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Mechanical behavior of lightweight concrete structures subjected to 3D coupled static–dynamic loads
Acta Mechanica ( IF 2.3 ) Pub Date : 2020-08-12 , DOI: 10.1007/s00707-020-02739-y
S. R. Wang , X. G. Wu , J. H. Yang , J. Q. Zhao , F. L. Kong

It is of great significance in the design and evaluation of anti-impact protective structures to investigate the dynamic mechanical properties of lightweight concrete structures. The present work aims to address this challenging task by the development of an improved large-diameter split Hopkinson pressure bar that can accurately predict the dynamic compressive strength and impact failure characteristics of lightweight concrete under different stress states. Our findings exposed that the impact resistance of lightweight concrete is substantially improved and the failure modes of it have altered under the 3D coupled static–dynamic loads. When the confining pressure remains at the same level and the loading strain rate is low, the unloading curve of lightweight concrete shows a significant hysteresis phenomenon. We have further found that for a higher strain rate the stress–strain curve can be divided into five stages: (i) the inertial-effect-enhanced stage, (ii) the nonlinear elastic deformation stage, (iii) the elastoplastic deformation stage, (iv) the strain-softening stage, and (v) the plastic flow stage. Based on the linear relationships among the logarithm of the strain rate, the dynamic increase factor (DIF), and the confining pressure conditions, we have constructed a two-factor equation for the DIF of lightweight concrete that depends on the confining pressure and the strain rate.

中文翻译:

承受 3D 耦合静-动力载荷的轻质混凝土结构的力学行为

研究轻质混凝土结构的动态力学性能对抗冲击防护结构的设计和评价具有重要意义。目前的工作旨在通过开发一种改进的大直径分体式霍普金森压力杆来解决这一具有挑战性的任务,该压力杆可以准确预测轻质混凝土在不同应力状态下的动态抗压强度和冲击破坏特性。我们的研究结果表明,在 3D 耦合静态-动态载荷下,轻质混凝土的抗冲击性得到了显着提高,并且其破坏模式已经改变。当围压保持在同一水平且加载应变率较低时,轻质混凝土的卸载曲线表现出明显的滞后现象。我们进一步发现,对于更高的应变率,应力-应变曲线可以分为五个阶段:(i)惯性效应增强阶段,(ii)非线性弹性变形阶段,(iii)弹塑性变形阶段, (iv) 应变软化阶段,以及 (v) 塑性流动阶段。基于应变率的对数、动态增加因子(DIF)和围压条件之间的线性关系,我们构建了一个依赖于围压和应变的轻质混凝土 DIF 的二因素方程速度。
更新日期:2020-08-12
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