Mechanism and Prevention of Dynamic Failure of Concrete Structures Due to Destructive Earthquakes

1995年1月17日发生的神户大地震，造成了许多建筑物和建筑结构的破坏性故障。在这些破坏中，出现了一些在过去发生的普通地震中没有观察到的破坏模式，例如，许多建筑物中水平方向的裂缝产生和发展，以及钢筋混凝土结构中的压缩断裂。这些现象不能用静力学或振动力学来解释，因此，有必要从动态力学和动态断裂力学的角度进行分析，以阐明这些破坏的机理，并找出防止这些破坏的方法。本文对钢筋混凝土结构在动态荷载作用下的变形和破坏进行了数值模拟和试验研究，根据分析结果， ...更多信息 为了探讨破坏性地震作用下混凝土结构动力破坏的机理，以便采取相应的预防措施，采用双特征线法和动力有限元法对T型柱和门型柱模型进行了数值分析，在双特征线法分析中，本文介绍了一种新的处理各向异性介质中应力传播问题的算法^<（1）（5）（11）>，也可用于处理部分碰撞问题^<（3）（7）（8）>或偏心碰撞问题^<（10）>，并将所得数值结果与相应的实验结果进行了比较。结果发现，在初始和最后阶段的影响和目标介质的边界条件的施加力对时间的速率深刻影响的各向异性体中的应力集中的大小。对于矩形截面长杆的局部碰撞问题，本文提出了一种新的数值计算方法，计算出的应力集中的大小和位置与实验结果吻合较好，在DYNA 2D和DYNA 3D分析中，结果表明，结构中产生的动应力值不仅与地震动的振幅有关，由地面速度的时间导数，柱与其上部结构之间的边界条件^<（9）>。少

The Great Hansthn-Awaji Earthquake which occurred on January 17, 1995 caused destructive failures in many buildings and architectural structures. In such failures, several specific destructive patterns emerged, that have not been observed in usual earthquakes which occurred in the past.The characteristic patterns of failures due to this earthquake are, for example, the crack initiation and development in horizontal direction in many buildings, and compressive fractures in concrete structures with reinforced bars. Such phenomena are not explained by static loading and/or the vibration mechanics, therefore an analysis in the term of the dynamic mechanics and dynamic fracture mechanics may be necessary to clarify the mechanism of those failures and to find out the method to prevent them.In the present research deformation and failure of reinforced concrete structures subjected to dynamic loading were both numerically and experimentally investigated, and based on the analytical results we … More tried to c1arify the mechanism of dynamic failure of concrete structures due to destructive earthquakes such that prevention measures can be taken.Numerical analyses for T-type column models and Gate-type column models were performed by using the bi-characteristics^<(2)(4)(6)> method and dynamic finite element method, DYNA-2D and 3D^<(9)(12)> In the bi-characteristic method analyses, we introduced a new algorism to treat the stress pmpagation in an anisotropic medium^<(1)(5)(11)> and also to treat partial impact^<(3)(7)(8)> or eccentric impact problems^<(10)>, and the obtained numerical results were then compared with the corresponding experimental results. It was found that the rate of applied force against the time in the initial and final stage of impact and the boundary conditions of the target medium deeply influence the magnitude of the stress concentration in anisotropic bodies. As for the partial impact problem of long bars with rectangular cross sections, a new numerical algorithm was found to work reasonably and the calculated magnitudes and positions of stress concentration showed fairly good agreement with the experimental results.In the analyses by DYNA 2D and DYNA 3D, it was found that the values of the dynamic stress induced in the structures are affected not only by the magnitude of the oscillation of the ground motion but also by the time derivatives of the ground velocity, the boundary conditions between the column and its upper structure^<(9)>. Less