Effects of Geometric Design on Early-Age Thermal Behavior of Drilled Shaft

Abstract

Abstract This article presents an investigation on the early-age thermal behavior of drilled shafts with different geometric dimensions through numerical analysis. Finite-element models by using DIANA software were developed to analyze the thermal behavior of drilled shafts. In order to validate the finite-element model, four concrete drilled shafts were constructed and evaluated under Florida conditions for monitoring their actual thermal behavior. The calculated temperatures from the analytical model matched well with the measured values from the constructed shafts. All the drilled shafts with a diameter greater than 1.83 m (6 ft) produced a high maximum temperature and a maximum temperature differential which failed the allowable temperature set by the American Concrete Institute and the Florida Department of Transportation to prevent thermal cracking. Also, it was found that the dimension of the drilled shaft had the greatest influence on the maximum temperature inside a shaft. Analysis was performed to investigate whether the use of drilled shafts with a centroid void in the shaft could reduce the maximum temperature and maximum temperature differential. The results indicated that this is a viable alternate shaft design for controlling the maximum temperature and maximum temperature differential in concrete drilled shafts at an early age.