KINGSTON BRIDGE, GLASGOW: STRENGTHENING AND RE-ARTICULATION

Kingston Bridge carries the M8 Motorway over the River Clyde immediately west of Glasgow City Centre. The bridge comprises a linked pair of triple cell, variable depth, post-tensioned concrete superstructures having a 143m main span over the river and two side spans of 62 meters carrying the motorway some 18 meters above the street level. The bridges were constructed between 1967 and 1970 in in-situ post-tensioned concrete using the balanced cantilever method. The relatively short side spans contain ballast concrete placed within the deck cells at the outer ends to generate positive reactions at the end support under the permanent loads. Post-tensioning consists of single and 4 bar Macalloy tendons longitudinally in the top and bottom slabs of the main and side spans and single bar vertical tendons in the webs. The reinforced concrete piers and pile caps are supported on a combination of bored cast in-situ concrete and steel "H" piles carrying load through the overlying alluvial sands and gravels to the sandstone bedrock some 30 meters below ground level. The foundations of the main piers lie immediately to the rear of the River Clyde Quay Walls, significant lengths of which have been subjected to multiple strengthening and failures over the years.