考虑面力效应的HFR-LWC梁抗爆理论模型与试验验证

THEORETICAL MODEL FOR HFR-LWC BEAM UNDER BLAST LOADING ACCOMPANYING MEMBRANE ACTION AND ITS EXPERIMENTAL VALIDATION

现有的抗爆设计规范通常将面力效应看作一种潜在的安全系数,而对面力作用在爆炸加载过程中的变化规律及其对结构抗力的贡献不做深入探索。该文对近距离爆炸荷载进行适当简化,并考虑面力效应的影响,建立一种基于等效单自由度(SDOF)法的梁式构件抗近距离爆炸分析模型。专门设计了一套面力加载装置,对8根考虑面力效应的混杂纤维轻骨料混凝土(HFR-LWC)梁进行抗爆试验研究,得到爆炸荷载超压时程曲线及梁的跨中位移、破坏模式等试验数据,分析了支承约束刚度、比例爆距及配筋率等对HFR-LWC梁抗爆能力和破坏形态的影响,进一步检验理论模型的可靠性。结果表明:改进SDOF模型的计算结果与试验数据吻合良好,为定量评估面力贡献和预测考虑面力效应的HFR-LWC梁爆炸动力反应提供一种有效手段。面力效应能显著提高HFR-LWC梁的抗爆性能,忽略其作用会严重低估结构的抗爆承载力。

Membrane effect is regarded as a potential safety factor in current blast-resistance design codes,but the membrane behavior and its contribution to structural resistance are not intensively investigated as yet.Based on the equivalent Single-Degree-of-Freedom(SDOF)method,a theoretical model for beam-like member under close-range blast loading accompanying membrane action is proposed.A special loading device of membrane action is manufactured in this paper,and the blast-resistant tests on 8 Hybrid Fiber Reinforced-Lightweight Aggregate Concrete(HFR-LWC)beams are performed.The overpressure history of shock wave,mid-span displacement and failure pattern of HFR-LWC beam are obtained.The influences of constraint stiffness,scaled distance of explosion and reinforcement ratio on load-carrying capacities and failure modes of HFR-LWC beam are discussed,and then the reliabilities of presented model are validated by blast-resistant tests.It is indicated that the analytical results based on the improved SDOF model are in good agreement with the experimental data,which provides a reliable tool for quantitatively estimating the membrane contribution to structural resistance and predicting the dynamic behaviors of HFR-LWC beam under blast loading accompanying membrane action.The blast-resistances of HFR-LWC beam would be significantly enhanced by membrane effect,and the ultimate resistances of beam-like member might be greatly underestimated if the membrane action is neglected.