Simulating offset blast loads experimentally using shake‐table‐generated ground motions: Method development and validation

The experimental investigation of the effects of blasts and other impulsive‐type loads on large‐scale structures provides valuable data to inform design decisions for structures and structural control devices; however, this type of testing presents significant security, safety, logistical, and economic challenges. In particular, only a limited number of facilities are capable of blast testing of large‐scale structures. In contrast, many structural engineering and structural control research projects now employ shake‐table testing. With this in mind, the authors have developed a technique to experimentally simulate the global response of a large‐scale, flexible structure subjected to blast loading using a shake‐table‐produced ground motion. A ground motion profile designed for experimental blast simulation is proposed, and an algorithm for shaping this ground motion, based on near equivalence of modal energy distribution, is presented. Validation is performed through a set of experimental studies on a laboratory‐scale nine‐story structure outfitted with a passive nonlinear structural control system. In the first part of the validation, explosive blast testing of the structure was performed at the US Army Corps of Engineers, Engineering Research and Development Center, Big Black Test Site; and in the second part, shake‐table testing of the same structure using a synthesized ground motion was performed at the US Army Corps of Engineers, Engineering Research and Development Center, Construction Engineering Research Laboratory. Comparison of the two studies demonstrates that an appropriately designed, shake‐table‐produced ground motion can be employed to experimentally simulate the global response of a structure subjected to blast loading with reasonable accuracy with and without a nonlinear structural control system.