Construction of single-track high speed rail lines in Brussels, Belgium, required an innovative precast, prestressed precambered composite trough bridge deck system to meet stringent site specifications. The resultant U-shaped bridge deck - a design born of the earlier Preflex and Flexstress beams, briefly described herein - permits spans as long as 92 ft (28 m). Variability in camber between measured data and that of traditionally computed methods led to a study to better evaluate time-dependent effects in concrete composite structures. This article presents a method of analysis to measure the creep and shrinkage effects on the long-term behavior of the decks. Strain measurements of the bridge deck 2½ years after construction are also compared with the theoretical values. The step-by-step method showed a better agreement with the measured strains than the values calculated by the age-adjusted effective modulus method. It is concluded that the research program on time-dependent effects has been successful and that the experimental results have in general agreed with the theoretical values.
