Support-induced membrane action can enhance the resistance, while altering the failure pattern, of reinforced concrete (RC) members under static/dynamic loadings. Nevertheless, the membrane effect on the load-response is regarded as a safety factor in current design guides, hence, a thorough understanding of the resistance capability of RC members in the presence of membrane actions is considered essential. To quantitatively depict the membrane behavior and its influence on the blast-resistance and failure pattern of Hybrid Fiber Reinforced-Lightweight Aggregate Concrete (HFR-LWC) beams, a specially built end-constraint clamp is developed to provide membrane actions on the structural component subjected to the blast load simultaneously. A series of field tests are conducted to investigate the dynamic behaviors of the HFR-LWC beams under close-range detonations. Overpressure-time histories of shock waves induced by the close-range explosive charge are captured. Then the deflection-responses and failure modes of the HFR-LWC beams are further investigated. The responses of the clamped HFR-LWC beam under blast loadings can be well simulated, and the blast-resistances of the beam-type members with membrane action are evaluated reasonably. The results show that membrane action is beneficial for the bridging effects of hybrid fibers and the interlocking effects of coarse aggregate, thereby giving rise to the ductile failures of HFR-LWC beam. The maximum deflections of the clamped HFR-LWC beam decrease by about 60% compared with simply-supported HFR-LWC beam in this paper, illustrating that the blast-resistance may be seriously underestimated if the membrane effects are ignored in structural design.

中文翻译：

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膜作用增强 HFR-LWC 梁抗爆性能的实验研究

支撑引起的膜作用可以增强钢筋混凝土 (RC) 构件在静态/动态载荷下的抵抗力，同时改变破坏模式。然而，在当前的设计指南中，膜对负载响应的影响被认为是一个安全因素，因此，对 RC 构件在膜作用下的抵抗能力的透彻了解是必不可少的。为了定量描述膜行为及其对混合纤维增强轻质骨料混凝土 (HFR-LWC) 梁的抗爆性和破坏模式的影响，开发了一种专门构建的端部约束夹具，以对受到的结构部件提供膜作用。同时承受爆炸载荷。进行了一系列现场试验，以研究 HFR-LWC 光束在近距离爆轰下的动态行为。捕获由近距离炸药引起的冲击波的超压时间历程。然后进一步研究了 HFR-LWC 梁的挠度响应和失效模式。可以很好地模拟夹紧HFR-LWC梁在爆炸荷载作用下的响应，合理地评价了带膜作用的梁式构件的抗爆性能。结果表明，膜作用有利于杂化纤维的架桥效应和粗骨料的互锁效应，从而引起HFR-LWC梁的延性破坏。与本文简支 HFR-LWC 梁相比，夹紧式 HFR-LWC 梁的最大挠度降低了约 60%，