Due to the highly demanding energy standards in Europe and challenging weather conditions, thermal break elements, such as aerated autoclaved concrete (AAC), have become increasingly popular in modern day residential buildings made of masonry cavity walls. Furthermore, a damp-proof course (DPC) layer is also used on top of the thermal break element to prevent water seeping and eventual entrapment due to capillary action. The presence of an AAC layer and of a DPC can have an adverse effect on the in-plane shear strength of a masonry wall, although information on this is barely available in the existing literature. This study aims at filling that knowledge gap through experimental investigations on traditional masonry walls and composite masonry walls, i.e. with an AAC and a DPC layer. The in-plane shear behaviour is compared between both types of wall specimens on the base of load-displacement curves and observation of failure modes. The capacity of analytical design approaches in predicting the test results has also been assessed. For the tested configurations, it can be concluded that the presence of AAC and DPC makes the failure mode switch from diagonal shear sliding combined with flexural toe crushing to horizontal shear sliding with crushing localized in the AAC layer, associated to a drop of the resistance by 6–9 % depending on the type of clay units and mortar. The proposed analytical method, derived from EN 1996-1-1, is providing a safe estimate of the test results with a similar level of accuracy for traditional and composite configurations (predicted values in the range of 75–86 % of the measured values). Finally, the influence of the definition of the compressed length and of the shear span ratio are shortly discussed.

中文翻译：

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具有防潮层和隔热层的未加固砌体墙面内剪切强度的实验表征


由于欧洲苛刻的能源标准和具有挑战性的天气条件，加气蒸压混凝土 （AAC） 等隔热元件在由砖石空腔墙制成的现代住宅建筑中越来越受欢迎。此外，在隔热元件的顶部还使用了防潮层 （DPC） 层，以防止水渗出并最终因毛细管作用而截留。AAC 层和 DPC 的存在会对砌体墙的面内剪切强度产生不利影响，尽管现有文献中几乎没有这方面的信息。本研究旨在通过对传统砌体墙和复合砌体墙（即 AAC 和 DPC 层）的实验研究来填补这一知识空白。根据载荷-位移曲线和破坏模式的观察，比较了两种墙体试样的面内剪切行为。还评估了分析设计方法预测测试结果的能力。对于测试的配置，可以得出结论，AAC 和 DPC 的存在使破坏模式从对角剪切滑动结合弯曲脚趾压碎转变为水平剪切滑动，压碎局限于 AAC 层，与阻力下降 6-9 % 相关，具体取决于粘土单元和砂浆的类型。所提出的分析方法源自 EN 1996-1-1，为传统和复合配置提供了测试结果的安全估计，具有相似的精度水平（预测值在测量值的 75-86% 范围内）。最后，简要讨论了压缩长度定义和剪切跨度比的影响。