Importance of shear assessment of concrete structures detailed to different capacity design requirements
Importance of shear assessment of concrete structures detailed to different capacity design requirements
复制标题
根据不同容量设计要求详细进行混凝土结构剪切评估的重要性
DOI：
10.1016/j.engstruct.2007.10.015
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发表时间：
2008
影响因子：
5.5
通讯作者：
A. Elnashai
中科院分区：
文献类型：
--
作者：
A. Mwafy;A. Elnashai
钢筋混凝土结构的剪切破坏意味着结构强度的迅速退化和耗能能力的显著损失。因此，有必要通过确保剪切供应超过与最大实际弯曲强度对应的能力来避免这种失效模式。本文提出了一种实用的、通用的方法，并在一个通用的非线性动力分析程序中实现，以预测结构构件的剪切破坏。剪切供需响应监测通过采用两种抗剪强度的方法。第一个是基于大量的实验结果，并已被证明是有效的代表剪切供应的降低与混凝土强度的退化。在剔除规范中使用的安全系数后，还选择了一个设计规范抗剪强度模型进行比较。分析模型以时间步长的方式实现，以考虑剪切-轴向相互作用，并考虑分析过程中施加的瞬时延性需求。所调查的结构实际设计和详细不同的设计地面加速度和容量设计要求，代表了广泛的当代建筑物的变化，在纵向（弯曲）和横向（剪切和限制）钢筋。一系列的非弹性反应的历史分析进行了使用一组地震记录的比例，以增加强度倒塌。在这项研究中，包括剪切作为破坏准则的抗震评估的意义得到证实。轴力的变化导致剪力供应的高波动性，降低了混凝土受压区对抗剪承载力的贡献。改进的反应的结构构件设计的现代抗震规定得到证实。剪切破坏可能是低至中等延性能力设计的建筑物的控制极限状态。这表明在设计规定，特别是那些有关梁的关键区域的改进。
Shear failure of RC structures signifies rapid strength degradation and significant loss of energy dissipation capacity. It is thus necessary to avoid this failure mode by insuring that the shear supply exceeds the capacity corresponding to the maximum realistic flexural strength. A realistic and versatile approach is proposed in the current study and implemented in a general nonlinear dynamic analysis program to allow for the prediction of shear failure in structural member. The shear demand-supply response is monitored through employing two shear strength approaches. The first is based on extensive experimental results and has proven to be effective in representing the reduction of shear supply with the degradation in concrete strength. A design code shear strength model is also selected for comparison after eliminating the safety factors used by the code. The analytical models are implemented in a time-step fashion to allow for shear–axial interaction and to account for the instantaneous ductility demand imposed during the analysis. The investigated structures were realistically designed and detailed to different design ground accelerations and capacity design requirements to represent a wide range of contemporary buildings with variations in longitudinal (flexure) and transverse (shear and confinement) reinforcement. A series of inelastic response history analyses is conducted using a set of earthquake records scaled to increasing intensities up to collapse. The significance of including shear as a failure criterion in seismic assessment is confirmed in this study. Variations of axial forces lead to high fluctuation in shear supply and decrease the contribution of the concrete compression zone to shear resistance. The improved response of structural members designed to the modern seismic provisions is confirmed. Shear failure may be the controlling limit state in buildings designed for low-to-medium ductility capacity. This suggests improvements in the design provisions, particularly those related to beam critical regions.