Mud wall construction in Spiti Valley

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Mud wall construction in Spiti Valley (Himachal Pradesh)

World Housing Encyclopedia
Earthquake Engineering Research Institute (EERI) and International Association for Earthquake Engineering
Report # 171
Report Date O5»O8-2012 Country INDIA
Housing Type Adobe / Earthen House
Housing Sub-Type Adobe / Earthen House: Rammed earth/Pise construction
Authors Ankita Sood, Aditya Rahul, Yogendra Singh, Dominik H. Lang

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This encyclopedia contains information contributed by various earthquake engineering professionals
around the World. All opinions, findings, conclusions & recommendations expressed herein are those
of the various participants, and do not necessarily reflect the views of the Earthquake Engineering
Research Institute, the International Association for Earthquake Engineering, the Engineering
Information Foundation, ]ohn A. Martin & Associates, Inc. or the participants’ organizations.

This report describes a building type found in Himachal Pradesh, a northern state in India. It is
concentrated in the upper reaches of the state in the Lahaul and Spiti districts, which are located in a
cold-desert area with very hot days and chilling nights. Precipitation usually only occurs in the form
of snowfall with almost no to very little rainfall. This dryness of the local climate is reflected in the
architecture of this construction typology which consists of thick mud Walls with small openings in
order to insulate the interior from the harsh outside climate. This style of construction which is
predominantly used for residential houses and temples is still being practiced though it shows high
seismic vulnerability.
1. General Information
Buildings of this construction type can be found in the Spiti river valley of the districts Lahaul and Spiti, in the state of Himachal Pradesh (Figure 1, Figure 2). As a specific term has not yet been coined for these houses, it was decided to name this construction type ‘Spitian architecture’. The addressed region is a desert a.tea Where timber is scarce and mud is the main locally available construction material. The addressed buildings are therefore made of rammed earthen walls and timber is solely used for floors and roofs as Well as for door and window frames. Natural stones are also scarce and are thus only used for foundations. This type of housing construction is cornrnonly found in both rural and sub—urban areas.
This construction type has been in practice for more than 200 years.

Currently, this type of construction is being built. The earliest good example is an 800 year—old Kii gompa (monastery) in the village Kii (Figure 3). This type of construction is still the main construction typology in the area. Figure 1. Typical Spitian mud house of Z storeys.
Figure 2. Location of the investigation area in Lahaul and Spici districts of state Himachal Pradesh, northern India.
Figure 3. View of Kii monastry in village Kii in Lahaul and Spiri district of Himachzl Pradesh.

2. Architectural Aspects
2.1 Siting
These buildings are typically found on both sloped and hilly terrain. They do not share common walls with adjacent buildings. Houses in the valley are built on flat lands while those on slopes and ridges are located on flat plateaus that are artificially cut into the topographical feature. In the Spiti river valley, the village Lossar is characterized by an entirely flat topography (Figure 4) whereas the village Kibber is located on slopes (Figure 5 and Figure 6). When separated from adjacent buildings, the typical distance from a neighboring building is a minimum of 0.3 meters.

2.2 Building Configuration
The houses are generally recmngular in plan Without any veranda.h. A typical house is of two to three storeys with the lower storey used for cattle and the upper storey(s) for the family, Openings are generally of small size. In some cases, skylights are provided in the roof in order to provide natural light to the interior corridors and staircases (Figure 7 and Figure 8).

2.3 Functional Planning
The main function of this building typology is a single—farnily house. In a typical building of this type, there are no elevators and no fire-protected exit staircases. The typical building has generally one door other than the main entrance door which can be considered as an escape route at the buildings rear. On contoured sites, these doors may be located at different levels (Figure 9).

2.4 Modification to Building
lt is assumed that buildings of Spitian architecture were designed and constructed under the influence of one particular architectural school that prioritized human comfort in the harsh Weather conditions While being constricted to using locally available materials. In recent nmes, various experiments of construction using conventional building materials (bricks) have failed as these materials do not provide the advanmges with respect to insulation (both during Winter and during summer) as mud. However, more contemporary materials have found their way into many Spitian houses, e.g. pre-cast RC lintels (Figure 10) which replace wooden lintels. The small openato-sky-and-sun bath spaces (Figure 11) were recently replaced by enclosed winter gardens with large glass windows. A new variant can also be found in some
places where single RC columns and beams are arranged (Figure 12).

