Tags:assessment, Blue Nile, Historical Bridge, Rehabilitation, replacement, strength and strengthening
Abstract:
Abstract: The Blue Nile steel bridge over the Blue Nile river in Khartoum State has been in surface for over 109 years. The bridge crosses the river at right angles, connecting Khartoum and Khartoum North. The bridge has a total length of 559 m and an overall width of 16.05 m between centers of trusses. Many strength assessment studies for the structural condition of the bridge were carried out. The first recorded study being in 1960, followed by studies on 1975,1981,1994,2004,2008 and 2009. All these studies revealed serious problems in some elements of the bridge. These elements include superstructure, bearings and substructure. All studies recommended repair and rehabilitation of the affected parts of the bridge. A rehabilitation program began on October 2017 to extend the life of the bridge for another 50 years. This paper includes a literature review on strength assessment of the bridge members, the method of selecting the rehabilitation strategy for the bridge along with the methodology by which main members were identified for strengthening or replacement. The strengthening of the existing side walk to be converted into roadway for private small cars is presented. The need to respect the appearance of the main members of the bridge to meet historical protection was respected. Due to the congestion created by closing the bridge, the need arise to reopen the bridge as quickly as possible. This dictated using strategies and construction methods to achieve the goal of opening the bridge to traffic partially in short time. These strategies and methodologies are presented. Lessons learned during assessment, design and construction stages are outlined, and recommendations are presented for the strength assessment of corroded members based upon results on the literature survey and experience obtained during execution of the rehabilitation of the bridge.
Rehabilitation of A109 - Years Old Blue Nile Steel Bridge