Axial capacity of driven and bored piles per EN 1997-1 Design Approach 1 (ξ3/ξ4 correlation factors) or AASHTO LRFD. Layered soil profile, shaft + base resistance, group efficiency, Vesic settlement.
Free preview: design resistance, utilization, and pass/fail. Sign in as Pro or Civil to unlock shaft chart, settlement, and step-by-step calculation.
Enter your email to receive the full pile capacity report with shaft breakdown, base resistance, partial factors, and settlement estimate.
Need the full geotechnical package?
FrameAI Civil automates foundation design from site data: shallow bearing capacity, pile design, slope stability, and EN 1997-1 design report generation.
DA1 requires checking two combinations: Combination 1 (γG=1.35, γQ=1.5; characteristic material parameters) and Combination 2 (γM=1.25 on φ′ and c′; resistance model γ_R=1.0). The correlation factors ξ3 and ξ4 from Table D.4 are applied to static load test results to derive the characteristic resistance R_c,k = (Q_s + Q_b) / ξ3 (or / ξ4 for the mean model).
Use AASHTO LRFD for projects designed to US bridge codes (AASHTO LRFD Bridge Design Specifications). AASHTO uses resistance factors φ from Table 3.4.2-1 (driven steel φ=0.65, driven concrete φ=0.55, bored φ=0.50, CFA φ=0.48) applied to the nominal resistance (Q_s + Q_b). No correlation factors are needed since these are already calibrated into the φ factors.
When piles are closely spaced (s/D < 3), the capacity of the group is less than the sum of individual capacities due to soil stress overlap. CIRIA C580 gives η = 1 − (n−1)·(D/8s) for driven piles in clay. FrameAI applies this reduction to both Q_s and Q_b when group spacing < 3D.
The α-method (EN 1997-1 §7.6.2.3) relates unit shaft resistance q_s to undrained shear strength c_u via an adhesion factor α. Driven piles: α ≈ 0.50; Bored/CFA: α ≈ 0.45. This captures the reduced shear strength at the pile-soil interface compared to the intact soil.
The Vesic method estimates two components: (1) elastic shortening of the pile material s_e = (Q·L)/(A·E_p), and (2) soil compressibility beneath the pile base s_c ≈ (q_b·D)/E_s. The sum gives the estimated settlement at working load. This is a first-order estimate; for critical structures, use a geotechnical specialist.
ξ3 and ξ4 convert measured pile test results to characteristic values. ξ3 applies when using the lower bound model (5% quantile), ξ4 when using the mean model. For n=2 tests: ξ3=0.89, ξ4=1.09. For n≥5: ξ3=0.75, ξ4=0.98. Always use at least 2 static load tests for reliable results.