Hybrid steel staggered truss frame (SSTF): A probabilistic spectral energy modification coefficient surface model for damage-control evaluation and performance insights

This paper attempted to quantify the inelastic seismic demand of hybrid steel staggered truss frame (SSTF) showing damage-control behaviour by using a probabilistic seismic demand spectral surface model. The study was commenced by developing the idea of hybrid SSTF composed of high strength steel members and low yield point steel dampers. In order to evaluate the structural damage-control behaviour, inelastic spectral energy modification coefficient surfaces were developed based on the single-degree-of-freedom (SDOF) analogy with bilinear kinematic hysteretic law. According to the statistical characteristics of the analysis data pool, it was found that the spectral energy modification coefficient followed a positively skewed probabilistic distribution. The energy modification coefficient surfaces were appreciably affected by structural parameters and statistical features of earthquake motions. Then, empirical expressions of the energy modification coefficient surfaces considering the influence of essential parameters were established. Based on previous experimental data, the finite element modelling techniques for developing a hybrid SSTF were verified. Cyclic pushover analysis and nonlinear response history analysis (NLRHA) of a prototype structure revealed that the hybrid SSTF showed favourable damage-control behaviour by concentrating inelastic actions in low yield point steel dampers. The insignificant post-earthquake residual deformations were also characterised. The adequacy of the proposed spectral energy modification coefficient surface model for evaluating the damage-control behaviour of hybrid SSTF was confirmed by NLRHA of the prototype structure.