This assignment was NCHRP Project 12-52, Load Resistance Factor Design for Horizontal-Curved Steel Girders.  The objective of this project is to prepare specifications for the design and construction of horizontally-curved steel girder bridges (both I-and box beam girders) in a calibrated load and resistance factor design (LRFD) format that can be recommended to AASHTO for adoption. The specifications are based on the Recommended Specifications for Horizontally Curved Steel Highway Bridges developed under NCHRP 12-38, which are in a load factor design format, supplemented by the FHWA large-scale curved I-girder tests as they became available.

Modjeski and Masters, as Principal Investigator, directed, coordinated and managed the overall project to produce LRFD-based horizontally-curved steel girder bridge specifications.

The following tasks were included in the research:

• Review and evaluate all pertinent domestic and international research.

• Review and modify for implementation, the background of the calibration procedures used in NCHRP Project 12-33 “Development of a Comprehensive Bridge Specification and Commentary”.

• Develop a set of draft changes to the AASHTO LRFD Bridge Design and Construction Specifications based on information gathered in Tasks 1 and 2.

• Evaluate 10 representative structures, using the draft.

• Provide an Interim Report documenting results of Tasks 1 through 4.

• Revise the draft and rework two design examples using comments provided by the panel.

• Submit revised material for review.