Use of precast prestressed concrete beams in continuous bridge construction

Abstract

Use of precast prestressed concrete beams is a common practice in Sri Lanka. The main advantages being factory production of beams, ease of erection and speed of construction. However there are inherent problems associated in these bridges when multi-spans are adopted. This is because expansion joints over each pier gives rise to problems such as deterioration, maintenance and performance. In coastal roads there are added problems of deterioration. A solution to these problems is the introduction of continuity over piers. However, continuity itself will have a few problems at the design stage which have to be carefully tackled. The problems are design complications arising due to differential creep and shrinkage, thermal movement and the behaviour of the beams over the pier at ultimate limit state. There are four continuity methods currently used in other parts of the world. Out of these, the most suitable type for Sri Lanka has to be selected by considering ease of construction and durability. When continuity is introduced, it is important to ensure that the existing standard sections can be used. The paper gives the details of analysis, design and also areas for further research.