Triage method for load rating bridge size two-cell reinforced concrete box culverts for the AASHTO LRFD design load.

Reinforced concrete bridge size box culverts (RCBCs), with structure length greater than or equal to 6.1 m (20 ft), are an integral part of the transportation infrastructure. Load rating RCBCs is essential, and the critical component is generally the top slab. The objective of this study is to propose a triage methodology to quickly and conservatively determine the rating factor (RF) for the top slab of a two-cell RCBC. The derivation of the demand equations is illustrated in this manuscript for the top slab and the AASHTO HL-93 live load. The finite element program CANDE is used to evaluate the influence of the cell clear height (H), cell clear span (S), fill height (HF), and the backfill modulus (E) on the demand loads. Multiple regression analyses showed that H had no significant effect on the dead load demands, while H and E had no significant effect to the live load demands. Conservative linear demand equations (LDEs) are presented to calculate the dead and live load demands leading to a quick determination of the RF. LDEs for single and multi-cell culverts can be derived following the LDE procedure outlined herein. [ABSTRACT FROM AUTHOR]