Experimental Study On Axial Compression And Seismic Performance Of Earthquake Loss And Weakly Bonded Ancient Masonry With High Ductile Concrete Reinforcement

The masonry structure has a history of more than five thousand years in our country,the existing ancient masonry buildings are countless,which have great historical and cultural value,and are the crystallization of ancient Chinese architectural wisdom.Most of the ancient masonry structures are too old at present,and their safety and durability can no longer meet the requirements of modern people.Moreover,most of the existing ancient masonry structures did not have relevant seismic design during the design and construction,and a strong earthquake will cause a large number of casualties.Therefore,it is extremely important to repair and strengthen ancient masonry structures to improve their seismic resistance.In order to solve this difficult problem,this paper uses the advantages of High Ductile Concrete(HDC),which has high toughness,high ductility and good bonding ability with the masonry surface layer,to propose the surface layer of HDC structure to reinforce the ancient masonry structure with earthquake loss and weak bonding,and studies the axial compression and seismic performance differences of the masonry structure before and after reinforcement to promote the further application of HDC to the actual project.The maj or research achievements of this paper:(1)Through the axial compression test of the damaged and weakly bonded ancient masonry structure reinforced by HDC,analysis and research of the damage characteristics,bearing capacity and deformation capacity of the damaged and weakly bonded ancient masonry structure reinforced by high ductility concrete under axial compression.The research shows that after the HDC surface structural belt reinforces the damaged and weakly bonded ancient masonry structure,the reinforcing surface layer can produce a strong hoop effect on the masonry,improve the brittleness of the masonry structure,and greatly improve the masonry structure,and give full play to the characteristics of high ductility of the reinforcement material and improve the deformability of the masonry structure.Among them,after surface layer reinforcement of HDC structural belt,the maximum increase of peak load of specimens reached 46.9%,and the maximum increase of ultimate displacement reached 68.3%.By analysing the testing result,the calculation formula of the bearing capacity of the damaged and weakly bonded old masonry reinforced by the HDC reinforced structural belt is proposed,and the calculation results agreed well with the experimental results.(2)Through the low frequency cyclic loading test of six HDC-reinforced seismically weakly bonded ancient masonry specimens,obtain the seismic performance indexes such as the failure characteristics,hysteresis curve,skeleton curve,stiffness degradation,energy dissipation capacity and other seismic performance of the masonry structure after the HDC structural belt surface reinforcement,to study the seismic performance of the HDC structure with surface layer to strengthen the earthquake loss and weakly bonded ancient masonry structure.The research shows that the high ductility concrete structure with surface layer reinforced seismic damage and weakly bonded ancient masonry structure can still be improved on the basis of restoring the original bearing capacity of the structure,improving the brittle failure of the original structure,and the structural ductility and deformability.There is a large improvement,and the HDC structure belt surface layer reinforces the earthquake loss and the weakly bonded ancient masonry structure works well.Among them,the peak load of the ancient masonry after the HDC structural belt strengthening,the maximum increase can reach 313.4%,and the maximum increase of the ductile displacement coefficient can reach 151.3%.In addition,the total area of the HDC reinforced surface layer,the strength of the specimen masonry mortar,and the number of openings of the specimen have a significant impact on the seismic performance of the reinforced masonry structure such as stiffness,ductility,bearing capacity,and energy dissipation capacity.(3)Based on the results of the low frequency cyclic loading test of the seismically weakened and weakly bonded ancient masonry specimens strengthened by HDC,the skeleton curves of the specimens are dimensionlessly processed to obtain the equation expressions of the three-line model of the skeleton curve.By fitting and calculating the stiffness degradation law of the ancient masonry structure with weak damage and weak bonding reinforced by HDC,obtaining positive and negative loading stiffness and unloading stiffness degradation formulas,so as to establish the weak bonding of the HDC structure with surface layer reinforcement seismic damage Resilience model of ancient masonry structure.The comparison between the test skeleton curve and the calculated skeleton curve shows that the two are in good agreement,indicating that the skeleton curve restoration force model has certain applicability.