life safety which is our

goal

as engineers but also

these small-scale interventions don't

detract from

the actual architectural heritage of the

structure

nor do they really get in the way

because these all of these temples are

used on a daily basis

by the local population

and that's all i've got for today

um i know i went through a lot very

quickly but if you have any questions

please feel free to let me know

thank you so much evan for this

wonderful fascinating presentation i

think you raise a very interesting

point at the end about um about

what would be required if you would do

if you would retrofit this temple

um up to current code and that would

require a

big frame and so on i think it's

something we'll definitely come back to

at the end um so thank you again

um that being said let's move on to our

third presentation

which is be by electionica

she is an assistant professor at the

national technical university of athens

in greece where she also received her

phd she's a member of 28 scientific

committees and the greek delegate for

eurocode 5

she has designed and supervised the

construction of about 80 modern timber

projects and 53 restoration projects

she has written extensively about

historic trimmer structures and will

discuss

their seismic performance today so evan

if you can stop sharing your screen

wonderful thank you um and lfteria the

floor is yours then

electivia we cannot hear you

we can see your screen

yes now we can hear you okay

so good evening i would like to thank

the

committee of iskarsak that gave us the

opportunity to speak about traditional

architecture and earthquakes

presenting our experience from all

around the world and mainly learn from

each other

i will speak about greece earthquake

and timber from prehistory till now

greece is one of the most seismic areas

of europe as you see the purple

colors in the right picture

and especially these areas of ionian and

and sea and we have extreme earthquakes

since antiquities in prehistory minimum

civilization has experienced

not only earthquakes but also volcano

eruptions as we will speak

later continuously we have this

seismic events in 1881 in hills island

in dodecanese

in 1933 in coast island

nearby 2017

we had in the same island and another

seismic event

important one and first in the next one

in lesvos

uh again three years ago

we had this um earthquake

we in this village this

village we lost about 70 percent of this

no classical buildings and um

generally we lose most of our

traditional architectural heritage

so in greece we have earthquakes but we

have timber structures

a lot of people ask me about this

because

this is a picture that i usually show to

my students also

it is from mainland of greece this is a

typical house in greece a traditional

one

but are these mushroom buildings or

timber buildings

well the answer is usually even the

tiles that martian are from stone

but in reality these are not mushroom

buildings these are

machinery and timber buildings because

we usually forget wood and wood that

is present is a is a

out of timber is are the roofs external

timber walls

internal timber walls the floors the

windows

and even the machinery

is reinforced in in my country with

timber elements

and we will focus on this timber

reinforcement

so we have a lot of timber actually when

we study

historic buildings even when we think

there are actually mastery buildings

so we go back and see these horizontal

timber reinforcements and

my phd was on this topic and

we see that continuously in greece and

in several other countries is from

cristian

india you will see next presentation

from mr lagrange

from neolithic era bronze age

continuously till 19th century we use

in this area of the world this uh this

system

helping martial buildings withstand

earthquakes

and we go back in time and we start from

british history we go to crete where

minons lived

and had a wonderful and

civilization crete and santorini were

located in a very very seismic area of

greece

you see this art and also not only

seasons at all

also they had volcano eruptions so all

this this civilization suffered from

this

we see starting this civilization was

was my main topic of my phd go back to

3000 before christ and we see

we we dictate this horizontal timber

reinforcements

in several levels of buildings

3000 before cries we see again

the same system of horizontal elements

of

trunks uh in the form of a grid placed

in again

only horizontally in different levels uh

along the height of of the first palace

of the stores the one you can visit now

is not the first palace is the next one

it was the one that was um built after

the destruction

of uh of uh of this period

because of an earthquake so we have this

this

grid this um horizontal grids that we

see again in a next period which is

called no palatial period

and it it starts in a 1500 before christ

the old policies were destroyed from an

earthquake and new palaces

are built but in santorini

um in domestic houses we still have

uh we they still use this uh reinforcing

system

of horizontal uh layers we have uh

this um opportunity to study this

because uh in

aggregate in santorini and

you can still see a three-story

buildings

standing i call this area the parthenon

of history because you can visit and see

this building standing in two-story and

we speak about two thousand before

christ

so this period in in in creed

and in all men on world new palaces were

built

uh quite high palaces three and four

stories

actually built of timber and stone not

stone and timber

timber played a very very important role

the everything

changed they stopped using these

horizontal ember reinforcements like the

previous years and they started using

a new system with vertical timber

elements

incorporated in in the walls actually

they were not just

vertical elements it was a three

dimensional timber frame

incorporated in the walls as you see

here you see the gaps here of the timber

and

here is from the restoration of evans

that did at the knuckles palace

you see here how he found it and the

restored

part with the indication of the places

of this vertical timber frame

that was inside in all these walls of

masonry

with vertical timbers longitudinal ones

at the level of the level here and

another longitudinal

one at the level of the lintel of this

element these timber frames are used to

be built here and we'll speak about them

later

so we have this kind of construction

inside the walls

on all stories of the three four stories

of the palace

so actually we speak about a

timber-framed world

reinforced by mastery and not the

opposite

and what are the are there any

anti-seismic

advantages of this system if you have

this timber frame in the wall repair is

easier and quicker

as it is in left gas system we have that

is considered one of the most important

anti-seismic systems of europe

professor juliatus has studied it a lot

and what is the conception and if the

brittle marginally

falls down very or is we have a failure

because of earthquake

the house is still standing so people

don't die and the building does not

collapse and then

you just uh restore the

the mastery and they continue to live

so in this case in in minoan

architecture we see

this concept it's similar but

the the the timber elements which are

next to the mastery are

inside the masonry and if we travel

4 000 years later and go to

italy in the 18th century and we see the

bourbon system that was

uh um evolved

there after a terrible earthquake we can

see

a lot of similarities with the mean one

especially the version

this one where this double frame was

incorporated in the machinery um

of of these buildings and

we have a second version it is a work of

a very good friend caller gary with

a single frame instead of having two

frames in barakata system you can find

a another version that you put one

single frame only in the inner part of

the wall

and it seems that it worked because in

this

um in these um photographs from the

earthquake that happened in messina

you see that the house still standing

because of this inner

um in inner timber frame in the wall

which is what we need in anti-seismic

design

and if we travel again from calabria to

mitilani

in 2017 we saw that

there were the in medellin in lesvos in

this island

uh in this village that was almost

destroyed from the earthquake

of this year we have the same exactly

system

that we meet in messina we knew that

this system existed

of a very good work of uh nicolas

caridis

for another village near this one about

the same uh mentality a thick mushroom

wall with an

in incorporated inside in the inner face

of it

a timber frame

and if we go back again we're going back

and forth for about four five

thousand years uh if we go back again to

to a minimum period we see that they use

this system in their walls but they do

something

more than that they take out from this

frame the mastery

and they build and they produce

these kind of frames which is exactly

the same system you see it here

here and here but if we take the mastery

you get a timber frame

that was sitting on these basis

and this is um

of great importance because it is

considered the most important

architectural and structural innovation

of menon civilization

this is called pirandor partition it's a

multi-door

polytheron in greek and it's it's it's

an

innovation a multi-functional

architectural and structural element

made of timber

that can control the communication

between the spaces control the light

control

the the ventilation and also

has a very important structural um

[Music]

