Council releases lightweight aggregate, tank structure research reports

Sources: American Concrete Institute Foundation, Farmington Hills, Mich.; CP staff

ACI Foundation’s Concrete Research Council has announced Interface Shear Transfer of Lightweight Aggregate Concretes with Different Lightweight Aggregates and Evaluation of Seismic Performance Factors and Pedestal Shear Strength in Elevated Water Storage Tanks. Both are aimed at advancing the knowledge and sustainable aspects of the concrete industry in conjunction with ACI technical committee efforts.

Missouri University of Science and Technology’s Lesley Sneed, principle Interface Shear Transfer investigator, tested applied shear force-slip relations and peak shear strength, and examined current shear-friction design provisions in ACI 318 “Building Code Requirements for Structural Concrete” and the Precast/Prestressed Concrete Institute PCI Design Handbook. Findings compel proposed revisions to both documents’ shear-friction design provisions of a smooth interface condition, plus consideration of updates for cold joint smooth interface conditions, leading to more accurate and economical designs.

“The research will move the building code forward,” affirms Sneed, FACI. “It demonstrates a needed next step in allowing for more efficient structural designs.” The project was supported by ACI-ASCE Joint Committee 445, Shear and Torsion, and was sponsored by PCI and Concrete Research Council.

Ryerson University’s Reza Kianoush, principal investigator behind Evaluation of Seismic Performance Factors, evaluated current code-recommended values for response modification factors, plus pedestal shear strength, for design of single-pedestal elevated concrete and composite steel-concrete water storage tanks. Investigators focused on two distinct research goals: the ACI 371E-08 equation for nominal shear strength of reinforced concrete pedestals and the effect of axial compression in enhancing the shear strength of the reinforced concrete pedestals; and, the effect of wall opening on the non-linear behavior of elevated water tanks. They aimed to propose response modification factors for ACI 371 and ACI 350.3 standards, while quantifying and including the effect of axial load in the current equation of nominal shear design of a pedestal.

“The information and data from this research will help to protect a valuable resource in areas with seismic activity,” observes Kianoush. “Updating the current design standards to better protect a water supply is an incredibly valuable endeavor.” The project was supported by ACI Committee 371, Elevated Tanks with Concrete Pedestals, and ACI Committee 350, Environmental Engineering Concrete Structures, and was sponsored by the Concrete Research Council.

The group opens an annual call for new proposals each August, all due by December 1. Additional information on the latest projects, research products, and upcoming requests for proposals can be obtained at www.ConcreteResearchCouncil.org.