Bridge Load Programmatic (2014)

Client: Fairfield County Engineer’s Office

Project Overview

Ribway was selected by the Fairfield County Engineer’s Office to provide engineering services for the inspection and load rating of 11 bridges and 2 culverts in Berne, Bloom, Clear Creek, Greenfield, Hocking, Pleasant and Walnut Township.

The superstructures were inspected noting the condition of the beams and deck for the bridges and the top slab and walls for the culverts. Field inspections included documenting the member sizes and measuring all section loss to provide the most accurate conditions of the structural members. Digital photos and notes of the structures were taken during the site visits. The load ratings were calculated according to the Load Resistance Factor Rating (LRFR) methodology. Bridge types load rated included: Timber decks on non-composite steel girders, steel plate deck on non-composite steel beams, pre-stressed adjacent box beams and reinforced concrete, cast-in-place box culverts. The structures were Level I Bridges.

Utilizing the inspection data, the bridges and culverts were modeled and analyzed yielding their respective load ratings using AASHTO Bridge Rating 6.5 (formerly VIRTIS) software. Hand calculations were performed where unique conditions were encountered. AASHTO Bridge Rating 6.5 did not have the ability to rate culverts which use steel mesh in lieu of reinforcement bars; therefore it was necessary to manually calculate the rebar equivalent steel areas.

The load ratings were further verified by Fairfield County’s supplied spreadsheet using the AASHTO software’s output. A Load Rating Summary was recorded by means of form BR-100. A Load Rating Report was generated for each structure.  The project was completed over a two-month period.