A Reinforced Concrete Shear Wall Building Structure Subjected to Internal TNT Explosions: Test Results and Numerical Validation

When an explosion occurs within reinforced concrete shear wall (RCSW) structures, the overpressures and duration of blast loads will be amplified by the confining effects of enclosed walls, which can cause a more severe damage to the structure than a free air explosion (FAE). However, research on RCSW structures subjected to internal explosions (IEs) are still limited and no benchmark tests exist. To provide a benchmark for studying the blast resistance of RCSW structures subjected to IEs, three Trinitrotoluene (TNT) IE field tests were conducted in this study on a 2-story, 3×3-bay, 1/3 scaled RCSW substructure, in which the overpressures, displacements, and crack patterns of RCSWs were recorded. The three tests were performed consecutively after each other on the same structure at TNT loads of 95.3g (Test-1), 253g (Test-2), and 400g (Test-3). The test results showed that the floor slab directly above the explosion and one of the RCSW confining the explosion failed in flexure (i.e., the support rotation angle exceeds 2°) in Test-2 with the scaled distance of 1.53, whilst the other three neighboring RCSWs failed in flexure in Test-3 with the scaled distance of 1.31. In addition, a detailed finite element model was established using LS-DYNA and was validated against the test results. The numerical simulation results showed that the energy released from TNT in IE scenarios (14.5 GJ/m3) was 1.95 times that in FAE scenarios (7.43 GJ/m3). The total blast loads applied to the RCSWs increased with the decrease of the area of opening. The average impulse applied to the four RCSWs were similar in IE scenarios, and the average impulse could be represented by the impulse at the center of each of the RCSWs (excluding the RCSW with window opening, as the opening is at the center). The shock and gas overpressure impulses at the center of RCSWs accounted for approximately 19.4% and 80.6% of the total impulse, respectively. Furthermore, the peak overpressures at the wall centers and the total blast loads experienced by the RCSWs under IE scenarios were 1.79 times and 11.13 times higher than those under FAE scenarios, respectively. This was due to the confinement of enclosed walls under IE scenarios. Consequently, the displacements and damage levels of the RCSW substructure under IE scenarios were much larger than those under FAE scenarios.