COBRAS
Concrete Bridge Assessment Program

Welcome to the COBRAS Concrete Bridge Assessment Program web site. This site provides information about the program, and how it may be used to perform yield-line analysis of concrete slab, and beam-and-slab bridges.

COBRAS is a yield-line analysis software program for assessing the ultimate load capacity of concrete structures, and in particular, concrete bridge decks.

A number of UK bridge authorities, consultants and overseas organisations are currently using the program to evaluate the load carrying capacity of concrete bridges that have failed assessment using conventional elastic analysis methods.

The program has been developed in the Engineering Department at Cambridge University by Dr Campbell Middleton and colleagues with support from various bodies including the Highways Agency, Transport Research Laboratory (TRL) and the Engineering and Physical Sciences Research Council (EPSRC). Over the last ten years an extensive research programme has been undertaken to validate the program's predictions. This has included calibration with non-linear finite element analyses undertaken in collaboration with the TRL and a series of tests on reinforced concrete slab and beam-and-slab bridge models. In addition comparisons have been made with the results from full-scale and model load tests and theoretical studies that have been published in the literature.