Study On Mechanical Properties Of Externally Prestressed Reinforced Steel Plate-Brick Masonry Composite Beams

This paper proposes a new type of underpinning technology,external prestressed steel plate-brick masonry structure to reinforce some existing old buildings in China.This technology combines the external prestressing technology with the steel plate-brick masonry combination structure.At the same time,it has the advantages of both.At present,there is no relevant theoretical and experimental research on this technology.In this paper,the steel-brick composite beam is selected as the research object,and the external prestressing reinforcement scheme with different linear arrangements is designed.Through theoretical analysis and combination.The mechanical properties of the paper were studied by theoretical analysis and related experiments,and finite element software was used to analyze the external prestressed steel plate-brick composite beam.The main research and results are as follows:The main factors influencing the mechanical properties of steel-brick masonry composite beams are briefly introduced,and different arrangements of external prestressed steel-brick composite beams are proposed.The calculation method of elastic and plastic normal section flexural capacity of composite beams is proposed.According to the characteristics of external prestressed structures,internal forces are applied to external prestressed structures.Analyze and consider the influence of prestress loss and stress increment,and derive the formula for calculating the ultimate flexural capacity of the external prestressed steel plate-brick composite beam.In terms of test,four specimen beams of different working conditions were designed,which were steel-brick composite beams without external prestressing,and linear,single-fold and double-fold external prestressed steel plates — brick The composite beam is subjected to the relevant static load test of the four specimen beams,and the specific failure process and final failure form of the beam,the strain distribution law of the mid-section and the load-deflection curve are obtained.The test results show that the final failure mode of the composite beam is the local buckling instability of the steel plate near the loading point;the steel plate of the composite beam spanning the middle section is linearly distributed along the height,which conforms to the flat section assumption;the external prestress can improve the resistance of the composite beam.Bending bearing capacity and ductility,the external prestressing reinforcement scheme with different linear arrangements has differenteffects on the ultimate bearing capacity and deformation of the composite beam.From the numerical analysis of the steel-brick masonry composite beam before and after external prestressing reinforcement was carried out by the finite element software ANSYS.The results show that the external prestress can improve the bearing of the steel-brick composite beam to a certain extent.Force and ductility,by comparing the mechanical properties of the externally prestressed steel plate-brick composite beam with different linear arrangements,and concluded that the double-retracted prestressed arrangement has the most obvious effect,which is the later external prestressed steel plate-brick masonry combination technology.The application in practical engineering provides a reference.