Steel bridge girder strengthening using postinstalled shear connectors and UHM CFRP laminates

A number of steel girder-RC bridges built in the past have noncomposite bridge decks. Many currently have load postings because of increased traffic loads. The main objective of this case study was the performance evaluation of a single span steel girder bridge with a noncomposite RC deck before and after strengthening using postinstalled shear studs and ultra high modulus (UHM) carbon-fiber-reinforced polymer (CFRP) laminates. The postinstalled shear studs were used to obtain a partial composite action between the concrete deck and steel girders to increase the load-carrying capacity and utilize the UHM CFRP laminates more efficiently. An AASHTO load-rating analysis carried out for an interior girder under an HS25 truck load showed an inventory level rating factor of 0.46 for the noncomposite bridge. Field tests were conducted before and after the installation of the shear studs and UHM CFRP laminates to determine the increase in the load-carrying capacity and reduction in maximum deflection. A finite-element model of the bridge was developed to validate the experimental data and analyze the bridge under varying wheel loads. Postinstalled shear studs are found to be capable of significantly increasing the load-carrying capacity of noncomposite bridges. The use of UHM CFRP laminates strengthened the steel bridge girders, reduced overall deflections, and increased the load-carrying capacity. The postinstalled shear studs and UHM CFRP laminates increased the load rating and removed the load posting on the bridge.