Shear behavior of RC members without shear reinforcement – development of a consistent experimental, analytical and numerical characterization methodology

在过去，人们一直致力于分析无抗剪钢筋混凝土板和梁的抗剪性能。虽然已经取得了相当大的进展，一个一致的描述剪切区的行为仍然缺乏。这一事实可以记录在科学界的一个持续的争议的现象，控制剪切行为的确切作用，对他们的充分量化和适当的代表性建模approaches.The建议的研究的主要目标是填补这一空白，通过开发一个新的，理论和实验框架，可以彻底描述剪切破坏过程。该理论框架将始终捕捉剪切破坏中涉及的基本机制，包括（1）裂纹局部化，（2）裂纹扩展，（3）由于骨料互锁引起的裂纹面的压敏摩擦，（4）粘结性能，（5）销钉作用，以及（6）压缩区的非线性材料行为。所提出的建模策略将联合收割机结合临界剪切裂纹横截面沿着的分析模型（I级）和具有离散裂纹表示的剪切区的丰富有限元模型（II级）。通过以不同的细节程度和不同的计算工作量来表示剪切区行为中涉及的基本机制，将有可能在模拟的准确性和效率之间进行平衡。成功实施的建模策略将导致一个非常有效的模拟剪切区的行为，包括准确预测裂纹扩展和量化的相互作用的剪切传递贡献（残余拉应力，骨料联锁，传力杆作用和受压区剪力）在整个加载过程中。将使用具有一组一致的组件测试的测试程序对开发的分析和数值模型进行校准。除了现有的和标准化的测试设置用于识别压缩，应变软化，脱粘和销钉作用的本构关系，一个新的测试设置的表征聚集联锁沿着裂缝面将被开发。两个层次的模型的验证将提供一组钢筋混凝土梁测试监测使用高分辨率测量技术（DIC）。通过汇集两个学科的最佳实践，即结构混凝土和数值力学，这项研究将显着提高我们的洞察力剪切区行为的行为。从长远来看，它将为结构设计方法提供良好的基础，以减少材料消耗，延长使用寿命，提高工程结构的可靠性。

Large efforts have been devoted in the past to analyze the shear behavior of RC slabs and beams without shear reinforcement. Albeit a considerable progress has been achieved, a consistent description of the shear zone behavior is still missing. This fact can be documented by an ongoing dispute in the scientific community on the exact role of phenomena governing the shear behavior, on their adequate quantification and their appropriate representation in modeling approaches.The major objective of the proposed research is to fill this gap by developing a new, theoretical and experimental framework that can thoroughly describe the shear failure process. The theoretical framework will consistently capture the elementary mechanisms involved in the shear failure, including (1) crack localization, (2) crack propagation, (3) pressure-sensitive friction of the crack faces due to aggregate interlocking, (4) bond behavior, (5) dowel action, and (6) nonlinear material behavior in the compression zone. The proposed modeling strategy will combine analytical models of the cross section along the critical shear crack (Level I) and enriched finite element model of the shear zone with discrete crack representation (Level II). By representing the elementary mechanisms involved in the shear zone behavior with a different degree of detail and different amount of computational effort, it will be possible to balance trade-off between accuracy and efficiency of the simulation. Successful implementation of the modeling strategy will lead to a very efficient simulation of the shear zone behavior including the accurate prediction of the crack propagation and the quantification of the interacting shear transfer contributions (residual tensile stress, aggregate interlock, dowel action and shear in compression zone) during the entire loading history.Calibration of the developed analytical and numerical models will be performed using a test program with a consistent set of component tests. Besides existing and standardized test setups used to identify the constitutive laws for compression, strain softening, debonding and dowel action, a new test setup for the characterization the aggregate interlock along the crack faces will be developed. The validation of the models at both levels will be provided by a set of reinforced concrete beam tests monitored using high-resolution measuring techniques (DIC).By bringing together the best practices of two disciplines, i.e. structural concrete and numerical mechanics, this research will significantly enhance our insight into the behavior of shear zone behavior. In the long run, it will provide a sound basis for structural design methods with reduced material consumption, extended service life, and increased reliability of engineering structures.