Monitoring And Simulation Of Internal Deformation Of Concrete Under Freeze-thaw Cycles

Concrete needs to maintain its good service performance and appearance integrity,in some serious environments,that is,to keep the concrete structure safe,which is known as the concrete durability.In recent years,due to insufficient consideration of durability,many engineering structures underwent premature failure or lost the stability of service.The typical failure feature of concrete engineering durability in China is "the chemical corrosion in the south and the frost corrosion in the north".Therefore,the analysis of damage process and failure mechanism of concrete in different working environments has an important significance in both academy and engineering application by monitoring and investigating internal deformation of concrete in the cyclic freezing and thawing process in the cold regions of China.Firstly,the experimental method is investigated in order to monitor the internal strain of freeze-thaw concrete and the tested specimen is designed and manufactured.Correspondingly,we conduct the waterproof treatment of strain gauges,and the strengthening treatment of interface between strain gauges and concrete,as well as the calibration of testing system.Thus,the internal deformation of concrete can be monitored through the internal strain values in the freeze-thaw process of specimens and the strain can be got.Besides,we investigate the influence of concrete saturation degrees,locations,different initial temperatures and freeze-thaw cycles on the internal strains of concrete specimens.Then,we simulate both temperature and pressure fields of fully saturated concrete specimens using the finite element method(ANSYS program).By comparing the simulative and measured temperatures,it verifies the feasibility and accuracy of the simulative model of concrete suffering from freeze-thaw cycles.Further,through the simulative results of temperature stress calculated by the second strength theory,we verify the conceptual and empirical judgment that the concrete is failed at the specimen's corner owing to the maximum temperature stress.Finally,adding the above simulative pressure caused by the changing temperature to the pressure calculated through the experimental strain caused by freezing water clearly shows that the specimen's corner will become the most vulnerable location and the maximum tensile strength will reach design value of tensile strength during freezing and thawing cycle.Besides,with the increase of freeze-thaw cycles,the core of the concrete specimen will fail because of the action from both pressures.