Research On Natural Vibration Period Of RC Frame With Infilled Walls And The Development Of Cracks

Reinforced concrete infilled frame structure have been widely used because of the economic application at the present stage,the infilled wall frame structure being the indispensable part,design of the infilled walls is simplified and natural vibration period of earthquake considering mainly manifests in the load,but the influence on the infilled wall stiffness in the current code considering to the stiffness of infill walls and the period shortening actor are not detailed enough to get accurate results in the seismic analysis in Chinese codes,at the same time for the cracking of infilled wall under seismic action and the change of stiffness are considered limited.This paper will adopt the method of theoretical calculation and finite element analysis,carrying on the analysis to the structure of a variety of models,this paper will give advice and construct corresponding measures according to the situation after the filling wall crack.First this paper use the knowledge of dynamics to deduce the stiffness matrix and the natural vibration period of single frame filled wall,and this paper will calculate the theoretical value of the natural vibration period of models.At the same time the results will be carried on the preliminary analysis,and draw the preliminary conclusions of theoretical calculations of the wall.Then the models use the ABAQUS software to analyse based on the numerical simulation,drawing the first 30 frequencies and corresponding period shortening factor of the models,and the numerical simulation results and theoretical results are compared,and this paper will give advice on the period shortening factor according to different opening rate and the number of the infilled walls.To study of period shortening factor,models are extended to the whole building,using ABAQUS software to analyze the obtained natural period of period shortening factor and comparing with the results above,and confirm the accuracy of single frame structure value.Finally,using ABAQUS software to analyze RC framework,the frame and opening infilled walls with 36% filled wall with dynamic analysis,and analyze the change of infilled wall on structural stiffness and earthquake action is generated,and to simulate the process of fill wall crack under earthquake according to the filling wall crack structure is put forward and corresponding measures.The results show that: the infilled wall is a factor that cannot be ignored in the seismic design,the number of infilled wall with rate of hole and infiledl walls on the natural period of the structure have a fundamental influence,and make detailed provisions in different situations;the cracking of filled walls can reduce the stiffness and the resistance to external action,but increasing structural measures in the infilled wall will reduce the development of cracks.