surprises and good fortune small post-tensioned concrete bridges
design intentions | construction by tom martin
John Laurie Boulevard: the south girder during rotation shows the excellent surface finish of the site placed concrete. The ropes at the north end of the girder are still attached as is the balance weight. In the background is the site for the construction of the north girder and for the drop-in girder. The rectangular opening in the bottom of the girder in front of the pier is to enable future inspection inside the box. The top and bottom rings of the bearing system are separated with a small gap behind which is located a backing plate to facilitate the welding of the joint once alignment is completed.
26
Tom Martin
In 1961 I had the good fortune to be in a team of structural engineers, led by Ove Arup, designing the Ankobra River bridge in Ghana. We drew, calculated and analysed while Arup worried about shapes, proportions and construction methods and whether intersections of planes should have curved or sharply angled transitions. In those days young engineers were paid the smallest of living wages but were also allowed the time to try alternative ideas and to develop their engineering judgement without always having an eye on the clock. I was studying Theory of Structures for the Institution of Structural Engineers’ examinations – I had discovered structural engineering after a talk on the factors affecting good industrial design at a Design Conference at the Earls Court Exhibition Centre. I joined Ove Arup & Partners who introduced me to the wonderful potentials of formed concrete and, particularly, to post-tensioning.
Made with FlippingBook interactive PDF creator