Improving Safety of Rebar Cages using Innovative Connectors
Phase I Review
Phase I of the project, titled “Improving the Safety of Rebar Cages using Innovative Connectors,” was conducted by the UNR research team from January 2020 to July 2023, with funding from the Charles Pankow Foundation and industry partners through the ASCE Construction Institute. This phase focused on enhancing the safety of below-grade Cast-in-Drilled-Hole (CIDH) pile rebar cages during site handling by exploring the use of mechanical connectors in place of traditional tie-wire connections. The research provided practical analysis and design guidelines to ensure safer processes for lifting, tilt-up, and placement of rebar cages.
Phase II Overview
The goal of Phase II is to study the failure mechanisms of rebar cages under lateral loading conditions, such as uneven tightening of guy wires, environmental loads, or accidental impacts. It seeks to develop practical guidelines for the analysis, design, and detailing of rebar cages to prevent failures during all construction stages. This phase builds on insights from Phase I, focusing on below-grade and above-grade cages with mechanical connectors or internal stiffening.
Statement of Problem and Research Gaps
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Limited understanding on loading conditions that impact the stability and performance of above- and below-grade rebar cages.
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Minimal research on the necessary base connection details to ensure stability of rebar cages.
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Limited experimental data on the failure mechanisms and strength limits of rebar cages.
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Limited design and handling guidelines for prefabricated rebar cages, specially above-grade cages
Phase II Objectives
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Loading Conditions: Identify and analyze the loading conditions for above- and below-grade rebar cages, including temporary guying and bracing systems.
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Base Restraint Analysis: Determine minimum base connection details for stability without external bracing. Mechanical connectors as splicers will be tested for base strength and splicing long cages.
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Failure Strength Testing: Conduct failure testing of rebar cages to establish allowable strength limits and safety factors.
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Rectangular Rebar Cages: Expand research to include rectangular cages, representing diaphragm walls and prefabricated wall cages.
Research Plan
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Comprehensive literature review on temporary structures to find provisions on loadings for design and assessment of rebar cages.
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Component-level testing of mechanical connectors for parallel-bar (splice) connections.
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Full-scale experiments on circular and rectangular rebar cages with different configurations.
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High-fidelity numerical modeling based on experimental data.
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Numerical sensitivity analyses for different cag configurations.
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Developing analysis and design guidelines.
Our Research Team
Hamed Ebrahimian, Ph.D, P.E.
Assistant Professor
Department of Civil and Environmental Engineering
University of Nevada, Reno (UNR)
Mohammad Esmaelian
Ph.D. Student
Department of Civil and Environmental Engineering
University of Nevada, Reno (UNR)
Gokhan Pekcan, Ph.D.
Professor
Department of Civil and Environmental Engineering
University of Nevada, Reno (UNR)
Sabin Acharya
Ph.D. Student
Department of Civil and Environmental Engineering
University of Nevada, Reno (UNR)
