Probabilisitic Analysis Of Peak And Residual Displacements For Inelastic Sdof System

In earthquake engineering, most engineering stuctures can be simplified or equivalent to inelastic single degree of freedom model, such as, rigid frame bridges, aqueduct, water tower, etc. Structures usually enter into the stage of inelastic deformation when subjected to earthquake excitation, so peak displacement and residual displacement of inelastic system are two important indices to assess seismic behavior and repairability of structures. P-A effect was remarkable due to the large horizontal displacement occurred on the top of structures and it aggravated the peak displacement and residual displacement of structures. In the meantime, cracking, crush and bond-slip occured when structures under earthquake actions. The resulting strength degradation, stiffness deterioration and pinching effect would influence peak displacement and residual displacement. In this study, applying nonlinear dynamic time-history analysis and probabilistic method, the influences of P-â–³effect, strength degradation, stiffness deterioration and pinching effect on the probability statistic values of both peak displacement and residual displacement were analysed quantitatively. Empirical probability distributions models and prediction equations of peak displacement and residual displacement were also established here. The main contents of the research include the following aspects:(1) Based on classical Bouc-Wen model and principle of dynamic equilibrium, a seismic dynamic analytical model of inelastic SDOF system called improved Bouc-Wen model was set up considering strength and stiffness degradations as well as P-â–³effect and pinching effect;(2) Based on the improved Bouc-Wen model, influences of P-A effect on hysteretic curve and time-history curve of bridge structures were analyzed by using an earthquake wave and an artificial simple harmonic waves.69earthquake records were used to study the impacts of P-â–³effect on peak displacement and residual displacement through quantitative analysis. The correlation between the peak and residual displacements was discussed. Distributions of residual displacement were obtained, and the prediction equations of peak displacement and residual displacement were also proposed considering P-â–³effect;(3) Based on the improved Bouc-Wen model, three conditions were considered to analyze seismic response of inelastic SDOF system, such as strength deterioration, stiffness degradation and both of the two preceding factors deteriorated simultaneously by using an earthquake wave and an artificial simple harmonic waves. The influences of strength and stiffness degradations on probabilistic characteristics of peak displacement and residual displacement were quantitatively investigated using69earthquake records. Predicition equations of peak displacement and residual displacement were also developed considering strength and stiffness degradations;(4) The physical meanings of pinching effect control parameters were analyzed. Differences of how pinching parameters influenced time-history curve of bridge structures under near and far field ground motions were also compared. The influences of pinching effect on probabilistic characteristics of peak displacement and residual displacement were quantitatively investigated using69earthquake records. Predicition equations of peak displacement and residual displacement were also developed considering pinching effect.