Dynamic analysis of elevated viaducts of Doha metro green line

¹ Cairo University, Structural Engineering Department and Dar Al Handasah, Bridge Department, Cairo, Egypt
² Dar Al Handasah, Bridge Department, Cairo, Egypt

^a Corresponding author: sameh.mehanny@stanfordalumni.org

Abstract

The 2.7 kilometers double track elevated viaducts of Doha metro green line, currently under construction, consist of cast-in-situ and precast segmental simply supported spans ranging from 20 to 35 m and continuous cast-insitu two and three spans (30-57 m), (50-51-44 m) and (37-68-37 m) U-trough decks. The non-typical configuration of the continuous span arrangements was imposed to the designer by existing underneath utilities and infrastructures. In order to ensure the passenger comfort and traffic safety by preventing track instability during train operation for this special landmark project, performing a dynamic analysis was vital. The dynamic analysis focuses on the vertical accelerations and vertical displacements as well as lateral frequencies of vibration. All simply supported spans as well as the continuous spans of the project are considered. The real train of the project composed of 6 vehicles with a total length of 120m and with actual axle loads (maximum axle load of 160 kN with 4 axles per vehicle) is adopted in the dynamic analysis. The analysis is carried out using both direct time integration of the equation of motion and modal time history analysis for different train speeds ranging from 60 km/hr to the maximum permissible speed along the metro line (160 km/hr) with the maximum operating speed ranging from 100 to 130 km/hr. For each train speed the maximum vertical acceleration and the maximum vertical deflection are monitored using the CSI bridge software and are compared to the allowable values given in EN 1991-2 and EN 1990-Annex 2. According to relevant Euronorm requirements, the vertical accelerations and the vertical deflections were found acceptable for all segments of the elevated viaduct.