Pile Load Test: Analytical Methods for Bearing Capacity, Including Brazilian Methods-Paper

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The paper compares analytical methods for estimating pile bearing capacity from static load-test load–settlement curves. It evaluates nine tests on root piles and continuous-flight-auger piles in Ipojuca, Pernambuco, Brazil. Tests were stopped at the design verification load rather than continued to failure, and the piles were not instrumented at depth, limiting direct assessment of shaft friction and tip resistance.<br /><br />Methods examined include Van der Veen, Chin–Kondner, Davisson, the Brazilian ABNT standard, Décourt’s stiffness method, and Massad’s approach, including the two-straight-lines method for short or rigid piles. Van der Veen, Chin–Kondner, and Décourt estimate ultimate load by extrapolation; Davisson and ABNT define conventional limit loads using pile elastic shortening plus a settlement allowance. Décourt and Massad can also help distinguish lateral resistance, unlike the other methods considered.<br /><br />Van der Veen, Chin–Kondner, and Décourt produced broadly similar ultimate-load estimates. Van der Veen generally gave values closest to the applied test loads, while Décourt estimates were somewhat higher. Davisson and ABNT were similar, with Davisson more conservative; however, the available settlements allowed Davisson’s method to be applied to only two tests and ABNT’s to none. Results from the lateral-resistance methods varied, preventing a clear conclusion about which was more conservative.<br /><br />The authors emphasize that extrapolated capacities remain predictions, especially when projected far beyond tested loads. They recommend caution in interpreting such estimates and note that measured pile properties and depth instrumentation would improve evaluation of structural behavior and the separate contributions of shaft and tip resistance.

Keywords

pile bearing capacity

static load test

load-settlement curves

Van der Veen method

Chin-Kondner method

Davisson method

ABNT standard

Décourt stiffness method

Massad approach

root piles