how can i say roll

also because you know what they did

in this period they did take

all martial walls on the ground floor of

the structure

and replaced it with a timber frame full

of openings

and it seems that it worked well because

we have a very

impressive example from a house in

akrotir in santorini that survived the

volcano eruption

and the earthquake where we see on the

ground floor

this incredible frame timber flame of

the

2004 cries having over it two stories

the upper story is missing because of

the origami no

but two stories mushroom like ball

on and in the frame so it seems

that they trusted timber and they

had the technology to build this kind of

construction

we're speaking of of an innovative

timber load bearing and reinforcing

system which was unparalleled

in in for prehistoric and historic

period

it gave the possibility to the minimum

technicians to build

to beat multi-story buildings with

numerous large

openings at all levels ground till the

upper level

a unique architecture of openness and

light

and thanks to this approach where other

civilizations

civilizations at mass like we see later

in order to support two stories they

took out

mars in order to support four stories so

we have a unique

for prehistoric and historic period a

construction that izuniku never before

found and never again because after

minorities come from athenians

know the mithinians the trojan war

and or uh you see the the in the missing

palaces we have organic timber

reinforcements they actually

almost all known ashler facades were

timber

there are in the reinforcements that

look like the minoan minori on

ones but they are not the same

and the architecture is completely

different but we don't have time to

say a lot about it we have to go through

about

five thousand years so and we don't have

much time

in classical and hellenistic period we

we don't have much information

because mainly important monuments were

built and so

uh ashley monuments are uh

we focus on archer monuments and we

don't have much information of other

buildings the only we information about

timber reinforcements we have about

the walls of others that were from adobe

and there were um they had timber

enforcements as

in prehistory and if we go to roman

period

we realize that timber reinforcements i

mean

are missing and i think it's

a theory of mind that that they took

romans took out

the timber reinforcements of mushroom

because they invented

the roman concrete and i think they

trusted a lot

roman concrete actually they didn't took

only out

uh timber enforcement they took also

stones

of their of their machineries so

and this tradition continues because

immediately the emotionally even till

the last centuries

it does not have anything reinforcements

and they have a lot of earthquakes

just like us while in greece as we said

the india especially after the fifth

century after christ

um timber enforcement are coming back

again

and we see it in byzantine monuments

there is a lot of work has been done of

this from several scholars

about the byzantine monuments we don't

have many examples of

non-monuments so in these cases

and we we find all these timber

reinforcements hidden

behind the decoration um

cleans and and the elements

in mainly in churches

and we go to post byzantine ottoman

period

of 15th and 19th century we have this

kind of architecture which is very

common all

around ottoman period in many countries

around mediterranean and then we meet

again this historic

let's say horizontal timber

reinforcement system which is

tying as a belt uh placed in several

levels along the height of the building

with consisted of actually two

longitudinal members and transversal one

timbers

in order uh connected with nails going

all around

the the structure

usually its position is for sure at the

level

of the roof and at the level of the

floor and in more

in in buildings that need more

reinforcement

also it is placed in several other

levels as the lintel

or the seal even in the middle of the

pierce between the openings

so we're speaking of a horizontal grid

again embedded in mastery in different

levels and either can be two two timbers

or in this case of a mosque in a

medieval part of roads

where there is a special type of

construction system that they use

only one stone as you see here again

the use of one piece of timber

25 centimeters width in different

different levels still the top

what is the main structural role of this

uh

this this system this horizontal grid

actually is what is presented by the

this very good

schedule for my professor professor

tulato who is the first one who studied

this kind of structures

and he learned us how to do it also to

to study them is the tying of the wall

like a belt

why because the typical collapse of of

all the of the structures during

earthquake

is the the walls go out and the roof

gets in and that's how people

are killed and how the properties are

lost and it's very interesting one of

the first things i did for my doctor

was to to check what does this mean

what what word we use for this system in

a modern greek we it's called xil of the

which means

we i tie the building with the wood

in ancient greek is called imantosis it

comes from a word

a verb imano which means belt

again and i checked in other languages

and i saw in english in french

in turkish in hebrew the same

word belt which indicates with

accuracy the main structural role of

this system

and in order to work as a belt we need

the continuity of the system and the

coordinates of the building so

you see here always the timbers are

closed

and and other

timbers are helping either diagonal or

horizontal to

reinforce the window like this

and sometimes we think the nucleus

season came

in greece and then and a

usually the architects uh the german

architects who came said that what what

is this system with

timber reinforcements why don't

take it out and in many cases they

started using all these uh

corner reinforcements which they thought

were enough but they were not

because you connect the the the corner

of the building at the outside

but the inside is not usually connected

and even if it's well

constructed the outer part inside

there's not

so if the timbers were in this

corner these horizontal demons they

connect both

sides of the of the masonry

and another thing that this system

provides is

it is the mechanism for tying the floor

and the roof to the

uh substructure to the walls because

otherwise

during an earthquake the the roof moves

and instead of having this time

the roof or the floor moves and produces

all these

damages as you see here

and of course in all these cases we can

see that

they in in all these cases the timber

ring for the timber belt at the upper

part of the wall was missing that's why

this all happened

and all this belt is very vulnerable

pressures even

if we don't have it around as a belt in

the building

just there are other causes that can be

pressures it is for

when you have it just in one wall it is

a working as a reinforcement as as

as in as in concrete the iron

uh for out of plane forces it is um

it is a reinforcement since timber is uh

is capable of

for tensile loads can be the

reinforcement of the brittle marshally

and

it gives us also ductility in the

masonry

even when the earthquakes comes in comes

in

in plane of the marshally this timber

reinforcement

can stop the cracks

like here if in this case we have the

timber reinforcements along the height

of the pier

this graph wouldn't involve like this

another

beneficial role is that due to the

connection of the two timbers

transversally they connect the two

outer layers of the masonry so

they improve the connection of of of the

width

of the of the of the mushroom you see

here

what happened again in this area where

timber reinforcements were not present

this transversal connection was known to

ancient builders uh not recently in the

18th century after christ even in the

18th century before christ if we

see all these walls uh egyptian uh in

egypt and in other places you will see

the use of

these transversal timbers that are

important for the

connection of the of of the

integri and the integrity of the of the

very big

width of this mushroom of a great width

eyes have a very beneficial role also as

a confinement

for this kind of locally

in in these machinery walls bit in for

the piece between the openings

like in this case when we have

horizontal

element on the lintel horizontal element

at the sill

and um a reinforcement

in the middle of the pier we did some in

a

research program with professor tillatos

and professor vizillo

did these experiments and we discovered

that uh the strength is is double

uh in when you have uh the timber

reinforcement and

since we're speaking about openings the

opening is a very weak

area and marginally and the end

especially for earthquakes

cracks usually develop around around

openings

so when you have a timber um

reinforcement on the seal on on

on the lintel of these buildings and all

of this

is sued is is connected the timber

