Application And Research On Underpinning Technology Of Bearing Wall In Existing Buildings

Based on the underpinning frame structure project of a five story masonry structure in Dalian city due to the change of the first floor function,this paper carries out three-dimensional numerical simulation analysis through the finite element analysis software,and makes a detailed analysis of the underpinning technical scheme of the bearing wall in the existing building,and studies the deformation and strength of the structure after underpinning,This paper analyzes the influence of different jacking height difference on the original structure in the construction stage,and analyzes the seismic performance of the underpinned structure based on the time history analysis method and response spectrum analysis method(1)This paper summarizes the reasons and common schemes of bearing wall underpinning for existing buildings,and introduces the general situation of the project;This paper focuses on the influence of underpinning of load-bearing wall on the existing building structure,demonstrates the feasibility of frame structure in the masonry structure transformation,and selects a reasonable demolition scheme of load-bearing wall according to the stress condition of the building.(2)Through the numerical simulation analysis of the whole structure of the house,the stress changes of the structure before and after the underpinning construction,the displacement deformation and stress changes of the structure are compared and analyzed.In order to ensure the stability of the structure in use,the thickness of the first floor is increased from 100 mm to 120 mm,and the second floor wall is strengthened by hanging reinforced shotcrete.By setting concrete shear wall at the corner of the frame structure,the bottom structure is changed into frame shear wall structure,so as to reduce the vertical weakness of the structure,In order to improve the anti overturning performance of the structure.(3)This paper analyzes the influence of uneven jacking on the internal force variation of the structure in the construction process,and compares and analyzes the deformation and stress variation of the structure by setting the side column,middle column and corner column with different jacking differences.The results show that the internal force of the structure near the column with jacking difference changes greatly,while the further away from the column,the smaller the internal force changes,and the settlement of the column in the structure has the largest influence on the internal force changes.(4)Based on time history analysis method and response spectrum analysis method,this paper analyzes the lateral and longitudinal seismic performance of the structure,and discusses whether the deformation law of each mode and the interlayer displacement conform to the safety and serviceability of the structure under the analysis of response spectrum method;This paper discusses the variation law of the bearing reaction and the displacement of each floor under the action of seismic wave,and verifies whether the seismic performance of the structure meets the design standard.