Seasonal shrinkage variation in bridge segments: Fid-Bau Portal

Seasonal shrinkage variation in bridge segments

Barr, B. I. G. / Vitek, J. L. / Beygi, M. A.

Abstract The paper reports on shrinkage data acquired during extensive monitoring of two major glued segmental bridges. For both bridges, three segments within a single half-span, corresponding to mid-span, quarterspan and support locations, were instrumented. Concrete strain was monitored by means of embedment type vibrating wire gauges distributed around the cross-section of each segment. The segments, manufactured on site by the short-line match cast method, were monitored regularly during storage (for up to 140 days) prior to erection. The segments for one bridge were cast in the Spring, whereas the segments for the other were cast in late Summer, resulting in significantly different seasonal effects during storage. Predicted shrinkage strains have been evaluated by means of a simplified form of the BP model, assuming both variable and constant relative humidity. Good agreement between predicted and measured shrinkage strains was observed in all cases where the variable humidity of the air was taken into account. The shrinkage values predicted using the assumptions of constant relative humidity are also in good agreement with the measured shrinkage strains; hence the model used in this study is suitable for use in the design process.