Seismic Vulnerability Assessment Of Residential RC Buildings In Yemen

Traditional buildings in the 20^th century in Yemen were mostly constructed without sufficient protection,and most of the reinforced concrete residential buildings in Yemen are built with beams and columns sustaining only the gravity loads.Therefore the seismic vulnerability of this type of structure needs investigation.This study aims to develop analytical seismic fragility curves for residential RC buildings in Yemen with varied heights.Three building heights were considered,namely:three,five,and seven stories.While in most studies,the infill walls were considered as non-structural elements,and their contributions to resisting earthquake actions were ignored,in this study,the contribution of the infill wall was taken into account by utilizing a compression strut modeling of the infill wall.In addition,an investigation was conducted to study the effect of soft stories on the seismic vulnerability of residential RC buildings.Finite Element models were generated for the examed buildings,and incremental dynamic analysis（IDA）were carried out 900 times to investigate the seismic vulnerability of the representative buildings.And the IDA curves were used as bases for the development of the seismic fragility curves for the buildings under consideration.This study identified three damage limit states,i.e.,Immediate Occupancy（IO）,Life Safety（LS）,and Collapse prevention（CP）.Then,the cumulative distribution function（CDF）was calculated to develop the seismic fragility curves of each representative building.Results of this study show that the height of the RC buildings plays a significant role in the seismic fragility of the building.The higher the building is the more likely it reaches or exceeds the damage limit states.Therefore,the higher the building is the more vulnerable to earthquakes.Comparing the fragility curves of the bare frame building with that with infill walls shows that taking the infill walls into consideration has decreased the probability to reach or exceed the damage limits.Thus,the buildings with infilled frame are less vulnerable to earthquakes due to the contribution of the infill walls on the seismic resistance.The contribution of infill walls was noticed on increasing the lateral stiffness of the building which led to enhance the performance of the building.The presence of the soft story increased the probability of reaching or exceeding the damage limits and this led to the start of the damage limits occurring at a smaller value of the spectral acceleration.Therefore,the buildings with soft story are more vulnerable to earthquake due to the sudden change of stiffness takes place along the building height which makes the story more flexible than the adjacent story.In general,the seismic fragility curves developed in this study would provide a good quantification of earthquake damage probabilities for residential RC buildings in Yemen and these seismic fragility curves could be used in seismic loss assessment in future researches.