Barba PUENTE CARLOS GILBERTO

Applicability of Nonlinear Strength Interaction Formula for Redundancy Evaluation of Steel Truss Bridges by Static Linear Analysis

Eiji IWASAKI 

Aging bridge structures in Japan has become a major issue, one-member failure can cause the collapse of the whole structure. Redundancy evaluation to determine risk of progressive collapse has become significantly important. The most accurate way to assess the breakage of a member would be a Dynamic nonlinear analysis which considers structural motion after breakage. But dynamic nonlinear analysis is complicated and time consuming. 
 In 2006, URS proposed 2 equations (Eq.1 Tension Members, Eq2. Compression Members ) in order to evaluate the redundancy of the remaining member when one member failed (Linear Method), throughout a simple Linear Static Analysis. In 2016, Iwasaki and Khuyen proposed similar equations, but that took into consideration the full moment strength of members depending on their cross-section and can also be done by a simple Linear Static Analysis(Nonlinear Analysis). In case of Through type Steel Truss Bridge, the nonlinear method seems to be more accurate than the linear method. 
 In order to apply the nonlinear methodfs equations generally, it is necessary to asses the accuracy of the nonlinear method in other type of steel truss bridge where the structural behavior is different. In this study the accuracy of both methods on a Deck type Steel Truss bridge was verified. The Nonlinear methodfs equations were more accurate in both type of steel truss bridge compared to the linear method. It was also found that the Linear methodfs accuracy 
decreased when the M/Mp ratio increased. Nonlinear Method maintains a high accuracy despite the type of Steel truss bridge and can be applied generally.