In-structure shock assessment and mitigation of structures
Date of Issue2012
School of Civil and Environmental Engineering
Protective Technology Research Centre
This thesis deals with soil-structure interaction effect and structural response analysis, in-structure shock assessment, and shock wave mitigation when a structure is subjected to a blast load. Dynamic media-structure interaction is analytically discussed in the background of an underground structure subjected to a soil-transmitted dynamic load, in which an interfacial damping is incorporated to represent the dynamic soil-structure interaction. The effects of the interaction are analyzed and the aspects affecting the interaction are discussed. With this soil-structure interaction, in-structure shock of a typical underground structure subjected to a soil-transmitted blast load induced by a subsurface detonation is analyzed with a simplified beam model and a rigid-body-motion included plate model, respectively. With acceleration time history of the derived structural member as excitation, shock response spectra are established to assess the in-structure shock level of the equipment attached to the buried structure. To mitigate the in-structure shock, a new design of underground structures is proposed by adding an isolation slab inside the structure. The excitation mechanism for the equipment within the structure is altered and the vertical shock level is effectively reduced. In addition, in-structure shock induced by a soil blast with non-zero rise time is also analyzed. A small scale test is designed and conducted to validate the prediction. Tests results indicate that the predictions are favorably comparable with the experiment. When subjected to a close range spherical airburst, the response of a blast mitigation cladding with metal foam core is determined by energy method. Shock theory and rigid-perfectly-plastic-locking model is adopted to obtain the response of metal foam under high velocity crushing. This prediction has practical significance since it delineates the situation of a cladding subjected to a close range detonation event with realistic boundary. Further, density gradient metal foam as core of a blast mitigation cladding is theoretically investigated with shock theory and rigid-perfectly-plastic-locking model.
DRNTU::Engineering::Civil engineering::Structures and design