Study On The Performance-based Design Method Of RC Members Considering The Effect Of Earthquake Duration

Performance-based design is the research trend of seismic design.At present,the damage quantification indexes of performance-based design method mainly include single-parameter damage index(such as deformation,ductility,degradation and energy)and double-parameter damage index represented by Park-Ang.The disadvantage of these damage quantification indexes is that seismic duration can not be considered or can not be considered effectively.However,under strong motion of long duration,the reinforced concrete(RC)structures undergo variable amplitude displacement histories,during which the capacity of the structures deteriorate and the damage accumulate.In recent years,such as the Fukushima earthquake in Japan in 2011,the earthquake in Chile in 2010,and the earthquake in Wenchuan in China in 2008,lasted for 300 seconds,200 seconds and 180 seconds respectively,causing serious damage to the structure.Therefore,it is necessary to consider duration influence in seismic design.This paper considers the relationship between the residual capacity of the RC members and the historical maximal displacement,the cumulative hysteretic energy and the material parameters of the members,based on the damage evaluation model and performance evaluation criteria for RC members under variable amplitude displacement histories,the performance-based seismic design method for RC members considering duration influence is proposed.The shortcoming of the RC members under the Code for Seismic Design of Buiding without considering the influence of strong motion duration is investigated,and proposes the corresponding correction method.The results show that the damage of RC members will be aggravated with the increase of the duration of strong earthquakes,the trend is to grow fast and then grow slowly.When the strong motion duration exceeds a certain threshold,the impact on the damage disappears.The increase of the stirrup ratio can reduce the damage of the members,and the effect of increasing the stirrup ratio under small ductility is more significant The difference of stirrup ratio between performance-based seismic design method and the Code for Seismic Design of Buiding for RC members under different fortification intensity is different.Through calculation and analysis,the correction value of the stirrup ratio of different self-vibration cycles of RC members under different fortification intensity is proposed.