There has been increasing interest in recent years in the design and construction of post-tensioned concrete bridges with external unbonded tendons. To assist in the design of these structures, the Highway Agency issued a Standard and Advice Note (BD 58 and BA 58) in 1994. These documents were based on a review of existing knowledge that included recommendations on where further research was required. To provide further information for designers a continuous two span bridge with an overall length of 80m was designed and a quarter scale model of the bridge was constructed and load tested to failure. The objectives were to monitor the construction of the beam and measure its flexural capacity. In addition its behaviour as it was load tested was carefully monitored to determine the increase in tendon force, estimate the geometrical non-linearity, measure the friction losses at the deflector and supports, and record the behaviour of the deflectors, support diaphragms and anchorages. This report presents a description of the model bridge and its construction, and describes the structural behaviour as it was loaded to failure. The design of the bridge is presented in a separate report. (A)

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