More Than a Facade

A need for a design and testing standard for partially composite precast concrete insulated wall panels



Photo of Edward Losch, PhD, PE, SE, RA

Edward Losch, PhD, PE, SE, RA

Structural Engineer

Losch Engineering

Photo of Marc Maguire, PhD

Marc Maguire, PhD

Assistant Professor

University of Nebraska-Lincoln



In 2014, the American National Standards Institute (ANSI) approved the Precast/Prestressed Concrete Institute (PCI) as an accredited ANSI Standards Developer. Since then, PCI has partnered with the American Concrete Institute (ACI) to develop and maintain a standard specification for the design, fabrication, and handling of precast and precast/prestressed concrete insulated wall panels. This panel type has been supplanting traditional hard-wall construction for many building types.

A variety of proprietary partially composite wall systems have been developed by industry. These systems use thermally efficient wythe connectors to produce lighter, thinner walls with higher R values and minimal thermal bridging between wythes. The ACI 318 Building Code does not yet specifically cover structural analysis and design procedures for these partially composite concrete members (ACI Committee 318 2014).

To remedy this situation, PCI has funded research to determine the strength characteristics of the various commercially available wythe connector systems. Double-shear push-off tests have been and are being conducted to determine ultimate shear strength, deformation and ductility for each manufacturer's connector type. The resultant values will then be used as input for multiple proposed design and analysis procedures for this product category. If approved, these procedures will be recognized by ANSI and be included in the upcoming PCI/ACI Precast Insulated Wall Panel Design Standard.


Precast concrete insulated sandwich wall panels have gained in popularity over the years. Typical applications include schools, gymnasiums, food processing plants, justice facilities and commercial/warehouse buildings. They provide a hard

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Traditionally, composite wall panels have been fabricated using continuous steel wire trusses for the wythe connectors (Figure 2). Often, solid zones of concrete are also used at the top and

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Before a standard design method can be implemented, a standard model for the wythe connector properties needs to be developed. While different connector systems may use specialized techniques that may

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Example connector properties are presented in Figure 13. Clearly, the behaviors of different systems provide different properties. For engineering purposes in the elastic range, the engineer requires elastic stiffness, elastic

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The Beam-Spring Model is intended to be a general-purpose model that can be used for any type of connector, whether truss, bar or plate. While not adopted into any design

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Conclusion and future work

Partially composite concrete sandwich wall panels are a rapidly growing segment of the market. These panels can be used for cladding or load bearing conditions and create a highly efficient

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Thank you to Fray Pozo-Lora for helping with compiling details for this paper. Special thanks for Taylor Sorensen for the thermal image picture.

Rights and Permissions

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