Numerical Study on Concentric Braced X Frames under Monotonic and Cyclic Loads

Abstract

Concentric Braced Frames (CBF) are designed for dissipating the seismic energy mainly through plastic deformations of diagonals in tension, while beams and columns, designed on the basis of the hierarchy resistance criterion, should resist the design loads in elastic field without undergoing buckling and yielding phenomena. For such structural systems there are still some uncertainties on the performances under cyclic loadings, due to the degradation of the strength and stiffness under tension for the occurrence of instability problems in compression. The current paper deepens such key issues, presenting the numerical simulation of some literature experimental tests conducted on CBX frames subjected to monotonic and cyclic loads both in presence and in absence of vertical loads. The refined FE structural models of the study systems are developed through the software ABAQUS v6.13-1. The models set up have provided a very good replication of both monotonic and hysteretic behaviours in terms of strength, stiffness, ductility and energy dissipation. They are powerful analysis instruments to perform parametric studies, aiming at detecting the main factors affecting the cyclic structural behaviour, thus leading towards appropriate design criteria.