Incremental Launching Construction Control of Long Multispan Composite Bridges

The low stiffness of steel U-shaped girders during incremental launching construction has led to the development of an innovative incremental launching construction method that addresses the special requirements of long, multispan composite bridges. A local stress control strategy is utilized to avoid local yielding of the bottom plate. Analysis of the geometric shape control characteristics of composite bridges located on vertical curves allows a control strategy for launching to be established and validated. The concept of state vector is introduced for geometric shape control and prediction. Field results reveal that most of the elevation errors fall into the range of +/- 1: 0 cm. This paper demonstrates that highly precise control of geometric shapes can be achieved via the proposed methodology. Through accurate analysis of the geometric shapes of composite bridges, errors can be detected and corrected in a timely manner. (C) 2015 American Society of Civil Engineers.