Study On Safety For Cast Steel Joints Of Jiangbei International Airport In Chongqing

Cast steel joint is a new type of structural joint developed with the application of the large-span steel truss. Cast steel joint has clear and direct load transferring path and great bearing capacity, and it can reduce the influence upon the internal force of the structure by the secondary stress of the joint plate and the joint sphere. Owing to its special and excellent performance, cast steel joint has a wide application in the construction of the large-span steel truss abroad, and it has a stepwise generalization inland. Whereas the design methods about cast steel joint are not mature, it is necessary that the corresponding application study be made. Entrusted by the project headquarters of Jiangbei international airport in Chongqing, this dissertation finishes the study on the appraisement for the safety of the cast steel joints in the steel truss of Jiangbei international airport. So far, the design methods about cast steel joint are not mature inland. The cast steel joint is under a complicated mechanical condition when it subjects to the actual load. Therefore it is very necessary that the experimental study on the large-scale and shape-complicated cast steel joint. Limited by the experimental equipment of the structural laboratory, the previous analogical experiments are almost model experiments, the reduced scale effect and the difference between the laboratory and the local of the construction cause the inaccurateness of the experimental result. In this experiment, combining the schedule of the construction, the track test on the cast steel joints of Jiangbei international airport in situ is finished. And besides, the support restraint condition and the loading procedure are approximate to the actual state, so the test result is authentic. Considering the limit of the modeling function of ANSYS program, it is difficult to build the solid model of the cast steel joint with complicated shape. In the analysis, finite element models built in Pro/E program are inducted into ANSYS program for elastic FEA, and then the stresses on the surface of the cast steel joint are obtained. On condition that both the test value and the calculated value match well, the inner stress distribution can be deduced by the FEA result. Checking the Mises Stress from FEA result, the conclusion can be drawn that the cast steel joint is always in the elastic state but not into the plastic state, which is in accord with the calculating hypothesis. Additionally, based on the FEA considering the typical detect of the cast steel joint, the effect of the defect upon the mechanical behavior of the joint is inferred. Finally, combining the test and the FEA, the mechanical behavior of the cast steel joint is revealed, and its safety is assessed, and the strength criterion is determined. The study result of this dissertation can be adopted as reference for similar structure and it can be adopted as basic material of the code for design of cast steel joint in compiling.