Concrete spalling behavior and damage evaluation of concrete members with different cross-sectional properties under contact explosion

Abstract

Concrete members such as columns, beams, slabs, and walls exhibit different damage modes under contact explosion due to their different cross-sectional properties, potentially posing distinct levels of threat to structural safety. Understanding the effect of cross-sectional properties on damage to concrete members is fundamental for accurately predicting blast response and rapidly assessing damage degrees of engineering structures. In this paper, FE models for concrete members under contact explosion were established and validated. Based on the FE models, parameter analyses were conducted to investigate the concrete spalling behavior of concrete members with varying cross-sectional thickness and width under contact explosions, and the stress wave propagation character was investigated to reveal the damage mechanics of concrete members and the effects of cross-sectional properties. It is found that, on the whole, the increase of both cross-sectional thickness and width reduces the concrete spalling damage on back surface, and the increase of cross-sectional width instead of thickness reduces the concrete spalling damage on side surfaces. Both the relation between spalling angle on the back surface and cross-sectional thickness and relation between spalling angle on the side surface and cross-sectional width are linear. Increasing the cross-sectional dimension restrains the concrete damage on the side surface more effectively compared to that on the back surface. According to the concrete spalling character, a damage index and a damage classification method were proposed, and based on the numerical results, a rapid damage evaluation approach was developed for concrete members with different cross-sectional properties under contact explosion.