Cable-stayed railroad bridges

Abstract

This paper presents some research results which investigate the use of cable-stayed design for railway bridges where the main bridge span is over 300m. According to investigations made by the Chinese Academy of Railway Sciences, nearly all types of cable-stayed highway bridges can be used for railways. However the optimum ratios of side span over main span (LI/L) and tower height over main span (H/L) are different due to the different ratios between live and total loads. These results also indicate that the economical tower height for the cable stayed railway bridge with a concrete tower and a steel girder span around 400m is between 0.24L to 0.28L. The recommended ratio of LI/L is not greater than 0.425. The stresses and deformations in different parts of the bridge, especially in the side spans and towers, can be significantly reduced if auxiliary piers are placed in the side spans. The effects of train braking forces upon the vertical supporting system of the bridge were analysed for two different supporting systems (with and without longitudinal supports). Side span, main span, tower and pier moments and axial girder forces are all calculated. Dynamic effects of railway load upon the bridge are also analysed as are initial cable forces and uplift forces and the effect of temperature. The recommended cable- girder stiffness ratio is between 5000 and 15000 for a 400m span. It is desirable to have higher initial cable forces and heavier side spans in order to resist the railway loads. The French title of this article is: Ponts ferroviaires a haubans. The German title of this article is: Eisenbahn-Schraegseilbruecken. For the covering abstract of the conference see IRRD 851274.