This study aims at providing research information on the pullout capacity of straight and headed-end GFRP bars embedded in bridge deck slab as pre-installed anchors for new bridge barrier-deck construction and as post-installed anchors for the replacement of deteriorated bridge barriers. In Phase I of this research, the pullout capacity of pre-installed ribbed-surface GFRP bars in twin- and triple-bar groups were investigated experimentally, considering different bar size, spacing and embedment depths. In phase II of this research, the pullout capacity of post-installed sand-coated and ribbed-surface GFRP bars were investigated experimentally considering different bar size and embedment depths and adhesive types. The experimental findings were compared with available experimental results and pullout formulas. Design values for the pullout strength of the GFRP bars as pre- and post-installed anchors in concrete were deduced.