Research On Seismic Performance Evaluation Method Of Multiple Targets Under Precautionary Intensity

Performance-based seismic design is the main development direction of the future seismic design.On the one hand,performance-based seismic design can guarantee the people's lives security;on the other hand,it can assess the expected seismic performance of future earthquakes,which can minimize the loss of property.On the basis of seismic performance spectra,the influence of the characteristic parameters on the seismic demand is researched.In this paper,the seismic performance evaluation of multi targets under precautionary intensity is carried out by comparing capacity spectra which is established by Pushover method with seismic demand spectra.The main research contents include the following aspects:?1?Because seismic records are important parameters for time history analysis,and different selection methods of seismic records are summarized.A complete set of seismic records of 0.45s characteristic period in?sites are selected by combining with two different indicators including V_s30 and characteristic period?by probabilistic method?.Characteristic period is calculated by probabilistic method and ATC 3-06method.They have good agreements by analyzing characteristic period.?2?On the basis of seismic performance spectra,the influence of the characteristic parameters on the seismic demand is researched.A complete set of seismic records are input into a single degree of freedom system,then seismic performance spectra can be established.The characteristic parameters of seismic performance spectra are analyzed,including the natural vibration period of empirical formula,the restoring force model,the second stiffness reduction factor and the yield point,which have effects on the seismic demand.?3?Eight story frame structures are designed according to 6,7,8 and 9 degrees.Capacity spectra is established by pushover method.Seismic demand spectra under different levels are established by the method of dynamic time history analysis.The capacity spectra and the seismic demand spectra that under different levels are drawn in same picture that the transverse and vertical coordinates are the spectral displacement and the seismic influence coefficient.If capacity spectrum curve is higher than the seismic demand spectrum curve,the structure can meet the requirements of security,otherwise the structure needs to be re designed.While the seismic demand spectrum is calculated by using dynamic time history analysis,the peak ground acceleration under different levels also can be obtained.According to the peak ground acceleration of large medium and small earthquakes under a certain precautionary intensity,the corresponding displacement under the precautionary fortification intensity is determined,and according to the displacement of large medium and small earthquake in the precautionary intensity,the corresponding capacity spectrum and demand spectrum are determined.By comparing with the capacity spectrum and seismic demand spectrum,seismic performance evaluation of multi targets under precautionary intensity can be achieved.