Research On The Collapse Mechanism Of High-Speed Rail Station With Long-Span SRC Frame

With the rapid development of high-speed railway transportation in China, the major central cities have built large railway stations. Due to the diversity of their functions and the high requirements of the accommodation space, the structure of the railway station is usually a complex and large span frame. Large railway station undertakes the heavy responsibility of the high-speed transportation hub, once its collapse occurs, there will be tremendous casualties and economic losses. Comparing with the existing anti progressive collapse analysis research which is mainly for ordinary reinforced concrete frame structure, the amount of research on such a long span steel reinforced concrete frame structure is very limited.Herein by referring to ordinary reinforced concrete structure anti-progressive collapse methods, LS-DYNA software was used with the method of nonlinear dynamics to dismantle components, numerical simulation of a typical large railway structure with fiber beam element was carried out. The analysis is aimed at researching on residual structural dynamic response in case of demolition of single bottom column, two bottom columns and three bottom columns, and studying typical frame collapse mechanism, as well as evaluating the applicability of the tying force method in Chinese anti progressive collapse guidelines for the long span SRC Frame. The main research contents and results of this paper are as follows:1. Dynamic response analysis of residual structural with demolition of angle column, the mid column of short and long side and the center column was carried out. The results of deformation of the structure show that the collapse did not occur when a column and two columns failure; When three angle columns failure, the structure collapse, and the other three conditions have not yet collapsed but have great vertical node deformations; The analysis results of the axial force of residual structure columns show that the axial pressure of the columns which are adjacent to the demolition column changes most obviously; The analysis results of the bending moment of two frames that include the demolition column show that the moment of the beam which is adjacent to the demolition column changes most obviously; The moment of the beam end which is close to the demolition column is positive, and its value gradually increases; The moment of the other beam end is negative, and its value most obviously changes.2. A typical frame was taken for analysis of the collapse mechanism. For one angle column failure, the frame structures with beam mechanism resist progressive collapse; and For one mid column failure, the mechanism is compressive arching action. For double-column failure, the case of angle columns failure and mid columns failure are with the beam mechanism to provide force for further resistance collapse. For three-column failure, the case of angle columns failure, the occurrence of collapse, before the collapse, the beam mechanism provides force; The case of three mid columns failure, axial tension appears in beam to resist collapse, namely catenary action.3. The collapse mechanism in the design of long-span SRC frame structure reference was explored. The results show that the anti-progressive collapse design of the structure which uses the beam mechanism formula in the tying force method of the Chinese guidelines can be conservative and the parameters of catenary action formula are not suitable for long-span SRC frame, if it is to be used, further research may be needed.