53
5.2 Tension load
N
N
hef c = 1.5 · hef
1.5 · hef
3 · hef
c Ac,N
1.5 · hef Ac,N
3 · hef
(a)
(b)
Fig. 5.8 Influence of a component edge on the shape of the concrete break-out cone (Fuchs, Eligehausen, and Breen (1995)) (a) fastening with an edge distance c ¼ 1.5 hef (b) fastening with an edge distance c < 1.5 hef
Edge distances The geometrical influence of component edges on the characteristic resistance with conical concrete break-out (Figure 5.8) can be also described with the help of the CC-method. If the edge distance of a fastener corresponds to the radius of the failure cone, the cone is tangent to the edge (Figure 5.8a) and the load-carrying capacity corresponds to the value of a one single fastener. If the edge distance is reduced (see Figure 5.8b), then failure cone and edge overlap and the characteristic resistance decreases. The influence can be described – as in case of spacing – by comparison of the base area of the idealized (truncated) break-out body with the base area of a single fastener which is not influenced by spacing or edge distances. Figure 5.9 explains the approach at the example of a single post-installed fastener at the component edge (Figure 5.9a) and a quadruple fastening positioned in the corner of a component (Figure 5.9b). Figure 5.10 shows the approach for a group with two post-installed fasteners in the corner of a component. In the example post-installed fasteners with an anchorage depth hef ¼ 80 mm are assumed. In Figure 5.10a the spacing is s < scr,N and in Figure 5.10b the spacing is larger. In the first case the break-out cones of both fasteners overlap and in the second they are separate. The geometrical influence of the overlapping of the failure cones with component edges is described by the comparison of the base areas. In addition, it is to be noted, that