Research On Structural Systems Reliability Of Rigid Frame

Most of structures are statically indeterminate structures in practical engineering, so that there are an astronomically large number of potential failure paths. Hence how to identify the dominant failure paths and how to generate the structural safety margins are also the matters that should be solved. They are also the matters in this paper.The system reliability of frame structure is studied, which is elastic-plastic and statically indeterminate. The safety margins of the failure paths is generated by means of the method for automatic generation of safety margins for frame structures, and the safety margin is the linear function of random variables. The reliability indexes of members are evaluated using first order- second moment method when some members has been failed; While evaluating the reliability of failure path, a failure path is modeled a parallel system; Then the structural systems reliability is evaluated using the PENT method; At the moment the structure is modeled a series system.Because there are so many failure paths, that the dominant failure paths those are contributive to the structural systems reliability is found out is ok; when finding the dominant failure paths, the reformative measures for branch-and-bound are adopted. The result is that the time is saved and the efficiency is improved.The even loads are dealt with equivalent loads. Then the correlation of these loads is considered. At last, the safety margin formula of rigid frame structure applied by even loads is deduced. It makes the analysis of system reliability of rigid frame structure is not limited to the condition that the rigid frame structure is only suffered form the centralized loads.According the above theories FORTRAN codes are by programmed. This program can calculate the structural systems reliability of plane frame subjected to concentrated load and uniformly distributed load, where only bending moment effect is taken into account; When evaluating the structural systems reliability of spatial frame, the interaction of bending moment and axial force are taken into account.