Experimental Research On Shear Capacity Of Reinforced Concrete Beam After Freeze-thaw Cycles

Freeze-thaw damage of concrete is one of main aging problems of our contry buildings. It has impacted on long-term use and safety operation of the buildings, meanwhile it brings huge security and economic loss to our social. Thereforce, research on shaer capacity of reinforced concrete beam after freeze-thaw cycle has an important theoretical significance and application value in whether riching the strength of concrete knowledge system or helping engineer use material strength and design concrete structure.This paper is a part of the NSFC (National Science Foundation of China) project.45different strirrup spacing beams is designed. Through the static load test, we research that different freeze-thaw cycle times and stirrup spacing have an effect upon the shear performance of concrete beams. To provide reference for the engineering application, we establish the theory calculation and standard calculation of shear capacity which is based on the experiment. This paper mainly works as follows:1. Mass loss, relative dynamic elastic modulus and ultimate compressive strength of C40concrete prism body and test cube that is produced with the same conditions of experimental beams to provide the basis for the static load test of beams.2. Observing the occurrence and development of bending fracture, shear crack and the damage form of the beams during the static load test of freeze-thaw beams.3. Rereashing the influence of difference freeze-thaw cycle times and stirrup spacing on the deflection of experimental beams, the strain of longitudinal reinforcement and stirrup, crack load and ultimate load through analying the results of static load test. The influence law is summarized.4. Truss-arch model is used to deduce theoretical calculating formula of shear bearing capacity of reinforced concrete under the action of freeze-thaw cycle and analyzing according degree of the formula with comparing with the test results.5. Considering the influence of freeze-thaw cycle on concrete, steel and the mutual influence between them, drawing comprehensive effect coefficient of Inclined section bearing capacity in the shear capacity formula of current concrete design standard. The relationship between coefficient and freeze-thaw cycles is got through the fitting.