Eccentric punching tests on column bases – New insights into the inner concrete strain development
Eccentric punching tests on column bases – New insights into the inner concrete strain development
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DOI：
10.1016/j.engstruct.2022.114273
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发表时间：
2022-07
影响因子：
5.5
通讯作者：
J. Ungermann;Philipp Schmidt;M. Classen;J. Hegger
中科院分区：
文献类型：
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作者：
J. Ungermann;Philipp Schmidt;M. Classen;J. Hegger
过去，尽管工程实践中经常出现偏心载荷，但主要研究中心受力柱底座的冲剪性能。为了考虑柱周围相应的不均匀剪应力分布，许多设计方法定义系数以增加作用载荷。由于偏心冲压测试的测试数据有限，无法可靠地评估设计方法。为了填补试验结果的这一空白，进行了四次中心加载和十四次偏心加载冲裁试验，以分析系统分级的载荷偏心的影响。试验揭示了载荷偏心对冲裁剪切能力和承载性能的显着影响。随着偏心率的增加，裂纹形成转移到更高负载的一侧，并伴随着不完全发展的冲孔锥体。对板中应变的创新测量可以分析混凝土内部的周向多轴应力状态。与中心加载的柱底座相比，该压缩环在偏心载荷下不会完全展开。基于这些测量的切向应变，导出了一种描述载荷偏心对冲剪强度影响的实验方法，并与欧洲规范 2、模型规范 2010 和下一代欧洲规范 2 的稳定版本的设计方法进行了比较。总体而言，结果表明具有偏心载荷的柱底座的更先进设计规定的优化潜力。
In the past, the punching shear behavior of centrically loaded column bases has been predominantly investigated even though eccentric loads frequently occur in engineering practice. To consider this corresponding uneven shear stress distributions around the column, many design approaches define coefficients to increase the acting load. Due to the limited test data for eccentric punching tests, an assessment of the design approaches is not reliably possible. To fill this gap of experimental test results, four centrically loaded and fourteen eccentrically loaded punching tests were conducted to analyze the effects of systematically graded load eccentricities.The tests reveal a significant influence of load eccentricity on the punching shear capacity and the load-bearing behavior. With increasing eccentricity, the crack formation shifts to the higher loaded side going along with an incompletely developed punching cone. Innovative measurements of the strains in the slab allow to analyze the circumferential multi-axial stress state inside the concrete. In contrast to centrically loaded column bases, this compression ring does not fully develop under eccentric loads. Based on these measured tangential strains, an experimental approach for describing the influence of the load eccentricity on the punching shear strength is derived and compared with the design approaches of Eurocode 2, Model Code 2010 and the stable version of the next generation of Eurocode 2. Overall, the results indicate optimization potential for more advanced design provisions of column bases with eccentric loads.