Study On Bond Prosperity At The Interface Of Composite Column With Core Of Concrete Filled Steel Tube Round About Fire

Concrete filled steel tube reinforced concrete (CFSTRC) are implemented comprehens-nsively in the high-rise building in our country, because of it's better mechanical property, And the fireproofing design has been paid more and more attention. The condition of co-working both steel tube and concrete lies to the reliable bond prosperity at the interface of steel tube and concrete core. Researches about the bond prosperity at the interface of steel tube and concrete are non-systemic both inside and outside China, and there is nearly none about remnants bond prosperity after firing.Push-out test of CFSTRC before fire was simulated by finite element method (FEM) analysis, temperature field of CFSTRC under fire was simulated, FEM simulation method about push-out test of CFSTRC after fire was introduced, and 3 push-out tests of CFSTRC round about fire and fire tests were done, and based on the tests, the method about simulating the push-out test of CFSTRC after fire was validated.Firstly, the interaction of steel tube and concrete was involved, contact analysis theory was adopted, proper parameters were adopted, and the push-out test of CFSTRC was simulated using a FEM software (ANSYS). The results of simulated accord to the test results of literature. Based on the results of simulation, the bond mechanism between steel tube and concrete was analyzed. The restriction of steel tube to concrete effects a lot on the friction bond force.Then, temperature field of CFSTRC under fire was simulated using ANSYS, and the results were compared with the test results of literature, and the veracity of the means to simulate temperature field was validated. Based on it, three serials of members were separately compared and analyzed, including serial of time of under fire, width of CFSTRC and size of the outside diameter of steel tube. Three factors influence the temperature field a lot.Thirdly, fire tests were done for two CFSTRC members, and push-out tests were done for one member before fire and two members after fire. The phenomena of fire tests and the process of bond failure were analyzed. The bond prosperity degenerates a lot after fire, so corresponding measures should be taken to reinforce the bond prosperity. The results of the tests of the three members were compared and analyzed.Finally, the coupling of thermal-structure analysis and it's steps were introduced to simulate the push-out test of CFSTRC after fire. Based on the results of the test in this paper, proper parameters of contact analysis was adopted, and the push-out test was simulated using ANSYS, and the results of simulated were compared and analyzed, so as to validate the rationality of the method introduced in the forth chapter.