Analysis Of Seismic Performance Of Existing Frame Factory Buildings Converted Into School Buildings And Comparison Of Reinforcement Solutions

With the update of the ground vibration parameter zoning map in China,the seismic protection level in many areas has been increased,and in these areas,there are some buildings with changed use functions,and whether the seismic performance of such buildings can meet the existing seismic protection requirements is a problem that needs to be studied urgently.Therefore,it is important to analyze the seismic performance of such buildings to fully understand the existing safety hazards and weak links,propose corresponding reinforcement plans and recommendations,and analyze the effectiveness of reinforcement measures to provide reference for optimizing structural design,improving building safety,and safeguarding people’s lives and properties.This paper is based on an example of a reinforced concrete frame industrial plant in Zunyi City transformed into a teaching building structure.In order to ensure the safety of the structure,the seismic intensity of the building was increased to 6 degrees.In order to ensure the safety of the structure,the seismic performance analysis and reinforcement plan comparison were carried out to provide some reference for the renovation and reinforcement of similar structures.Firstly,we conducted on-site inspection of the structure,tested the concrete strength,verified the cross-sectional dimensions of the structural members,identified the seismic measures,and tested the self-oscillation frequency of the structure;based on the on-site inspection results and the basic information of the structural design,we established the finite element model before and after the retrofitting of the structure;we conducted modal analysis and nonlinear time analysis of the structure,and compared the seismic response of the structure before and after the retrofitting under the effects of multiple earthquakes,fortified earthquakes,and rare earthquakes,respectively.The seismic response of the structure was compared with the seismic response of the structure;the horizontal load carrying capacity of the frame column reinforced by the increased section method and the outer cladding steel method were compared,and the effects of three different section sizes of steel on the performance of the reinforced column were compared,and finally the effects of the four types of reinforced frame columns on the overall deformation of the structure were compared under the action of rare earthquakes,and the most reasonable arrangement of the reinforced column area was given to provide reference for the reinforcement design.The main conclusions of this paper are as follows:(1)Suggestions for the selection of connection forms when modeling infill walls are presented:when shell units are used for infill walls in numerical simulations,coupling connections(Coupling)are recommended for such retrofit structures between the four corner points of new infill walls and the two sides of frame columns and the top surface of beams,and C coupling connections(Coupling)are also used between the four corner points of original infill walls and the two sides of frame columns,and the bottom surface of original infill walls and frame beams The top surface of the original infill wall and the frame beam are coupled with the shell solid coupling(Shell Solid Coupling).(2)Time-course analysis of the frame before and after the retrofitting,the inter-story displacement increased by 31.53%under the effect of multiple earthquakes compared with that of the structure before the retrofitting;the inter-story displacement increased by 33.86%under the effect of seismic fortification compared with that of the structure before the retrofitting,and the damage level increased by one grade;the inter-story displacement increased by 4.92%under the effect of rare earthquakes compared with that of the structure before the retrofitting,which is close to that of the structure after the retrofitting..The reasons for the different results were analyzed and the following conclusions were obtained:when the frame structure renovation requires a large number of additional infill walls,if the infill walls are not reliably connected to the main body,the structural stiffness will be weakened,which will cause the structure’s ability to resist the seismic action to be reduced,and the structural damage level will be increased under the larger seismic action.(3)Compare the influence of outsourced section method and increased section method on the bearing capacity of frame column,it is suggested that the outsourced section reinforcement method is preferred under the condition that the bearing capacity of positive section is the same;when the outsourced section method is used to strengthen the frame column,considering the influence of the cross-sectional size of the reinforced angle,it is suggested that the angle with short side length and wide side thickness is used under the condition that the amount of steel used and the bearing capacity of positive section are similar,so as to achieve better reinforcement effect The different areas of reinforced frame columns have a significant impact on the overall deformation capacity of the frame structure.Under the premise of reinforcing the same number of frame columns,when reinforcing the frame columns in the direction of higher stress,it is recommended that the frame columns with the same cross-sectional size be reinforced at intervals in the direction of the long side of the structure and continuously in the direction of the short side,so that the seismic capacity of the structure can be improved after reinforcement.