Experimental and numerical investigation of dynamic progressive collapse of reinforced concrete beam-column assemblies under a middle-column removal scenario

One static and four dynamic collapse experiments have been conducted on beam-column assemblies under a middle-column removal scenario to investigate the dynamic collapse responses. All the assemblies had identical configurations, materials, and boundary conditions. Numerical analyses were conducted for an in-depth comprehension of different behaviors of the assemblies under static and dynamic collapse scenarios. To ease the assessment of the dynamic collapse responses of the beam-column assemblies, a new assessment procedure was proposed based on the energy-method and was proved to be efficient and accurate by comparing with the experimental and numerical results. Research indicated that the dynamic collapse behaviors of the assemblies were influenced by two key factors, i.e., the dynamic stress distribution characteristics and the material strain rate effect. Under the dynamic collapse scenario, the structural resistance of the assemblies was impaired during the stage of compressive arch action (CAA) due to the dynamic stress distribution characteristics. Whereas the material strain rate effect could enhance the resistance in the stage of the catenary action (CA). Moreover, both factors contributed to increasing the largest deformation of the assemblies. The dynamic amplification factor (DAF) was also evaluated based on the proposed assessment procedure and the traditional one. At the critical deformations during the CAA and CA stages, the DAFs obtained through the proposed procedure were found to be greater than those determined by the traditional procedure in which the dynamic stress distribution characteristics and the material strain rate effect were both neglected. Further, the DAFs suitable for practical engineering design were also discussed.