Evaluation of Thermal Effects on Cable Forces of a Long-Span Prestressed Concrete Cable–Stayed Bridge

The structural temperatures and thermal effects on the cable forces of a long-span cable-stayed bridge with prestressed concrete girders were monitored. The temperatures were distributed as a three-segment polyline through the depth of the girder on hot sunny days, in which temperatures on the top surface and bottom surface were 15.4 degrees C and 10.3 degrees C higher than those on the webs, respectively. The monitored temperature distribution was quite different from the specification in the current Chinese design code, resulting in adverse load effects, especially on hot sunny days. Some cables were predicted to have remarkable thermal effects on internal forces, such as those near the side piers, in the center of the side span and near the towers, which were verified by field measurements. Therefore, special attention should be paid to these cables in the design and maintenance of the bridges on hot sunny days. Based on the monitoring of structural temperatures, the variations in cable forces induced by temperature were separated from those induced by traffic loads, which was helpful in safety evaluations of such bridges.