Time：5月15日 17:10 -17:35
Title: DYNAMIC RESPONSES OF REINFOCED CONCRETE STRUCTURES UNDER SUDDEN COLUMN REMOVAL SCENARIOS/柱突然失效情况下的钢筋混凝土结构动力响应研究
Abstract: To investigate structural responses under progressive collapse situations, experimental and numerical analyses of sub-assemblages under middle column loss scenario were conducted. The substructure included a two-span beam, a middle column joint and two column stubs at both sides of it. Two test series were carried out including quasi-static and actual dynamic blast-induced tests. The static tests showed development of alternate load paths in the sub-assemblages through compressive arch action (CAA) and catenary action (CA) whereas the blast tests conducted highlighted the effect of contact detonation on dynamic responses of structures. After completion of test series, physics-based finite element analyses were employed to study the behaviour of the sub-assemblage structures under dynamic regime considering various factors such as horizontal restraint stiffness and charge weight. It is concluded that the simplified static approach in lieu of dynamic analysis can be considered as a conservative method for practical design purpose. Nonetheless, this method may over-estimate structural resistance if localised damage is induced by a contact-detonation event. To model more realistic structural behaviour, two-dimensional reinforced concrete beam-column frames were tested under different boundary restraints and loading conditions, i.e. quasi-static and free-fall dynamic cases. Compared to the sub-assemblage tests, the 2-D frame specimens included two columns at both sides of the removed column with the boundary conditions simulated as either fully or partially restrained. The frame tests highlighted the development of CA in fully restrained specimens under both static and dynamic conditions, even after bottom rebars had already fractured. For the partial-restraint cases, CA was limited due to excessive inward movement of side columns.
Keywords: reinforced concrete, sub-assemblage, catenary action, compressive arch action, free-fall dynamic
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