Numerical simulation of reinforced concrete beams with different shear reinforcements under dynamic impact loads
Numerical simulation of reinforced concrete beams with different shear reinforcements under dynamic impact loads
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DOI：
10.1016/j.ijimpeng.2011.08.003
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发表时间：
2011-12-01
影响因子：
5.1
通讯作者：
Sharma, Akanshu
中科院分区：
文献类型：
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作者：
Ozbolt, Josko;Sharma, Akanshu
混凝土/钢筋混凝土结构的性能受到加载速率的强烈影响。钢筋混凝土结构构件在冲击荷载作用下的行为与在准静态荷载作用下的行为完全不同。这种差异归因于应变率对强度、刚度和延展性的影响以及惯性力的激活。这些影响在实验中得到了明确的证明。此外，对于表现出损伤和断裂现象的混凝土结构，破坏模式和开裂模式显著依赖于加载速率。随着加载速率的增加，破坏模式有从Ⅰ型向混合型转变的趋势。此外，理论和实验研究表明，裂纹达到临界扩展速度后，有裂纹分支。本文重点研究了不同抗剪钢筋量的钢筋混凝土梁在冲击作用下的三维有限元研究。采用速率敏感的微平面模型作为混凝土的本构关系，采用激活能理论研究了应变率对混凝土力学性能的影响。惯性力通过动态有限元分析被隐含地考虑。然而，冲击不是通过两个物体的显式建模来建模的，而是通过增加载荷点位移直到最大值并以试验报告的速率来建模的。数值研究结果表明，采用本文方法进行的数值分析可以很好地模拟钢筋混凝土梁的冲击性能。分析中预测的静态和动态反应、裂纹模式和失效模式与实验观察到的结果非常一致。得出的结论是，在冲击载荷下，在这项工作中模拟的顺序（钝头冲击，速度约为1 m/s），剪切钢筋不会被激活，因此，动态反应，不像静态反应，几乎是独立的梁中的剪切钢筋的量。然而，剪切钢筋的存在显着影响的裂缝模式和裂缝分布均匀的剪切钢筋的存在下，从而避免了剪切塞的形成。(C)2011爱思唯尔有限公司保留所有权利。
The behavior of concrete/reinforced concrete structures is strongly influenced by the loading rate. Reinforced concrete structural members subjected to impact loads behave quite differently as compared to the same subjected to quasi-static loading. This difference is attributed to the strain-rate influence on strength, stiffness, and ductility as well as to the activation of inertia forces. These influences are clearly demonstrated in experiments. Moreover, for concrete structures, which exhibit damage and fracture phenomena, the failure mode and cracking pattern depend significantly on loading rate. In general, there is a tendency that with the increase of loading rate the failure mode changes from mode-I to mixed mode. Furthermore, theoretical and experimental investigations indicate that after the crack reaches critical speed of propagation there is crack branching. The present paper focuses on 3D finite-element study of reinforced concrete beams with different amount of shear reinforcement under impact. The experiments reported in literature are numerically simulated using the rate sensitive microplane model as constitutive law for concrete, while the strain-rate influence is captured by the activation energy theory. Inertia forces are implicitly accounted for through dynamic finite element analysis. However, the impact was modeled not by explicit modeling of two bodies but by incrementing the load point displacement till the maximum value and at the rate reported from the test. The results of the numerical study show that the numerical analysis using the procedure followed in this work can very well simulate the impact behavior of reinforced concrete beams. The static and dynamic reactions, crack patterns and failure modes as predicted in analysis are in close agreement with their experimentally observed counterparts. It was concluded that under impact loads, of the order as simulated in this work (blunt impact with velocity of around 1 m/s), the shear reinforcement does not get activated and therefore the dynamic reactions, unlike static reactions, are almost independent of the amount of shear reinforcement in the beams. However, the presence of shear reinforcement significantly affects the crack pattern and the cracks are well distributed in the presence of shear reinforcement, thus avoiding the formation of shear plugs. (C) 2011 Elsevier Ltd. All rights reserved.