The Experimental Research Of Different Loading Rates On Shear Resistance In Concrete

Concrete is a kind of material which is very sensitive to strain rate,and it will exhibit different characteristics under dynamic loading with different properties.With the change of loading rate,its bearing capacity,stiffness and toughness will also change.Currently,many scholars have studied the mechanism of shear transfer,but there are few researches on the shear transfer performance of concrete under different loading rates,and the concrete structure is inevitably affected by earth pressure,wind force and earthquake force.So the study of shear resistance is still a long way.In this paper,the shear resistance of concrete under different loading rates is studied.Which includes:(1)Considering the effect of different loading rates on the shear resistance of concrete,shear tests of reinforced concrete specimens under different loading rates were carried out,including direct shear tests and shear tests after prefabricated cracks were applied by splitting loading method.The damage characteristics and morphology of the specimen are analyzed.(2)Through the force analysis of pre-cracked specimens and un-pre-cracked specimens,the shear stress calculation formula of the specimen shear failure surface is obtained;According to the shear stress shear slip curve of the shear surface,the relationship between the splitting load-the strain curve of the steel bar and the shear stress-the strain of the steel bar.The effects of loading rate,concrete strength,cracks and loading position on ultimate bearing capacity and stiffness were analyzed.Based on the experimental results,the formulas for calculating the shear strength of concrete at different loading rates is established.(3)The speckle images in the splitting and shear tests were collected and processed.Based on the obtained strain field,the deformation and failure evolution process of the specimens and the variation of the surface strain field of the specimens were analyzed.