Rehabilitation of the Komati River Bridge B1604

Abstract

In this paper, the retrofitting and rehabilitation of the Komati River Bridge, Bridge B1604 on the N4 in Mpumalanga, South Africa, is presented. The bridge consists of 17 simply supported spans, 20 metres in length, with a post-tensioned beam and slab deck. The deck is supported on steel bearings, and the abutments are of the spill through reinforced concrete type. The wall type piers are founded on shallow rock with pad footings. The bridge was constructed in 1940, and in 1998 the deck was widened on both sides with larger pre-cast, post-tensioned beams. SMEC South Africa under a Trans African Toll Concessions (TRAC) appointment inspected the bridge in 2014 as part of South African National Roads Agency’s (SANRAL) routine bridge inspections. It was found that the old beams had extensive bending cracks. The cracks were mainly caused by locked in loads due to the jamming of the steel bearings. The rehabilitation design was completed by SMEC South Africa and was implemented by DSC Zendon cc with TRAC as the client in 2017. The repairs included the replacement of 272 steel bearings with elastomeric bearings, crack injection and carbon fibre strengthening of 68 deck beams. DSC Zendon cc utilised mobile platforms to access the soffit of the deck. Hanging platforms were used to minimise the impact on the Komati River and its crocodiles.