Analysis and Control of Cable-Stayed Bridges Subject to Seismic Action

Abstract

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link AbstractCable-stayed bridges are key points in transport networks and at present one of the most challenging structures for the civil engineering community. The integrity of these bridges should be guaranteed even under extremely large earthquakes. This paper begins with a discussion of the advantages of a new non-linear static "Pushover" procedure that includes the three-dimensional contribution of the governing vibration modes. The efficacy and the accuracy of the proposed Pushover in the non-linear seismic analysis of bridges with significant coupling between the towers, deck and cable system is verified. In the second part of this paper, the seismic responses of several cable-stayed bridges have been studied, verifying the influence of the tower shape, cable arrangement and the main span length on the structural behaviour under strong ground motions. Severe damage is identified at critical tower sections by means of extensive non-linear dynamic analyses. Finally, retrofit solutions with viscous dampers (VDs) and yielding metallic dampers (MDs) connecting the deck and the tower in the transverse direction are explored. The proposed connection with dampers effectively prevents yielding of the reinforcement and cracking in the tower legs.Keywords: cable-stayed bridges; nonlinear seismic behaviour; retrofit; dampers; pushover analysis; tower shape; main span.vibrations, 3,4 spatial variability of the seismic excitation 5 and the use of seismic devices.6 Few studies are focused on the response of cable-stayed bridge towers to seismic effects. The towers play a paramount role in the global integrity of the structure and should survive large earthquakes.7 Guidelines on the conceptual design of the towers of cable-stayed bridges to withstand seismic ground movements have been provided in Ref. [8]. The seismic response of a relatively small bridge (284 m span) with metallic towers for three different shapes has been studied in Ref. [9]. However, there is a need for parametric studies on the seismic behaviour of cable-stayed bridge towers with different dimensions and cable arrangements. The present paper is focused on two essential aspects of the project of cable-stayed bridges in seismic areas that are relevant to engineers: (1) the inelastic analysis and (2) the design of the towers and their connection with the bridge deck.The selection of the analysis strategy is an important step that should be decided in accordance with the relevance of the structure, the seismic risk and the stage of the construction project. There are several analytical strategies available for designers to study the seismic behaviour of structures in the elastic 10 and inelastic ranges, 11 with different levels of accuracy and associated computational costs. The most rigorous procedure when large inelastic response is expected is the non-linear response history analysis (NL-RHA). Unfortunately, the...

Deck–tower interaction in the transverse seismic response of cable-stayed bridges and optimum configurations

“…Rion-Antirion bridge, Greece). Recent studies on cable-stayed bridges with this type of connection have found that the decktower reaction significantly increases the transverse shear force and bending moment in the towers, making the transverse component of the earthquake more demanding than the longitudinal (along-deck) and vertical directions [14,15]. Indeed, the damage in the tower of the Chi-Lu bridge tower during the Chi-Chi earthquake (Taiwan 1999) can be directly attributed to the transverse response, and it is arguably the most severe seismic damage ever reported in a cable-stayed bridge [16].…”

Design of hysteretic dampers with optimal ductility for the transverse seismic control of cable‐stayed bridges

“…In order to obtain F Rd , the admissible values of the structural response are set as follows: (1) the maximum admissible percentage of the input energy that is dissipated by inelastic excursions in the towers during the earthquake is considered 25% (i.e. ad m D 0:25) [21], and (2) the maximum admissible deck-tower relative displacement is set as u max d T;ad m D 1:0 m in this work, which is the distance between the deck and the tower in the transverse direction in the proposed bridges (Figure 2 (e)). The performance factor F Rd included in Table III is calculated from the results of the dynamic analysis, as discussed in the next section.…”

“…The ductility of the damper ( d ) is selected in this step from a set of trial values (outer loop in Figure 1(a)). As opposed to previous design approaches in which the plate dimensions are constrained based on certain 'workable' values that indirectly limit the ductility of the damper [6,21], in this study, d is a design variable that will define the damper dimensions (Step 6).…”

“…wind actions) [19]. Camara and Astiz [21] conducted a numerical investigation on the seismic response of cable-stayed bridges with VD and with the triangular-plate added damping and stiffness (TADAS) yielding MD proposed by Tsai et al [22]. Calvi et al [20] proposed a conceptual design of VD in the deck-tower connection in order to control both the longitudinal and the transverse responses of the bridge.…”

“…Calvi et al [20] proposed a conceptual design of VD in the deck-tower connection in order to control both the longitudinal and the transverse responses of the bridge. Camara and Astiz [21] conducted a numerical investigation on the seismic response of cable-stayed bridges with VD and with the triangular-plate added damping and stiffness (TADAS) yielding MD proposed by Tsai et al [22]. Although the efficiency of the TADAS devices in the protection of the towers was comparable to the VD, the dimensions of the triangular plates (width and height) were fixed and, thus, the dissipation capacity of the dampers was not explored.…”