Six normal and high-strength reinforced concrete slabs were subjected to simulated blast loading using a Blast Loading Simulator at the U.S. Army Corps of Engineers, Engineering Research and Design Center. A blind prediction contest was sponsored to evaluate the effectiveness of various modelling approaches to predict the blast response of the normal and high-strength concrete slabs. This paper describes a contest submission in the single-degree-of-freedom (SDOF) category generated using software program RCBlast. RCBlast was developed to perform inelastic analysis of structural members subjected to blast-induced shock waves. The program uses a lumped inelasticity approach to generate resistance functions for SDOF analysis. Incorporated into the development of the resistance functions were: material models and dynamic increase factors (DIF) appropriate for normal and high-strength concrete and steel reinforcement; member modelling capable of describing the gradual formation and progression of plastic behavior, and; hysteric modelling to account degradation in stiffness and energy dissipation.

The aim of this research is to study the blast load response of different types of one way reinforced concrete slabs. The slabs include two material combinations based on their strength namely, the High-Strength Concrete with High-Strength Steel reinforcing bars (HSC-V) and Normal-Strength Concrete with Normal-Strength Steel reinforcing bars (NSC-R) and also two different reinforcement ratios. Experimental data obtained from tests conducted on 12 reinforced concrete slabs in a shock tube (Blast Load Simulator) were used to perform advanced finite element analysis to study the behavior of these slabs subjected to blast loading. Finite element models of these 12 slab panels are developed in LS-DYNA and the blast pressures equivalent to those generated in the experiment are applied on them. The response of material combinations to blast loading is studied using two different concrete models available in LS-DYNA namely, Winfrith Concrete Model (WCM) and Concrete Damage Model Release 3 (CDMR3) with steel being modeled using a plastic kinematic model and the results are compared with experimental data. Compared to NSC-R slabs, the experimental deflection of HSC-V slabs was lower by 9% for slabs with the higher - 0.68% - reinforcement ratio. For the slab with the lower - 0.46% - reinforcement ratio, the experimental deflection was lower by 5% for HSC-V slabs compared to NSC-R slabs, indicating that the usage of high strength materials marginally improved the deflection response of the slabs

Simulation of structural behavior of Reinforced Concrete (RC) subjected to shock loading is an important aspect of blast-resistant design of military and civilian structures. Depending on the application, different analytical approaches of varying complexities can be used to predict the nonlinear response of various concrete elements to blast loads. This paper reports the findings of a comprehensive study submitted for a Blast Blind Prediction Contest that involved various simulations of blast-loaded concrete slabs. The NSF in collaboration with ACI-447 and ACI-370 committees, Structure-Point and UMKC/ SCE sponsored the contest that included four categories requiring the use of Single Degree Of Freedom (SDOF) and physics-based (HYDROCODE) simulation techniques to predict the responses of one-way reinforced concrete slabs to two levels of blast loading. The study investigated the varying blast response characteristics associated with the use of two classes of concrete, Normal and High Strength and two classes of reinforcement, Normal and High Strength Vanadium. A testing program that encompasses all contest categories was completed at the Blast Loading Simulator (BLS) at the ERDC/ USACE, Vicksburg, MS to collect relevant shock loading and structural response data for various testing configurations. Various SDOF tools (i.e. P-I curves, UFC-3-340-02 charts, RCBlast, and RCProp/ SBEDS) and HYDROCODE constitutive models (LS-DYNA MAT-159, MAT-085, and MAT-072R3) were utilized to simulate various test setup information in order to predict maximum and residual responses and cracking patterns of tested RC slabs. Despite their major differences in modeling capabilities, analytical efforts, and inherent accuracy, all utilized simulation techniques were successful in predicting blast responses of investigated RC slabs with sufficient practical accuracy. Acknowledging their modeling limitations, SDOF simulations exhibited excellent capabilities in predicting overall behavior and maximum responses with a level of accuracy that is well suited for design applications. On the other hand, HYDROCODE simulations proved superior in their response and damage predictions owing to their modeling capabilities that allowed realistic end conditions, material nonlinearities, and strain-rate effects.

The structural response assessment of reinforced concrete slabs subjected to impulsive loads due to a detonation of an explosive is an essential task for the design of blast resistant concrete structures. Nonlinear dynamic finite element methods and analytical modeling provide a valuable tool for predicting the response and assessing the safety of a reinforced concrete component. The proposed Finite Element analysis and analytical modeling approaches were validated using a series of shock tube tests conducted on conventionally constructed and high strength reinforced concrete slabs by the University of Missouri Kansas City at the Engineering Research and Design Center, U.S. Army Corps of Engineers in Vicksburg, Mississippi. The aim of the paper is to present the modeling techniques adopted in both the Finite Element and analytical modeling approaches in order to conduct the structural response assessment of RC slabs subjected to impulsive loads due to detonations. The numerical modeling was conducted utilizing LS-Dyna® finite element software package. The analytical approach utilized a fiber analysis method coupled with a single degree of freedom time stepping method. The constitutive models, loading and boundary conditions utilized are discussed in detail.

A batch of blast resistance reinforced concrete slabs were tested in the shock tube facility at the University of Missouri Kansas City (UMKC). Based on the results from the tests, a blind numerical simulation contest was announced by UMKC in collaboration with the American Concrete Institute (ACI). The authors of this paper participated in the contest and received the test results only after completing their simulations. In this paper two basic numerical approaches are described. The first is a preliminary section rigidity assessment and the second is a full numerical simulation performed with the LS-DYNA code. The numerical results are compared with the UMKC test results and the influence of the numerical parameters is further discussed. The section rigidity assessment approach is then used to explain some unexpected results.