Numerical Simulation of Responses and Failure Modes of Reinforced Concrete Beams under Drop-Weight Impact Loadings
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摘要: 钢筋混凝土在动态冲击下表现出与静态加载不同的结构响应,且破坏模式更为复杂。在钢筋三折线本构模型中引入应变率效应,利用ABAQUS显式动力分析模块,对钢筋混凝土梁在不同高度冲击下的结构响应进行了数值模拟。得到的冲击力和跨中挠度时程曲线与实验结果吻合较好,验证了模型的有效性。基于该模型,研究了配筋率分别为2.56%、2.66%和2.76%时,钢筋混凝土梁在不同冲击速度下的结构响应。结果表明:增大配筋率能够提高梁的承载能力;随冲击速度的增大,配筋率对梁抗变形能力的增强效果逐渐减弱;当冲击速度为4.85 m/s时,配筋率对梁破坏模式的影响微弱;当冲击速度大于4.85 m/s时,随配筋率的减小,破坏模式由剪切破坏转变为弯曲破坏。Abstract: Reinforced concrete structural members subjected to impact loads behave quite differently as compared to those subjected to quasi-static loading, with their failure mode becoming more complex.In this work, by introducing the strain rate effect of reinforcement in the trilinear model of the reinforcement, we simulated the structural responses of reinforced concrete beams under different impact loadings based on the dynamic analysis module of ABAQUS.The curves of impact-time and mid-point deflection-time were observed to agree well with those from the experiments.Based on this model, we simulated the responses of beams with the reinforcement ratios of 2.56%, 2.66%, and 2.76%, respectively.The comparison shows that the bearing capacity and deformation resistance of the beams increased with the increase of the reinforcement ratios; the enhancement effect of the reinforcement ratio weakens gradually as the impact velocity increases; when the impact velocity is 4.85 m/s, the reinforcement ratios have slight effect on the failure mode of beam at low impact velocities; in addition, when the impact velocity is higher than 4.85 m/s, the failure mode changes from shear failure to bending failure with the decrease of the reinforcement ratio.
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Key words:
- drop weight impact /
- reinforcement ratio /
- strain rate effect /
- reinforced concrete
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Dilation angle/(°) Eccentricity fb0/fc0 K Viscosityparameter Density/(kg·m-3) E/GPa ν 30 0.1 1.16 0.666 7 0.000 5 2 400 26.48 0.167 Reinforced grades Diameter/mm ρ/(kg·m-3) E/GPa ν Yield strength/MPa Ultimate strength/MPa HPB235 8 7 862 210 0.3 400 540 HRB335 10 7 860 200 0.3 438 687 HRB335 12 7 850 200 0.3 438 687 表 3 模拟与实验结果对比
Table 3. Comparison of results between FEM and experiment
Method Drop height (m)/Mass (kg) Impact velocity/(m·s-1) Maximum impact force/kN Maximum deflection of mid-point/mm Experiment 1.2/124 104.0 28.3 FEM -/124 4.85 149.1 30.7 Experiment 2.4/124 94.7 51.2 FEM -/124 6.86 134.7 56.5 Experiment 4.8/124 173.9 90.4 FEM -/124 9.60 181.2 102.9 表 4 冲击力峰值结果对比
Table 4. Comparison of the results of maximum impact force
Impact velocity/(m·s-1) Reinforcement ratio:2.56% Reinforcement ratio:2.66% Reinforcement ratio:2.76% Max. impact force/kN Time/ms Max. impact force/kN Time/ms Max. impact force/kN Time/ms 4.85 114 0.66 149(+30.0%) 0.6 170(+49.0%) 0.5 6.86 125 0.50 134(+7.2%) 0.5 201(+60.8%) 0.4 9.60 169 0.33 181(+7.1%) 0.3 222(+31.3%) 0.3 表 5 跨中位移峰值结果对比
Table 5. Comparison of results of maximum mid-point deflection
Impact velocity/(m·s-1) Reinforcement ratio:2.56% Reinforcement ratio:2.66% Reinforcement ratio:2.76% Max. deflection/mm Time/ms Max. deflection/mm Time/ms Max. deflection/mm Time/ms 4.85 38.26 16.0 31.72(-17.10%) 13.32 27.70(-27.60%) 12.3 6.86 68.15 25.5 56.56(-17.00%) 17.30 49.73(-27.03%) 15.6 9.60 120.33 26.0 102.94(-14.43%) 25.00 91.37(-24.07%) 21.0 -
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