Development of fire protection for bridge cable systems

Fire protection of bridge cable systems has been identified as an important mitigating action with respect to operational risk as well as the safety of existing and new bridges. In particular, cable supported bridges have been demonstrated to be vulnerable to vehicle fires. With the design of fire protection concepts for New Little Belt Bridge and Great Belt East Bridge, a process with development of fire protection of cable systems has been started.

The project is based on the development of a fire protection concept for main cables based on insulation mats and currently a concept is being developed with use of intumescent coatings. The R&D project and handling of the design challenges on cable systems on suspension bridges is presented, and it includes details about the main cable, cable clamps and suspenders based on numerical modelling and testing of the steel performance during fires up to 1100°C. The fire protection relies on use of insulation mats and intumescent coatings and in developing the concept, one of the main challenges is to document the performance of the design concepts unique to each bridge.

Furthermore, it is difficult to get access to information on material performance in suchparticular applications. Hence, in the current project, it has not been possible solely to rely on thesupplier information and it has been necessary to carry out numerical modelling of performance during fire as well as use of laboratory testing.In summary, the objective is to investigate the combined performance of the steel cable and the applied insulation concept.

For solutions, design has not only to consider the fire protection of steel but also to address issues regarding cable durability and allowance for operation and maintenance.