爆炸荷载作用下材料强度设计值的确定方法

Method to determinate design value of material strength for structures under blast loads

爆炸荷载作用下,结构设计时需确定相应的材料强度设计值。该值的确定方法目前在概念层面上还存在混乱,各文献中取值不一。基于材料动力性能和可靠度理论,给出爆炸荷载作用下材料强度设计值的一般性确定方法。首先,考虑爆炸荷载作用引起的材料应变率范围,确定材料强度动力提高系数。然后基于全概率理论,即设计基准期内构件的失效概率等于该构件在此时期内各种不相容失效事件的概率和,得到构件的目标可靠指标。最后采用试算法,对爆炸荷载作用下钢筋混凝土轴拉和轴压构件进行可靠度分析,分别获得钢筋和混凝土的强度设计值,并以材料强度"综合调整系数"的形式表示,以便应用。

When designing structures under blast load,it is necessary to know the design values of the related material strength.However,the current available methods to obtain these values are,to some extent,disputed at conceptual level,which leads to various values used in published papers.Based on material dynamic performance and reliability theory,a general method was proposed in this study to determine design values of material strength under blast load.Firstly the dynamic increase factors of the material strength were obtained,depending on the strain-rate range of the materials caused by the blast load and material characteristics.Then by means of total probability theorem,i.e.,the failure probability of a component during design reference period is the sum of the probability of all incompatible failure events in this period,the objective reliability indexes of components were obtained.Finally using trial-and-error procedure,reliability analysis was performed for reinforced concrete components under axial tension and axial compression caused by blast loads.As a result,design values of strength for steel bars and concrete under blast loads were derived,which were expressed in the form of 'integrated adjustment coefficient' for the convenience of application.