A new RMC Research & Education Foundation report states the case for engineers, practitioners and code officials to consider design loads versus prescriptive reinforcement requirements for concrete walls framing low-rise buildings in moderate or lower seismic zones.
“Simulation-based Investigation of the Performance of Low-rise Concrete Walls with Low Reinforcement Ratios” covers RMC Foundation-funded research at the University of Washington. Department of Civil and Environmental Engineering investigators aimed to identify opportunities for achieving target wall performance and load capacity while using less and more widely spaced steel reinforcement than ACI 318, Building Code Requirements for Structural Concrete allows.
The report represents a first step toward re-evaluation of standards for lightly-loaded concrete bearing walls. “Once combined with experimental data, we believe it will help provide the basis for important changes to ACI 318,” say authors and lead researchers Dr. Dawn Lehman and Dr. Laura Lowes.
In “Simulation-based Investigation,” they note: a) lightly-reinforced concrete walls, including insulated concrete formwork (ICF) walls, are used commonly for residential and low-rise construction; b) ICF construction can be advantageous because the insulating formwork provides a higher level of insulation than traditional construction and results in greater energy efficiency; c) rebar placement is a primary cost of low-rise reinforced concrete and ICF construction; and, d) in regions of low-to-moderate seismicity, ACI 318 Code requirements for minimum reinforcement, rather than design loads, typically determine rebar volume.
“Reducing reinforcement requirements for low-rise walls in regions of low to moderate seismicity would provide both cost and sustainability benefits for reinforced concrete wall construction,” affirms National Ready Mixed Concrete Association Senior Vice President of Structures and Codes Dr. Scott Campbell, who served as technical reviewer for the report.
“Our mission includes improving quality and sustainability in the concrete industry,” adds RMC Foundation 2022 Chairman Rodney Grogan (MMC Materials) “Reducing our embodied carbon impacts through optimized design and making the energy advantages of ICF construction more financially accessible are right in line with that mission. We’re pleased to make this important research available to influencers of the ACI Code.” — www.rmc-foundation.org