Figure 4. Houses located on flat topography in the village

Figure 5. Houses located on slopes. Figure 6. Houses built on lwilly slopes in the village Kibber.

Figure 7. Sky-light as seen from terrace. Figure 8. Light pouring in through sky-light above.

Figure 9. Doors at different lcvels. Figure 10. Precast RC limcls in a new constructiun.

Figure 11. A small open-to-sky sun bath space at first floor level
of an older house.
3. Structural Details
3.1 Structural System
Figure 12. RC framed structure with mud Walls infill and rnucl
[Matécial rm; :41 |5\’nh€§pi$t’
Rubble Stone (mu stonc) in mud/llmc mortar nr without
mortar (usually with timber roof)
Stone Masonry
l2 |D1@s§@d stone nnilsonxy (in lime/cement mom!)
ls lMud walls
l4 |Mu<| walls with horizontal Wood clcmznts
Ad<>be/ Earthen Walls
ls lAdobe block Walls
la |Rmm¢d earth/Puss constmcuon
lv ‘Buck masonry m mud/Lime mortar
Umeinfomd “mom? ls |Bn¢1< masonry m mud/Lime mortar with vmml posts
alls . .
“’ 9 nck masonry m llmc/cement mun“
l10 |cQn¢<¢m black masonry in cement mortar
ln |c|@y bnck/rile rr\as0m’y,Witl1 Wooden posts and beams
Clay brick masonry, with concrete posts/tic columns
Confined masonry and hams
hs ‘Concrete blocks, u’¢ columns and beams
l14 |smn¢ mnsnnry ln ccmcnl mortar
Reinforced masonry l15 |Clay bnck masonry 1n cement mortar
lm ‘Concrete block masonry in cement x-norm:

‘Marcia! |’l‘y-11: nf Imd-Bearing Stnwmte ‘$1 |S\ihtypen {Most appimprizte type
‘17 ‘Flat slab SI‘r\1C\f\.\r€ El
‘is ‘l)CSlg.\1C(‘l for gravity loads Only,Wlth URM ll1fil.lVJ2.|.lS II]
Xn”r:‘s°“‘ ‘°*“““g ‘19 ‘DCSlgflCd for sclsmlc effects, with L‘RMinfil1\va]ls [I
Designed rut seismic effects, with structural infill walls [I
‘21 ‘Dual system – Frame with Shear wall \:\
‘22 ‘Moment frame with in-Sl[\l Shear walls [I
Structural concrete Structural wall
‘23 ‘l\1iOmCD[ (mic with precast shear walls lj
‘24 ‘Moment frflmé El
‘zs ‘Prcstrcssed moment mimewmi shear walls [I
Precast C<>ncrCti: ‘Z6 ‘Large panel precast walls El
‘21 ‘Shear wall structure with walls cast’in~situ [I
‘zs ‘Shear wall structure with precast wall panel structure [1
‘29 ‘Wiui brick tnzsflnty p2(ElL\K)l’15 [I
M m nt~r sisun ,. . .
fifmc“ e 5 ‘an ‘V/ilhcasLAn»5|!\1c0ncrctcW2\ll5 [I
‘31 ‘With lightweight parliflons |:|
Steel ‘$2 ‘Concentric connections in all panels |f_|
raced frame
‘as |12¢¢¢iitti¢ C0nnCCtl0nS lfl H few panels [I
‘$4 ‘Bolted plate lj
Structural wall
‘ss ‘Welded plate \:\
‘so ‘matcii \:\
‘av ‘\m1.< With bamboo/reed mesh and post (\Wartlc and Daub) [I ‘38 ‘Ii/iasonry with horizontal beams / planks at intermediate U €V€lS b I nad~bearing timber _ Tlm CY fume ‘39 ‘Post and beam frame (H0 special C0l”Ll’l€CL\()Il5) [I ‘4n ‘mind time (with special COHHCCUOHS) {:1 ‘41 ‘Stud-wall ffélmt with plywood/gypsum l)0’a\’Ki sheathing [1 ‘42 ‘Wooden panel walls |:| ‘43 ‘Building protected with basc—is0lat|0n systems |:| Seismic protection systems Othcr ‘44 ‘Building protected with sclsmlc dixlhptfi [I ‘Hybrid systems ‘45 ‘othcr (dcscnbcd below) [1 3.2 Gravity Load-Resisting System The verdcal loaclaresisting system is earthen walls. The vertical load~resisting system consists of 300 ~ 500 mm wide walls made of rammed earth resting on a foundation base made of undressed field stones with mud mortar. 3.3 Lateral Load-Resisting System The lateral l0ad—resisting system is earthen Walls. The same 300 — 500 rnm wide walls made of rammed earth, which are basically constructed to rcsist the gravity load, also constitute the lateral load resisting system. The walls have practically no tensile strength and very little shear strength resulting in extremely poor inaplane and OI.1t~Of—pl2nE: resistance against lateral loads. 3.4 Building Dimensions The typical plan dimensions of these buildings are: lengths between 8 and 12 meters, and widths between 3 and 10 meters. The building has 2 to 3 storeys. The typical span of the r0ofing/ flooring system is smaller or equal to 4 meters The typical storey height in such buildings is 2.5 meters. The typical structural wall density is more than 2O % 3.5 Floor and Roof System ‘Material Description of flab!/mofsystein ‘Moat appropriate flour ‘M051 approptlitt ruof Masonry ‘Vaulted ‘Cnrnpnsltc system of cnncrcte ‘olsts and masonry panels Structural concrete ‘Solid slabs (cast—in—p|ace) ‘Wafflc slabs (cL\st—ln—pl.1cc) ‘Flat slabs (cast—in—placc) ‘Precast joist system ‘Hollow core slab (precast) ‘Solid slabs (precast) ‘Beams and planks (precast) with concrete topping (c:isl—in—sil:u) ‘Slabs (posmcnsionedj ‘Stccl ‘Composite steel deck with concrete slab (casl—m—situ) Timber ‘Rammed earth with ballast and concrete or plaster finishing beluga planks or beams with ballast and concrete or plaster finishing “I’hat:hed roofsupportecl DD wood purljns ‘xlsod shingle roof ‘xlclmsl planks or beams that support clay lziles ‘Wood planks or beams supporting natural sroncs slates ‘Wood planks or beams that support slate, metal, asl>cst0s—ccmcnt or plastic
‘corrugated sheets or Llles
“nod plank, plywood or mznufactuzecl wood panels on joists supported by
cams or walls
‘Described below

