DESIGN OF CONTINUOUS SFRC BRIDGE DECKS FOR SERVICEABILITY CRITERIA

摘要

Five bridge decks using steel fibre reinforced concrete (SFRC) at high dosage for structural purposes have been built in Quebec since 1998. Field observations indicated that, in some cases, deck portions built using conventional reinforcement without fibres experienced important cracking. Further investigations showed that, while new bridge decks with conventional reinforcement only were adequately designed for strength, serviceability criteria have not always been considered adequately. The paper describes the main criteria and assumptions used in the design of one bridge deck where reinforcement transverse to the longitudinal girders was optimized by considering the structural contribution of fibres. The paper presents the behaviour in service conditions of conventionally reinforced bridge decks in comparison with an optimized design which uses 80 kg/m~3 of steel fibres and reduced reinforcement. The behaviour of the bridge deck in the longitudinal direction, with and without the presence of fibres, is discussed and illustrated with a model prediction and field observations on actual bridges. The paper focuses on the effects of differential shrinkage on transverse cracking in continuous structures. The role of fibres and then-contribution in reducing crack width is presented. Predicted crack width and spacing are compared to those observed on the actual bridge.