A major part of central European infrastructure buildings was designed decades ago and has different needs of strengthening. Increasing traffic volume, increasing axle loads, and a growth in transport volume as well as more restrictive design rules are the reasons why the support regions of existing bridges and flat slabs often show a lack of punching resistance today. At the University of Innsbruck, a system for subsequent strengthening by the use of concrete screws was developed. Various laboratory tests showed that the system leads to a significant increase of punching resistance with minimal efforts for its installation. This article deals with the development of a numerical model that can predict the punching loads of unstrengthened and screw-strengthened punching plates. Further the punching loads from the laboratory tests and the simulations are compared to the predictions of a design approach. The presented novel design approach is an advancement of the existing Eurocode 2 provisions and allows the influence of the screws on the punching resistance to be taken into account. The comparison shows that the numerical model predicts the punching resistances in an appropriate way and the design approach predicts them on the safe side. The presented design approach was included into the technical assessment for the concrete screws of the system reLAST as post-installed punching reinforcement system [Z-15.1-340 (2019)] in order to be applicable in practice.

中文翻译：

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混凝土螺钉作为后安装的冲孔钢筋

中欧基础设施建筑的主要部分是几十年前设计的，有不同的加固需求。交通量的增加、轴荷的增加、交通量的增加以及更严格的设计规则是当今现有桥梁和平板支撑区域经常表现出缺乏抗冲性的原因。在因斯布鲁克大学，开发了一种通过使用混凝土螺钉进行后续加固的系统。各种实验室测试表明，该系统以最小的安装努力显着提高了抗冲击性。本文介绍了一种数值模型的开发，该模型可以预测未强化和螺钉强化冲孔板的冲压载荷。此外，将来自实验室测试和模拟的冲压载荷与设计方法的预测进行比较。所提出的新颖设计方法是对现有欧洲规范 2 规定的改进，并允许考虑螺钉对冲压阻力的影响。比较表明，数值模型以适当的方式预测了冲压阻力，而设计方法则在安全方面进行了预测。所提出的设计方法已被纳入系统 reLAST 作为后置冲孔加固系统 [Z-15.1-340 (2019)] 的混凝土螺钉的技术评估中，以便在实践中适用。所提出的新颖设计方法是对现有欧洲规范 2 规定的改进，并允许考虑螺钉对冲压阻力的影响。比较表明，数值模型以适当的方式预测了冲压阻力，而设计方法则在安全方面进行了预测。所提出的设计方法已被纳入系统 reLAST 作为后置冲孔加固系统 [Z-15.1-340 (2019)] 的混凝土螺钉的技术评估中，以便在实践中适用。所提出的新颖设计方法是对现有欧洲规范 2 规定的改进，并允许考虑螺钉对冲压阻力的影响。比较表明，数值模型以适当的方式预测了冲压阻力，而设计方法则在安全方面进行了预测。所提出的设计方法已被纳入系统 reLAST 作为后置冲孔加固系统 [Z-15.1-340 (2019)] 的混凝土螺钉的技术评估中，以便在实践中适用。