Method for the investigation of the punching shear behavior of continuous flat slabs under consideration of moment redistributions and membrane actions

钢筋混凝土板的冲剪性能100多年来一直是人们研究的重点。为了研究冲切区域弯矩和剪力之间的复杂相互作用，进行了大量的冲切试验，这些试验是建立各种冲切抗力模型的基础。由于实际钢筋混凝土板的试验非常复杂，几乎所有的冲切试验都是在孤立的试件上进行的，这些试件只模拟了所考虑的板柱节点周围的拱形弯矩区域。虽然孤立冲切试验对于系统地研究影响冲切强度的主要参数是非常有用的，但由于可能不会出现隆起和下垂弯矩的分布或压膜作用，因此该试验不适合描述实际板的行为。现有的钢筋混凝土板的冲切试验证明，冲切强度和板的变形都明显受板的连续性影响。然而，由于缺乏试验数据，将现有的冲切抗力模型扩展到一致考虑弯矩重分布和压力膜作用的影响仍然是不可能的。现有实验的另一个缺点是，由于技术原因，测试是在按比例进行的样品上进行的。因此，所研究的板的冲切行为仅受尺寸效应的轻微影响。因此，未来有必要在实际边缘条件下进行进一步的冲压试验，以一致地扩展现有的冲压模型，以反映力矩重分布和膜作用的影响。该研究项目的主要目的是在考虑板的连续性的有利影响的情况下，对板的冲切性能进行基础性研究。在第一步中，将开发自适应冲压试验装置，该装置允许通过具有变化的、载荷依赖的边缘条件的孤立试件来对平板系统的冲压行为进行实验研究。在相应的平板体系中发生的这些决定性的与荷载有关的边缘条件的控制，如压膜作用和弯矩重分布，应在分析模型的基础上通过同时计算来执行。实验研究将得到额外的数值模拟的支持，以更详细地调查和评估平板系统和孤立试件之间的差异。随后，建立了一个基于物理的冲切抗力模型，该模型考虑了弯矩重分布和压力膜作用，可以对内柱钢筋混凝土扁板的冲切强度进行真实的预测。

The punching shear behavior of reinforced concrete slabs has been in the focus of research for more than 100 years. To investigate the complex interaction between bending moments and shear forces in the punching region, a large number of punching tests has been conducted, which served as the basis for various punching shear resistance models. Since experiments on actual reinforced concrete slabs are very complex, almost all punching tests have been performed on isolated specimens modeling only the hogging moment region around the considered slab-column connection. Although isolated punching tests are very useful to investigate the main parameters influencing the punching strength in a systematic manner, the tests are not suitable to describe the behavior of actual slabs since distributions between hogging and sagging moments or compressive membrane action may not occur.The existing punching tests on actual reinforced concrete slabs prove that both the punching strength and the slab deformations are significantly influenced by the effects of slab continuity. Nevertheless, due to the lack of experimental data, the extension of the existing punching shear resistance models for a consistent consideration of the effects of moment redistribution and compressive membrane action is still not possible. A further disadvantage of the existing experiments is the fact that the tests have been performed on scaled specimens due to technical reasons. Hence, the punching shear behavior of the investigated slabs is only marginally influenced by size effects. As a consequence, further punching tests with realistic edge conditions will become necessary in the future to consistently extent the existing punching models for the influences of moment redistribution and membrane action. The main goal of the research project is the fundamental investigation of the punching shear behavior of flat slabs under consideration of the beneficial effects of slab continuity. In a first step, an adaptive punching test setup will be developed, which allows for an experimental investigation of the punching behavior of flat slab systems by means of isolated specimens with varying, load-dependent edge conditions. The control of these decisive load-dependent edge conditions such as compressive membrane action and moment redistribution, which occur in the corresponding flat slab system, shall be performed by simultaneous calculations on the basis of an analytical model. The experimental investigations will be supported by additional numerical simulations to investigate and evaluate the differences between flat slabs systems and isolated specimens in more detail. Subsequently, a physically based punching shear resistance model will be developed, which allows for a realistic prediction of the punching strength of reinforced concrete flat slabs at interior columns under consideration of moment redistribution and compressive membrane action.