Cable loss and progressive collapse in cable-stayed bridges

Abstract

The failure of one structural element can lead to the failure of further structural elements and thus to the collapse of large sections or the entire structure. Such disproportionate collapses have been discussed and investigated for some years, but mainly for buildings. In the field of bridge engineering, this phenomenon attracts only sporadic attention. Although international guidelines for cable-stayed bridges require that the loss of one cable must not lead to the collapse of the entire structure, comprehensive analyses that include non-linear dynamic effects are rare. To simply account for dynamic effects, a quasi-static analysis with a dynamic amplification factor of 2.0 is recommended. This value is possibly too large, leading to uneconomic solutions. Therefore, this work examines the structural response of a cable-stayed bridge to the loss of one cable by means of dynamic analyses including large displacements. The effects of cable sag, transverse cable vibrations and structural damping are determined and dynamic amplification factors are computed.

A Study on Potential Progressive Collapse Responses of Cable-Stayed Bridges

“…The dynamic amplification factor (DAF) adopted by Wolff and Starossek (2009) is defined as (1) and the equivalent DAF (Zoli and Woodward 2005) due to sudden loss of cable(s) is calculated from (2) where S dyn(t) is the maximum/minimum value of the response at instant time t of the dynamic response, S healthy is the response obtained from the static analysis of the healthy bridge [ Figure 1(a)] and S F0 and S F1 are the responses obtained from the static analysis of case F0 and F1 shown in Figures 1(b) and 1(c), respectively.…”

“…However, application of a DAF = 2 (obtained for a single degree of freedom system) has been questioned by some researchers (Ruiz-Teran and Aparicio 2007;Wolff and Starossek 2009;. Wolff and Staroussek (2010) found that applying a single DAF for different structural components in a cable stayed structure cannot adequately capture the dynamic effects, because the value of DAF for each structural component depends on location of the ruptured cable and type of the state variable (i.e.…”

“…At the global level, most of the research on the potential progressive collapse response of cable stayed bridges take advantage of linear elastic FE models to determine the DAF for different structural components and investigate the contributing factors (such as bridge geometry, location of ruptured cable, load cases, duration of cable loss and damping ratio) on the magnitude of DAF (Zoli and Woodward 2005;Ruiz-Teran and Aparicio 2007;Wolff and Starossek 2009;Wolff and Starossek 2010;Starossek 2011). On the other hand, some researchers have used the sophisticated continuum-based FE models and hydro-codes for investigating the local behaviour of cable stayed bridges subjected to abnormal loads such as blast and fire Tang and Hao 2010;Son and Lee 2011;Wang 2011).…”

Dynamic Analysis of Cable-Stayed Bridges Affected by Accidental Failure Mechanisms under Moving Loads

“…The stress distribution arising from such a loading scheme is combined with the effects of other existing loading schemes by means of proper factored loading combinations. However, recent papers have demonstrated that such a simplified approach becomes unsafe in many cases, leading to dynamic amplification factors higher than those suggested by existing recommendations [17][18][19]. In particular, some parametric studies have been developed for bridge typologies subjected to accidental cable failure by using a numerical approach based on classical standard linear dynamic framework [18,19].…”

Research on the feasibility of large-span cable structure under impact

“…Huang Yan accurately developed a completely general analytical method for the static analysis of cable structures [11] . M.Wolff [12] modeled a cable-stayed bridge, examined the dynamic response of a cable-stayed bridge to the loss of a cable, and evaluated the effects of cable sag, transverse cable vibrations and structural damping in nonlinear dynamic analyses. Mozos [13,14] systematically studied on the response of cable stayed bridges, the pylons and the stays to the sudden rupture of one of its stays.…”