爆炸荷载下钢筋混凝土桥面板损伤机理研究

为揭示钢筋混凝土桥面板在爆炸荷载作用下的动态力学响应及损伤机理，在RHT动态本构和显式动态数值分析模型合理性验证的基础上，研究了不同TNT当量、板厚度以及钢筋直径对桥面板受爆力学性能的影响。研究结果表明：基于RHT动态本构的显式动态数值分析结果与构件抗爆试验表征一致，能够反映结构在爆炸荷载下的动态力学响应和损伤机理。TNT炸药当量是影响钢筋混凝土桥面板破坏形态的主要因素，在小当量条件下（2 kg TNT），结构发生轻微损伤，板在2个方向力学特征与单向桥面板的受力规律一致，同时应力及变形时程曲线呈自由振动特征，振动周期为3.68 ms。TNT当量逐渐增加时（5，10 kg TNT），桥面板在数毫秒内发生损伤，板在2个方向最大正应力逐渐趋于一致，损伤特征主要表现为局部冲剪破坏，刚度下降后导致其振动频率降低，振动周期分别增加至4.38，8.64 ms。TNT当量进一步增加时（20 kg TNT），结构直接发生大范围冲剪破坏，并迅速失效。板厚增加能够显著提升结构的抗爆性能，增加13%及30%时，损伤区域范围分别降低57.5%及82.5%。钢筋直径增加时，在一定范围内提升了结构刚度，但对于结构的整体抗爆性能改善并不显著。

Damage Mechanism of Reinforced Concrete Bridge Decks Under Blast Loads

In this study, the RHT dynamic constitutive model based on explicit dynamic numerical analysis was used to reveal the dynamic mechanical response and damage mechanism of reinforced concrete bridge decks under blast loads. The effects of the TNT equivalent, plate thickness, and steel bar diameter on the mechanical properties of the structure subjected to blast loads were investigated. The TNT explosive equivalent is the critical factor that influences the failure mode of the reinforced concrete bridge deck. Under a small equivalent weight (2 kg TNT), the structure is slightly damaged. The mechanical properties of the plate in both characteristic directions conform to the force law of a unidirectional plate, and the stress and deformation time-history curves exhibit free-vibration characteristics with a vibration period of 3.68 ms. When the TNT equivalent gradually increases to 5 and 10 kg TNT, the bridge slab is damaged within a few milliseconds, and the maximum normal stresses in both slab directions tend to be equal. The damage modes mainly occur as local punching and shear failure. After the stiffness decreases, the vibration frequency decreases, and the vibration periods under the 5 and 10 kg TNT weights increase to 4.38 and 8.64 ms, respectively. When the TNT equivalent is further increased to 20 kg TNT, the structure directly undergoes large-scale punching and shear failure and fails rapidly. The antiblast performance of the structure can be significantly improved by increasing the plate thickness. When the increments are 13% and 30%, the damaged area decreases by 57.5% and 82.5%, respectively. When the steel bar diameter increases, the structural rigidity improves slightly, but the antiblast performance of the structure is not significantly improved.