um part of the of the window

all this provides a very very strong

uh perimeter around the wind around the

this

vulnerable area of the machinery and can

helps a lot during earthquake because

otherwise things like this can happen

or like this

and the older builders were so confident

about the precious role of the timber

reinforcement

that in these cases as you see they

preferred to pass

the timber enforcement in front of the

window not caring so much about the view

going around in order to protect their

building

instead of cutting it

and the this a seismic structural role

of minon

and historical of prehistoric and

historic timber enforcement was not

really recognized

by scholars mainly coming from west

actually

even if you study byzantine schwarze or

other

uh very important scholars that study

byzantine architecture they were they're

saying that probably they used this kind

of reinforcement

only during construction still the

mortar will become

hard well i i wouldn't agree because

as i told you there are details that

showed show us

how the effort to connect and work as a

belt

this type of of reinforcement and

i was lucky enough one of the first

things i found for my phd

is a saying in a book of bible the

wisdom of shira

which was written in the second century

before christ and it says

um well in translation

what we really where i i was sure as a

structural engineer seeing all these

details

but it says that they deliberately

use the in they use all these timber

reinforcements just for earthquake a

wooden beam fairly

bonded into a building will not turn

loose by an earthquake

so the mind firmly fixed on a reasonable

counsel will not be afraid in a crisis

so we learn from the past we have to

learn from the past

because ingenious systems can be found

that can surprise the modern engineer

who in many cases realizes that he

discovers

through modern analysis models and all

these

what has discovered hundreds of years

ago there is a lot of hidden knowledge

even in the most poor or humble ones

about the effort of the traditional

builder to save his building

and withstand the forces induced in his

structure with

excellent solutions giving us ideas

for compatible and successful

interventions as you see here

uh drawing of my professor professor

tuladus the effort for

for a one-story building to connect the

walls

or here in in

in another building in roads that before

any calculation or any modeling we have

to understand

what is the structure and we see what

that the builder 300 years ago

realized that he had to connect the wall

that is parallel to the beam because

in an earthquake event it will go out of

plane

so because usually the floor or

um in the roof these beams connect only

the opposite walls not the one

that is parallel to them what he did is

to put little small pieces in order to

collect

connect the last beam to the timber

lacing on this

wall and it's very interesting because i

saw this kind of details in an american

manual that was written

30 40 years ago for a timber structure

exactly the same

idea to connect the last beam to the

timber wall

using these little elements the idea

that the builder had

300 years ago and other manuals too

this structural system are worth

recognized and preserved not only for

theoretical and historical reasons we

don't have to study them just for this

it's because mainly for practical

because their study dictates the

appropriate

interventions for each one avoiding

repairs

and reinforcements incompatible in my

country for many years

they replaced the timber floors and the

timber roofs

with concrete slabs that had a really

really

big problem because we need to establish

a diaphragmatic action for the floors

and the

and the roofs and most importantly

we don't just need that because the

concrete slab can give it

we need to connect this diaphragm with

uh um successfully with the the

marginally average

but we can do this with timber we don't

use concrete we don't need concrete

slabs anymore

we can use plywood we can use other

elements that

can help us increase the diaphragmatic

um

behavior of roofs or timber roofs the

original timber roofs and floors

um and and and

improve the diaphragmatic action but the

most important

is to connect this with with a

super the structure of mushroom that is

under them

we can use the original timber lacings

at this level

if they are rotten we can replace them

if they are

are okay we can reuse them

we can um connect the roof and the floor

on them by screwing by metal

angles whatever is necessary and one

thing more because

all this can move out of the wall all

together

we need to connect also to improve the

connection of this timber layer

lacing with the wall underneath

how can we do it there are very simple

methods

either with steel roads like this ones

you see here

with timber dowels because in this case

in

in roads we were not allowed to use

steel

ones because of uh special reason so why

we used timber dowels to connect the

timber lacing here with the

wall under it or when we don't have

these

timber dowels or steel dowels we can use

a very

simple system putting incorporating

small pieces of timber under the

longitudinal ones

like like there are in in in real

uh timber lacings we usually have the

longitudinal

ones and over the the the transversal

ones in this case we

can can incorporate them under so we

have

a mechanical anchorage without any

sophisticated

steel or other element to connect the

roof

with underneath machinery the historical

structures important or humble ones gain

the respect not only as a part of our

tradition and history

but in strictly engineering terms as

constructions

that survived and worked properly for

many years actually centuries

study then we can discover innovative

earthquake-resistant solutions of the

past that can inspire us

to use them in the future either for

historic buildings that need to be

reinforced and saved or why not for new

structures too

thank you

thank you so much electeria for that

wonderful presentation

with so much details and great graphics

we'll move on to the last presentation

of this webinar series

which will be by randolph langenbach

after teaching architecture at uc

berkeley randall served

as a senior analyst at the federal

emergency management agency fema in

washington dc

in 2003 he was awarded a rome prize

fellowship at the american academy in

rome for his writing about historic

buildings and his photography

his durian room coincided with the 2002

malays

earthquake providing yet another

experience of research and documentation

of extensive damage to historic masonry

buildings

which began already in 1981 with the

mexico city earthquake

randall is the author of many papers and

several books on traditional

construction

he has given lectures and keynote

addresses in many countries around the

world

and in 2015 he was invited by pbs nova

to appear in their tv documentary about

the gorkha

earthquake in nepal landolf welcome

rambo welcome the floor is yours

there okay can you hear me now

yes i can hear you probably oh good

um you're screen sharing like you need

to go in presentation mode i think

um you are sure you are

screen sharing yes i can see your screen

but all the

slides are small yeah no i need to uh

launch it there we go well yes now

go ahead randall yes and uh thank you

uh and uh tim and and to

my colleagues and hello serea i'm

particularly

fascinated by your talk and you'll see

so much overlap and thanks for the

reference

um and i start by simply

saying um i'm i'm proud to be a part of

these three

webinars and to uh close the discussion

i started this work 30 years ago but i

am not a structural engineer

i came at it uh through my

work in heritage which was a training in

britain as

well as the united states and uh

i just show that i've been around the

world to many places and have studied

earthquakes

after they've occurred um starting with

the one in mexico

which happened on my own birthday as did

the one that just happened in

2007 as well ironically

um so i um

start with the place that motivated me

on this subject which was i i was in

india for a year on a fellowship

and and i went to kashmir and i really

sort of discovered its traditional

construction

and a book that i did was later uh

published by unesco

in 2009 and it's available on on

you know in amazon and other sources and

uh

i um elif the rio was just talking about

what in them

kashmir is called talk construction and

i

am actually um the word of being applied

to

as an engineering word was something

that my own publication did because it

was an architectural term

that i had been told and i thought it

was

meant to discuss the structural but

nevertheless dodgy duary is an

interesting word because it's ancient

persian

uh for a patch quilt wall and it's

what in english we call half timber

and it's a single wife of masonry a

single leaf of masonry

confined by timbers but putting the two

together

you have heavy masonry walls below and

by putting

uh as they often did the lighter form of

