Modeling of Reinforced and Fiber-Reinforced Concrete Slabs under Impact Loads

摘要

Current modeling procedures used to investigate the performance of reinforced concrete structures under impact are almost entirely confined to hydrocode approaches (e.g., LS-DYNA). While such procedures are capable of providing highly detailed representations of reinforced concrete structures and elements, they have often met with limited success due to the fact that: i) they typically employ complex micro-modeling representations of the structure under consideration, which can be expensive in preparation and computation, ii) they often require extensive characterization of material properties which are typically unknown, or calibration against previous test data, and iii) many of the commercial programs have shown deficiencies in their abilities to adequately capture cracked concrete response, particularly with regard to brittle shear-governed behavior. This paper summarizes the application of an alternative modeling procedure for reinforced concrete slab and shell structures subjected to blast and impact loads. The nonlinear finite element program employed uses a layered thick-shell element with reinforced concrete constitutive modeling done in accordance with the formulations of the Disturbed Stress Field Model (DSFM), a smeared rotating crack procedure shown to be capable of accurately capturing the behavior of shear-critical elements under conventional static loading conditions. This approach differs from that typically used within hydrocodes and results in comparatively simple model construction and reduced computation costs. The program is used to model the response of intermediate-scale reinforced concrete and steel fiber-reinforced concrete (SFRC) slab-like elements tested under repeated high-mass low-velocity impacts. Using simple finite element meshing techniques and predefined material behavioral models requiring only basic user input, good correlation between the observed and modeled slab response was attained.