Behaviour of very long cable-stayed bridges during erection

Abstract

Stonecutters Bridge and Sutong Bridge in China have pushed the world record for main span length of cablestayed bridges to over 1000 m. The design of these bridges, both located in typhoon-prone regions, was strongly influenced by wind effects during erection. Rigorous wind tunnel test programmes were devised and executed to determine the aerodynamic behaviour of the structures in the most critical erection conditions. Testing was augmented by analytical and numerical analyses to verify the safety of the structures throughout construction and to ensure that no serviceability problems would affect the erection process. This paper outlines the wind properties assumed for the bridge sites, the experimental test programme with some of its results, the dynamic properties of the bridges during free-cantilevering erection and an assessment of their aerodynamic performance. The similarities and some revealing differences between the two bridges in terms of their dynamic response to wind action are also discussed. INTRODUCTIONTwo new cable-stayed bridges in China have surpassed the current world record in main span length by breaking into the realm of over 1000 m span. Sutong Bridge sets the new record at 1088 m span, with Stonecutters Bridge following at 1018 m (Figure 1). Figure 2 shows the bridges during free-cantilevering erection. Sutong Bridge, which is the key element of a large crossing over the Yangtze River, features a conventional layout (Figure 3) with A-shaped towers and an all-steel superstructure with regular backspans. Stonecutters Bridge, located in the urban area of Hong Kong and hence subject to geometrical constraints, has very short backspans made of concrete to balance the long steel main span. It further features single-pole towers (Figure 4) and a twin-box grillage deck (Figure 5), making it a rather unusual configuration.

Editorial

“…N An enlightening study into the behaviour of very long cablestayed bridges during erection where dynamic behaviour in a typhoon-prone zone is examined for the Stonecutters Bridge in Hong Kong and the Sutong Bridge across the Yangtze River in China (each with a main span in excess of 1000 m) (Morgenthal and Yamasaki, 2010). N Finally, a very useful paper on estimating the response of cable-stayed bridges in seismic zones with cautionary warnings where estimates may be inaccurate in some cases (Walker and Stafford, 2010).…”