This CD-ROM contains 15 papers that were presented at sessions sponsored by ACI Committees 447 and 370 at the ACI Fall 2010 Convention in Pittsburgh, PA. In this publication, engineers report on how they are approaching the challenging task of predicting the response of structures subjected to blast and impact loading. Both experimental and analytical efforts are represented, often in tandem. The analytical approaches taken include single-degree-of-freedom modeling, highly nonlinear transient dynamic finite element simulations, and coupled Lagrangian-Eulerian simulations. Papers in the publication cover the design and evaluation of new and existing structures, as well as techniques for strengthening existing structures. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-281

The numerical simulation of the response of reinforced concrete components and structures subjected to blast and impact loads are of vital interest to the design of such structures. Both researchers and designers have a wide variety of choices. Designers often focus on the usage of results from single degree of freedom analyses published in a number of design guides, such as the Unified Facilities Criteria. Researchers often tend to use finite element codes which vary from advanced hydrodynamic codes often used by Army researchers to commercially available codes such as ABAQUS® and LS-DYNA® amongst others. The primary objective of this research is to study the behavior of both high strength concrete and normal strength concrete reinforced with high strength low alloy vanadium (HSLA-V) reinforcement that meets or exceeds blast resistance criteria using conventional materials. The research presented in this paper focuses on the numerical simulation and comparison with experimental data from reinforced concrete slabs using HSLA-V steel. Two sets of experiments and the numerical simulations to compare with the experiments performed are described in this paper. The experimental work involved the fabrication and testing of two types of reinforced concrete panels namely High Strength Concrete with HSLA-V Steel Reinforcing bars (HSC-VR) and Normal Strength Concrete with HSLA-V Steel Reinforcing bars (NSC-VR). The panels were subjected to blast loadings using the Blast Loading Simulator (shock tube) at the U.S. Army Engineering Research and Development Center. Data recorded included pressures at various locations, mid-span displacements from accelerometers and laser devices, and observed damage patterns. The numerical modeling effort focused on using LS-DYNA and attempting the simulation using two commercially available material models. Results from the numerical simulation are compared with the experimental values in order to determine the accuracy of the models. The concrete material models considered were Winfrith Concrete Model and Concrete Damage Model Release 3. Both the models gave deflection values that compared well with the experimental results for normal strength concrete but gave stiffer predictions for high strength concrete.

Explosive wall breaching will be a key warfighter capability performed in future military operations by dismounted soldiers in urban terrain environments where the close proximity of urban structures, possibly occupied by non-combatants, significantly restricts the use of large demolition charges or large caliber direct-fire weapons. During the past several years, the U.S. Army has focused considerable attention toward improving methods for breaching walls in the urban combat environment. One major thrust is finding a one-step method to breach the toughest wall that regular Army units are likely to face: an 8-in.-thick, double-steel-reinforced concrete wall. The desired breaching method will produce a totally cleared, man-sized opening through the wall in a single step. Under an Army-sponsored research program, the U.S. Army Engineer Research and Development Center (ERDC) investigated new explosive wall-breaching systems and numerical techniques to model the breaching systems’ interactions with the wall targets. As a first step in this process, ERDC used simple arrangements of Composition C-4 (C4) explosive to conduct a baseline experimental study of breaching effectiveness against reinforced concrete walls. The primary goal of the numerical effort was to evaluate and validate the predictive capability of both the algorithms in the codes and the constitutive model for the concrete. Numerical simulations of selected experiments were conducted using Zapotec. Zapotec links CTH, a Eulerian shock physics code, and Pronto3D, a transient, solid dynamics Lagrangian code. In these simulations, the concrete and reinforcing steel were modeled as Lagrangian materials, and the C-4 and air were modeled as Eulerian materials. Quasi-static, high-pressure mechanical property tests, e.g., triaxial compression and uniaxial strain, were conducted on the concrete to establish the coefficients for the Microplane constitutive model that was used to simulate the responses of the concrete. This paper presents an overview of results from both the experimental efforts and the numerical simulations.

Successful modeling of the performance of concrete substructures under blast loading requires an understanding of the limits of the material model and a reasonable bounding of the anticipated results. This paper presents a case study of a prestressed bridge double tee section under both near and far range threats. A conventional SDOF analysis was employed to bound the anticipated structural response. In addition, finite element analysis was conducted in LS-DYNA utilizing three different constitutive material models for the concrete under the two loading conditions. Determining the accuracy of the finite element analysis results was found to be challenging due to the wide range of responses corresponding to the respective material models.

This paper discusses simulation methodologies used to analyze large deflection static and dynamic behavior of polymeric foam insulated concrete sandwich wall panels. Both conventionally reinforced cast-on-site panels and precast prestressed panels were considered. The experimental program used for model validation involved component-level testing, as well as both static and dynamic testing of full‐scale wall panels. The static experiments involved single span and double span sandwich panels subjected to near‐uniform distributed loading. The dynamic tests involved spans up to 30 ft tall that were subjected to impulse loads generated by an external explosion. Primary modeling challenges included: (1) accurately simulating prestressing initial conditions in an explicit dynamic code framework, (2) simulating the concrete, reinforcement, and foam insulation in the high strain rate environment, and (3) simulating shear transfer between wythes, including frictional slippage and connector rupture. Correlation challenges, conclusions and recommendations regarding efficient and accurate modeling techniques are highlighted. The modeling methodologies developed are now being used to conduct additional behavioral studies and parametric analyses, and assess and improve methodology currently used in the design of foam insulated precast/prestressed sandwich panels for blast loads.