Influence Of P-Delta Effect On Seismic Response Of A High-rise Shear Wall Structure

Tangshan is a city with frequent earthquakes,and a magnitude of 7.8 earthquake occurred.The intensity of the epicenter is 11 degrees,and now the fortification intensity in this area is VIII degree.In China,there are less earthquake damages to the nearly 100 meters high rise structure in the past.In this paper,the building that ratio of height to width is 6.18 and numerical simulation of a high-rise building of VIII degree seismic fortification intensity in Tangshan is carried out,and the influence of the P-Delta effect is analyzed.It provides a basis for the study of the structural seismic theory.Based on the finite element analysis software SAP2000,this paper establishes a three-dimensional finite element model of a high-rise shear wall structure in Tangshan on the basis of the actual construction drawings.And the modal analysis of the structure was made by this paper.The dynamic time history analysis of the structure is carried out under the condition of VIII frequently occurred earthquake,VIII fortification earthquake and VIII rarely occurred earthquake.The influence of horizontal seismic action on the P-Delta effect is analyzed and compared.This paper obtained the following conclusions:(1)By analyzing the natural vibration characteristics of the structure,the first thirty periods and vibration modes of the structure are obtained.The basic natural vibration period of the structure is 1.3s,and the first vibration mode is Y to translational motion.The natural vibration period of the structure is calculated by using the empirical formula of natural vibration period recommended by various countries,and comparison with the result of SAP2000 calculation.The difference is not significant,and the model can be used for subsequent calculation and analysis.(2)In the frequently occurred earthquakes and the rarely occurred earthquakes,this paper has dynamic time history analysis of structure.The results shows that this structure's angles of drift isn't greater than 1/1000.And in the rarely occurred earthquakes,this structure's angles of drift isn't greater than 1/120.It meets the requirements of the code “under frequently occurred earthquakes,the structure is not bad”,“under the rarely occurred earthquakes,the structure will not fall”.(3)The effect of P-Delta effect on this structure is very small and almost no difference under the case of VIII frequently occurred earthquake.The lateral stiffness of shear wall structure is large,and its influence can be ignored.In the case of VIII fortification earthquake and rarely occurred earthquake,the P-Delta effect increases the deformation of the structure and has a negative effect on the structure.It is necessary to consider the effect of P-Delta effect when calculating the seismic response of the shear wall structure.