Response of Reinforced Concrete Bridge Columns Subjected to Blast Loads

TLDR

Most blast‑resistance research focuses on buildings, yet bridges present unique challenges—open access, direct loading, and proximity to blast threats—that complicate standoff and expose components to large blast loads. The study aimed to investigate blast‑loaded concrete bridge members through experimental and computational research funded by the National Cooperative Highway Research Program. Finite‑element models were used to explain the cross‑sectional response mechanisms that cause side‑cover spalling in slender reinforced concrete members by reproducing the experimental behavior. Experimental tests revealed previously undocumented side‑cover spalling of reinforced concrete walls under blast loads, a phenomenon not reported in earlier literature.

Abstract

The vast majority of past research on blast-resistant structural design focuses on buildings, with limited attention directed specifically towards bridges. Although many of the same principles apply, bridges pose unique challenges that are not often encountered when designing buildings for blast resistance. Specifically, establishing standoff with bridges is difficult because they are intended to provide open access to the traveling public, and structural components are directly loaded rather than having loads transferred to them through a facade system. Thus, relative to buildings, bridge components may be exposed to large blast threats that can be in close proximity to the potential target. To address these unique challenges, experimental and computational research was carried out, through support from the National Cooperative Highway Research Program (NCHRP), to understand the behavior of blast-loaded concrete bridge members. Although spalling of concrete cover off the back of reinforced concrete walls subjected to blast loads is a well-understood phenomenon, specimens experimentally tested for the current research exhibited spalling of side-cover concrete, which previously has not been reported in the research literature. Using detailed finite-element models, this paper explains the cross-sectional response mechanisms that cause spalling of side-cover concrete in blast-loaded slender reinforced concrete members by numerically reproducing the behavior observed during the experimental testing program.