Analysis of continuous composite beams including partial interaction and bond

Negative bending moments arise near the intermediate supports in continuous beams; thus, when steel-concrete composite beams are considered, tensile stresses act on the concrete slab. As a result the structural response generally becomes nonlinear due to two main effects: the slip at the slab-profile interface and cracking in the concrete slab. in the present paper a method of analysis for continuous composite beams based on a specific kinematic model of the cross section is proposed. The main feature of the model is the capability to take into account the slip at the slab-profile interface and the slip at the concrete-reinforcement interface. This approach allows the introduction of a constitutive relationship for bond between reinforcing bars and concrete in the theoretical analysis; thus, the tension stiffening effect in the negative bending moment regions can be computed, and the actual mechanical behavior of reinforcing bars of the slab can be analyzed. The results of numerical analyses are compared with experimental data, showing very good agreement and the capacity of the model to simulate the main aspects of the structural behavior of composite beams.