Experimental study on damage effects of RC frame structureswith masonry walls under explosion loads

Reinforced concrete (RC) frame structures are the most widely adopted structural form in civil infrastructure, government facilities, commercial buildings and critical public premises, undertaking irreplaceable roles in normal political and economic operations. However, with the growing frequency of terrorist explosion attacks, accidental industrial and gas explosion incidents, alongside the complex and volatile global security environment, RC frame structures have become both high-priority attack targets and the critical line of defense for personnel protection. To investigate the damage effects of multiple explosion scenarios on RC frame structures, a full-scale two-story RC frame structure with infill masonry walls, designed in line with current building design codes, was constructed. A series of field explosion tests, including external and internal explosion scenarios with TNT equivalents of 11.573 kg and 20 kg, were conducted on this structure. The load characteristics of shock waves, dynamic response and failure modes of structural components were examined. The results show that under close-range external explosion, the floor slabs and masonry walls can attenuate the shock wave loads propagated into the adjacent room, with a peak overpressure reduction of 84.75%. The floor slabs and masonry walls exhibit local shear failure, while the damage to the internal components and the global structure remains limited. In contrast, under internal explosion, the floor slabs and masonry walls show global shear failure, with more severe damage compared to the RC columns and beams. In addition to the shock wave loading, the explosive ejection of wall and slab fragments from the detonation room is the primary cause of damage to the masonry walls and slabs along the shock wave propagation path. Finally, based on damage assessment criteria, the damage levels of components, rooms, and the RC structure for each test were determined. The damage severity and affected range of the RC structure under internal explosion are significantly greater than those under external explosion with the same equivalent.