Blast-Resistant Design Approach for RC Bridge Piers

Piers are vital structural elements that provide support to the superstructure of a bridge. However, they are vulnerable to both deliberate and accidental explosions due to their easy accessibility. The explosion's impact on the pier might potentially lead to the complete collapse of the bridge, resulting in significant loss of life and economic damage. Therefore, it is imperative to include blast-resistant design measures for the bridge pier. The current study focused on analyzing the model and design technique for blast-loaded RC piers. The study specifically included both the direct shear and flexural responses. Initially, a series of six field ground explosion tests were conducted on 1/5-scale circular and square RC columns. These tests involved the use of TNT charges with scaled lengths ranging from 0.86 to 1.22 m/kg1/3. Subsequently, numerical simulations were performed using the newly developed Structured Arbitrary-Lagrangian-Eulerian (SALE) solver. The accuracy of the FE analysis method was confirmed by comparing the experimental incident and reflected overpressure-time histories acting on the periphery of the pier. The deviations for most measuring points were found to be less than 20%. Subsequently, a total of 176 explosion scenarios were simulated using numerical methods. A model was developed to determine the distribution of blast loading on the pier caused by ground explosions. This model takes into account the shapes of the pier cross-sections (circular and square), the diameter or edge length of the pier (ranging from 0.2 to 1.6 m), the scaled distances of the explosive charge (ranging from 0.3 to 2.3 m/kg1/3), as well as the effects of blast wave reflection and diffraction by the pier. In addition, an analytical model based on Timoshenko beams was developed to represent a system with multiple degrees of freedom (MDOF). This model was verified by comparing it to both existing explosion tests on RC columns and more accurate numerical simulations of bridge piers subjected to blast loads. The differences between the model and the tests or simulations were found to be less than 5%. In conclusion, a design technique that is resistant to blasts was shown. This procedure includes the blast loading distribution and MDOF models mentioned before. It offers a dependable and effective tool for evaluating and designing bridge piers to withstand blasts.