近距离爆炸作用下RC桥墩毁伤模式及其轴力效应数值模拟

Numerical simulation of damage mode and axial load effect of RC bridge columns under close-in explosion

为研究近距离爆炸作用下钢筋混凝土桥墩的毁伤模式,利用显式非线性动力分析软件LS-DYNA建立了包含空气域、炸药和RC桥墩的精细化三维数值模型,通过与已有文献的试验结果进行对比,验证了有限元模型的有效性,并进一步分析了轴力效应对RC桥墩毁伤模式的影响.结果表明:近距离爆炸作用下RC桥墩的毁伤模式可归纳为无剥落破坏、剥落破坏和冲切破坏3种;对于圆柱试件,以爆炸距离0.2 m为例,当比例距离Z≥0.200 m/kg^(1/3)时,发生无剥落破坏;当0.117 m/kg^(1/3)≤Z<0.200 m/kg^(1/3)时,发生剥落破坏;当Z<0.117 m/kg^(1/3)时,发生冲切破坏.在近距离爆炸作用下,轴向荷载对RC桥墩抗爆性能的影响与其毁伤模式有关,当RC桥墩的毁伤模式是无剥落破坏或者轻微的剥落破坏时,随着轴向荷载的增加,RC桥墩的毁伤程度有所减轻;但当RC桥墩的毁伤模式是严重的剥落破坏或者冲切破坏时,随着轴向荷载的增加,RC桥墩的毁伤程度加剧.研究结果可为RC墩柱抗爆设计和毁伤评估提供参考.

In order to study the damage mode of reinforced concrete(RC) column under the action of close-in explosion, the explicit nonlinear dynamic analysis software LS-DYNA was used to establish a refined three-dimensional numerical model including air, explosive and RC columns. The effectiveness of the finite element model was verified by comparing with the existing experimental results. Furthermore, the influence of axial force effect on the damage mode of RC bridge column was analyzed. The results show that the damage mode of RC bridge column under the action of close-in explosion can be divided into three types: non-spalling, spalling and breaching. For the cylindrical specimen, taking the standoff distance of 0.2 m as an example, when the scaled distance Z is greater than or equal to 0.200 m/kg^(1/3), non-spalling occurs;when Z is greater than or equal to 0.117 m/kg^(1/3)and less than 0.200 m/kg^(1/3), spalling occurs;when Z is less than 0.117 m/kg^(1/3), breaching occurs. Under the action of close-in explosion, the effect of axial load on the blast-resistant performance of RC column is related to its damage mode. When the damage mode of RC bridge column is non-spalling or slight spalling, the damage degree of the column is reduced with the increase of axial load. However, when the damage mode is severe spalling or breaching, the damage degree is aggravated with the increase of axial load. The results can provide reference for the design and damage evaluation of the RC columns.