Effect of Temperature Gradient on Continuous PSC Bridge for Straight and Curved Profile

Abstract

There is a long term deflection in continuous Pre-stressed Concrete Girders (PSC) due to creep, shrinkage and daily atmospheric temperature variation, inhibiting lower load bearing capacity. These causes decrease in service life of bridge and in the long run require strengthening with external pre-stressing to secure its original load bearing capacity. Among these three variables the effect of temperature is predominant compared to creep and shrinkage, which in turn, are directly depending on the effect of temperature. Variation in temperature distribution in bridge structure can be described in terms of i) Effective bridge temperature or uniform temperature and ii) Temperature difference or temperature gradient. The uniform temperature change only causes change in axial length of the member while the temperature gradient causes bending deformations. If the longitudinal expansion due to uniform temperature is prevented the girder may experience considerable axial forces which could lead to damage of the structure and cracks may appear in the structure. It is preferable to adopt expansion joints for the free movement of the structural member due to variation in temperature and also to provide the required steel or pre-stressing force to encounter the bending deformation due to temperature gradient. It is also intended to know the variation of temperature gradient as the number of continuous span increases and the amount of flexural moment developed due to temperature gradient.