About the seismic design of a "two storey-X" concentrically braced frame

Abstract

The present paper analyses several seismic design procedures for concentrically braced frames equipped with a „2 storey-X” bracing system. The procedures were applied on a ten level structure situated in Bucharest, considering that the lateral loads are taken entirely by the braced frames. The concentrically braced frames were designed using four procedures (the one indicated in the in charge seismic design code and three other alternative procedures). The main objective was the strength hierarchisation of the structural elements in order to obtain by design a global plastic failure mechanism for the concentrically braced frames. Dynamic nonlinear analyses were performed with each designed frame configuration in order the study the sequence of the plastic joins formation, as well as the values of forces and deformations in the different structural members of the frame. Another objective was the comparison of the estimated steel consumption.