Research On Displacement Angle Of Reinforced Concrete Frames

Performance-based seismic design (PBSD) has been well accepted as the advancedseismic design method by most of the countries in the world. However, PBSD remains to beimproved in many aspects. This paper presented the seismic assessment methods of framestructures based on the displacement angle for reference. It would be some meaningful andvaluable suggestions for the existing seismic assessment of frame structures, and it alsoprovided the basis for the seismic assessment of strengthened structure.This paper introduces the performance based seismic design method, then, the evolution(both in China and other countries) and the basic principle used in the Pushover analysismethod are summarized. By using SAP2000, six reinforced concrete frame structural aregiven as examples. This paper mainly covers the following aspects:(1)Using the multiple of yield displacement quantify the different elastic-plastic state offrame structure. This paper studies the variation of the roof displacement angle andinter-story drift angle and the deformation of structure from the whole process of elastic todestruction, comparing with the statistical results of displacement angle with test anddeformation shape with first vibration mode and calculated by the simplified theory formula.(2)From comparative analysis of a few representative countries’ empirical formulas forestimating reinforced concrete frame structural natural periods, also contrast with thesimulation results, this paper gives the proposal to select the empirical formula. The transientperiod and transient damping ratio of structure under different elastic-plastic states arestudied with energy method.(3)Introducing the structure’s equivalent participate coefficient of vibration model toconsider higher mode effects, this paper studies the conversion relationship ofmulti-degree-of-freedom with single degree of freedom, and also considering the precise ofmulti-modal. Using seven kinds of equivalent linearization method to calculate the equivalentperiod and equivalent damping ratio of structure, comparing with the calculated results byenergy method, this paper presents the suggestions of the calculation method of equivalentperiod and equivalent damping ratio.(4)Seismic performance evaluation based on displacement angle for frame structureunder multiple intensities is putted forward. The curve of S_a-S_d is transformed into curve ofα-S_d. From the comparative analysis of seismic action with the curve of α-S_d, thendetermining the performance intersection point of structures at the stage of small earthquakes and large earthquakes in different intensities, using the roof displacement angle andinter-story drift angle assess the seismic performance of structure under multiple intensities.(5)Finally, this paper studies the seismic evaluation methods based on the displacementangle of frame structures of install viscous damper and viscoelastic damper, and analyzes theimpact of the dissipation shock absorber on the performance point and the seismicperformance.