3.6 Foundation
lT7pe lD:,:cdpwim-i
W flrpwnfim we
‘Wall or column embedded in soil, without footing
‘Rubble Stflflti, ficldstonc isolated footing
‘Rubble stone, fieldstone stztip footing
Shallow foundation lReinfi)rced-concrete isolated footing
Rcinfnrccdecnncrttc strip {mung
‘Mat foundation
‘No foundation
Deep foundation
|Rc1nforccd—concrct€ hearing piles
IRcinf0rccd—concrctc skin fricnon piles
Steel beating piles
Steel skin friction piles
xvma piles
Cast—in—place concrete piers
loam IDcscnbeil below
Locally available stone is used for foundation. A trench is dug about 300 rnrn in depth and 500 mm in width. Courses of
stones with mud mortar are then laid in the trench up to the ground level. The same courses are then taken up to 600 to
900 mm above the ground in order to form the lower portion of the Walls. Through this procedure the Walls are
protected from direct rain water splashes ancl snow. Generally, there is no plinth in these houses (Figure 13).
Figure 13. Lower portion of the wall made up of field stones. The front door is arranged at ground floor level Without any plinth.

‘Income class llvlost appropriate type
la) very low-inconlc class (very poo!) Z
lb) l0\v~inC0me @1255 (poor) Z
lo niiddloincome class Z
4. Socio-Economic Aspects
4.1 Number of Housing Units and Inhabitants
Each building typically has 1 housing unit. Generally, the building is occupied by one family only. The number of
inhabitants in a building during the day or business hours is less than 5. The number of inhabitants during the evening
and night is 5—1O. These numbers apply to the summer months. During winters, the number of inhabitants in a building
during the clay and during the night is less than five as the young people move to other places, mainly Delhi and Goa, for
4.2 Patterns of Occupancy
In large houses, the ground floor is generally used for cattle or as storage space. The first floor has a iiving/ prayer room,
1 or 2 bedrooms, a kitchen and a toilet. In houses with three storeys, the entire top floor is used as a prayer room. The
occupancy pattern changes in winters, when the inhabitants also move to the cozy ground floor. Houses have a small
front yard (Figure 14) for household chores and to keep the cattle (yaks).
4.3 Economic Level of Inhabitants
la) l1igl1—incornc class (nth) Z
limit» ofhousing unit price to annual income [Most appropriate type l
‘+1 | Z l
‘ .
5:1 or Wm [I
1=1 or better [1
‘Khumn Z of financing for on appmpfim we
()\vne! financed Z
lvnnnnal Savings Z l
llnformal network: Friends and relatives Z
lsnnu lending institutions / micrrvfinance insumtion lj l
‘Commercial banks/mortgages |j
‘Employers [1
Investment pools [1
Government-owned housing [1
cmnnannnnn (explain below) I 1]
other (explain hclow) [1
In each housing unit, there is 1 bathroom Without toilet and 1 toilet only.
The toilets are a dry type and are always located on the first floor While the septic tank is located at ground level. The
septic tank has a small opening in the outside for periodic cleaning (Figure 15). The opening is packed again and again
with dry stones (Figure 16).

4.4 Ownership
The type of ownership or occupancy is individual ownership.
yptufwmeralmipot i
Fimw A Wmmmwe
\ \ w
‘Outright ownership [1
‘Ownership wizh debt (mortgage or 011167) El
‘Individual ownership Z
\0wnmmp by 21 group or P001 of persons [I
‘L0ng—tcn’n lease El
‘mm (explain below) [1
Figure 14. Typical front yard. Figure 15. Over-ground septic tank’s opening can be
seen at ground floor level.
K3-3i ,
Figure 16. Septic tank’s opening closed with dry stone packing.

