Study On The Arch Action And Catenary Action For RC Frame Structures To Resist Progressive Collapse

Progressive collapse of a structure refersto the condition when the failure of a local component leads to global system failure. Progressive collapse of building structures is initiated when one or more vertical load carrying members, particularly columns, are seriously damaged or collapsed due to accidental loading. Once a column fails, the building’s gravity load transfers to neighboring members in the structure. If these members are not properly designed to resist and redistribute the additional load, the rest part of the structure also fails. As a result, a substantial part of the structure may collapse, causing greater damage to the structure than the initial impact.The compression arch action and catenary action in the Reinforced Concrete (RC) frame structures for Progressive Collapse Resistant design is systematically investigated in this study.The main objectives of the research are as follows:The similarity of compression and tensile membrane action in floors is compared with arch action and catenary action in beams. For the widely used structure form, cast-in beam-slab structure, the constraint provided by the slab can be viewed as the flange for the beam. The axial constraint of the beam end has a close relationship with the development of compression arch action.For RC frame structures, when an internal column collapses and fails to carry load, the beams extended over the column turn into a two-bay beam. FEM software ABAQUS is used to investigate how the compression arch action and catenary action develop in the two-bay beam. Since there is snap-through phenomenon during the loading, modified Riks method is used to trace the whole force-displacement curve because this method has better convergence compared with other general static analysis method.During a progressive collapse, a structure will undergo three major phases: elastic phase, elastic-plastic phase and plastic limit phase. Compared the simulated results by the FEM software ABAQUS and test data obtained from experiments,the thesis analyzes parameters that affect the compressive arch action and catenary action in the two-bay beam under concentrated force in the mid-span.This study also explains how the parameters act on the load and axial force-displacement curve.The parameters include the top and bottom reinforcement ratio, the span-height ratio and the axial constraint.Finally, this research will conclude that the compressive arch effects and catenary action should be incorporated into the assessment of vulnerability to progressive collapse of the RC frame.Further study should aim at simulating the dynamic behavior of the whole structure in progressive collapse and the nonlinear behavior of beam deformation and reinforced concrete material.