to the effects of external influences such as general soil movement (mudslides) or the proximity of adjacent structures.

The soil movement induces an additional loading on the pile, in a similar manner to that experienced by piles within a group. The loading is a function of the relative displacement between the pile and the surrounding soil. The soil displacement thus has the effect of shifting the P-Y (for horizontal slides) and T-Z (for vertical slides) curves by an amount equal to the local soil movement.

Where such soil shifts are required, the SLID input provides a facility to define soil displacements with respect to the global axes thus permitting directional shifting of the curves which would not be otherwise possible for P-Y data.

16.1.5. Soil-Pile Interaction Results

In addition to displacements, reactions, stresses, or other results, the PILECALC command produces a

list of data and useful intermediate information. This data can be found in the Jobname_CAPNODE.POUT file in the solver output folder.

16.1.5.1. Displacements and Reactions

The displacement listing is in three parts:

• During the iteration stage of the program, pile cap displacements and reactions, along with the convergence parameters will be output in a section titled “Pile Cap Displacements And Reactions Iteration Report.”

• Displacements and reactions for all the nodes on the structure (excluding the nodes defining the bottom of the piles) are output. The displacements and reactions will be in the global coordinate system.

• A detailed report of the global displacements down the piles is also output in the global coordinate system.

16.1.5.2. Forces and Stresses

For each pile element, a detailed report providing both forces and axial, bending, and combined stresses is printed for all the subdivisions down the pile. The combined stress is calculated as the sum of the absolute values of axial and biaxial bending stresses, and adopts the sign of the axial stress.

16.1.5.3. UNITY Check Data

Optional utilization check results for either API LRFD, API WSD or ISO codes of practice may also be reported by selecting to include them in the PILEGEN command’s CHECK option.

The API LRFD standard utilizes limit state checks with resistance coefficients to achieve the desired level of safety. In keeping with this principle, applied loads must be multiplied by appropriate factors, as defined in the code of practice (Section C, Loads), to develop the design load case combinations necessary for processing. Since the pile-soil interaction is nonlinear, any loading must be factored before being applied.

For the WSD method the desired safety limits are achieved using safety factors. In order to account for extreme environmental conditions a one-third increase in the allowable stress is permitted, and this can be requested using the LOADTYPE option in the PILEGEN command.

The ISO 19902 checks adopt a similar philosophy to the API LRFD code. Thus, applied loads must be multiplied by appropriate factors, as defined in the code of practice (Section 9.10.3). The LOADTYPE

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option in the PILEGEN command can be used to define extreme loadcases, which will affect the design axial pile capacity computed because a different resistance factor is used.

The following utilization checks are undertaken when requested:

API WSD (Edition 21)

where

fa = axial stress

Fxc = inelastic local buckling stress

fby, fbz = bending stresses (including second order effects using the PDELTA option in the PILEGEN command)

Fb = allowable bending stress

A one-third increase in the allowable stresses is included if an extreme loadcase is being processed.

API LRFD (Edition 1)

where

fc = axial compressive stress

Fxc = inelastic local buckling strength

fby, fbz = bending stresses (including second order effects using the PDELTA option in the PILEGEN command)

Fbn = nominal bending strength

Φc = resistance factor for axial compressive strength

Φb = resistance factor for bending

Note: for tensile piles the axial term of the above check is changed to

where