5. Seismic Vulnerability
5.1 Structural and Architectural Features
iMOBC appropriate type
True False N / A
Lateral lnad path
Thc stttiettate contains a cornplctc load path tnt scismlc tntee etteets ttnnt ant
horizontal direction that sewes to transfer inertial forces from the building to the
llatailding Configutzllun
iThc building is regular with regards [O both the plan and the elevation.
Roof construction
The roof diaphragin is considered to be rigid and lt is expected that the roof
structure will maintain its intcgnty, i.e. shape and form, during an earthquake of
intensity expected in this atea.
El Z U
Floor construction
The floor tliaphragm(s) are considered to be rigid and it is espeeted that the floor
st:tuctu:te(s) will maintain its integrity during an earthquake of intensity expected
in this area.
Cl Z U
Fntindatinn performance
There is no evidence of excessive foundation movement (e.g. settlement) that
w<>i.ikl affect the integrity or pttttaitnanee of the structure in an carthq uakc,
\X’all and frame structures — redundancy
The nttttihet ntlines ofwalls or ttanaes in each principal tiltcclion is greater than
or equal to 2.
Wall Prupotiilunfi
lilfeighttto-thickness tatififihe shear walls at each tlnnt level 15:
Less than 25 (concrete walls); Less than so (reinforced masorir) walls); Less than
13 (unrclnforccd masonry walls);
El U Z
Foundal:|oi1—wall connecnon
Vertical l0atl—bca.t1ng clcrrlcnts (columns, walls) arc attachctl to the foundations;
concrete columns and walls arc rlowclctl into the foundation.
Walltroof connccnuns
Extctlot walls arc anchotccl tnt outsofsplanc scismic etteets at cach diaphragm
level with inetal anchors OI straps
Cl Z U
wall openings
The total width of door and window openings in a wall is:
For brick masorlr) construction in ccmcnt mortar : less than ‘/1 of the distance
bctwccn the a<l]accnt U055 walls: For atlobc m{150nry, stonc ttiasnnty anti brick masonry in mud mortar: less than l/3 of the distance between the adjacent cross walls; For precast concrete wall structures: lcss than 3/4 of the length ofa iperimeter wall. Z U U Quality tit building ntatetiais Egtiality tttlstiilding inatcrials is considered ttt be adequate per the teqtiitentents tit national cticlcs and standards (an estimate). III Z U Quality ofworlimansllip Quality 0f\vt)rkmansl’lip (based nti vistial insptetinn offcw typical builtlings) is considered in he good (pet local constmction stantiatdsi. El Z El Maintenance Buildings nt this type arc generally wcll maintained and thcrc ate nn visible signs ntdetetintatinn ofbuilcling elements (concrete, steel, Llinltiet) El Z U 5.2 Seismic Features Sttuctu l . amen? Seismic Deficiency Eanltqtaake esilient iFeatutes artbqualre Dru-nage Patterns Wan lThc walls arc naade ofrarnrncd tatth which has very l.lttlc L sheat and hending strength. The flexible tlndts and tttnrs are alsn simply testing over the walls. In sntht cases Opening si/cs ate also qttite large. Not known during any past earthquake. siit it is expected that the walls will fail in out—of—plane action. Roof and Floors ‘Roof and floors arc matlc ofwoodcn girders, without any st bracing or mcasutt: to prevent the relative movement. cxpcctetl that thc wooden at tlnnts/tnnt. wit known during any past earthquake, Bttt it is girders will movc tclativc to each Other and relative [0 walls, resulting in the collapse 5.3 Overall Seismic Vulnerability Rating Thc overall rating of the seismic vulnerability of the housing typc is A: HIGH VULNER/JBILITY (/12., 1/eyypaur reirmzr pejormanre), the lower bound (i.e., the Worst possible) is A: HIGH VULNERABILITY (i.e., very poor seismic performance), and the upper bound (i.e., the best possible) is /l.’ HIGH l/ULNERABILITY (La, 1223/ poor reirmzr peifamzrmre). I” I QT QT Q.” l Vulnerability High l medium-high medium nledinm»low low very low l very poor poor moderate good very good excellent l F 1 U l Vulnerability Class 5.4 History of Past Earthquakes ‘Dar: lEpicen|er, region ‘Magnitude Imensity ltsss ‘Kashmir \> MW’ 1.0 l
lino lKumaun l> M 8.0 l
l 1203 l(;m~h31 ‘MW sm l
ltsss lShnt-ngar (Kashrntr) lmw as l
lioos l1 l1974 ll’attan lMw 5.2 l
lwst lKarakorarn, om, Tartgir, Khanbari valleys lm 6.2 l
l1991 jiimtmht (Uztarakhancl) ‘MW as, mb (,1 (nvtn), Ms 7.1 (USGS) ll (MMI) = vm
liwv l(Ihamol1 (Ghatwal region) lMw 6.4, Ms (ts, ml as (mo), ms as (USGS) ll (mu) = VIII
lzoos lhllizzafarabad (Kashmir) [MW 7.6 h to XII \
References: Hicyilrnaz el a/. (2012), Rautela el al (2009)
Comment on structural vulnerabilig: The structural configuration of these buildings is quite regular. Further, these
buildings have a complete and direct load path in the form of thick mucl Walls. The main source of deficiency in these
buildings lies in their main construction material, i.e. rammed earth, which has poor in-plane and out-of-plane resistance
against lateral loads. The geographical area, Which is characterized by very difficult geo—environrnental conditions, has a
scarcity of any other construction material. At the same time, the region is remotely located and not well connected with
the mainland, making the transportation of better (in terms of more seismically resilient) construction materials very
difficult and costly. The flexible roof system also adds to the vulnerability as it provides no lateral restraint to the Walls in
the out-of-plane direction. As a result, the walls act as vertical cantilevers above the foundation, and are highly prone to
failure in out—of~plane action. Nevertheless, the seismic vulnerability could be significantly reduced by using some simple
strengthening measures which would involve the use of a little amount of timber in the walls and bracing of the roof

6. Construction
6.1 Building Materials
Structural element Building material Characteristic strength Mix proportions / dimensions Comments
\‘(‘alls Locally available mud No standard values a\ ailable. No measurements available.
Founrlaiion Field stones Not possible to he obtained.
Frames (hcams at COlumns] 1\‘,\
Roofand llt\or(<) wmi, mull \X”oo0den ties can be located at roof, llntel and sill levels On both sides of the
Walls [O support them In 0u{—0f—Pl’tii‘|li action (Figure 25). The corners of walls flfld ]t)lfll$ Of girders With vertical posts Cflfl also be
strengthened using diagonal bracings. This provides a rcsilicnt alternative system to fCSlS( vertical and lateral loads in the form of
the W00 Flexible mot/tletii system The mfllfl cause hi damage to 5\1Cl\ itihr and floor systems is the relarivc movement between the mam gl\’<l€f5, This relative
l”flO\’Cl”flCfll Cflfl be rCS[(lC[Cd by pi’O\’lCllng l”lOi’l7.t)n[nl l7i’flCing ih the plsiie hr the ceiling, l\”l[CICOflflCCllflg the g‘lrdCl’S (Figure 26).

