## 4 Test Setup, Instrumentation, and Crack Formation
### The Effects of Investigated Parameters on the Behavior of Anchors
#### 5.3.3 The Effect of Crack Width  
The effect of the crack width was investigated for anchors installed in weak mortar joint and brick locations (L4T and L6, respectively). For the cracked T-joint location L4T, several target values of crack width were investigated, namely, 0.30 mm, 0.50 mm, 0.60 mm, 0.80 mm, and 1.20 mm. It is noted that the  
Figure 19: Displacements at tension resistance (d\({}_{\text{FRu}}\)) vs. location for anchors installed in walls made with weak mortar. Figure 18: Tension resistance (F\({}_{\text{Ru}}\)) vs. location for anchors installed in walls made with weak mortar. targeted crack width values were not always reached with accuracy. Figure 20 shows the reduction of the tension resistance for increasing crack width. It also indicates that for extreme crack widths, a certain threshold is reached, and the resistance does not drop to zero. This effect can be attributed to the fact that, although the anchor in the drill hole is crossed by the crack, a substantial portion of the injection mortar remains in contact with the base material and, thus, it can transfer load. It is also observed that the scatter of the tension resistances is larger when the anchor is installed in a cracked mortar joint, compared to anchors in an uncracked substrate. Part of the scatter can be attributed to the scatter of the measured mortar compressive strengths. Similar to tension resistances, the respective displacement values present significant scatter (Figure 21), with the exception of the anchors installed in a 1.20 mm wide crack. In that case, premature pull-out of the anchor from the mortar joint occurs at a small displacement value with limited scatter. In general, the displacement values are so scattered that it is not possible to draw a trend line between the displacement at tension resistance and the crack width. Figure 21: Displacement at tension resistance (d\({}_{\text{FRu}}\)) vs. crack width (w\({}_{\text{tot}}\)) value: Anchors installed in T-mortar joints made with weak mortar. Figure 20: Tension resistance (F\({}_{\text{RU}}\)) vs. crack width (w\({}_{\text{tot}}\)) value for anchors installed in T-mortar joint locations made with weak mortar. For anchors installed in the middle of an uncracked brick with adjacent cracked joint (L6), the effect of cracks was investigated for widths equal to 0.30 mm, 0.50 mm, and 0.80 mm. In this case too, the increase in the crack width leads to reduced tension resistance (Figure 22). Nonetheless, for anchors embedded in bricks, the displacements at which the tension resistance is activated show a clear tendency to increase with increasing crack width (Figure 23). They are, as a rule, smaller than for anchors embedded in mortar joints. Figure 23: Displacement at tension resistance vs. crack width value for anchors installed in uncracked brick joints and uncracked bricks with cracked adjacent horizontal mortar joints made with weak mortar. Figure 22: Tension resistance vs. crack width value for anchors installed in uncracked brick joints and uncracked bricks with cracked adjacent horizontal mortar joints made with weak mortar. The effect of crack opening has shown that the design of anchors must be based on criteria, one of them being a limiting value of the expected crack width. Indeed, the design of anchors should follow a realistic scenario and avoid adopting overconservative tension resistances corresponding to excessively large cracks. Thus, the study presented in [21] was undertaken.