Performance of precast prestressed steel-concrete composite panels under static loadings to replace the timber transoms for railway bridge

Timber is widely used as transoms in numerous railway networks all over the world and currently in use on the existing Sydney Harbour bridge railway system. Now-a-days, the timber transoms, in numerous railway networks, are edging towards the end of their design life. Moreover, often these timber transoms are subjected to repeated mechanical loadings, chemical degradation and prolonged environmental exposures. As a result, frequent maintenance and sometimes complete replacement to ensure the functionality of the railway network significantly increases the track maintenance cost. Therefore, the paper aims to presents alternative solutions to replace the timber transoms with other more durable and virtually maintenance free materials that will improve the long-term functionality of the transoms in Sydney Harbour bridge railway system. To achieve the goal of the study, an experimental investigation was carried out on the precast prestressed steel-concrete composite panels using two different connectors like AJAX ONESIDE blind bolts and LINDAPTER blind bolts. The experimental results of precast prestressed steel-concrete composite panels under two-point bending test were also compared with the conventional reinforced concrete. It can be concluded that the prestressed panels performed better and exhibited less cracking, less deflection and higher stiffness compared to the conventionally reinforced concrete panels. Moreover, the prestressed panel with AJAX ONESIDE blind bolt connectors shows slightly higher deflections and lower uncracked stiffness in comparison to the prestressed panel with LINDAPTER blind bolt connectors. Therefore, LINDAPTER blind bolts connectors, are preferable in connecting the bridge stringer steel and the prestressed composite panel, could be a viable solution to replace the existing timber transoms of the Sydney Harbour bridge railway line.