Experiment Research And Theoretical Analysis On Mechanical Behaviors Of Steel Reinforced Recycled Aggregate Concrete Column After Fire (High Temperature)

Steel reinforced recycled aggregate concrete (SRRAC for shot) give full play to the advantages of steel reinforced concrete and recycled aggregate concrete. With the advantages of superior carrying capacity, high rigidity, good seismic performance, energy saving, environmental protection and sustainability, it has a broad application prospect. Domestic and foreign literatures which are about the performance degradation mechanism and evaluation theory of SRRAC after fire are still blank. The related research is very necessary and significant.The mechanical behaviors of SRRAC column after fire are research in this thesis with experimental research, numerical simulation and theoretical analysis.Firstly, the mechanical properties of recycled aggregate concrete and steel after different high temperature are tested. Indexes of physical and mechanical properties of the two kinds of materials are obtained. The mechanical properties deteriorate law of recycled aggregate concrete and steel after different high temperature with the change of temperature are analyzed. The compressive strength calculation formula of recycled aggregate concrete after high temperature is proposed.Replacement ratio, high temperature, constant temperature time, cover thickness, eccentricity ratio, reinforcement and stirrup forms for change parameters,54SRRAC column specimens are designed and tested to study their mechanical behaviors after fire. They include48axial compression specimens and6eccentric compression specimens. Ignition loss of specimens is obtained. Base on ignition loss, the estimation method of highest temperature which specimens had been suffered is proposed. Through the experiment, failure pattern and process of specimens are obtained. Section stress characteristics and failure mechanism are revealed. Load-deformation features, section strain distribution, residual bearing capacity, rigidity, ductility, damage and their degradation rules are studied. The results show that, after fire, the bearing capacity and rigidity of SRRAC column are decrease, and the ductility and damage are increase. Degradation rule of the mechanical properties are mainly affected by the parameters such as highest temperature, constant temperature time, eccentricity ratio and cover thickness eccentricity, etc.In addition, the temperature field of SRRAC column is simulated in a fire by ABAQUS software and its influence factors are analyzed. The results show that the highest fire temperature, constant temperature time and cover thickness has a great influence on the distribution of temperature field in cross section.Finally, based on the results of experimental study and numerical simulation, the mechanical characteristics and bearing capacity on normal section of SRRAC column after fire are analysis. The method of equivalent section and strength reduction are used to calculate normal section bearing capacity of axial compression and eccentric compression. The calculation results are consistent with the experimental result. And, on this basis, the evaluation method of SRRAC structure after fire was discussed.