Re-use of Old Pile Foundations in AmsterdamÂ-Paper

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The paper examines how existing pile foundations can be assessed for reuse when buildings are renovated, expanded, or subjected to increased loads. Reuse can reduce material use, costs, and construction time, while avoiding disruption and damage risks in dense historic neighborhoods. However, old records may be incomplete or unreliable, and foundations may differ from their original designs.<br /><br />Assessment begins with signs of past performance, such as cracks and uneven settlement. Because calculations based on archived data or new soil investigations still depend on uncertain pile dimensions and as-built conditions, the authors identify load testing as a key tool. Static tests can be conducted while the superstructure remains in place; dynamic and rapid tests generally require access to exposed pile heads. Separate inspections and material tests are also needed to assess whether piles will remain sound over the renewed service life.<br /><br />Two Dutch examples illustrate the approach. In a 1900 Hague building, investigation traced severe localized settlement to a past façade alteration that concentrated loads; strengthening the ground-floor structure redistributed them. In Amsterdam, static tests on timber piles beneath three historic bridges found capacities ranging from 75 to 420 kN—often well above the previously assumed 60–120 kN. Some piles were damaged or displaced, but many remained in good condition.<br /><br />The authors conclude that systematic investigation can reveal opportunities to reuse foundations, though uncertainties must remain part of design decisions. If capacity is insufficient, loads may be redistributed or new piles added, with care needed to manage differential settlement between old and new foundations.

Keywords

pile foundations

foundation reuse

load testing

static pile test

settlement assessment

historic buildings

structural renovation

timber piles

soil investigation

differential settlement