Experimental Study On Axial Compression Behavior Of Masonry Columns Strengthening With Bamboo Scrimber Reinforcement Mesh Mortar Layer

Since 1960s,masonry structure has been widely used in civil houses.Due to the reduction of building function and reliability,the bearing capacity and seismic performance of such old buildings have been weakened.However,most of the buildings still have the use function,so it is not in line with the national conditions to demolish a large number of such buildings.Therefore,the more reasonable way is to take appropriate reinforcement and repair measures to make them continue to serve the national economic construction on the premise of meeting the safety and applicability.It is a new method of strengthening masonry structure.It is a thin-layer structure which is made up of the bamboo scrimber reinforcements and the high-grade cement mortar.This reinforcement method does not change the cross-section size of the original structure,which is convenient for construction,strong adaptability and reliable stress.The research shows that with the increase of the reinforcement ratio of the bamboo scrimber reinforcements net,the reinforcement effect is more obvious,and the ultimate bearing capacity,section stiffness and ductility of the reinforced members are effectively improved.According to the actual needs,four groups of 12 brick masonry columns are designed and manufactured in this paper.Based on the test and ABAQUS finite element simulation,the failure mode,load displacement curve,ultimate bearing capacity and bamboo bar strain of each specimen are studied.The main research contents are as follows:(1)Through the axial compression test of the unreinforced brick masonry column,the failure mode in the test process is described,and the phenomenon is analyzed.At the end of the test,the measured data are summarized,and the ultimate bearing capacity and load displacement curve distribution are obtained.(2)The axial compressive bearing capacity of brick masonry columns strengthened with low reinforcement ratio,high reinforcement ratio and four sides were tested.The failure mode was studied.The ultimate bearing capacity of brick masonry columns after reinforcement and the strain of bamboo bars under compression were tested.The load displacement curve and the load strain curve of bamboo bars were obtained.(3)The ultimate bearing capacity,load displacement curve and the change rule of the strain of the bamboo bar are compared and analyzed.It is concluded that the bamboo scrimber reinforcement mesh mortar layer to strengthen the brick column can improve the cracking load,ultimate bearing capacity and stiffness of the brick column under the axial pressure.Increasing the longitudinal bamboo reinforcement ratio,the ductility of the brick column is improved.The strengthening layer improves the crack form and failure mode of the brick column.Compared with the two-side strengthening,the four-side strengthening makes the compressive strength of the bamboo reinforcements more fully utilized.(4)According to the analysis of the test results,the calculation formula of the axial bearing capacity of the brick column strengthened by bamboo scrimber reinforcement mesh mortar layer is given.After comparison,the theoretical value is very close to the measured value.The calculation formula facilitates the application of the strengthening method in the strengthening and transformation of the masonry structure in rural areas.(5)Using ABAQUS finite element software,the model of unreinforced brick column and reinforced brick column is established.The stress-strain law of the model under axial load before and after the reinforcement of brick column is calculated and compared.The influence of the thickness of mortar in reinforcement layer,the spacing between re arranged bamboo bars and the strength of masonry mortar on the bearing capacity of brick masonry column is analyzed,and the corresponding suggestions are given.