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Example 1

Example 1 Consider a steel H-pile (HP 250x85) 25m long, embedded fully in a granular soil. Assume that The allowable displacement at the top of the pile is 8mm. Determine the allowable lateral load, Let Use the elastic solution. Solution From Table 11.1a, for an HP 250x85 pile, (about the strong axis) And let From Eq. (11.90), ()Here, so the pile is a long one. Because. Eq. (11.85) takes the form And it follows that At and (see Table 11.14), so This magnitude of is based on the limiting displacement condition only. However, the magnitude of based on the moment capacity of the pile also needs to be determined. For , Eq. (11.87) becomes, According to Table 11.14, the maximum value of at any depth is 0.772. The maximum allowable moment that the pile can carry is, Let . From Table 11.1a, and , so Now, Because the deflection criteria apply. Hence, Example 2 Solve Example 11.11 by Broms’s method. Assume that the pile is flexible and is free headed. Let the yield stress of the pile material, the unit weight of soil, and the soil friction angle Solution We check for bending failure. From Eq. (11.101), From Table 11.1a, Also, And From Figure 11.32a, for the magnitude of (for a free-headed pile with is about 140, so Next, we check for pile head deflection. From Eq. (11.102), so, From Figure 11.33a, for (free-headed pile): thus, (by interception) And