P-Delta Effects on a Helical Pile

A. INTRODUCTION – MODEL DATA

In this document we will examine the influence of the P-Δ effect in helical piles. Analysis of piles in accordance with the assumption of small deformation is not always a valid one. For flexible piles where significant lateral deflection is expected, second-order effects could lead to an incorrect calculation of moments and subsequently design of the piles. Specifically, the additional moment contributed from the Axial load along the pile multiplied with the lateral pile deflection, is not considered in small deformation analysis (Fig. 1). As a result, for such scenarios the use of the P-Delta effect option within DeepFND is essential.

Figure 1: P-Delta Effect in Flexible Piles

B. DEEPFND SOFTWARE – SOIL PROPERTIES & STRATIGRAPHY – DM EDIT

Table 1: Soil Properties and Soil Layer Elevations

Figure 2: Soil Properties & Soil Layers in DeepFND

C. DEEPFND/HELIXPILE SOFTWARE – PILE SECTION PROPERTIES

Table 2: Pile Properties

Figure 3: DeepFND – Helical Pile Properties

D. DEEPFND/HELIXPILE SOFTWARE – ANALYSIS SETTINGS

1. Bearing Capacity Method: Meyerhoff/Hansen

2. Installation Torque: AC358-2007 Torque Factor Profile

3. P-DELTA: Check the model with and without the P-DELTA Effects

E. DEEPFND/HELIXPILE SOFTWARE – ANALYSIS RESULTS

Figure 4: Pile Displacements without P-DELTA Effects with DeepFND i) 0.8 kips lateral load, ii) 2 kips lateral load

Figure 5: Pile Displacements with P-DELTA Effects with DeepFND i) 0.8 kips lateral load, ii) 2 kips lateral load

Figure 6: Pile Displacements Comparison with and without P-DELTA Effects in DeepFND

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