Stability evaluation of steel girder members in long-span cable-stayed bridges by member-based stability concept

Abstract

The member-based design concept utilizing the buckling length of each structural member has been widely used to assess the buckling instability of steel structures. Since steel girder members in conventional cable-stayed bridges are generally exposed to large axial forces, the buckling instability of these members should be carefully investigated in the design stage. However, analytical approaches for obtaining the buckling lengths of steel members, such as the alignment chart, story-buckling and story-stiffness methods, may not be adopted to cable-stayed bridges because these approaches imply some theoretical assumptions that are adequate only for steel framed-structures. Furthermore, the boundary conditions of steel girder members supporting by cables are obscure to be prescribed in general terms. Numerical eigenvalue analysis may be one of the most excellent candidates for determining the buckling lengths of steel girder members in that this method can handle the interactions among members implicitly without any irrelevant assumptions for cable-stayed bridges. This paper discusses detailed procedures for obtaining buckling lengths of steel girder members in cable-stayed bridges by numerical eigenvalue analysis. In order to avoid the problem of generating excessively large buckling lengths in some girder members having small axial forces, a modified eigenvalue analysis is proposed by introducing the concept of a fictitious axial force. Practical application example for a real cable-stayed bridge is illustrated with some discussions on the effect of the proposed modification and stability evaluation by member-based stability concept.

High-efficiency Algorithm for the Most Unfavourable Load Case Combinations of Multilayered Frame-Type Wharf Structure

“…Chen et al [10] proposed a framework for fatigue analysis of a long-span suspension bridge under the combined effect of railway, highway, and wind loading. Yoo et al [11] discussed detailed procedures for obtaining buckling lengths of steel girder members in longspan cable-stayed bridges by a modified numerical eigenvalue analysis. During this procedure, the external loads were considered by combining the dead load (selfweight and attachments) and live load (lane load).…”

“…with their load case combinations were synthetically discussed. This paper established a high-efficiency algorithm for estimating the most adverse combined internal force results and the corresponding unfavourable load case combinations of different important components for multilayered frame-type wharfs based on the premise of previous research results [6][7][8][9][10][11][12][13][14]. This algorithm employs the load combination principles of high-pile wharf structures [15] to determine the most adverse combined values of internal force and their corresponding load case combination results for significant components of multilayered wharf structures in the Three Gorges Reservoir of China.…”

Nonlinear Stability Analysis of a Composite Girder Cable-Stayed Bridge with Three Pylons during Construction

“…Shu and Wang investigated the stability characteristics of box-girder cable-stayed bridges by three-dimensional finite element methods taking into account geometric nonlinearity and many design parameters, such as the main span length, the cable arrangement, and the type of pylons [4]. Yoo et al proposed a modified eigenvalue analysis by introducing the concept of a fictitious axial force to obtain buckling lengths of steel girder members in cable-stayed bridges, which could avoid the problem of generating excessively large buckling lengths in some girder members having small axial forces [5]. Thai and Kim proposed a fiber hinge beam-column model to predict ultimate load-carrying capacity and ultimate behavior of cablestayed bridges, which included both geometric and material nonlinearities [6].…”