Abstract Tension loaded anchorages far from the concrete edge may fail due to concrete cone failure, steel failure, pull-out failure or splitting of the concrete member. In the case of concrete cone failure, a conical concrete breakout body forms, where the angle of the initial crack of the concrete cone to the concrete surface is approximately 35° and the diameter of the concrete cone is about 1.5 times the anchor embedment depth. If closely spaced anchor groups are loaded in tension, their concrete breakout bodies may overlap with each other and therefore, the full concrete cone resistance for a single anchor group may not be reached. In the current design method of anchorages, this case is not explicitly addressed, and very limited test results are available. The fib Bulletin 58 recommends using a fictive, reduced anchor embedment depth in the corresponding equations when calculating the concrete cone resistance. This reduced embedment depth is calculated so as to exclude the overlap of adjacent theoretical concrete cone breakout bodies, by assuming the side angle of the concrete cone as 35°. In this work, 3D finite element simulations were carried out to investigate the influence of a neighbouring anchor group on the tension behaviour of an anchorage. The numerical investigations were performed by varying the spacing between the neighbouring anchor groups with anchors of equal embedment depths. The different loading scenarios include simultaneous as well as successive loading of the neighbouring anchor groups (one anchor group loaded after another). The numerical results are evaluated in terms of load-carrying capacity, developed stresses and the propagation of the cracks in case of closely spaced anchor groups. Based on the numerical results, a new “virtual edge approach” is recommended to calculate the concrete cone resistance of closely spaced anchor groups subjected to tension loads. The recommended analytical approach verified against the limited experiments available in the literature.

中文翻译：

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中心拉力载荷作用下相同构型密排锚群的数值研究

摘要 远离混凝土边缘的受拉锚固可能因混凝土锥体破坏、钢筋破坏、拉拔破坏或混凝土构件的劈裂而失效。在混凝土锥体破坏的情况下，混凝土锥体初始裂缝与混凝土表面的夹角约为35°，混凝土锥体的直径约为锚杆嵌入深度的1.5倍。如果紧密间隔的锚固组承受张力，它们的混凝土突破体可能会相互重叠，因此，可能无法达到单个锚固组的完整混凝土锥体阻力。在当前的锚固设计方法中，没有明确解决这种情况，可用的测试结果非常有限。fib Bulletin 58 建议使用虚构的，在计算混凝土锥体阻力时，在相应的方程中减少锚栓嵌入深度。通过假设混凝土锥体的侧角为 35°，计算该减小的嵌入深度以排除相邻理论混凝土锥体突破体的重叠。在这项工作中，进行了 3D 有限元模拟，以研究相邻锚杆组对锚杆受拉行为的影响。数值研究是通过改变具有相等嵌入深度的锚固件的相邻锚固件组之间的间距来进行的。不同的加载场景包括相邻锚组的同时加载和连续加载（一个锚组一个接一个加载）。数值结果根据承载能力进行评估，在紧密间隔的锚固组的情况下，产生的应力和裂纹的扩展。根据数值结果，建议采用一种新的“虚拟边缘方法”来计算受拉载荷作用的紧密间隔锚杆组的混凝土锥体阻力。推荐的分析方法与文献中可用的有限实验进行了验证。