Development and study of closure strip between precast deck panels in accelerated bridge construction

Abstract

This research investigates the use of glass fiber reinforced polymer (GFRP) bars in bridge decks and ultra-high performance fibre-reinforced concrete (UHPFRC) as filling materials in (i) panelto- panel closure strips between transverse precast full-depth deck panels (FDDPs) supported over girders and (ii) the shear pockets for the panel-to-girder connection. The experimental research program included three phases. Phase I examined pullout strength of straight-end and headed-end GFRP bars embedded into UHPFRC to determine the required closure strip width to develop bar full strength. Phase II included the development and study of closure strip details incorporating UHPFRC as joint-filling materials and GFRP bars projecting into the joint. Three joints of width 200 mm between precast FDDPs were developed, namely: angle-shape joint (Ajoint), C-shape joint (C-shape), and zigzag-shape joint (Z-joint), with 175-mm projecting length of GFRP bars into the joint. Two series of 2500x600x200 mm one-way slabs were cast to investigate the flexural strength of the jointed precast slabs compared to cast-in-place slabs. Two types of concrete were used to fabricate the precast FDDPs, namely: normal concrete (NSC) and high-performance concrete (HPC). Correlation between experimental results and available design equations for moment and shear capacities, as well as CHBDC and AASHTO-LR applied factored design moments, was performed. All specimens failed in either flexural or flexural-shear mode outside the UHPFRC-filled joint. Phase III included testing three pairs of 3700x2500x200 mm laterally-restrained precast FDDPs incorporating the three developed joint details in the transverse direction of the girders. Each pair of specimens was tested under 600x250 mm wheel loading located beside the closure strip, considering (i) constant amplitude fatigue (CAF) loading up to 4 million cycles followed by increasing static loading to-collapse, and (ii) incremental variable amplitude fatigue (VAF) loading to-collapse. The failure mode of the tested slabs was punching shear, with the transverse UHPFRC joint diverting the extension of the punching shear plane to the adjacent precast FDDP segment. Results of fatigue load tests on the three-jointed pairs of slabs showed high fatigue performance. A new prediction model for fatigue life of the GFRP-reinforced, UHPFRC-filled jointed deck slabs was developed.