The strengthening of concrete structures is becoming more and more important. To achieve this need for strengthening measures, technically innovative, simple and economical systems for subsequent strengthening are required. At the University of Innsbruck, a system for subsequent strengthening of the punching shear zone through the installation of concrete screws has been developed. These screws are installed from the soffit side of the slab in vertically predrilled holes and are arranged concentrically around the support. This paper discusses the results of four test series, with a total of 21 specimens used to develop the system. The system, which can be very easily installed, demonstrates a significant increase of the shear punching capacity and a reduction in brittle failure modes. In addition, cyclic loading with typical levels of service load has no negative effect on the effectiveness of the system. Finally, the influence of the flexural reinforcement ratio on the effectiveness of the strengthening system was investigated.

中文翻译：

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混凝土螺钉作为后安装的冲剪钢筋

加强混凝土结构变得越来越重要。为了满足这种加强措施的需要，需要技术上创新，简单且经济的系统来进行后续加强。在因斯布鲁克大学，已经开发了一种通过安装混凝土螺钉来随后加强冲剪区域的系统。这些螺钉从平板的拱腹侧安装在垂直预钻的孔中，并同心地围绕支撑布置。本文讨论了四个测试系列的结果，总共使用了21个样本来开发该系统。该系统可以很容易地安装，证明了剪切冲孔能力的显着提高和脆性破坏模式的减少。此外，具有典型服务负载水平的周期性负载不会对系统的有效性产生负面影响。最后，研究了抗弯配比对增强体系有效性的影响。