Dynamic Assessment of Bridge Load-Carrying Capacities. I

Abstract

A one-fifth model reinforced-concrete beam-slab bridge deck was tested to destruction, and the vibrational response to ambient excitation was measured at different stages of cracking and spalling. Observations showed that the neutral axis remained close to the lower flange of the T-beam throughout the loading range. A method capable of assessing the load-carrying capacity as well as the structural condition of a T-beam slab bridge deck has been developed. This requires prior information on the geometric dimensions and fundamental modal frequency of the structure, and two methods are discussed and proposed for assessment. The results of a parametric study of the effect of different boundary conditions on the fundamental modal frequency are presented in this paper. Different potential sources of error in this process are discussed and the manner of implementing the method is presented.