HYSTERETIC CHARACTERISTIC WITH P-Δ EFFECT AND ITS INFLUENCE ON COLLAPSE RESISTANCE CAPACITY OF STRUCTURE UNDER EARTHQUAKES

P-Δ effect is one of the crucial reasons causing the collapse of structures under strong earthquake excitations. Numerical example shows that the lateral stiffness of structure decreases when the P-Δ effect is considered, and the backbone curve is easy to behave a negative slope when the geometric nonlinearity and the material nonlinearity are combined. A simplified trilinear curve including the elastic range, the yield range and the softening range is used to simulate the characteristic of the backbone curve, and the hysteretic models including the nonlinear elastic model, the full elasto-plastic model and the Clough model are developed. The influence of the hysteretic characteristic on the collapse resistance capacity of the structure is researched by a series of incremental dynamic analysis (IDA) for the single-degree-of-freedom (SDOF) system. The results demonstrate that the collapse resistance capacity of the structure is not always proportional to the energy dissipation capacity, while the biasing movement tendency when the structure goes into the negative stiffness branch is the main reason causing the collapse of the structure.