ABSTRACT
The AASHTO LRFD Bridge Design Specifications define Non-Redundant Steel Tension Members (NSTM) as primary steel members subject to tension, whose failure could potentially lead to the collapse of a portion or the entire bridge. Bridges with NSTMs must adhere to special mandatory bi-annual hands-on inspections according to the National Bridge Inspection Standards (NBIS). These additional inspections, beyond routine checks, incur unnecessary costs for bridge owners.
Research indicates that bridges with traditionally designated NSTMs often retain significant strength reserves even after NSTM failure. AASHTO introduced a new guide specification in 2018 and outlined a detailed procedure for reclassifying NSTMs as System Redundant Members (SRMs). The procedure requires detailed nonlinear finite element analysis (FEA) to assess the available additional system redundancy.
This paper summarizes the FEA results for a newly designed steel arch bridge. AASHTO guideline procedure were directly followed to remove NSTM designation from the tension-tie members of this bridge.
