Strengthening of Burri box Girder Bridge by using External post Tensioning Technology (Sudan)

Abstract

Ageing, and increasing traffic loads, has become a major problem into today bridge industry. These bridges go deficiency in its Load Carrying Capacity from ageing, exhibited in excessive deformation which renders the bridge usage to an unacceptable level. These will either, impose traffic restriction, or upgrading the existing bridges to defy these adverse conditions. At Burri Bridge, after 33 years on operation, signs of ageing showed in the excessive deformation and the departure of the deformed shape of the super structure from the design profile, and travelling along the bridge was un-comfortable and difficult trip riding. The Objective was to explore the strengthening of the Burri Bridge by using external post tensioned tendons to mitigate the ageing effects and to elevate the capacity of the bridge. It was requisite to examine the bridge before the application of external tendons to insure the stresses in its past status will qualify it for repair. Hence, the present study contains the analysis of the Bridge superstructure in two stages. The first is done in its Past status, and the second when external tendons are added to boost its capacity and defy the effect of past load level, and a new standard load tested. The model was analyzed using Midas Civil software. The study includes the design of the anchor beams where the fresh external tendons are terminated. The study proved that, the capacity of the Bridge is increased by 4.6 %, and this is interpreted in the increase of the Ultimate Flexural Strength and the decrease of the deformation after adding these external tendons. Some of the Techniques implemented are presented.