construction the uh

dodgy dwari on top of the heavier walls

the weight of the superstructure then

helps to hold the

substructure levels how many

which could be several floors from

collapsing

and then here's a very traditional

building and i only show this because

this has sort of become a forgotten

technology

and that people rip out the timbers and

simply

build a brick wall as they do here which

then um usually with cement

uh mortar uh produces a

a rigid section uh you know like a shear

wall in the building where

the flexibility of the surrounding

building is lost

and i show this

because the building on the right was

under demolition

but it shows the construction with the

single life of masonry

what we call an america wife is one

layer and in britain it's called a leaf

i believe and uh i

then take you back to ancient rome

here to show their selenium and

alistaria took us back

thousands of years before to show

the traditional construction with

heavier

timber but that this kind of

construction

existed it was unearthed in herculaneum

in the archaeology and this timber

lacing i show

here is what she was talking about

um is very common for the what's called

in

in srinagar talk and in

pakistan batar construction and

here is a picture that i shot back in

1981

in a building that's long since gone

that was along a canal that they filled

in and turned into a highway

um but you see the timber is in the wall

but notice that the windows are not

lined up

and the piers in between the timbers

are you know have a vertical joint

separating the masonry from the

surrounding masonry such that this

building sort of

almost is working like a frame but that

not the soft story and beneath this

building went through

an earthquake in the 1880s and

it's also a very soft soil site

you know so that the subsidence of film

buildings i think they learned to

reinforce them with timbers

because unreinforced masonry buildings

would not stay together and

apparently in the 1880s there was a

palace that fell down

whereas these rickety tumble down

buildings as it was quote from the 19th

century

uh remains standing and this

on the right here shows that the uh

timber lacing goes through i don't know

whether you can see my cursor when i

wrap it around but there's a cross piece

here just as it was shown in the

examples that electria showed

uh for uh greece but uh

this is an extraordinary picture to show

how the building is held together

and the timber lacing is hidden behind

probably for a weather protection

because there's a

lacing layer just above the window

openings

in this case this is a bearing wall

masonry building this is not

dodgy construction but what's very

interesting

and i oppose this and in my book um

i have a whole two pages about how

the indian building code then has

inserted the requirement that you have

vertical reinforcement

in the corners of these buildings which

in in my opinion

is a big mistake because when you look

at the buildings

uh the um

the um

uh sorry i'm changing so that i

can change the slides by hand here

um the uh here in pakistan

this building is under construction and

if you

had vertical array um you know like uh

reinforced um

rebar uh with concrete around it in the

corners of these buildings

as the building settles over time or

moves or

there's differential settlement it is

uh effectively pulled apart and the

bearing of the mason

the overburden weight of the masonry

which holds this together

with the horizontal reinforcing would be

lost

and i think that's extremely dangerous

then the whole question of diagonals

comes up

of course and here they are training uh

carpenters and

masons in uh in the pakistan side of

kashmir

uh but with diagonal

diagonals in the frame i'll get back to

that a little bit later

because um some one of the most

extraordinary earthquake

damage sites that i visited though are

those in turkey

several earthquakes in a row 1999 a

very large earthquake but the

traditional buildings

um you know when i asked engineers

coming back who had

surveyed it uh when i was at berkeley um

you know did you see the traditional

buildings there they said i didn't i saw

them but i didn't pay any attention

i didn't shoot any pictures i had to get

in

i got an airplane and just headed over

there and yes there were traditional

buildings everywhere and there was

even extraordinary examples like this

where the building had been abandoned

probably for 10 to 20 years

and the back wall had been effectively

stolen all the

masonry taken out for other construction

and the only damage to this building

even though

there were many collapsed concrete

buildings around it

was the holes you see in this picture on

the left and the right

where you see a little bit of rubble on

the floor of the building and there

the proof that the back wall didn't fall

down in the earthquake because there's

no rubble on the ground

behind it so you see it here and

when there was a study done by

engineering

professors in the area in in

turkey the traditional buildings

including unreinforced masonry

are the columns on the right and the

ones

on the left are the reinforced concrete

frame buildings and so the difference in

the performance

is extraordinary traditional buildings

did survive much better than the others

here you see why these buildings

have very soft or weak mortar

with um sometimes under fired masonry

but

with a mud or a lime mortar and then

when they're

plastered over on the inside the outside

you can see

how much movement the wall went through

in the earthquake

and so and what's interesting here is

that

this view i shot through a window

because i didn't have access to the

inside of the building the building had

survived

almost completely intact and yet when i

was there

the buildings behind it which had

collapsed in the earthquake

uh were gone they'd already been uh

demolished and carted away so

but uh i found this uh picture

to show how the performance

was so different and the soft story

collapse of those behind

but then other uh reinforced concrete

frame buildings with what they call

tulip block which is a holoclay tile

brick

that they used throughout turkey for

construction

it's a very brittle material and then

when it's

mortared together with cement mortar

this is the kind of collapse performance

it doesn't help

hold the building up it just simply

participates in its collapse

and a very remarkable picture by

you know a turkish colleague here

showing the collapse uh what had been

that four and a half story

concrete building on the right but the

traditional

building here with a masonry uh lower

floor

and a upper floor of

uh what the turks called humish

construction which is half timber

construction

the only earthquake damage to that

upper floor is the hole you see on the

left

and a little bit of movement around

the masonry elements on the section

below

so i show an earthquake that

happens subsequent to the 1999

earthquakes

further to the west uh in central

anatolia

and here you see the movement of the

elements of the buildings of what

are traditionally constructed buildings

in a farm village

in a remote area outside of ankara

that village is called yuba

and the government sent engineers in and

they all

said these buildings need to be replaced

and they built a new village on

fire up on the on the on the hills

behind

the village itself was down if you can

see my cursor here

down here and the occupants of that

village were

given these uh house houses at a cheap

rate but then i found one that hadn't

been stuccoed and

plastered yet and this construction

is dangerous in an earthquake far more

dangerous with a concrete

slab across the top

over tula blocked with no reinforcement

or if it has reinforcements

it's a steel rebar embedded in it

and uh and also the buildings were

remote from the

village from the river from the barns

where the people keep their animals

and the whole business was just

completely

a mistake but i want to

just mention this the diagonals that

i've

seen of the reconstruction

elements um are often

um in in the in the

proposed reconstructions of buildings

and in in turkey and

in other areas that i've seen but it's

interesting to compare that with the

gaiola construction

and the lisbon earthquake and realize

that an essential difference

the uh hysteresis loop in the study made

of a section of the original

1755 pumblina construction

uh is a very nicely wide

loops here the buildings were six

seven and eight stories high and that

weight on their interior walls with

infill

with even though they have diagonals

would not

burst them they they they it they

performed

well well it was interesting alistaria i

grab screen grabbed one of your pictures

uh but i want to point something out

that you didn't have time to mention

but i'm sure you've followed uh

what's interesting here about diagonals

is they do not go corner to corner

they stop short of the corner almost

like construction

era supports but that in terms

of studies that were done in uh by

romanian engineering professor

[Music]

