| The historic buildings used masonry,raw soil or the raw soil of outsourcing masonry structure are widely distributed in our country.On account of the natural disaster and man-made sabotage during the past long time,there are varying degrees of damage about the most existing masonry buildings.In addition,other causes such as material weathering exacerbate the reduction of the structure bearing capacity.With the development of economy and culture in China,people take the protection of masonry buildings more and more seriously.However,existing protective methods can hardly satisfy the requirement to protect historic building performance,We need to find a method to enhance the structure performance which can cause minimum affect on appearance and historic information of historic buildings.This paper,aiming at main characteristic about masonry structure performance reinforcement of historic buildings,proposed a mortar joint injection permeability reinforcement method on the basis of analyzing the existing protection methods advantages and disadvantages,and researched for the effect on masonry walls’ anti-seismic performance of historic buildings after using this method based on experiment.The main research contents and results are as follows:(1)Referencing to 3 common masonry structure materials of historic buildings named lime,sticky rice mortar and hemp mortar,designed and fabricated 3 groups of 54 cubic specimens and 3 groups of 54 prism specimens,each group includes 6 briquettes without reinforcement,6 methyl methacrylate reinforced briquettes and 6 epoxy resin reinforced briquettes.Through mechanical properties test,comparatively study the failure mode,cube compressive strength,stress strain curve,and elasticity modulus of the mortar briquettes above-mentioned.And discuss the strengthening effect of the two different reinforcing materials above.The results showed that methyl methacrylate and epoxy resin can enhance the briquettes strength,enlarge elasticity modulus,and the former can obviously enhance the mechanical properties of lime briquettes,and epoxy resin perform better on sticky rice mortar and hemp mortar briquettes.(2)In order to reflect the characteristics of historic buildings masonry structures as much as possible,used old bricks of low-grade and some weathering and sticky rice mortar,designed and built 2 groups of 18 masonry specimens including 6 specimens without reinforcement,6 methyl methacrylate reinforced specimens and 6 epoxy resin reinforced specimens.Through the masonry compressive strength test,comparatively analysed the failure mode,compressive strength,and elasticity modulus of the reinforced specimens and non-reinforced specimens,and built the relevant compressive constitutive relation.The test results showed that with methyl methacrylate and epoxy resin,the masonry specimens compressive strength enhanced by 22.7% and 35%,and the elasticity modulus enhanced by 10.7% and 22.6%,the reinforced effect is obvious.(3)Based on the above research results,designed and built two groups of wall specimens with different thickness.The first group includes one briquette without reinforcement,one epoxy resin reinforced briquette,and one methyl methacrylate reinforced briquette,average wall thickness is 240mm;the second group includes one briquette without reinforcement and one epoxy resin reinforced briquette,Wall thickness is 370 mm.Under low cyclic loading experiments,studied the failure process,seismic performance of reinforced specimens and non-reinforced specimens,and the reinforcement effect of wall thickness.Comparatively analysed the shear bearing capacity,ductility factor,and energy-dissipating capacity of the wall specimens.The result showed that for wall specimens with same thickness,with methyl methacrylate and epoxy resin material,ultimate load were increased by 19% and 29%,ductility coefficient were increased by 42% and 31%,energy dissipation capacity are improved obviously and the method is feasible.The epoxy resin material enhancement effect is slightly reduced with the thickness of wall increasing.(4)Using the finite element analysis software of ANSYS and corresponding constitutive relations,established the integral finite element models of 3 walls including non-reinforced,epoxy resin reinforced and methyl methacrylate reinforced.Through the analysis of a series of numerical mode,this paper studied the skeleton curves and failure forms and compared with the test results,its stress characteristics are consistent with the experiment.The results showed that the constitutive relations and finite element analysis model was reasonable and the result was reliable,which can provide a reference for the analysis of the anti-seismic performance of such structure. |
