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Title: Load Rating of 87-Year-Old Reinforced Concrete Tee Beam Bridge

Author(s): Farhad D. Panthaki

Publication: Web Session



Appears on pages(s):



Date: 11/19/2018

The presentation will describe the process of determination of load ratings for an 87 year old reinforced concrete tee beam bridge carrying a roadway over a river. Due to the absence of plans for this town-owned bridge, detailed field measurements were performed on the visible portions of the structure to develop the bridge framing plan and cross-section. The importance and level of detail of the field measurements will be emphasized in order to enable accurate determination of dead loads and member capacities. In addition to the field measurements of the structure, non-destructive testing (NDT) utilizing the ground penetrating radar (GPR) method was required for determination of element details hidden from view. The NDT testing process enabled the determination of overlay thickness and variation across the roadway, concrete deck thickness and reinforcing bar pattern, and the layout and pattern of the longitudinal reinforcing steel and the stirrups in the reinforced concrete beams. Load ratings were performed utilizing the guidelines provided in the AASHTO Manual for Bridge Evaluation (MBE) for the H20, Type 3, Type 3S2 and HS20 live loads. Due to the age of the structure, the load rating method used was the Allowable Stress Method, since it was the standard design method in use during the era of the original design of the structure. In addition, the Load Factor method was used to determine HS20 load ratings for comparison and reporting purposes.