| With the acceleration of China’s industrialization process,the use demand of some buildings has changed,the production process has been improved and the production equipment has been replaced.Many original buildings such as civil buildings and industrial buildings originally designed according to the old code can no longer meet the use demand.At this time,it is often necessary to strengthen and transform the original buildings,among which “joist and column pulling” is common in practical projects.Based on the reconstruction project of “joist and column extraction” of a waste incineration power plant in Zaozhuang City,Shandong Province,this paper uses the drilling machine to chisel out the column concrete and reinforcement,and then installs the steel pad and Jack for step-by-step unloading,monitors and obtains the stress and displacement of the key components in the whole joist and column extraction process of the structure,and uses the finite element simulation software to simulate and analyze the whole construction process,and obtains the following results:(1)Taking the “joist and column pulling”project of an industrial plant in Zaozhuang,Shandong Province as an example,according to the reinforcement and transformation scheme,the construction process of structural reinforcement and transformation,the layout scheme of structural monitoring points and the data collection and processing of monitoring points during column pulling,jacking and unloading in the process of “joist and column pulling”are formulated.The monitoring results show that the maximum stress and displacement of the structure after column pulling are within the safe use range,It shows the feasibility and safety of the reinforcement scheme of joist and column.(2)On the basis of the actual project,according to the construction drawings provided by the project,the finite element fine modeling was carried out,and the “life and death unit” technology in ABAQUS was used to realize the simulation of the entire construction conditions of the bracket extraction column,and the simulation results were compared with the monitoring results and found that the stress change trend of the steel reinforcement obtained by the two was similar,and the error of displacement size was not large,which verified the accuracy of the model.This simulation result can provide a reference for the actual beam extraction project.(3)The spatial frame model is established,and the reinforcement stress and displacement data in the process of column extraction are extracted.The influence of upper beam column components on the structural stress and displacement in the process of joist column extraction is studied and analyzed.The results show that after considering the upper beam column members,the reinforcement stress obtained by structural simulation is reduced by 11.7% ～ 31.5% and the displacement is reduced by 24.5% compared with the plane frame,that is,after considering the spatial synergy,the additional tension provided by the upper beam column will reduce the structural stress and deformation.(4)In the process of joist column extraction,the influence of column extraction time on structural stress and displacement is considered.The“equivalent reaction force method”is used to replace the supporting effect of the original components on the structure.The time history curves of structural displacement,velocity and axial force under different column extraction time are analyzed,and the structural dynamic amplification factor based on displacement is obtained.The results show that the faster the column extraction time,the more obvious the displacement and velocity response of the structure,the greater the peak value of axial force of adjacent columns,and the greater the dynamic amplification factor of the structure.Compared with the static analysis,the maximum displacement and axial force of the structure increase greatly.Therefore,it is suggested to consider the dynamic effect under the rapid column extraction in the reinforcement design. |
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