Force Analysis And Control During Construction Of Vertical Displacement Of Buildings

With the rapid development of China's economy,due to the adjustment of urban planning,the transformation of the old city and the protection of ancient buildings and other reasons,in consideration of the construction cycle,project cost and other factors,the whole building moving technology is often used.During the construction of the building moving by trailer,the stress analysis and control of structure jacking is one of the key parts and technical difficulties of the project.Taking the moving construction by trailer of a hotel building group as an example,this thesis focuses on the stress analysis and control in the process of structural jacking.By considering the construction speed,jacking difficulty,construction period and project cost of building moving,the SPMT full steering trailer moving mode is selected.This project is the largest building group of moving construction by trailer in China at present.It is the first frame structure building adopting trailer moving in China,and its monomer is also the largest frame structure building adopting trailer moving.The project adopts the underpinning structure wrapped around the column,the PLC hydraulic servo multi-point synchronous self-locking jack for lifting,the diamond wire saw cutting system for static cutting,the combination of jack and steel cushion block is used to lift the whole building 1.1m,and the vehicle drives under the underpinning structure according to the design position and carries out position calibration.The trailer bears the weight of the upper structure according to the step size until the upper structure is separated from the jacking support column to complete the loading process.During the jacking process,the displacement monitoring,the jacking point force monitoring and the underpinning beam strain monitoring should be paid attention to ensure the orderly and safe jacking process.The finite element software SAP2000 is used to simulate the stress of the structure in the process of lifting,and the influence of the three-dimensional model with and without underpinning beam on the internal force of the superstructure under different embedded ends and different load combinations is discussed.In order to effectively simulate the boundary conditions of the structure after the column is broken,the joint element in the finite element software is used to simulate the constraint conditions of the column in the vertical direction and limit the degree of freedom in the horizontal direction.Compared with the fixed hinge support model,it is found that the fixed hinge support model can replace the joint element support model for analysis when the vertical displacement difference between adjacent columns is small.At the same time,it is found that the jacking column side of the first floor frame beam is the place with larger force and the most obvious change of internal force when it is jacked in the underpinning beam structure model,which needs to be paid more attention in the process of jacking.It is inevitable that there will be vertical displacement difference between adjacent columns in the process of jacking,which will cause damage to the superstructure.For this reason,the underpinning beam structure model and the non underpinning beam structure model are established respectively,and the limit value of the vertical displacement difference between adjacent columns of the structure model with and without underpinning beam is 2.3mm.Based on the limit value of vertical displacement difference between adjacent columns determined by underpinning beam structure model,the control limit value of displacement and load in jacking construction is determined.At the same time,the measured data in the process of lifting and the possible failure of individual hydraulic jack are simulated and analyzed.