Kinetic analysis and rehabilitation of old bascule bridge in Tianjin, China

Movable bridges involve a combination of structural, mechanical and electrical components with specific kinetic characteristics in operation. This paper presents the structural evaluation, kinetic analysis and innovative retrofit design in the rehabilitation of an 80 year old rolling lift bascule bridge in China. Structural inspection and evaluation were firstly performed, reaching the decisions to preserve the original style and re-enable the rolling function by replacing severely corroded members and the deck system, re-balancing the counterweights, and restoring the mechanical and electrical systems. Then, based on a transformable 3-D FE model, the structure of the bascule bridge was analysed at different states of opening. Dynamic effects caused by abrupt stopping of the mechanism were analysed using a rigorous modal superposition method, and with an approximate equivalent static method. A low-depth steel orthotropic deck system was designed and finally new counterweights were optimised. The refurbished bridge is now fully operational.