andrea dutu and her students

uh this allows movement to take place

um in a very subtle way while

still at the same time these panels keep

the wall from

collapsing all together so this

this kind of intersection is better than

corner to corner for diagonals

and what's very interesting is a study

that was done by an arab engineer in

britain

kubele hicklemas whose family originally

is from turkey

did a finite element

model in arab and every time he

runs the video that he did from the

model it would

blow up and i wrote i corresponded with

him

and this is a three-dimensional real

model he did

with engineering professors in peshawar

pakistan

um i suggested he take the diagonals out

well he couldn't um because of the

work he had done to do the modeling but

he shortened them

if they were shortened the most that he

could do

it provided a nicely looped

hysteresis loop whereas absent that

there was it was very

uh strong but very stiff and it would

blow up

from the forces involved and the other

important thing is that

they put an overburdened weight on the

wall

as i mentioned was true for the uh

post 1755 construction that

was done in lisbon

well this diagonals um is a

even comes to 1906 earthquake

uh where they one of their top engineers

who studied the damage afterwards

said that diagonal framing is not

desirable

but i found a very interesting example

in the set 2017 earthquake when i got

inside a very tall

12-story apartment house a

condominium structure in central mexico

city

after that earthquake and the

interior wall had a

non-a diagonal but a structural

subdivision of the wall

of this reinforced concrete construction

and a lot of the buildings did have

diagonals in the walls which were

revealed by the earthquake from

collapses

but the exterior walls of this building

had diagonals

and the diagonals themselves

remained intact but had broken the frame

in the structurally in the corners and

not

collapsed the building but it broke the

frame in the corners such that they are

now demolishing this building and

replacing it

uh they came to that decision and i

switched to this

up in the rural uh pakistan kashmir with

this uh

fellow i ran into when we drove through

there

and the interesting thing to notice

is the um

uh asymmetry of his infill where he's

diagonally his diagonals but

they are not coherent from corner to

corner

i think that this is not an accident i

think that the word

was don't do corner to corner diagonals

and that this

um that this message

has been lost over time and that there's

a belief that

you must do that for structural

strength well um as i will point out

strength is not what one needs for an

earthquake because the earthquakes

are always overwhelming of strength

but it's performance and ductility

and energy dissipation and i'll have

more about that later

but i want to then switch to my

one experience with being on tv with one

of my

um proposed inventions

which is uh called gabian bans and this

is after the nepal earthquake

which we've also heard about in these

this series

um uh from uh bathroom very nicely

um and uh but the rebel stone

construction

here of the school was the

collapsed almost um entirely

all over the place and then the

government was saying you have to build

and reinforce concrete and saying

well excuse me you've got to be kidding

these

um these houses that the gorkha

earthquake

uh affected so much um

were uh where this

were off the road sometimes miles off

the road grid

and the idea of carrying all of the

building materials for a new building

when

all of the building materials for the

collapsed building are on the site

are impossible so i proposed something

which was just simply to wrap it with um

galvanized wire mesh and then i changed

to polypropylene because the galvanizing

was

so badly done that it the galvanized

wire would rust out in certain areas

but here you see the installation of one

of my proposed

gabien vans for the rebuilding of a

house

uh of a family in manku village

way up in the high mountains remote from

the

roads and uh the

idea is to just simply wrap not the

whole building this is not gaming

baskets

but i call them gaming bands because the

whole idea is to not have

the stones inside the wrapped band

where they will wedge together in an

earthquake they have to be just

one layer of stone so that they remain

at rest

and the band delivers its weight to the

wall and then

uh where it turns the corner it holds it

together and this is the

family of the fellow with the shovel

hand on the shovel is the man who will

live in this house and

uh he's a

low-caste hindu and then the

carpenters of the village are helping

them build the house

and this was a later project that i

participated in with the same concept

here it's wrapped with polypropylene uh

geogrid

and uh i the house and manku

here shown you know we were blessed by

the gods with a

rainbow as it was coming to the finish

of the walls

but a a soon-to-be colleague of mine who

was first in nepal as a peace corps

volunteer

years ago with his nepali friends and he

still had from that

experience went back to um

to nepal and built this school building

for uh for the village that they had

come

from using the same technology after

the nova show was broadcast in the u.s

so um i switched now

the conventional wisdom is that

modern frame structures uh of reinforced

concrete are safer than uh

than the traditional buildings well this

is proven actually not to be true and

what's interesting is to start by

showing you one that

a reinforced concrete frame building

that did survive the earthquake in gold

check after the 99 quake

uh whereas so many buildings in that

area

that killed almost 30 000 people largely

were

killed in collapsing concrete buildings

and i

point this one out because this one did

survive

only because it was not finished yet

number one it didn't have the weight of

all the masonry walls for the

subdivision of it into rooms above but

secondly the stiffness from those

masonry walls very often

uh mortared with cement mortar

uh would have made given this building a

soft story collapse almost for sure as

you see here in the magella tower

of istanbul islamabad in pakistan

and the 2005 kashmir earthquake remote

from

kashmir these two of the

this complex of buildings pancaked

uh they were completely finished and

occupied and you see

the car is actually squashed under under

it

of course like so many of these

buildings they were pancake collapsed

i think the term pancake collapse was

invented

uh from the building and reinforced

concrete

in the modern era

then the question is can these

traditional

technologies give us ideas of how to fix

the construction of concrete buildings

so they perform better

and this um my first thinking on this

dates back to 1985 the

earthquake in mexico city which was the

first

earthquake that i uh after moving to

california began studying this as

a subject uh because uh where i came

from in new england

and i studied textile mills that were

six seven eight stories of masonry they

didn't have earthquakes there

but the vibration of the machinery would

vibrate the building for 120 years of

its existing

