Fatigue Behavior of Concrete Bridge Decks Cast on GFRP Stay-in-Place Structural Forms

Abstract

The first part of the thesis addresses the fatigue performance of concrete bridge decks with GFRP stay-in-place structural forms replacing the bottom layer of rebar. The forms were either flat plate with T-up ribs joined using lap splices, or corrugated forms joined through pinand-eye connections. The decks were supported by simulated Type III precast AASHTO girders spaced at 1775mm (6ft.). Two surface preparations were examined for each GFRP form, either using adhesive coating that bonds to freshly cast concrete, or simply cleaning the surface before casting. For the bonded deck with flat-ribbed forms, adhesive bond and mechanical fasteners were used at the lap splice, whereas the lap splice of the unbonded deck had no adhesive or fasteners. All the decks survived 3M cycles at 123kN service load of CL625 CHBDC design truck. The bonded flat-ribbed-form deck survived an additional 2M cycles at a higher load simulating a larger girder spacing of 8ft. Stiffness degradations were 9-33% with more reduction in the unbonded specimens. Nonetheless, live load deflections of all specimens remained below span/1600. The residual ultimate strengths after fatigue were reduced by 5% and 27% for the flat-ribbed and corrugated forms, respectively, but remained 7 and 3 times higher than service load. The second part of the thesis investigates the performance of bridge deck overhangs reinforced by GFRP rebar. Overhangs of full composite slab-on-girder bridge decks at 1:2.75 scale were tested monotonically under an AASHTO tire pad. Five tests were conducted on overhangs of two lengths: 260mm and 516mm, representing scaled overhangs of 6ft. and 8ft. girder spacing, respectively. The 260mm overhang was completely reinforced with GFRP rebar while the 516mm overhang consisted of a GFRP-reinforced section and a steel-reinforced section. The peak loads were approximately 2 to 3 times the established equivalent service load of 24.3kN, even though the overhangs were not designed for flexure according to the CHBDC but rather with lighter minimum reinforcement in anticipation of shear failure. The failure mode Abstract ii of each overhang section was punching shear. The steel-reinforced overhang section exhibited a greater peak load capacity (13.5%) and greater deformability (35%) when compared to the GFRP-reinforced overhang section.

Behavior of Ultrahigh-Performance Concrete Bridge Decks with New Y-Shape FRP Stay-in-Place Formworks

“…Several FRP stay-inplace formwork configurations for decks have been proposed and investigated in previous studies. Flat plates with T-shape ribs (Oliva et al 2008, Bank et al 2010, Nicoletta et al 2019), flat plates with perforated rib connectors (Zuo et al 2018a, b), flat plates stiffened by bonded hollow square sections (Dieter et al 2002, Alagusundaramoorthy et al 2006, Hanus et al 2009, corrugated plates (Honickman and Fam 2009, Liu et al 2011, Fam and Nelson 2012, He et al 2012, Richardson et al 2014, a plate attached to the bottom of grid reinforcements (Ringelstetter et al 2006, Fang et al 2016, and pultruded hollow box sections with moulded grating (Gai et al 2013) are examples of FRP stay-in-place formworks. Cost analysis of reinforced concrete bridge decks with FRP stay-in-place formworks showed a 24% ~ 57% project cost reduction when compared to conventional concrete bridge decks (Berg et al 2006, Ringelstetter et al 2006, Matta et al 2007.…”

Behavior of Hybrid Reinforced Concrete Bridge Decks under Static and Fatigue Loading

“…According to these researchers, the slabs performed well compared to the Eurocode serviceability limit states, even with conservative loading and contact areas. Richardson et al [ 36 ] studied the fatigue of concrete decks with GFRP stay-in-place forms by performing static and fatigue testing on the specimens. These researchers found that the decks built this way can withstand at least three million cycles with appropriate performance under service load.…”