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Abstract
1- Introduction
2- Failure mechanisms of shear pocket connection
3- Proposed design procedure of shear pocket connection
4- Experimental investigation
5- Finite element analysis (FEA)
6- Discussion
7- Conclusions
References
Abstract
Current bridge design codes do not provide adequate criteria/procedures for designing full-depth precast concrete deck systems, especially those with shear pocket connections. Instead, these systems and their connections are designed on a case-by-case basis by either conducting necessary testing or adopting the design criteria/procedures developed primarily for cast-in-place concrete deck systems. Shear pocket connections formed using steel hollow structural sections (HSS) provide a promising solution to connecting precast concrete deck panels to the supporting girders due to their superior structural performance and simplicity of panel fabrication. The main objective of this paper is to develop criteria/procedures for designing HSS formed shear pocket connections in full-depth precast concrete deck systems. These procedures will assist bridge designers in selecting pocket dimensions, HSS thickness, pocket anchorage and reinforcement necessary to maximize the connection capacity while allowing adequate construction tolerance. Experimental investigation (push-off testing) and finite element analysis (FEA) were performed to validate the developed design criteria/procedures. Analysis and testing results indicated that the developed design criteria/procedures for HSS formed shear pocket connections are satisfactory.
Introduction
Full-depth precast concrete deck systems is one of the promising technologies for accelerated bridge construction (ABC) because the construction of cast-in-place concrete bridge decks is one of the most time-consuming and labor-intensive operations in bridge construction [1]. Prefabrication of concrete bridge decks offers an opportunity to significantly reduce construction duration, traffic disruption, and bridge life-cycle cost. According to the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) bridge design specifications section 9.4.1, full composite action between bridge deck and supporting girders is highly recommended as it improves the superstructure stiffness and economy [2]. Full-depth precast concrete deck panels are made composite by connecting them to the supporting girders using different types of shear connectors, such as bent bars, headed studs, or threaded rods with nuts [3]. These connectors are either embedded into the concrete girder during fabrication or welded to the top flange of steel girder before or after installing the precast concrete deck panels. Two approaches are commonly used to anchor the shear connectors into the full-depth precast concrete deck panels: (1) using longitudinal troughs (channels) in each deck panel above every girder line in case of continuous shear connectors; or (2) using isolated shear pockets in each deck panel above every girder line in case of discrete clustered shear connector. Fig. 1 shows examples of these connections that are used in bridge construction in the US, such as wedged shear pocket connections, longitudinal channel connections, and hollow structural section (HSS) formed shear pocket connections. The maximum spacing between shear connectors/ pockets had been studies thoroughly in several experimental and analytical investigations conducted by [4–7]. Researchers indicated that stress concentration in the deck panel around the pocket need to be resisted by providing special confinement reinforcement, which makes the HSS formed shear pockets advantageous over other types of shear pockets as they eliminate the need for additional/special deck reinforcement.