Analysis of Some Building Damage Phenomena in the Wenchuan Earthquake

Earthquake Research in ChinaVolume 26, Number 2, 2012Analysis of Some Building DamagePhenomena in the W enchuanEarthquake'Li Min' and Li Xiaojun2)1) China Earthquake Networks Center, Bejing 100045, China2) Institute of Geophysics, CEA, Beiing 100081 , ChinaThe Ms 8.0 Wenchuan earthquake caused a great deal of damage and collapse toengineering structures. Survey of disaster and engineering damage was made in detail bythe authors and other researchers in the extreme earthquake disaster area. The papermakes an overview of the earthquake disaster status and damage phenomena which includebrick -concrete buildings， frame structures， brick-wood structures， and timber frameresidential buildings. Furthermore， the causes of the disaster and building damagephenomena are briefly discussed. In addition, some typical damage phenomena arespecialized. A ccording to the phenomena mentioned above, some feasible seismic measuresare suggested for the development of buildings in future.Key words: Wenchuan earthquake ; Earthquake damage survey ; Damage phenomena ;Rural housesINTRODUCTIONIn August 2008，the authors made an investigation and analysis of the earthquake damage inGaoyuan village, Longchi village, the urban area of Dujiangyan city, Bailu town, Xiaoyudong,Yingxiu, Hanwang and so on. Based on the house survey from the earthquake disaster area, byanalyzing the degrees and patterns of the house damage, damage analysis was done to find out thecauses of the damage and lessons learned , and provide reference for improving and perfecting thehousing construetion, especially seismic design to improve the seismic capacity of residentialbuildings.The Dujiangyan city ，Pengzhou city, Mianzhu city and other related area, where a detailedsurvey of building damage was carried out in this study, were in the extreme earthquake disasterarea. The seismic intensity was VII ~ IX in Dujiar中国煤化工zhou, X~XI inWenchuan and VIII ~ X in Mianzhu ( Yuan YifarEhe basic seismic:fYHCNM H G"' Received on February 7, 2010. This project was sponsored by the Basic R&D Fund for Central Level PublicService Research Institute, China ( 2006A02)..244Earthquake Research in Chinafortification intensity in these areas was all VII degree which was much less than the practicalintensities in the extreme earthquake disaster area, the earthquake caused severe damage andcollapse of a lot of houses and other engineering structures ( Yuan Yifan， et al. ，2008; LiXiaojun, et al.，2008). Viewing from the earthquake damages to urban housing, houses withframe structure of first storey and the brick -concrete of the upper storeys were damaged moreseriously, while the damage to houses with the reinforced concrete structure was lighter. Housesbuilt before the late 1990s were damaged more seriously, while houses built later were damagedlightly. Viewing from the damage to the self-built house, houses with chaos in the housingstructure were damaged more seriously, while the damage to houses with single-brick structurewas lighter (Ge Xueli et al. , 2008). In addition, houses designed in strict accordance with therequirement of seismic design code for buildings and through the seismic reinforcement before theearthquake ( such as adding structural columns， ring beams， etc. )，had good seismicperformance ( especially in the realization of“surviving a severe earthquake" ). W hen earthquakeoceurs, the dislocation of the fault often occurs in hundreds of millimeters to several meters inhorizontal or vertical direction, which directly causes serious damage to foundation and structureof the buildings across or adjacent to the fault. At the same time, strong ground motion near thefault caused by a sudden dislocation of the fault can also lead to serious damage to nearbybuildings. One phenomenon in this earthquake was that most severely damaged areas were nearthe fault, which demonstrates the seriousness of damage on the earthquake fault and the areanearby once again. Therefore the engineering site should avoid active faults as far as possible.In this paper, we use seismic damage survey data of houses from seriously damaged areas toanalyze the seismic damage