Response Evaluation of Reinforced Concrete Block Structural Walls Subjected to Blast Loading

Abstract

With the introduction of the new American and Canadian standards for blast resistant design, there is a need to evaluate the response of different structural components under such extreme loads. This paper focuses on experimentally evaluating the damage levels and the out-of-plane response of fully grouted reinforced concrete block structural walls under blast loading—a load that they are typically not designed to resist. The scaled walls reported in this paper cover a range of design parameters and charge weights that reflect different vulnerabilities and threat levels. Three different reinforcement ratios and three different charge weights have been used, with scaled distances as low as 1.61 m/kg1/3 and two different boundary conditions, to evaluate the walls’ response. In general, the results show that the walls are capable of withstanding substantial blast load levels with different extents of damage depending on their vertical reinforcement ratio and scaled distance. However, brittle behavior was observed in the walls with a reinforcement ratio higher than 0.6%. This is attributed to the fact that seismically detailed (concrete or masonry) structural walls designed to respond in a ductile manner under in-plane loads might develop brittle failure under out-of-plane loads. This is a consequence of the increased concrete block wall reinforcement ratio in the out-of-plane direction compared with the same in the in-plane direction. The maximum experimental support rotation values were compared with the corresponding values predicted using an available nonlinear single-degree-of-freedom (SDOF) model presented in the Unified Facilities Criteria document. In general, the comparison between the experimentally obtained and the analytically predicted support rotation values indicated reasonable agreement. The test results are expected to contribute to the growing masonry blast performance database of experimental results and to the future development of reinforced concrete block wall design provisions under blast loading in North America, in which a balance between the wall strength and ductility might be necessary to remain below the different damage classifications specified by the performance-based design oriented ASCE and Canadian Standards Association (CSA) standards.