working life and i got

um i was familiar with

uh masonry buildings that were durable

uh that were big and so i then

looked at uh i went to mexico city after

the 85th quake and i saw this

building under construction at the time

had

collapsed on the left there and on the

opposite side of the street

that where i'm standing looking at that

building

my back is up against this building here

pretty much where that man is sitting on

the curb

and i then turned around and

photographed this former power plant

um abandoned at the time but saw that

it had no visible damage from the

earthquake at all

and then looking further in the same and

the juarez hospital 561

people were killed in the pancake

collapse of this

building but while i was standing

photographing

the it where i was standing

for to take that picture i turned to my

left 90 degrees

and photographed that building it's the

rear of that building the windows are on

the other side

but notice that the floor levels uh

reinforced concrete framework that

they've subdivided

into smaller panels the

walls above between the floors

uh and i so randall sorry to interrupt

very briefly but we need to wrap

up your presentation in let's say two

minutes so we'll still have time for

questions

surgery thank you do my best because i

propose

armature crosswalls and i think that

what's really important here is that the

soft mortar

and the use of diagonal struts that you

must

have weaker mortar than the brick

masonry and here's another example of

the san salvador earthquake

where the impaneling of the masonry

worked and i

showed this before that makes that point

uh so the haiti earthquake is

that's a concrete building that was the

capital building

and uh the uh cathedral collapsed

and when you look at it the rebar is

rusted in most of their concrete

buildings which of course they do

um the uh whereas this building has

hardly ever been written about

and it's impaneled um actually

cast concrete um flat blocks

uh form the impaneling of it

but then if you say that i'm well i'm

against reinforced concrete construction

uh well no but not concrete construction

because here is a building that's 2 000

years old

with a concrete dome and unreinforced

concrete

and this building this ruin has been in

ruins most of its existence and that

roof that you see there is roman

concrete

um so i my last section here

is just to show a revolution in

engineering where

the traditional construction of the

roman era

they the tallest building in the world

at the time the empire state building

is uh masonry exterior

as is the flat iron building and at the

time

these were built the first skyscrapers

in the world

uh 1901 the uh

uh textbook for these uh

it says that there's still no or

approximate values to be given for the

infill masonry

but the masonry here you see the flood

building

in san francisco it went through the

earthquake as you see here

completely burned out such that even

the um some of the interior columns had

expanded such that they were compressed

but

i'll skip that but you see here

the monadnock building is still there

every single one of these steel frame

buildings where masonry cladding

survived the 1906 earthquake

completely burnt out by the fire and

then have been put back into service

and many of them half of two-thirds of

them still exist

today 115 years uh uh

after the earthquake and fire and

when in the 9 11 attack i finally

figured out why

these buildings didn't collapse from the

expansion of the

steel and the interiors because the

exterior was protected by the masonry

that enveloped it

and surrounded it and it was in in

framed with it so the question of why

uh those and not these well i i'm

going to end with a picture of a

mosque with a minaret that rocked back

and forth i'm sure

uh just as elossaria was saying and

a minaret with steel reinforcing in it

was the uh the

concrete was crushed when it rocked back

and forth and collapsed

so i leave you with this final comment

traditional construction resists

earthquake

by not engaging with it

flexibility flexibility and energy

dissipation

not strength is what's important the

same is for

a palm tree which survives

wind hurricanes and the oak trees

and as i've seen a number of times

blown over and destroyed palm trees

a good metaphor for earthquake resistant

construction

when the earthquakes are stronger than

the

design forces for which they're designed

so my email address is there i'd love to

correspond

and thank you very much

wonderful presentation randolph thank

you so much

i would also briefly want to pitch one

of the new books that recently came out

because you briefly discussed

early skyscrapers donald friedman one of

our expert

iscarson members just wrote a book that

was published by the association for

preservation technology called the

structure of

skyscrapers detailing their early

history

i also think randall that your analogy

of um

of the palm tree is wonderful um thank

you panelists for turning on your video

again

um i'd like to take some questions but

first i'd um

like to go back to a point that that

actually all of you in one way or

another alluded to and that's

um the inappropriateness of building

codes

and so i was wondering evan if you could

first

maybe comment on your perspective um

from nepal and then seattle

left area you are on the eurocode 5

committee so you are involved with

writing building codes

and randall if you've made comments

about you know

how they are not um appropriate so

i i think we can have an interesting

discussion there so um

evan you want to start yeah sure so um

one issue that i've i've noticed across

the board of course dealing with these

traditional constructions

is that a lot of building codes are are

more

focused on new construction new

construction materials

based off of research on that matter

but there is not

usually as much in terms of dealing with

the existing

uh vernacular architecture the

varying materials that you see of

especially throughout the

the hill villages in nepal but but also

in the united states with an

unreinforced masonry structures

there's not as much education for

engineers

uh in in these types of uh

situations dealing with the traditional

constructions

so that also leads to not as as many

regulations in the codes for these

things

it's given the energy dissipation that

all three of us have discussed

the more ductile nature of some of these

constructions also it's a lot harder to

calculate

um and really follow exact mode paths as

opposed to

um the homogeneity of concrete and steel

which is easier to put numbers to so um

it the

in order to provide your engineering

proofs

and show that this ductility is uh

is more applicable and and allowable

for some of these buildings and it's not

necessarily meaning that it's not

safe it's harder both from a

engineering numerical standpoint it

takes a lot more

numerical analysis and testing to

get some sort of accurate result

and it's also a matter of being able to

communicate that to the building

officials

and show them that even though this

doesn't

follow the main guidelines outlined

in new construction this is actually per

engineering judgment

uh something that we we could be okay to

