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Study on mechanical behavior of rockfall impacts on a shed slab based on experiment and SPH–FEM coupled method
Structures ( IF 3.9 ) Pub Date : 2021-05-20 , DOI: 10.1016/j.istruc.2021.05.021
Hanqing Zhong , Liang Lyu , Zhixiang Yu , Chun Liu

The mechanical behavior of rockfall impacts on shed slabs was studied in three aspects: the rockfall impact force, the inertia effect coefficient, and the structural damage evaluation. A test model composed of a concrete slab and a cushion layer was constructed. Nine batches of impact experiments with energies ranging from 50 to 250 kJ were conducted. The dynamic impact model was established using LS-DYNA to analyze the dynamic impact response characteristics and inertia effect based on the SPH–FEM coupled method. Moreover, random sample expansions were calculated, and methods for assessing the impact force and inertia effect coefficient were proposed. In addition, the applicability of the proposed equation was verified by comparing the calculated results with relevant published experimental data and the Japanese calculation method of impact force. Furthermore, the velocity and mass of the rockfall were selected as the main control variables for damage assessment. A damage assessment index based on punching bearing capacity was established, and the level of damage was classified. Additionally, the influence of the parameters of the concrete slab and cushion layer thickness on damage assessment was analyzed. The impact resistances of the Ultra-High Performance Concrete (UHPC) and normal concrete slab were compared. The results demonstrated that the effect of impact force and the concurrent impact-induced inertia effect should be considered in structural designs. The larger the mass rockfall, the greater the damage sustained by the slab under the same impact energy. The compressive strength of concrete and the yield strength of steel have the greatest and least influence on the damage degree, respectively. A 90 cm-thick sand cushion on a slab increases the impact resistance of the slab by 25%–30%, compared with a 60 cm-thick sand cushion layer. Moreover, it was found that the UHPC concrete slab has good impact resistance, which is approximately twice that of the C40 concrete slab. One of the highlights in this paper is that the SPH–FEM coupled method is proposed to reproduce the physical phenomenon of sand pit-forming. Compared with FEM, SPH–FEM generates a simulated value that is closer to the experimental value.



中文翻译:

基于实验和SPH-FEM耦合方法的落石冲击棚板力学行为研究

从三个方面研究了落石冲击对棚板的力学行为:落石冲击力,惯性效应系数结构损伤评估。建立了由混凝土板和垫层组成的试验模型。进行了9批能量在50到250 kJ之间的冲击实验。基于SPH-FEM耦合方法,使用LS-DYNA建立了动态​​冲击模型,分析了动态冲击响应特性和惯性效应。此外,计算了随机样本扩展,并提出了评估冲击力和惯性效应系数的方法。此外,通过将计算结果与相关的公开实验数据以及日本的冲击力计算方法进行比较,验证了所提方程的适用性。此外,选择落石的速度和质量作为破坏评估的主要控制变量。建立了基于冲孔承载力的损伤评估指标,并对损伤程度进行了分类。另外,分析了混凝土板和垫层厚度等参数对损伤评估的影响。比较了超高性能混凝土(UHPC)和普通混凝土板的抗冲击性。结果表明,在结构设计中应考虑冲击力和同时发生的冲击惯性效应。质量落石越大,在相同的冲击能量下,平板承受的破坏越大。混凝土的抗压强度和钢的屈服强度对损伤程度的影响分别为最大和最小。平板上90厘米厚的砂垫可将平板的抗冲击性提高25%–30%,与60厘米厚的沙垫层相比。而且,发现UHPC混凝土板具有良好的抗冲击性,大约是C40混凝土板的抗冲击性的两倍。本文的重点之一是提出了SPH-FEM耦合方法来重现砂坑形成的物理现象。与FEM相比,SPH–FEM生成的模拟值更接近实验值。

更新日期:2021-05-20
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