Finite element modeling of tornado missile impact on reinforced concrete wall panels
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This study describes a finite element model for the impact of large tornado missiles on reinforced concrete wall panels. The analysis predicts the dynamic response of wall panels when impacted by a missile with a large contact area such as an automobile. The development and current status of tornado-generated missiles and their impact effects on concrete wall panels are summarized along with the failure criteria for concrete material in the theory of plasticity. Quadratic finite elements are used to discretize the domain of the wall panel. Fundamental assumptions are based on the Mindlin and Reinsser's plate theories. An "embedded" model is employed to account for the reinforcing bars. The nonlinear behaviors of concrete and of steel bars are analyzed by means of rate-dependent constitutive relationships. A new strain rate-stress relationship is proposed, and the relationship between the fluid parameter 7 and the coefficient a is set up. A model is proposed to describe the initial and subsequent yield surfaces of concrete material, which avoids underestimation of the effect of high hydrostatic stresses on the yielding behavior of concrete. Ottosen's four-parameter failure criterion is used to define the failure surface of concrete. A crack monitoring algorithm accounts for post-cracking and post-crushing behavior of concrete. An explicit time integration scheme is used to solve the nonlinear dynamic equations carried out using the finite element discretization of a concrete wall panel. A computer program is developed in accordance with the above conditions.