The Response Of The Pinching Hysteretic Structure Subjected To Seismic Sequence

The main purpose of this research work is to study the response characteristics of the pinching hysteretic structure subjected to seismic sequences.The two key points of this study are the “seismic sequence” and the “slipping and pinching effect”,and the two important contents are the "ductility demand" and "residual deformation" of the structural response.Furthermore,The two ground motion intensity research indicators are the "peak ground acceleration" and the " input energy",respectively.In this study,two seismic sequence models were used: repeated earthquake sequences and measured seismic sequences,and the effects of the sequence model on the structural response were considered by comparing the results of time-history analysis.The pre-study is based on the PGA as the intensity index of ground motion.Through a large number of time-history analysis,the ductility demands and residual deformation characteristics of the pinching hysteretic structure are studied,and the results of two seismic sequence models are compared.In the latter study,the response of the structure was studied based on the energy index,and the applicability and rationality of the two research indicators were compared.Research indicates that:(1)The sliding pinching effect of the structure is directly related to its ductility,and compared with the bilinear structure,the pinching hysteretic structure is obviously affected by the seismic sequence,and this phenomenon of the short-period structure is more significant.(2)In the earthquake sequence,the cumulative effect of the aftershock damage is not only related to its own ground motion intensity,but also related to the severity of damage caused by the main shock to the structure.The foreshocks have little effect on the structural response of the main shock.(3)The ratio of residual displacement to maximum displacement approximately obeys an exponential probability distribution.Based on the numerical regression analysis,the empirical formulas for estimating the ductility demand amplification and the probability density distribution of residual displacement are proposed.Through the corresponding time history analysis of real seismic sequences,it is found that the results of the repeated seismic sequences are also basically applicable to the case of real sequences.(4)In most cases,the input energy of the ground motion acting alone on the intact structure is greater than the input energy of the ground motion in the earthquake sequence.For the same input energy,the latter earthquake in the seismic sequence is more likely to produce a larger displacement response than the former ground motion.(5)Compared with the PGA,the input energy can largely reflect the ductility demand of the structure.Using the energy index as the research index of the structure under the seismic sequence is more reasonable,and it can avoid or reduce the influence of the sequence model.In addition,it can simplify and facilitate the research.