Strengthening of bridge over Iron Cove, Sydney NSW: a realistic design load

Generally, strengthening of bridges is carried out in accordance with the 1996 Austroads Bridge Design Code (’96 ABDC). Because of the earlier studies conducted in assessing the bridge, it was evident that strengthening the bridge as per ’96 ABDC would have been exceptionally expensive. In addition, it was thought that the bridge would not experience the live loads stipulated in the ’96 ABDC for the next 50 years or during its expected life. Therefore, the Bridge Section proposed a realistic method of determining live loads for strengthening the bridge for legal loads based on the current legal loads experienced by the bridge, the probability of multiple presences of legal loads and the predicted future growth of legal loads over the route. The method was to conduct a traffic survey of the bridge and determine the actual legal loads on the bridge and determine the multiple presences of these loads on different lanes. This paper discusses the use of the approach and it is believed that the use of such an approach would be beneficial in strengthening other similar bridges with more than two lanes of traffic. (a) For the covering entry of this conference, please see ITRD abstract no. E211602.