A damage analysis of steel-concrete composite beams via dynamic methods. Part II: Analytical models and damage detection

This paper is the second part of an experimental-analytical investigation on the dynamic behavior of damaged steel-concrete composite beams. In the first part of the research, experimental results of a comprehensive series of dynamic tests performed on composite beams with damage in the connection were presented and discussed. Experimental observations suggested the formulation of a composite beam analytical model, where the strain energy density of the connection also includes an energy term associated to the occurrence of relative transversal displacements between the r.c. slab and the steel beam. A comparison with experimental results shows that the model enhances accuracy in describing the undamaged state of composite beams and that it is also appropriate to accurately predict the dynamic behavior under damaged conditions. A damage detection technique based on the measurement of variation in the first flexural frequencies was then applied to the suggested model and gave positive results.