Experimental Research On Reinforced Concrete Bending Members Under Freeze-thaw Cycles

As the dominant structure in the infrastructure construction,concrete structures have been widely used in numerous fields,as a result is that the environment concrete structure was exposed to become more and more complicated.The influence caused by freezing and thawing damage,one of the main factors, performed increasingly prominent.At present,agreat deal of important results have been acquired about the experimental reach on the action of concrete under freeze-thaw cycles,but systemic study on the characteristic of reinforced concrete bending members is so little, so it is significant for both theory and application to study on reinforced concrete bending members under cyclic freezing and thawing.As a part of the project of Natural Science Foundation of China "reaserch about mechanical performance of reinforced concrete and pretsressed concrete structure under freeze-thaw cycles "(50978224), experiments on deformation and strength of reinforced concrete beams, a total of48beam elements, whose strength degree were geared to C40、C50after different cycles of freeze-thaw cycling under static Load were made. Based on the comparison between experimental results of specimens after freeze-thaw cycling and that in normal environment, failure criterion of concrete component after freeze-thaw cycling is established. Main researchful contents in this paper are as follows:1. Freeze-thaw cycling experiments of Concrete test specimens100×100×100mm3and heteromorphic concrete specimens100×100×400mm3were made.Cycles of freeze-thaw cycling include50,100and125. Weight loss and dynamic elastic moduli are measured.2. Experiments on uniaxial compression under normal environment and after freeze-thaw cycling were made using universal test system for concrete.3. Through static load tests, we carry out the bearing capacity、cracking moment and stiffness of the components under different times of freezing and thawing cycles.The studied result shows that the influence of reeze-thaw cycling and class on basic properties of concrete is obvious. With the increasing of the cyclic number,the capability of basic concrete declines obviously. Under the same number of freeze-thaw cycling, Increase of concrete level slows down the descent velocity.