Evaluation of requirements for global analysis in EC3 for the structural analysis of the simple-span under-deck cable-stayed bridge

Abstract

Paper presents structural behavior analysis of the multi-span steel rigid beam of the unconventional under-deck cable-stayed (UDCS) bridge. Direct anchorage of cable-staying system into the rigid beam causes it’s essentially a nonlinear behavior. The structural response of the rigid beam of the considering bridge under distributed transverse load approach the one of a beam-column with the elastic restraints at the points of struts connection to the beam. Paper presents computational and computer-aided analysis of the UDCS bridge rigid beam by using calculation model composed of simply supported steel beam-column members. The calculation model used for the geometric nonlinear analysis fits within the framework of the existing steel design standards. The recommendations for the global analysis of the form currently included in the European steel standards were selected for this purpose. The performed computer aided analysis of both UDCS bridge as whole structure and arbitrary structural model of beam-column is supported by two main components the finite element analysis (FEA) and the requirements for the structural design. Accordingly to the nature of structural behavior of the rigid beam of the UDCS bridge and requirements of the global analysis, the effects of the deformed geometry and imperfections shall be considered. The concept of equivalent geometric imperfections was used with the values which reflect the possible effects of both types - geometric and physic imperfections. The comparative analysis was performed to declare the accuracy of the proposed computational method by using numerical results obtained by FEA. The obtained errors fit within the desirable limits. The evaluation of current European steel structures design practice performed to present practical applicability of the global analysis currently stated as alternative method and included in the standards of the form of recommendations and requirements.