of ordinary residential buildings in urban area andself-built housingand public buildings in rural area, and discussed the causes of the significant differences ofdamage patterns and degrees on the building structures.1 ANALYSIS OF FIELD SURVEY DATA OF SEISMICALLY DAMAGED BUILDINGSI.1 Urban Commercial and Residential BuildingsMost of houses along the streets in Dujiangyan downtown were 5 ~ 6 storey brick -concretebuildings. Usually the first storey was with the frame structure. Prefabricated panels were widelyused for floors and roofs, and the wall thickness was usually 240mm. Many of these houses weremoderately or severely damaged, or even partly collapsed in the earthquake. Generally, the firstand second floors were most seriously damaged, and the degrees of damage decreased with theincrease of floor number. Patterns of housing destruction were: damage to the plastic hinges at thecapitals or the end of columns on the first floor (Fig. 1); X-shaped cracks, inclined cracks orhorizontal cracks on spine wall of the first and second floors, mortar surface spalling at crackingpositions, and even bricks were cut, split, or crushed ( Fig. 2); serious cross-cracks on wallsunder windows ( Sun Jingjiang, et al.，2008 ; Zhang Minzheng, 2008 ).Most of houses in new residential areas in Dujiangyan city were 5 or 6-storey, brick -concreteor frame structures built after 2001. Most of these houses were largely intact or slightly damaged.Observed from the facade, lttle cracking phenomena were found on the outer vertical walls andgables. Horizontal cracks or peeling plaster layer were seen at a few entrances of buildings.Cracks were commonly found on stairwell treads, and usually started from the third step (Fig. 3).This may be related with the retention of construction joil中国煤化工uld be seen ininner longitudinal and transversal bearing walls on theFon other floorsremained largely intact.YHCNMHGIn the heavily damaged zone of Hanwang, Deyang city, the first floor of a 5-storey brick-concrete residential building with ring beam and constructional columns near fault surface rupture中国煤化工YHCNMH G中国煤化工YHCNMH G中国煤化工YHCNMH G中国煤化工YHCNMH G中国煤化工YHCNMH G中国煤化工YHCNMH GVolume 26, Number 2251concrete ring beams and constitutional columns in brick structure houses for the enhancement ofanti-collapse performance.ACKNOWLEDGEMENTSThis research was supported by the Basic R&D Fund for Central Level Public ServiceResearch Institute , China ( 2006A02 ).REFERENCESGe Xueli, Huang Shimin, Xue Yantao, et al. Damage analysis and reconstruction suggestions on buildings inDujiangyan of W enchuan M.8. 0 earthquake [J].Earthquake Resistant Engineering and Retroftting, 2008 ,30 (4): 2~ 11( in Chinese with English abtract).Li Xiaojun, Yu Aiqin, Gan Pengxia et al. Survey and analysis of the disaster and engineering damage of Beichuancounty seat in M.8. 0 W enchuan earthquake [J]. Technology for Earthquake Disaster Prevention, 2008, 3(4): 352 ~ 362( in Chinese with English abstract).Sun Jingjiang, Ma Qiang, Shi Hongbin, et al. Building damage in eities and towns located in higher intensityareas during W enchuan earthquake [J]. Earthquake Engineering and Engineering Vibration, 2008, 28 (3):7 ~ 15( in Chinese with English abstract).Wen Ruizhi, Wei Jingzhi, Zhao Jisheng, et al. Damage analysis for the buildings in countryside at W enchuan Ms8. 0 earthquake and some recovering suggestions [J]. Technology for Earthquake Disaster Prevention, 2008,3 (4): 391 ~ 397( in Chinese with English abstract).Yuan Yifan, Sun Baitao ( executive editor in chief). General introduction to engineering damage during theW enchuan earthquake[ J]. Earthquake Engineering and Engineering Vibration, 2008, 28 ( Supplement) : 1~ 114( in Chinese with English abstract).Zhang Minzheng. Building damage in Dujiangyan during the Ms 8. 0 Wenchuan earthquake [ J]. EarthquakeEngineering and Engineering Vibration, 2008, 28 (3): 1 ~6 ( in Chinese with English abstract).About the AuthorLi Min，born in 1985， graduated with a master degree from Institute of EngineeringMechanics, CEA in 2010, is an assistant engineer of China Earthquake Networks Center. Hermajor is research on earthquake engineering. E-mail: limin@ seis. ac. cn中国煤化工MHCNMHG