Analysis On The Stress Of Masonry Building Underpinning Structure Strengthened By Translation

Historical buildings record the evolution of urban development and carry valuable historical and cultural information.Under the background of conflict with urban planning,it is urgent to protect and utilize it rationally.The technique of building displacement provides an effective way to solve this problem.Masonry structure is the main structural form of historic buildings.As vertical compression members,brick walls and columns have good compressive ability.However,due to the weak bonding ability between mortar and blocks,their tensile,shear and flexural abilities are very low,showing brittleness.In addition,the structure has experienced natural environment erosion and man-made damage during long-term use.The bearing capacity and deformation resistance of structural components cannot meet the safety requirements of the current standards,let alone effectively resist the additional role of translation process.Targeted reinforcement measures should be taken to ensure the safety of underpinning and translation processes.According to the example of translation project of Xiangjiang Hotel,this project is a modern protection building,and as the largest independent foundation masonry building translation project in China at present,it has outstanding engineering characteristics.Therefore,the research group proposed to use high-performance cement composite mortar steel network(HPFL)to reinforce the brick masonry first and then replace it.In order to explore the mechanical properties of brick walls and columns with direct support and reinforced support structures,finite element analysis was used in this paper.Considering that the project is difficult and has certain risks,the mechanical response of the brick masonry underpinning structure strengthened by HPFL under different translation conditions is further analyzed.Finally,a comparative analysis is made based on the monitoring data of the project.The main research work and conclusions are as follows:(1)Based on the existing mechanical performance tests of the masonry wall underpinning structure,the constitutive relationship and failure criteria of each material in the brick wall underpinning structure were reasonably selected,and the finite element software ABAQUS was used for modeling and analysis of the brick wall underpinning structure.The results of finite element simulation and test are compared to verify the applicability and feasibility of the model in the finite element analysis of masonry underpinning structure.(2)Vertical loading and horizontal monotone displacement loading were carried out on the brick wall underpinning structure,and the mechanical performance of the brick wall underpinning structure under each load was studied,and the influence factors such as reinforcement method were comprehensively analyzed.Results show that under the vertical load,the reinforcement or the reinforcement of the brick wall underpinning structure has a certain wall Liang Xiao should,and,after that the HPFL strengthening in increasing the compressive bearing capacity of the wall itself at the same time,also can effectively improve the overall stiffness of the wall,to strengthen the walls and underpinning structure,ability to work,so as to improve the compressive bearing capacity of the specimens;Double reinforcement reinforcement effect is superior to the single side reinforcement,mortar strength grade to improve the shear performance of the brick wall underpinning structure makes little sense,for the average layer is not high of masonry buildings,with the increase of the vertical stress,brick wall and the pin button at the bottom of the beam the bonding effect between friction and surface also increases,hindered the levels of wall slip,so as to improve the shear bearing capacity of the specimens.(3)Vertical load was carried out on the brick column underpinning joints,and the mechanical properties of specimens under vertical load were analyzed.Then the horizontal low-cycle reciprocating loading is carried out on the specimen,and the influence of the strengthening mode and the mortar strength of the reinforcement layer on the seismic performance of the brick column underpinning joints is analyzed.The results show that the HPFL reinforcing old brick column,HPFL can play a role of the ferrule,the brick column formed certain binding,enhance its integrity,can significantly improve the brick pillars underpinning node of compressive strength and horizontal bearing capacity,enhance the ductility of underpinning node,it is better to use in engineering,underpinning node can effectively resist various adverse effects in the process of translation,and can satisfy the requirement of building subsequent use of seismic.(4)This paper introduces the application of masonry reinforcement underpinning technology in the translation project of Xiangjiang Hotel.Through finite element simulation,the mechanical response of the brick masonry underpinning structure strengthened by HPFL under different translation conditions is further analyzed.Finally,a comparative analysis is made based on the monitoring data of the project.The results show that ABAQUS is feasible to simulate the mechanical response of the brick masonry underpinning structure under different translation conditions,which is in good agreement with the actual stress state,and the error of the finite element calculation results and the actual engineering monitoring results is within the acceptable range.Finite element simulation can be used to predict the stress of brick wall underpinning structure and brick column underpinning joints in practical engineering.