| Since the Wenchuan earthquake,China’s western region has entered a new round of seismic active period.Because of lacking reasonable calculation and seismic fortification measures,the brick masonry buildings in rural areas of the region are urgently in want of seismic reinforcement.Reinforcing birck masonry structure with embedded horizontal steel bars is a new type of reinforcement technology,whitch is discovered in the areas of Gansu、Qinghai and Xinjiang province in recent yeas.Centering on the new technology,this paper,on the basis of tests and theoretical analysis,looks into the bonding mechanism and seismic performance of brick masonry walls reinforced with embedded horizontal steel bars.The main contents and conclusions are as follows:(1)In order to study the bonding mechanism of brick masonry walls reinforced with embedded horizontal steel bars,this paper makes 75 specimens reinforced with embedded bars for pull out tests.45 are made of ordinary mortar,24 are made of high strength polymer cement mortar,and 6 are made of a new type of caulking mortar.After the pull out tests,this paper acquires the failure modes,the bond-slip curves,and the strain distribution pattern along the length of the embedded bars.Based on the analysis of the bond-slip curves and the influencing parameters,this paper puts forward the bond-slip constitutive model of brick masonry walls reinforced with embedded steel bars,establishes the bond-slip mathematical expression,and provides and proves the rationality of the parameter equation for bond-slip characteristics through comparison with test results.Besides,after analyzing the strain distribution pattern along the length of the embedded steel bars,this paper establishes the matrix equation method to solve the bond stress by strain,obtains the stress distribution along the length of the embedded steel bars,and comes up with the analytic function of the bond stress distribution.(2)In order to study the seismic performance of the brick masonry walls reinforced with embedded bars,this paper selects high strength ordinary mortar as the caulking material.In consideration of factors like the reinforcement ratio,compressive stress and earthquake damage,11 specimens of brick masonry walls,which have different aspect ratios,were carried out.Through quasi-static tests the failure characteristics,deformation capacity,shear capacity,energy dissipation capacity,hysteretic behavior,steel bars strain and stiffness degradation of the brick masonry walls were investigated.Through the analysis of the failure modes,this paper concludes that walls reinforced with embedded bars is good for seismic resistance because they could stand firm in spite of cracking in an earthquake.By analyzing the hysteresis curves,this paper obtains various seismic resistance indices(e.g.shear capacity,energy dissipation capacity,hysteretic behavior,and stiffness degradation)of the walls reinforced with embedded steel bars,and establishes the restoring force model for such walls.According to the failure characteristics of the walls,this paper proposes the calculation model of shear capacity;the theoretical results of the shear capacity obtained from the formula are in good agreement with the testing results.(3)For the brick masonry walls reinforced with embedded steel bars,this paper regards the brick masonry as an orthotropic continuum,in consideration of the bond-slip between the masonry and the embedded rebar,introduces the aforementioned bond-slip constitutive model to create a nonlinear finite element model of the walls reinforced with embedded rebar,and compares the results of the finite element numerical simulation with test results.It is discovered that the results are consistent with the test results on failure modes,shear capacity and deformation,hysteresis curves,bars stress,etc.,indicating that the finite element model established in this paper is feasible for simulating the walls reinforced with embedded bars. |
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