In LRFR calculations, permanent loads are separated into the three variables DC, DW, and P, because each is assigned an independent load factor ([gamma]) for each load rating limit state.
As with load factor rating, LRFR live loads are temporary loads that act on a structure.
454: Calibration of Load Factors for LRFR Bridge Evaluation, [beta] is defined as follows:
Because the LRFR live-load factors depend on average daily truck traffic (ADTT), researchers used traffic data for calibration.
To enable a smooth transition from load factor rating, the LRFR research team set a goal to make the manual practical and easy to use.
As with LRFD, LRFR promises a more uniform level of safety and a lower risk of over- or underdesigned members.
Although the general equations are similar for the current LFR and new LRFR methodologies, and the procedures are straightforward, the implementation of a new load rating method can be time-consuming and costly for State DOTs.
LRFR provides a simplified approach through the use of the HL-93 live loading as a screening check for all other legal loading.
LRFR enables bridge owners to apply traffic volume and other site-specific data when determining live-load factors for a bridge.
LRFR facilitates using the past performance of a bridge to help determine its serviceability rating.
LRFR provides procedures for load rating vehicles with loads that exceed the legal limit (or permit vehicles).
LRFR provides procedures for evaluating fatigue on existing steel bridges, combining specifications from AASHTO's guide Specifications for Fatigue Evaluation of Existing Steel Bridges and AASHTO's LRFD Bridge Design Specifications.