Testing of Existing Foundations as Part of Inner-city Redevelopment Projects-PPT Presentation

PPT Presentation

Pdf Summary

The presentation discusses the challenges of reusing existing foundations in inner-city redevelopment. Reuse can reduce cost, construction time, vibration, access difficulties, and conflicts with underground infrastructure. It may also be necessary for historic buildings. However, the key question is whether the foundation can safely support the proposed structure over its future service life.<br /><br />Assessing existing foundations is difficult because important information is often missing or uncertain: original design loads, pile dimensions and lengths, installation records, loading history, and current material condition. Soil conditions may also have changed, while corrosion, concrete deterioration, or timber decay could reduce long-term performance.<br /><br />A case study at an old school in Breda illustrates the approach. The building, originally constructed around 1880, was to be converted into 60 apartments, adding approximately 10% to the foundation loads. Records and visual inspection identified reinforced concrete piles with 250 × 250 mm heads, but their lengths and test capacities were unknown. Rather than rely on the building’s history, engineers performed new pile load tests.<br /><br />Static load testing can assess a pile’s actual performance in its current condition and provide direct evidence of capacity and serviceability. It is the only available option when the existing structure remains in place, though testing requires excavation and disconnection of the pile head, and the superstructure limits the achievable test load.<br /><br />Four piles were tested. Three showed no geotechnical failure and settled only 1–4 mm at the maximum test load. The fourth behaved differently, failing geotechnically with 43.5 mm of settlement at 75% of the planned load. Further investigation linked its reduced capacity to an old underground trench that had left the pile toe outside the stiff soil layer. The other piles exceeded the proposed working loads, and the project accepted a lower safety factor for the weaker pile. Ultimately, all piles were reused.

Keywords

foundation reuse

inner-city redevelopment

pile load testing

static load test

existing foundations

historic building conversion

foundation capacity

soil conditions

pile failure

Breda case study