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Figure 14.5. Row of anchorages used to support an embedded retaining wall

Figure 14.5. Row of anchorages used to support an embedded retaining wall

The design of the anchorages will rely on the results of investigation and suitability tests. The final design resistance will be confirmed by acceptance tests. The proof loads and lock-off loads required in these tests must be calculated.

Notes on Example 14.1

O The value of characteristic stress at 0.1% tensile strain is one of the main criteria for assessing the capacity of the anchor based on the tendon strength as required in EN 1537.

© Equation for establishing anchorage resistance from the grout/ground interface taken from BS 8081.17 In a traditional design, it would be usual to have a factor of safety of at least 3.0 applied to the anchor's design load. In this case, it is approximately 3.03.

Example 14.1 Grouted anchor Verification of strength (GEO)

Design situation

Consider a grouted anchorage that is required to support an embedded retaining wall. Separate calculations of wall stability indicate that the anchorage system must provide horizontal resistance of at least Rd SLS = 121kN/m to avoid a serviceability limit state and

Rd ULS = 133kN/m to avoid an ultimate limit state.

Working anchorages, with bond length L = 4m, will be installed into sand with characteristic angle of shearing resistance 9>k = 35°. The anchorages will be installed at an angle 0 = 30° to the horizontal and at a horizontal spacing s = 1.2m. The anchor bore diameter D = 133mm . Factor from BS 8081 for Type B anchorages to obtain shear stress along anchor bond length kN

Preliminary design of working anchorages Design Approach 1

Actions and effects

The design axial load that each anchorage must resist is: Pd = max(Rd,ULS > Rd,SLS) * )) = 184.3 kN

Material properties and resistance

The tendon chosen for the working anchorages is a multi-unit comprising seven drawn-wire strands of nominal diameter d = 15.2mm, with sectional

2 N area At = 165mm , characteristic tensile strength fpk = 1820-, and mm

0 0