Bridges

Since the early 1920’s steel-concrete composite bridges have been widely used on New Zealand’s State Highway Network. Unfortunately, many shear connector types that have been used are not supported by current design rules within the standards referenced in the Transport Agency’s Bridge manual. This paper presents the results from a two year research programme that has developed a new design guide for assessing the load resistance of existing composite road bridges. The research consisted of an investigation of as-built records of 124 composite bridges to identify the most common shear connector types, together with an evaluation of historical material strengths to facilitate bridge assessments when using the new design guidance. From international push test data, structural reliability analyses were undertaken to develop a new design equation for the most common shear connector type. A set of different design procedures were subsequently developed using partial shear connection theory to enable the bending resistance to be assessed. It is expected that the resulting design and assessment guidance will lead to improved load capacities for existing bridges, which will significantly increase the efficiency of the existing highway network, thereby opening it up to heavier 50MAX and high productivity motor vehicles (HMPV).