Seismic response of a four level framed building with composite RC and steel structures designed according to venezuelan codes

The objective of this chapter is to determine the structural behavior and seismic response of a four level framed building with composite RC and steel structure designed according to Venezuelan seismic codes. The structural system consists of RC frames in the first three levels and the fourth level has structural steel frames. Also, the building has rigid diaphragm and regular plant. First, it was performed a linear static analysis to design all structural elements. Then, static pushover analysis was realized to obtain real and idealized capacity curves and performance points in all frames. In the obtained results it was evidenced greater ductility in direction X frames and greater resistance reserve in the external frames while the determined performing points showed adequate resistance values for all frames, but low stiffness in two directions X frames. The seismic action is carry on through various synthetic design spectrum compatible accelerograms defined by the seismic codes used in this chapter with three levels of intensity corresponding to three specific Limit States. Dynamic analysis is used to compute parameters of ductility, over strength and maximum displacements. It was obtained that one direction X frame reached the collapse Limit State in a very rare earthquake, implying a general collapse of the building. Finally it was performed incremental dynamic analysis to obtain fragility curves and damages probability matrix; it was evidenced that the structure has a very high probability of significant lateral displacement despite an adequate and normative design of structural elements.