Influence of hysteretic characteristic on collapse resistance capacity of structure with P-Δ effect

The characteristic of the seismic response of the structure with consideration of P-Δ effect is studied. The numerical results show that the stiffness of the structure decreases when the P-Δ effect is considered, and the backbone curve is easy to generate a negative slope when the geometric nonlinearity and the material nonlinearity are combined. The trilinear curve is more appropriate than the bilinear curve when simulating the characteristic of this backbone curve. On this basis, the hysteretic characteristics of the nonlinear elastic model, the full elasto-plastic model and the Clough model with a negative slope are analyzed, and the influence on the collapse resistance capacity of the structure are discussed. The results show that the displacement is more likely to concentrate on one side for the full elasto-plastic model with plump hysteretic loops, which results in a relatively lower collapse resistance capacity. On the contrary, the vibrations of the nonlinear elastic model and the Clough model with whole or part pinching are more symmetrical, and the corresponding collapse resistance capacities are better. It demonstrates that the collapse resistance capacity is not only related to the energy dissipation capacity of the structure. Rather, the biasing movement tendency when the structure goes into the negative post-yield stiffness branch is the main reason to cause structural collapse.