Shear capacity of reinforced concrete one-way slabs without shear reinforcement under single loads

现有的无抗剪钢筋混凝土板的抗剪承载力模型大多是基于梁的抗剪性能的认识而建立的。板在单一荷载作用下的承载性能被认为是由不同的方法的有效宽度，捕捉实际的承载性能不够。根据最近的研究，剪跨高比和荷载传递的影响，由于直接压缩支柱不同的板和梁。特别是，取决于静力系统和弯矩-剪力比的剪切作用和有效宽度之间的相互作用似乎是有意义的。在同时作用单一和线荷载的情况下，由于弯曲产生的较大压缩力的影响尚不清楚，特别是对于带有倾斜压缩压杆的加腋板，研究项目的总体目标是分析单向混凝土板在单一荷载作用下的抗剪承载力，并建立一个一致的抗剪承载力模型。特别是，应研究支撑条件、约束程度和静力系统（悬臂板、单跨和多跨板）、剪跨高比和配筋率对单个荷载的荷载传播和抗剪承载力的影响。通过对板带和宽板的试验，评价了有效宽度的影响。此外，还应分析多个单一荷载的相互作用。通过实验和理论研究解决了这些悬而未决的问题。理论研究的出发点是剪切设计的现有模型。基于文献中的板在单一荷载下的剪切试验，建立了一个数据库，以评估现有的方法。实验研究扩展了迄今为止尚未研究的参数数据库。通过对非线性有限元模型的试验和参数研究，量化了弯矩-剪力相互作用对受剪承载力的不同贡献。结合实验测试数据，提供了一个足够的数据库，允许开发一个扩展模型的混凝土板在单一荷载下的抗剪承载力。

The present models for the shear capacity of reinforced concrete slabs without shear reinforcement were mostly developed based on the knowledge of the shear-bearing behaviour of beams. The slab-loadbearing behaviour under single loads is considered by different approaches for an effective width, which capture the actual bearing behaviour insufficiently. According to recent research, the influence of the shear-span-to-depth ratio and the load transfer due to a direct compression strut differs for slabs and beams. In particular, the interaction between arching action and effective width for shear depending on the static system and the moment-shear ratio seems to be of significance. In case of simultaneously acting single and line loads, the influence of the greater compression force due to bending is not clarified, especially for haunched slabs with inclined compression struts.The overall objective of the research project is to analyse the shear-bearing behaviour of one-way concrete slabs without shear reinforcement under single loads and to develop a consistent model for the shear capacity. In particular, the influences of the support conditions, the degree of restraint and the static system (cantilever slab, single- and multi-span slab), the shear-span-to-depth ratio and the reinforcement ratio on the load spreading of a single load and the shear capacity should be investigated. By tests on slab stripes and wide slabs, the influence of the effective width is evaluated. In addition, the interaction of multiple single loads should be analysed. The open questions are adressed by experimental and theoretical investigations. Starting point for the theoretical investigations are the present models for shear design. Based on the shear tests on slabs under single loads from literature, a database is established in order to evaluate the existing approaches. The experimental investigations extend of the database for parameters, which have not been studied so far. By evaluation of the tests and parameter studies on nonlinear finite-element models, the different contributions to the shear capacity depending on the moment-shear interaction are quantified. In combination with the experimental test data a sufficient database is provided allowing to develop an extended model for the shear capacity of concrete slabs under single loads.