## 1 Introduction  
With the continued growth of the global economy, transportation systems have developed significantly. As a core component of transportation networks, bridges play a critical role in national infrastructure, as well as in military and economic sectors [1, 2]. Even under exceptional circumstances, it is essential to monitor the protective status of existing reinforced concrete bridges [3, 4]. In recent years, with the intensification of international conflicts, bridges, being critical nodes in transportation networks, have become prime targets for terrorist attacks and localized warfare. Over the past three decades, global terrorist activities have shown a notable upward trend, with the \"911\" attacks standing out as the most well-known example. This event not only caused significant casualties and property damage but also had profound implications for global political, economic, and security landscapes. Due to their openness and relatively low level of security, bridges are often targeted in terrorist attacks. According to reports, between 2002 and 2008, 187 terrorist attacks on bridges occurred worldwide, with car bombs being the primary method of attack. The power and location of the explosion can result in varying degrees of damage to the bridge. The blast shockwaves can damage critical structural components of the bridge, potentially leading to functional failure or, in severe cases, the total collapse of the bridge, posing a serious threat to human life and socioeconomic development. Several incidents of terrorist attacks and accidents involving vehicles transporting flammable and explosive materials have resulted in severe disasters for bridge structures globally. For example, in 2007, the Sarafiyah Bridge in Baghdad, Iraq, was subjected to a car bomb attack, leading to its progressive collapse and resulting in the death of 10 people. In 2009, two trucks carrying butter and fireworks collided on the Fengxingpai Bridge of the Daguang Expressway in Jiangxi Province, China. The ensuing fire and explosion caused one hollow slab to break and fall, severely damaging seven others and leading to extensive destruction of the bridge. In 2023, the Sitong River Bridge in Myanmar suffered a bomb attack, destroying approximately 65 feet of the bridge deck and severing two piers. Additionally, because of the strategic importance of bridges for troop movement and material transport, military actions targeting bridges are also frequent. For instance, in 1945, the Ludendorff Bridge collapsed following sustained shelling and previous structural damage from unexploded ordnance. In 1993, during the Bosnian War, the Mostar Old Bridge was shelled by the Croatian Defence Council (HVO), eventually collapsing after enduring continuous bombardment. In 2022, during the Russian invasion of Ukraine, an explosion occurred on the Crimean Bridge, which connects the Crimean Peninsula with Russia's Krasnodar Krai, igniting seven fuel tanker cars on the railway section of the bridge and causing three fatalities, as well as partial roadway collapse. In 2023, following the October 2022 explosion of a truck on the Crimean Bridge that caused a railway tanker fire and disrupted road traffic, the Crimean Bridge was again attacked by two unmanned surface vessels, resulting in the road bridge being disabled and the death of two individuals. These attacks not only caused significant damage to the bridges themselves but also led to transportation disruptions and impeded material supplies, dealing major strategic blows to adversaries. From these examples, it is evident that transportation bridges, due to their importance in logistics and strategic mobility, have become key targets in warfare. Striking these targets can weaken the enemy's strategic capabilities and logistical support, thereby exerting a significant influence on the course of the conflict. Polyurea elastomer is a polymeric compound formed through a rapid cross-linking polymerization reaction between isocyanate components and amine compounds.