Probabilistic Approach to Integrating Thermal Effects in Camber and Stress Analyses of Concrete Beams

Abstract

The accuracy of camber and corresponding stresses of precast pretensioned concrete beams (PPCBs) is routinely compromised due to ignoring the thermal effects resulting from continuously changing weather conditions, affecting the deck placement on site. While accounting for the effects of a known temperature gradient down the beam depth is straightforward, the temperature gradient varies by region and meteorological season. Using Monte Carlo simulation to probabilistically determine the thermal effects, this study accounts for these variations in combination with the camber and stresses established for PPCBs subjected to dead load and prestress. To utilize the outcomes of this study in design practice, suitable thermal multipliers are proposed. Recommended multipliers produced more realistic camber predictions because the mean absolute error between the measured and predicted values was 5%±5%. The corresponding error increased to 13%±10% when the thermal multipliers were ignored. The impact of the thermal effects was relatively less on stresses, but it was observed that the stress on the beam’s extreme compression fiber can exceed the allowable stresses in warm summer days.