A Methodology for Condition Assessment of T-Beam Bridges without Structural Plans

This study presents a nondestructive method for load rating of reinforced concrete T-beam bridges with limited or missing structural information. To compute load rating factor of a bridge, the capacity of the bridge as well as the dead load and live load effects need to be determined. In the proposed approach, a large number of T-beam bridges with different structural dimensions such as skew angle, span, width, and thickness was first analyzed using finite element method to obtain their natural frequencies. Then, a non-dimensional frequency parameter that plays an important role in identifying the flexural rigidity of T-beam bridges was computed using the natural frequencies obtained from numerical analyses. This population of generated data was then used to create an artificial neural network model that can predict non-dimensional frequency parameters for any T-beam bridges with different geometrical characteristics. Next, the flexural rigidity of a bridge was determined based on the measured natural frequencies derived from vibration testing. The cross-sectional area of the internal reinforcing steel was estimated through a quasi-static load test coupled with an optimization approach. Finally, these structural and material properties that were initially unknown but were estimated through the proposed methodology were used to determine load effects and ultimately the bridge’s capacity and rating factor. Experimental tests on two in-service RC T-beam bridges were conducted and the proposed methodology was used to obtain the rating factors of the bridges. Results indicate that the nondestructive methodology described in this work can satisfactorily estimate the rating factors of T-beam bridges without structural plans.