Minimum distances and critical distances to the edge of the concrete and between anchors

During the design phase of the fixings, it´s important to differentiate between the minimum and critical distances between anchors and the edge of the concrete. These values can be found in the manufacturer´s approvals and technical documentation.

There are 2 types of edge distances that should be clarified and taken into account when designing anchors:

• Minimum distance to the edge, c_min: minimum anchor installation distance from any edge of the concrete. The anchor must not be installed at a shorter distance as this implies a risk of cracking the base material, even without applying any load to the fixing.
• Critical distance to the edge, c_cr: the distance the anchor can be installed from any edge of the base material without affecting its resistance capacity. Below this distance, the fixing can still be carried out, up to the minimum distance to the edge, but certain equations must be applied that reduce its resistance. As a general criterion, the value of the critical edge distance will be greater than the minimum edge distance: c_cr ≥ c_min

Critical distance to the edge

Minimum distance to the edge

• Minimum spacing, s_min: minimum installation distance of the anchor with respect to any other anchor. The anchor must not be installed with a smaller spacing as this implies a risk of cracking the base material, even without applying any load to the fixing.
• Critical spacing, s_cr:distance at which the anchor can be installed with respect to any other anchor without its resistance capacity being affected. Below this distance, the fixing can still be carried out, up to the minimum spacing, but certain equations must be applied that reduce its resistance. As a general criterion, the value of the critical spacing between anchors will be greater than or equal to the minimum spacing: s_cr ≥ s_min

Critical distance to the edge

Minimum distance to the edge

There are 2 types of spacing or distance between anchors that we must consider for the design phase of the anchor:

The reduction in resistance for installing an anchor below the critical edge c_cr) and/or critical spacing (s_cr) distance should be calculated by applying certain equations from the EN 1992-4 standard. Eurocode 2. Design of concrete structures. Part 4. Design of fastenings for use in concrete. This reduction can be obtained quickly and easily using our anchor calculation software INDEXcal.

The critical and minimum distance values are indicated in the European standards.

Latest revision: FAQ22 rev0