Linear Redundancy Analysis Method Considering Plastic Region for Steel Truss Bridges

This paper describes a linear redundancy analysis procedure to identify fracture critical members in steel truss bridges by considering progressive collapse analysis that propagates damage from the initially fractured member to other members. The conventional linear approach assesses structural robustness by checking the strength of every single member through linear equations of member strength for all types of cross sections. However, results are more accurate if member strength is assessed with a nonlinear curve rather than a single linear equation. This paper presents a new linear redundancy analysis method that uses a more accurate nonlinear equation for member strength that accounts for the effect of the plastic region before the cross section has completely yielded. The proposed method can be applied to steel truss bridges with typical sections, such as I-shaped, H-shaped, and box-shaped cross sections. A nonlinear redundancy analysis of a typical steel truss bridge was conducted to validate the proposed criteria. The results of the proposed method were found to be consistent with the results of the nonlinear redundancy method, which is well known as a highly accurate approach. (C) 2016 American Society of Civil Engineers.