Structural Evaluation of Thermal Integrity Testing Results of Transmission Foundations-Paper

Paper

Pdf Summary

The paper examines how Thermal Integrity Profiling (TIP) can help assess drilled-shaft foundations for transmission lines, particularly large shafts where access may make other testing methods less practical. TIP measures concrete temperatures during curing to estimate effective shaft radius and identify possible irregularities, including concrete inclusions, cage displacement, and inadequate cover. It also provides information unavailable from conventional integrity testing, although results must be interpreted alongside construction records and engineering analysis.<br /><br />The authors describe a Midwest transmission-line project where TIP was used on selected foundations. Three examples illustrate how results can guide decisions. One shaft showed typical oversizing and no significant concern. A second displayed indications of contaminated concrete and reduced effective dimensions; coring confirmed sand lenses and poor concrete, and the foundation was abandoned and rebuilt after design review. A third showed cage eccentricity, limited cover, and a localized reduction near the shaft bottom. Correcting the TIP interpretation for heat from a recently grouted casing improved the estimated cover. Structural reassessment, including review of shear capacity and serviceability, supported acceptance subject to reduced line loading and monitoring.<br /><br />The paper emphasizes that TIP findings should not be treated as automatic pass/fail criteria. Apparent anomalies merit review in context, including field measurements, casing and grout effects, concrete strength, loading, and foundation design. Properly applied, TIP and thorough documentation can support targeted investigation and structural evaluation, help distinguish tolerable construction variations from serious defects, and increase confidence in foundation construction.

Keywords

Thermal Integrity Profiling

TIP

drilled-shaft foundations

transmission lines

concrete curing

shaft radius

foundation integrity

cage displacement

construction records

structural evaluation