Scaling laws of the structural responses for RC frame structures under external explosions

Abstract

The dynamic response of reinforced concrete (RC) frame structures under external explosions is a critical concern in protective engineering. Scaled experiments are the mainstream for representing the dynamic responses and damage characteristics of prototype structures. However, it is well known that the behavior of structures subjected to blast loads may deviate from the scaling laws due to size effects. This study aims to explore the scaling laws on the structural responses of RC frame structures under external explosions, and to provide suggestions for making scaled experiments more representative to prototype tests through following the scaling laws. Initially, an external explosion test was conducted on a 1/3 scaled two-floor RC frame structure to study the typical characteristics of damage modes and dynamic responses. Subsequently, based on the design of the tested RC frames, four numerical models with scaling factors of 1/3,1/2, 2/3, and 1 were established using LS-DYNA. The similarity analysis of blast loads, damage modes and structural deformations between scaled and prototype models was carried out. The results showed that the vertical deformations of the scaled models deviated from the scaling laws. To address this issue, a modified formula for the scaling law of the vertical deformations in RC frame structures subjected to external explosions was proposed and validated. This formula was used to adjust the live loads of the scaled models and can be conveniently applied in both numerical simulations and actual experiments. The numerical results confirmed that the relative deviation of the vertical deformations between the scaled and prototype models was less than 6.8%.