Analysis And Reliability Assessment On Progressive Collapse Resistance Of RC Frame Structures

The performance of RC frame structures in the progressive collapse-resistance was analyzed by the alternative path method in this thesis. Fourfailure conditions relating to the independent of corner-column removed,transverse or longitudinal peripheral-column removed and interior-columnremoved were selected for the evaluation. Based on the analytical results bothin elastic and plastic methods, it was found that the linear analysis under GSAcriterion rather than the plastic method was conservative; and the robustnessof residual structure was quantified in accordance with the result from thereliability analysis in plastic equilibrium method.(1) The RC frame structures designed according to the Chinese designcode were analyzed using the structural finite-element analysis softwareSAP2000in linear elastic simulation, and the influence of beam-span, seismicgrade and the position of removed column was also discussed in thissimulation.(2) A plastic equilibrium method for static-load analysis is proposed inthis thesis. The method, which is based on the beam-slab failure mechanismand the floor ultimate load, would be more suitable for the evaluation of theprogressive collapse-resistance performance for the frame structures afterinitial failure. The advantage of the slab effected treated in this method ismuch proper than the traditional ways, which makes the proposed method notso conservative. Actually, the compressive membrane and the tensionmembrane action in the slab which was fixed supported on four sides wouldincrease the load capacity of the structure after interior-column removed.(3) The catenary action was not considered in the proposed method,which caused errors in the analysis. In order to eliminate the errors, a datebase of20beam tests was used to develop a statistical plastic hinge rotationmodel for the catenary action, and the shape of the resistant force curve in thecatenary which was either based on the straight-line mechanism or theparabola mechanism was computed, and the resistance forces in differentmechanism were derived and compared. (4) The robustness of the structure after the initial failure is important inthe evaluation of the progressive collapse-resistance performance. Thecollapse probability of RC frame structure after removing critical componentswas calculated by the structural system reliability method, and a quantitativeindex of the structural robustness was derived.