Analysis On The Influence Of The Stiffness Of The Underpinning Structure On The Upper Structure Performance Of The Jack Liftiing Building

China's urbanization is developing rapidly,the number of existing buildings is huge,in the process of use,due to various problems caused by uneven settlement of buildings,tilt,etc.,affecting the normal use of buildings and even to the safety of life and property poses a serious threat.The technology of building rectification and reinforcement comes into being,although there are a lot of practical projects that have applied the method of lifting and tilting,but the dependence on engineering experience is large,and the mechanical analysis and displacement control of the lifting process are not fully mature.In this paper,a 5-storey 3-span frame structure and a shear wall structure based on the 2# building of Guilin Taoyuan in Guangxi Province are established,firstly,the linear analysis and nonlinear analysis of the two structural forms with different sedimentation conditions are carried out,and the plastic hinge of the beam is compared with the variation amplitude and deformation of the bending moment.Then the stiffness rise after the original stiffness rise and nonlinear analysis is carried out for the two different structures,and the stiffness of the change beam is changed,and the bending moment change,deformation and rising displacement of the upper structure beam are compared and analyzed.Through the simulation analysis and study of the above aspects,the conclusions are as follows:(1)The settlement of local column or wall limb only produces plastic hinge on the beam connected with the settlement column or the wall limb,which has a slightly greater influence on the beam end bending moment of the adjacent span and the generation of plastic hinge span,and has little effect on the beam at the distal end and across the span.(2)Away from the settlement column or beam end plastic hinge development is fast,the degree of bending moment redistribution is also greater than the sedimentation end.The greater the stiffness of the beam end node,the faster the development of the plastic hinge.(3)The beam end bending moment of linear analysis settlement decreases gradually from the bottom to the top layer,the beam end bending moment of nonlinear analysis,because of the appearance of plastic hinge,the bending moment difference of the same end is not big,and the degree of beam end bending moment redistribution decreases gradually from the bottom to the top layer.(4)In the process of increasing the ratio of the original stiffness to the upper frame beam or the stiffness degree from 1 to 11,the drop amplitude of the beam end bending moment connected with the settlement column or the wall limb is 30%~50%,and the influence on the span and the span is mainly in the 1-layer beam,which has little effect on the bending moment of the remaining beams.(5)The non-linear stiffness of the top rise,the upper frame beam or the continuous beam to bear the proportion of the top lift is small,mainly by the replacement beam,so the structure of beam end bending moment is relatively small,the bending moment value of the replacement beam end is larger,(6)In the process of the lifting of the structure,the rising displacement of the beam end connected with the top lift column or the wall limb decreases gradually from the bottom to the top,the top node is not more than 33% on the rise of the amplitude frame structure,and the non-linear stiffness rise does not exceed 20%,the original stiffness of the shear wall structure does not exceed 60%.The non-linear stiffness top rise does not exceed 20%.(7)In the process of increasing the ratio of the beam to the upper frame girder or the stiffness degree from 1 to 11,the rising Displacement drop degree of the top rise of the frame structure or the shear wall structure rises in the 35%~55%,and the nonlinear stiffness of the top rise in the 70%~80%.For the top rise of the shear wall limb,the greater the stiffness of the wall limb,the smaller the change amplitude of the rising displacement.(8)The change of stiffness degree has a significant effect on the force of the lifting structure,and increasing the stiffness of the replacement beam during the lifting process will increase the integrity of the structure,reduce the internal force and deformation of the superstructure,and be beneficial to the upper structure.