Strengthening of New Construction:
Seismic Deficiency Description of Seismic Strengthening provisions used
Low iirplane and 0ul—Of—pl&:\n1: Indian code IS 13821 = ms suggest: Simple imam to improve the selarmt resistance Ormua Walls. These are “mint to those
strength ofdr) Stunt’ \\’Bll5 ‘described above nit existing buildings and consist tie <1) wooden bands In WL»\llS at Imtcl and routluicl, (ll) pillars/buttresses DJ
M11 iunetions, (HI) <i!flgO|1fll bracing in comers, (IV) reinforcement ofmud walls using cane, bamboo, I)!‘ tirnbet.
Flexible mi/n<»i>r system Flexible roofs and floors MC I0 he provided with Lllagonul braemgs as pt!’ IS mas 1 2009 (Figure 25>.
Lack of anchorage of roof with Indian code IS 1382″ : 1993 suggests Ci)nnCCli()n of roof girders with the roof band, which in turn is connected with the di>nr and
walls ‘WmLlO\V frames,
Indian standard IS 13827 : 1993 provides some simple measures for improving seismic resistance of earthen buildings. A
large sample of existing buildings in the region was surveyed during this study. However, no strengthening or retrofitting
measures could be observed in any of these buildings.
8.2 Seismic Strengthening Adopted
Ha; xeiymiz 5/renlg//Jening dmrihed in //le a/love /a/1/P heenperjbrmerl in derign am] i’0n§/mzlianpraztire, and :0, /0 112/14! exlenl?
No case of strengthening of such buildings was observed during an extensive survey of the study area.
8.3 Construction and Performance of Seismic Strengthening
Wax t/J0 mn.rtr~14rliw1 i/at/rerted in t/ye Jamt manner as l//e mu» ronrtrurlian?
The strengthening measures suggested above are mainly based on Indian standards IS 13827:1993 and IS 13935 : Z009.
The same (or any other strengthening measures) have not been ohserved in practice, and therefore no information about
their performance during past earthquakes is available.
hmamm andwill
mars»-u uwlvezled
i umn am
vmsal battens
um: Band
Figure 25. Retrofitting details for the walls.
< _ moumm Dligom Figure 26. Retrofitting details for the roofi References I. Indian Standard, Improving Earthquake Resistance of Earthen Buildings – Guidelines. IS 13827: 1993. Bureau nFInclian Standards (BIS), New Delhi, October 1993 (reaffirmed I998), 20 pp. Z. Dhajji Dewari. I-Iicyilmaz, K., Botl1ara,]., and Stephenson, M. (2012). Report no. 146, World IIousing Encyclopedia, Earthquake Engineering Research Institute, United States. 3. Timber—reinforeed Stone Masonry (Kori Banal Architecture) oFUttarakhand and Himaehal Pradesh, Northern India. Rautela, P., Girish, ]., Singh, Y., and Lang, D.I I. (Z009). Report no. 150, \3Vorld Housing Encyclopedia, Earthquake Engineering Research Institute, United States. 4. Indian Standard, Repair and Strengthening of Masonry Building — Guidelines. IS 13935 : Z009. Bureau ofIndian Standards (BIS), New Delhi. Authors I. Ankita Sood MURP student, Department of Architecture and Planning, Indian Institute of Technology Roorkee (IITR), Roorkee 247667, INDIA Email: ankita.sood87’ Qgrgaihom Z. Aditya Rahul M.Arch. student, Department of Architecture and Planning, Indian Institute of Technology Rnorkee (IITR), Roorkee 247667, INDIA Email: aditrahul algigaiicnm 3. Yogendra Singh Professor, Dept. of Earthquake Engineering, Indian Institute ofTcchnologq* Ruorkcc, Roorkcc 247 (>67, INDIA
Email: yngenfer a>
4. Dominik II. Lang
Senior Research Engineer, NORSAR, Kieller Z027, N()R\‘(/AY
Email: duminik tiinorsannu
1. Qaisar Ali
Professor, Civii Engineering Department, UET Peshawar, Peshawar, Pakistan
Email: drgaisarali @n\