Experimental Research And Nonlinear Finite Element Analysis On The Shearing Capacity Of Recycled Concrete Beams

It is significant to sustainable development on building industry by recycling of the construction waste. In order to vigorously develop recycled concrete in engineering, we need to study the mechanical properties and structural properties of recycled concrete.In this paper, experimental research on basic mechanical properties of three intensity levels C20, C30&C40 of recycled concrete in three different recycled coarse aggregate replacement ratio (30%, 50%&100%) was studied; three recycled concrete beams with different replacement ratio (30%, 50%, and 100%) and one natural concrete beam were cast, and analyzed the shear properties of recycled concrete beams; based on ANSYS nonlinear finite element analysis, the shear properties of recycled concrete beams in different shear span ratio and different longitudinal reinforcement ratio were analyzed. The main conclusions are as following:1. The cubic compressive strength and prismatic compressive strength of recycled concrete are higher than natural concrete basically, the strength reach the highest by the recycled aggregate contents at 30%. With recycled coarse aggregate replacement ratio increased, splitting tensile strength of recycled concrete increased up to 28%. Flexural strength of recycled concrete did not change significantly. With recycled coarse aggregate contents increase, elastic modulus reduces. For the recycled concrete by the substitution at 100%, modulus of elasticity decreased by 21.2% ~ 24.4%. Put forward the relationship between elastic modulus and compressive strength for the recycled concrete.2. The cracking load and failure load of recycled concrete beams in different replacement ratio were all less than normal concrete beams. The higher the recycled coarse aggregate replacement ratio is, the smaller oblique section cracking load is, the greater the diagonal cracks under the same load average width is, and the smaller the diagonal cracks average width is when the beams destructed.3. With the increasing replacement ratio of recycled coarse aggregate, ultimate shear capacity of recycled concrete beams decreases , up to 8.5%; with shear span ratio decreases, it increases; when the longitudinal reinforcement ratio was appropriate, increases reinforcement ratio will significantly improve the shear capacity and reduce deflection. If reinforcement ratio is too large, increases ratio of reinforcement to improve the shear capacity cannot produce significant effect.4. Based on the experimental results and regression analysis, a formula for the shear capacity calculation of recycled concrete beams was suggested.