Development Of Seismic Fragility Curves For Residential Buildings In Yemen

The most dominant structural system of reinforced concrete residential buildings in Yemen is a weak reinforced concrete skeleton of beams and columns.In this type of buildings,the interior infill panels(i.e.walls)are constructed using 20 cm,thick hollow concrete blocks,while the exterior infill panels(i.e.walls)are built from masonry backed with a mix of stone pieces and plain concrete.The floor system in this type of construction utilized hollow concrete rib slab with 30 cm.In absence of national building codes in Yemen,most of the recently constructed reinforced concrete structures,either non-engineered structures or have been designed in conformance with requirements of different international building codes however the ACI-318 code is the most common used by practical engineers in Yemen.Moreover,the engineered buildings are designed to resist gravity loads and the effect of seismic loads is ignored.Thus,this type of construction is believed to be vulnerable to seismic damage.Due to the lack of actual seismic damage data quantifying probable earthquake damage of reinforced concrete residential buildings in Yemen motivated the development of analytical seismic fragility curves for different buildings classes representing broad categories of common reinforced concrete residential buildings.And the main contents and conclusions of this study are as follows:(1)Different building classes(A-C)based on area following a field survey carried out by the researcher was investigated.Three height classes were considered: three,five and seven-story buildings under each of the area classification(i.e.A-C).The effect of a locally dominant vertical irregularity(balconies)on the seismic vulnerability of the building was also considered.A total of eighteen representative buildings were analyzed.(2)Finite element models of the eighteen representative buildings were developed.Nonlinear static(pushover)analysis was carried out using ETABS v17 software to obtain the capacity curves of each building class.(3)Four damage limit states were identified: slight,moderate,extensive and complete damage.These damage limit states were computed based on the bilinear idealization of the capacity spectrum of each representative building class following an equation from literature.Seismic fragility curves,which are a lognormal cumulative distribution function,were developed for each representative building class.The seismic fragility curves developed in this study are expected to provide a good quantification of earthquake damage probabilities for a reinforced concrete residential building in Yemen.