NONLINEAR DYNAMIC RESPONSE OF PLATES ON TENSIONLESS TWO-PARAMETER FOUNDATIONS SUBJECTED TO BLAST LOADING

Abstract

This article investigates the dynamic response of plates on two-parameter elastic foundations under blast loading, specifically accounting for the nonlinear separation-recontact (uplift) phenomenon. A finite element model is developed to compare the structural behaviors of bilateral and tensionless (compression-only) foundation models. The results indicate that neglecting the foundation's tensionless nature leads to a significant underestimation of the structural response, particularly in terms of peak deflections for thin plates. Parametric studies reveal that the second foundation parameter provides a notable stiffening effect, which reduces downward displacements but can influence the maximum upward movement during the vibration phase. Furthermore, a stiffness threshold is observed as the plate thickness increases, beyond which the effects of plate-foundation separation diminish and the results of both foundation models converge. The study also confirms that the instantaneous natural frequencies of the plate are not constant but fluctuate throughout the vibration process due to the varying effective contact area. These findings emphasize the critical importance of incorporating nonlinear foundation characteristics for the accurate safety assessment and structural integrity design of plates subjected to impulsive loads.