The clay block structural masonry is the most common building system in Brazil, being used even in buildings with ten or more floors. Sometimes, when the buildings are already in use and the total load is fully completed, the dwellings users need to change hydraulic, gas or electrical installation position in masonry walls, cutting the structural elements. This is the most critical problem for building masonry safety because it was not originally predicted during design. The aim of this study was to evaluate the influence of chases on the mechanical behavior of structural masonry walls under compression using clay blocks small-scale models with proportions of 1:5. Three chase positions and depth were tested, as follows: horizontal, vertical and inclined chases, with depths of 20%, 30% and 50% in relation to masonry thickness. Also, concentric and eccentric loads were considered during tests. From experimental results, it was possible to conclude that the presence of horizontal and inclined chase changed the failure mode characteristics of masonry. For masonry with mid-height horizontal chase, it was found to have a significant drop on the residual strength. From experimental tests, it was possible to obtain a relationship between the strength reduction and the chase depth and load conditions. The strength reduction due to the second-order effects induced by the horizontal chases can be successfully evaluated by normative models, specially EN 1996-1-1.

粘土砖砌体是巴西最常见的建筑系统，甚至在十层或十层以上的建筑物中也使用过。有时，当建筑物已经投入使用并且全部负荷全部完成时，住宅用户需要更改砖石墙中的液压，燃气或电气安装位置，以切割结构元件。对于建筑砌体安全而言，这是最关键的问题，因为它最初并不是在设计过程中预测的。这项研究的目的是使用比例为1：5的粘土块小规模模型，评估在结构压缩时，追逐对结构砌体墙体力学行为的影响。测试了以下三个机架位置和深度：水平，垂直和倾斜机架，深度分别为砌体厚度的20％，30％和50％。也，测试期间考虑了同心和偏心载荷。从实验结果可以得出结论，水平和倾斜追逐的存在改变了砌体的破坏模式特征。对于中等高度水平追赶的砌体，发现其残余强度显着下降。从实验测试中，有可能获得强度降低与跟踪深度和载荷条件之间的关系。可以通过规范模型（尤其是EN 1996-1-1）成功评估由于水平追逐引起的二次效应而导致的强度降低。对于中等高度水平追赶的砌体，发现其残余强度显着下降。从实验测试中，有可能获得强度降低与跟踪深度和载荷条件之间的关系。可以通过规范模型（尤其是EN 1996-1-1）成功评估由于水平追逐引起的二次效应而导致的强度降低。对于中等高度水平追赶的砌体，发现其残余强度显着下降。从实验测试中，有可能获得强度降低与跟踪深度和载荷条件之间的关系。可以通过规范模型（尤其是EN 1996-1-1）成功评估由于水平追逐引起的二次效应而导致的强度降低。