Partial-interaction flexural stresses in composite steel and concrete bridge beams

Even though mechanical shear connectors in composite steel and concrete beams require slip to transmit shear, most composite bridge beams are designed as full-interaction because of the complexities of partial-interaction analysis techniques. However, in the assessment of existing composite bridges this simplification may not be warranted as it is often necessary to extract the greatest capacity and endurance from the structure. This may only be achieved using partial-interaction theory which truly reflects the behaviour of the structure. This paper develops a new concept of the partial-interaction focal point and simplifies partial-interaction theory to derive a simple procedure for deriving the partial-interaction flexural stresses from standard and easily obtained full-interaction parameters. This will allow engineers to develop more accurate procedures for determining the strength and endurance of existing composite bridge beams. Use of the procedure is illustrated by way of an example.