live with a lot of things in uh building

codes in

here in the states as well are

prescriptive measures that

um have one intent for

say secondary columns um where you have

trusses bearing on unreinforced masonry

piers

if you do a full building retrofit that

is not

quite as applicable

as opposed to the existing condition

so it's just a better understanding of

the traditional methods would really

help

both the building officials and the

engineers um

justify and work with existing

structures

thank you very much lefteria what are

your perspectives also as a

as someone involved in writing the

building codes

does this come up in these meetings i'm

curious yes

actually yes and now in europe

there is a new code

is going to be new code for existing

buildings i think it's understood that

we have a very big gap

on this part and we have to feel it

uh and even now we in eurocode 8 which

is about earthquakes

there is a part on eurocode 8

about existing buildings concerning

earthquake

and for concrete for steel for timber

it is written now now so in 2-3 years it

will

come up and also i know there is a new

code in europe is going to be there is a

big

discussion and big demand of course on

existing

buildings not just for earthquake for

general so we

we need to do that but before we go to

codes

i would like to comment that as i told

you i'm a structural engineer

but i i i work many many years with

architects and i teach in architecture

and i learned

and from my education and also from

practice that before any calculation

before

any modeling we have to understand the

structure and this is a very big

problem because we can modalize the

wrong structure

even for the simplest building i have

some examples concerning roofs

for example this kind of roofs that

i didn't mention my presentation about

post and beam rooms very

common in our area which are uh in many

cases i realized that was

modernized completely wrong from our

colleagues

and it gave a completely wrong

impression so the first thing

is the civil engineer to go together

with the architect on site

and understand the structure and then go

to his office and use the computer and

the model

and then okay it is important to know

the standards too

but the the biggest danger is the other

thing

and one of the big i think the most

important for the calibration of our

models

is the pathology one thing is to

understand

the structural system and the other

thing is to understand the pathology

we have the pathology has to calibrate

our models our models has to show

the pathology of the structure if they

don't

it's the models are wrong so

so we have to to to think about it and

the standards is the last thing i think

on this of course as a civil engineers

we need

we need that especially the ones who are

who

of us that are working in on on these

topics and restoration

is very difficult also in my in my

country because we have nothing

we have very few things to to think what

is the material what is the strength

how is connected together how we many

many

uncertainties and for this the

scientific community

has to to to work a lot and

help us and the last thing that i would

like to say is education

that especially civil engineers in

most of our in many countries are not

educated in calculating not calculating

understanding and calculating the the

existing structure

and um of course because architects

it is a big part of their education but

not civil engineers

first to to to respect and understand

this kind of structures because it needs

a special mentality to to work with this

and the first is the respect

and think that we don't know everything

they knew a lot of things

before and second is

how in our universities are going to

introduce courses for end civil

engineers

for for the existing buildings

vernacular and monuments to not only

monuments vernacular too

i think you're spot on there left area

and that's also one of the reasons why

we're doing these webinars

um of course so so i'm thank you for for

bringing that up and clarifying that

uh randolph do you want to have a few

last words on um

quotes and traditional construction or

the lack thereof or their

inappropriateness

um yes i i think it's very interesting

to

take a look at the california building

code because they

they did introduce a code for

historic structures they don't

necessarily have to be on the designated

list

of accepted heritage structures but they

have to

you know qualify for it in effect

and the value of that code is it allows

the engineers

free reign to make a proposal they don't

have to

follow the code and so much of the

trouble

uh with applying in in the us in

particular i think

and i think also eurocode 8

that the codes are for new construction

and so then when there's a complete

retrofit

um you have to bring the building quote

uh quote up to code uh

and then these buildings don't lend

themselves to that because

certainly masonry is then just treated

as dead weight

it's not given a structural

performance level analysis that

where it participates as i have tried to

show

in the short talk

where the masonry itself is

a a major part of what should be seen as

a code conforming

and i say this in the context of

reinforced concrete because

the idea that somehow it's subordinate

to the reinforced concrete frame and

that should be treated as dead weight

is wrong when it comes to earthquakes um

for two reasons one is that the force

level that uh is in the code for

earthquake um lateral strength and all

of that is

is reduced because they discovered that

if they

uh apply in linear elastic analysis

for beyond code level

earthquakes that nobody would be able to

afford building a building that would

only be applied to nuclear power plants

and to immediate occupancy buildings

like hospitals

and then all other buildings are have a

reduced code levels

and a linear elastic analysis approach

to code conforming design well it's

the buildings are beyond elastic limit

if you then have a real earthquake

at the design level

of the earthquakes not reduced in force

level

and then so the the

role of the masonry infill and all of

that has to be a part of the calculation

i mean that you know and and when i was

in nepal

and where are your calculations it was

uh

chaturbathra said where where are the

calculations when i was trying to

convince them that the uh

gaming ban was a good idea for uh

reconstructing rural houses and and so

the um the the the

coming up with a way of analyzing the

role of the masonry not as a subordinate

or a separate material

because then of course it's just dead

weight or it's uh

the lateral forces you apply to it are

not

integrated together with the uh in

framing so

so uh confined masonry

the term confined masonry is probably

the best

analysis for something like the uh

dodgy construction or mush construction

but

but it the the confined

masonry approaches are limiting when

you want to turn to heritage structures

and

and deal with them particularly with

timber framing and whatnot like that so

i think that that's uh important these

are

important considerations and we need to

work towards

getting them into the code so that

