Phase I: Improving Safety of Rebar Cages using Innovative Connectors
Funded jointly by Charles Pankow Foundation and a consortium of industry partners through ASCE Construction Institute, the UNR’s research team have started Phase I of the project titled “Improving the Safety of Rebar Cages using Innovative Connectors” in January 2020 and completed in July 2023. The objective of Phase I was to examine the application of mechanical connectors to improve safety during the site handling process of below-grade Cast-in-Drilled-Hole (CIDH) pile rebar cages. Through an experimental and analytical research investigation, the application of various mechanical connectors was examined to replace traditional tie-wire connections at selected locations along the cage. The deliverables provided practical analysis and design guidelines for rebar cages to promote safe site handling process including lifting, tilt-up, and final placement below-grade.
Deliverables
Guidelines for Circular Rebar Cage Assembly with U-bolt Connectors
Through extensive parametric studies and dimensional analysis, analytical models were developed to characterize the stiffness properties of a rebar cage as a function of its physical properties. The derived stiffness properties can then be used to develop a simplified beam model for rebar cages that do not have internal stiffening elements. This will enable engineers to analyze the deflection of rebar cages under site loading conditions without relying on complex and expensive numerical models. The information contained in this guideline is intended to assist those involved in the design, construction, and fabrication of rebar cages, including but not limited to rebar cage fabricators and practitioners, contractors, construction engineers, design engineers, and academics.
Best Practice Manual for Circular Rebar Cage Assembly with U-bolt Connectors
This Best Practice Manual has been prepared based on the recommendations outlined in the document titled "Guidelines for Circular Rebar Cage Assembly with U-bolt Connectors." Its purpose is to provide practical examples of a conservative and safe design approach for determining the number of U-bolt connectors to be used in circular rebar cages in cases where engineering calculations for rebar cage deflection are unavailable.
Research Summary: Application of U-bolt Connector for Improving the Safety of Rebar Cages
This document summarizes the extensive study on the application of U-bolt connectors for improving the safety of rebar cages. The study consists of the following sections:
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Component-Level Experimental Tests
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Full-Scale Experimental Tests
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Finite Element Modeling
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Analytical Investigation
Journal Papers
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"Experimental Investigation of U-Bolt Connectors for Application in Rebar Cages" in Journal of Structural Engineering
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"Full-Scale Testing and Analytical Modeling of Rebar Cages Reinforced with Mechanical U-Bolt Connectors" in Applied Science
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"Application of Cage Clamps in Rebar Cages to Enhance Stability and Safety: Experimental and Analytical Investigations"