Modeling Steel Braces to Retrofit Concrete Structures Under the Impacts of Blast Loading

Abstract

Over the past years, Iran has been subjected to terrorist and sabotage activities. Hence, it is critical to investigate the impacts of explosions on existing buildings nationwide. As we know, most buildings constructed in different area of the country are made of reinforced concrete due to the abundance and the economic viability of materials constituting concrete. For this, the goal of this study was to investigate and model steel braces to retrofit concrete structures subjected to blast loading. To demonstrate the accuracy of the modeling process, this study used an experimental study for validation and modeling results were found to be acceptable compared to experimental results; this indicated the efficiency of ABAQUS finite element software. The study also used a one-story, single-span reinforced concrete frame with a net height of three meters and the span length of four meters, as the frame was subjected to two different blast scenarios, one two meters from the left column and the other three meters from the center of the span on the ground surface. The scenarios were carried out in the form of three 10, 50, and 100 kg charges, and then the frame intended was reinforced by three types of steel X-, V-Chevron, and Inverted-V Chevron bracing. Later, various blast scenarios were examined. Analyses were performed at the time of 2.5 ms and the results demonstrated the good efficiency of using steel braces to retrofit reinforced concrete frames against blasts. Out of the used braces, V-Chevron and Inverted-V Chevron braces were found to have higher stability against blasts, while the X-bracing showed a greater level of energy absorption. Meanwhile, the results indicated the good stability of the braces at the time of 2.5 ms. The only weakness noted pertained to the way braces were connected to the frame, as damages were noted to have affected the braces.