Quantification of seismic demands of damage-control tension-only concentrically braced steel beam-through frames (TCBSBFs) subjected to near-fault ground motions based on the energy factor

Abstract The tension-only concentrically braced steel beam-through frames are compelling options for low-to-medium rise buildings in low to moderate seismic regions. This paper quantifies the seismic demand of damage-control TCBSBFs under near-fault ground motions. Firstly, the hysteretic model of TCBSBFs in the damage-control stage is validated based on the test database of a prototype structure. Subsequently, representative single-degree-of-freedom (SDOF) systems with the verified hysteretic law are subjected to 320 near-fault seismic records. A parametric study including more than 8,208,000 nonlinear spectral analyses is carried out. The effect of the hysteretic parameters (i.e. the post-yield stiffness ratio and the ductility in the damage-control stage) and the damping ratio on the energy factor is examined in detail. The results revealed that the energy factor demand of bilinear slip kinematic SDOF systems representing the TCBSBFs under near-fault ground motions is sensitive to the hysteretic parameters in the damage-control stage. On the basis of 8,208,000 computed values of the energy factor, the probabilistic distribution of the energy factor exhibits a certain degree of positive skewness. In order to ensure the seismic reliability of TCBSBFs, a probabilistic model of the energy factor governed by the lognormal distribution is developed to facilitate the performance-based seismic design of TCBSBFs. Based on regression analysis of the database, two empirical formulas are proposed for two key parameters. The design model may offer practical guidelines for the design of TCBSBFs.