Study On Influence Of RC Frame Structure With Different Arrangement Of Infill Walls

Our country is located in the most active Eurasian and Pacific Ocean seismic belts in the world,and has become one of the most earthquake-prone countries in the world.The sudden and unpredictable nature of earthquakes can cause devastating and serious damage to buildings,structures and related measures,resulting in enormous loss of human lives and material wealth.The reinforced concrete(hereinafter referred to as RC)frame structure is a load-bearing system formed by reinforced concrete beams and columns in a rigidly connected manner.The infill wall serves as a non-load-bearing structure and plays a role of enclosing and separating.Although the filling wall is an unstructured component,a large number of experiments and post earthquake investigation also find that the filled wall absorbs a part of the seismic force during the earthquake,which has some influence on the seismic performance of the RC frame structure,which also proves that the filled wall is involved in the overall stress of the frame structure.According to China’s specification "Technical Specification for High-rise Building Concrete Structures"(2010 edition),it is stated that: When the infill wall is a masonry wall,the period reduction coefficient is in the range of 0.6-0.7.Different layouts of infill walls and masonry materials will have different effects on the overall stiffness of the RC frame structure.However,a simple stiffness reduction does not fully reflect the influence of different infill walls on the structure.Therefore,this paper uses ABAQUS software to establish an RC frame structure with infill walls.Through different filling wall arrangements in horizontal and vertical directions,the influence of different layouts of infill walls on the seismic performance of RC frame structures is studied..The main contents are as follows:1)Review and collect information of existing domestic and foreign scholars on the experimental and theoretical analysis of the infill wall frame structure;summarize the calculation formula of the natural vibration period of the frame structure under consideration of the influence of the infill wall and do not consider different filling Influence of Wall Arrangement on Seismic Performance of RC Frame Structures.2)Use ABAQUS finite element software to establish a corresponding RC frame structural calculation model with infill walls.By analyzing the data,the same structure,the structure of the filling wall,the natural vibration cycle is much smaller than the pure frame structure,the size of the vibration cycle is not only affected by the filling rate of the filling wall,but also related to the layout of the filling wall.3)Through the establishment of 8 sets of RC frame structure models with horizontally different infilling wall layouts,we can see that the different horizontal layouts have different effects on the fundamental natural vibration period;In the influence coefficient of the vibration period,a linear regression analysis is performed on the linear regression equation to obtain the influence coefficient of the filling rate and the natural period.The value of the natural vibration period of the frame structure specified in the “High Regulations” of China is set to 0.6-0.7,and it is substituted into the regression equation of the fitting curve.It can be seen that the required self-vibration cycle reduction factor in the code can only satisfy the filling rate of 55%-80% of the infill wall structure.4)For the different arrangement of the infill wall structure in the horizontal direction,8 sets of models were established to conduct elasto-plastic time history analysis.Through the analysis of acceleration time history,displacement time history and shear stress time history,it was found that when the filling rate of the infilling wall is constant There is no direct influence of the unevenly arranged infill wall on the acceleration peak of the top layer;the energy dissipation effect of the infill wall increases linearly with the increase of the filling rate;the infill wall should be arranged along the weaker direction as much as possible to avoid the increase in stiffness difference.The risk of lateral migration of the structure is exacerbated;over-concentrated and densely-arranged infill walls should be avoided,to avoid torsion damage of the structure due to the increase in stiffness difference.5)Through the establishment of 8 sets of vertical RC frame structure models with infill walls,the model is subjected to elasto-plastic time history analysis.According to the simulation analysis,it can be seen that RC frame structures with different vertical infill wall arrangements are in the same At the filling rate,the non-arranged infill wall at the bottom had the greatest effect on the period of natural vibration,and the influence from the bottom to the top gradually decreased,indicating that the bottom infill wall contributed more to the structural stiffness than the upper infill wall.6)For RC wall structures with infill walls with different vertical layouts,when the filling rate of the infill walls is constant,the non-uniform arrangement of the infill walls in the vertical direction has no direct effect on the top-level acceleration peaks;when the filling rate is fixed,vertical and non-uniform arrangement of fillings occurs.The wall is more uneven than the horizontal layout of the infill wall on the impact of the RC frame structure greater.When the bottom layer is an overhead layer with no infill walls,the higher the filling rate of the top infill wall,the greater the displacement of the top layer.When the top layer and the bottom layer are all weak layers,the interlaminar shear force of the bottom layer of the structure increases.At the same time,the sudden displacement of the bottom layer will cause the whiplash effect to increase,and the shear stress of the top layer of the structure will increase.7)For an RC frame structure with an overhead layer(with no infill wall)installed on the bottom layer,the structure seismic response should be reduced by improving the stiffness of the lowest structural column or by appropriately reducing the filling rate of the infilling wall above the structure.The appropriate reduction of the filling rate of the two-layer infilling wall to form a stiffness transition layer can achieve the purpose of making the seismic response transfer to the second floor relatively evenly and reducing the weakness of the bottom layer.