Strengthening Hollow Core Concrete Bridges with Deficient Transverse Hinge Joints with a Steel and Concrete Composite Anchorage System

Hollow core concrete bridges have been widely constructed in China during the last two decades. The most simple span bridges, with standard lengths of 13 m, 16 m and 20 m, are hollow core concrete bridges. For this type of bridge, the hollow core slabs are precast and simply lifted into place. After the prefabricated hollow core slabs are put in place, the embedded rebars extending from the prefabricated slabs are bound together and the concrete is poured into the space between the slabs, forming a lateral hinge joints between the slabs. A lot of hollow core concrete bridges built early in the 1990s have small hinge joints and very few rebars embedded to form strong lateral connections between the slabs. With an increase of overweight vehicles and the continuous aging of the structures, structural deficiencies such as intensive cracks running through the mid-span and severe deflection progress rapidly resulting in loss of structural capacity and even collapse. The failure of hollow core concrete bridges usually initiates from the failure of the hinge joints, which are the weakest links of the system. When the hinge joints start to lose their ability to hold the adjacent slabs securely, more and more vehicle loads are shifted onto the slabs with deficient hinge joints, which worsens the condition of the slabs and eventually results in systematic failure. To save the hollow core concrete bridges from failure, the authors propose an effective strengthening method to stop the progress of the deficiencies and improve the capacity of the structure.