people are not

frightened away from doing the

structures by being told their

building is not code conforming i think

those are great points and i think we're

all in agreement probably

at least the people here coming to this

webinar linear elastic analysis is not

the way to go for the type

of buildings that we have been

discussing through these three webinars

anyway i want to move on to another

topic and this is

probably the last question we can take

because of time constraints

but there were several questions um

about

the timber and the masonry interaction

timber connections and the

deterioration so could any of you maybe

speak about

um the connections between the timber

elements the connections to the masonry

and

uh their longevity because evan for

example you spoke about

deterioration robbing randolph you

mentioned

um setting the timber back in the

masonry to give more weather protection

i think people want to hear about that

i i can do it

so various things with the timber and

masonry um was it was a big player uh

in the heritage sites that i was working

in in nepal

one thing that we

did a rising damp is a large issue as

well

um in these types of structures so uh

they were

typically raised up on stones

above the plinth um and set onto those

um in areas where there was

um lower grade wood of course there was

a structural wood which was pine

um which was more uh was less

rot resistant but those

interfaces between timber and masonry

closer to the ground we we use copper

sheeting

which was a traditional method of

of keeping the rising damp out of lower

portions of wood where it was

interfaced with masonry so that was one

item there the typical overhangs of

these large roofs were meant

to protect the the wood connections uh

from from rot there but

one of the the biggest issues that we

were seeing the timber connections

the timber lacing on a lot of these

walls um

which was set um towards the top uh

at each floor wasn't always continuous

uh the the buildings that behaved uh

better

were able to have the exterior top plate

and interior top plate

um were connected through the wall um

and that was that allowed continuity as

i've seen in some of the presentations

around the corners

also the uh the wall ties

going to these top plates had pegs um

that were hammered in through the wall

ties um and

areas where these had deteriorated the

the traditional method for these was to

take them out when they're deteriorated

and put new ones in

and just keep that maintenance and where

those areas

where they were deteriorated or were not

properly secured

was where we saw the most movement and

the the most failure of those

uh timber connections great thanks evan

alefteria you have um do you want me to

speak to let's go to lefteria

first and then very briefly randolph and

then we'll wrap up the webinar

all right thank you hello

yes thank you there is always the

problem with wrote

with timber especially when it is

incorporated in machinery

concerning or in areas that cannot be

ventilated

and the water is trapped for example the

part of the roof that

gets in masonry but for these cases

there are now a lot of methods for

locally replaced timber with a new

timber etc the problem is

with the timber reinforcements in

machining which is very difficult

to replace or to do something when it is

inside you cannot see what is the

condition or you cannot take them out

and you cannot put another one easily

inside

only if it is at the external part of

the wall

when it is in hidden in the wall it's

very very difficult so it's

one of the most difficult cases of

restoration now the one that was the

strength of the mushroom before

now it is a weak point because we we

find gaps in the place of these

timber lacings and what do we have to do

in most cases unfortunately you cannot

put a new timber in the old

gap it's almost impossible but you can

either groot it or use steel elements

and replace

the the the the function of the original

timber frame

timber time with other

exterior or internal usually steel

elements

and of course it depends on the

species of timber that there are in the

wall if it is durable

we can still find it in other cases no

thank you randolph final comment um

yes i agree with all of these uh

statements what i found interesting is

how many buildings have the

timbers visible on the exterior i showed

one example

there wasn't where i mentioned it but

the

the timbers that are visible of course

the long

timbers that are on the uh

exterior and interior sides of the

masonry wall

are then visible and they can be seen if

they're rotting

and and in effect many masonry walls are

thick enough such that they can be taken

out and replaced or

parts of them replaced and also the

thing to bear in mind is

the um in the solid wall um

bearing ball building systems with the

uh horizontal timbers

only horizontal timbers the timber

framing the the

bands that go around the building um

are uh elevated some um

very often above where the rising damp

would be

and they're not touching the ground

there's not a sill plate for these

buildings and masonry does that

such that the masonry walls can remain

intact while a repair is done you don't

have to

demolish the walls to get the timbers

out and the crossover timbers

uh in effect can be left behind

and new ones uh drilled in or

put in depending on the technology that

you're working with

in the era that this is done but then

that in the modern area you could

uh drill through and connect the front

and the back timber with the cross

pieces

so i think it's um

it's good to try to reconstruct as even

i think

you have done and i know very well about

time square because i

i studied that very much myself too but

i it didn't

make it i've mean deliberately didn't

make it go into my talk because

the time limit and that i uh but i

was very interested because there were

uh

rotted timbers in the palace itself that

led to

a reconstruction of the exterior and the

whole wall was leaning when i was there

and

and that wall that was leaning was a

reconstruction

after the 1934 earthquake

in the earlier uh construction

was in many ways a more durable form of

construction than the

uh than the reconstructed wall of the

nineteen thirty fourth because i

remember that so with that i i

closed my comment and uh and my um

my uh uh happiness with uh sharing the

podium with alexaria um

a dear colleague and with eva uh

you as well within nepal

and then to get to know you tim

thank you randolph and thank you

everyone for

speakers for um sharing your work again

thank you all the attendees everyone who

asked questions who

engaged in a chat we really appreciated

to make these webinars lively

this also concludes our third webinar on

traditional

architecture and earthquakes we will

also post this

webinar on youtube again so you can

re-watch it

you can contact us at iskarsa gmail.com

if you have further questions

and then finally please note that

on april 29th we will have another

webinar

hosted by chola akintunde on

authenticity and reconstruction thank

you very much everyone

and bye bye thank you everybody

happy nepali new year to the nepali

friends out there

bye