近场近地爆炸下建筑柱爆炸荷载分布规律及简化模型

Distribution pattern and simplified model of blast load for building columns under near-field near-ground explosion

为了快速评估近场近地爆炸荷载下建筑柱的动力响应和破坏模式,通过数值仿真方法,探究了近场近地爆炸工况下冲击波在建筑柱迎爆面的分布规律,并提供了该工况下的爆炸荷载简化模型。为此,首先利用已有实验数据验证数值模型,并建立典型近地近场爆炸工况的数值模型,然后研究比例爆距和比例爆高对建筑柱冲击波特征参数的影响规律,最后拟合出柱迎爆面反射冲量和正相超压持续时间的计算公式,将柱迎爆面各点爆炸荷载转化为等效三角形荷载模型,为工程实践中建筑柱遭受近场近地爆炸作用下的抗爆设计提供荷载输入。研究结果表明:当比例爆高小于0.3 m/kg1/3、比例爆距在0.4~0.6 m/kg1/3范围时,最大反射冲量沿柱高可简化为三折线分布;当比例爆距在0.6~1.4 m/kg1/3范围时,最大反射冲量沿柱高可近似简化为双折线分布;在同一比例爆距和比例爆高工况下,随着炸药当量的增加,柱迎爆面相同比例高度处反射超压峰值保持不变而反射冲量正比于当量的立方根。

To rapidly assess the dynamic responses and failure modes of the building columns under near-field near-ground explosions,in this paper numerical simulation method is employed to investigate the distribution pattern of the shock waves that are applied on the front face of building columns under near-field near-ground blast scenarios,and a corresponding simplified blast load model is proposed.To this end,firstly,the existing experimental data of overpressure and impulse were selected to validate the numerical model for blast load.Then,a typical numerical model under near-field near-ground blast scenarios was established to study the effects of the scaled distance and the scaled height of spherical charges on the characteristic values of the shock waves acting at the building columns.Finally,formulae for the maximum reflected impulse and the representative value of the positive overpressure duration were derived based on nonlinear regression analysis,and the blast load at each location of the column front face was represented by an equivalent triangular load model.The results indicate that when the scaled height of the charge is less than 0.3 m/kg1/3,the distribution of the maximum reflected impulse along the column length can be represented as a trilinear model and a bilinear model for the scaled distance of 0.4−0.6 m/kg1/3 and 0.6−1.4 m/kg1/3,respectively.In comparison,the distribution of the shock waves in the transverse direction of a column section was approximately uniform.Moreover,under a given scaled distance and a scaled height,the peak reflected overpressure remains constant as the charge weight increases,but the maximum reflected impulse is proportional to the cubic root of the charge weight at the locations with the identical scaled height of the column.