Extrapolating ACI 318-19(22) shear concrete breakout provisions for complex anchorages.
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Author Archives : Richard T. Morgan, P.E.
Richard T. Morgan, P. E., is the Manager for Software and Literature in the Technical Marketing Department of Hilti North America.
Designing For Yield Based on Anchoring-to-Concrete Provisions
The American Concrete Institute (ACI) standard ACI 318, Building Code Requirements for Structural Concrete, includes provisions to design cast-in reinforcing bars for development, i.e., embedding a bar deep enough to develop the yield strength without splitting failure occurring. Splitting failure refers to cracking and splitting in the concrete around bars in tension. Post-installed reinforcing bars have typically been designed using ACI 318 anchoring-to-concrete provisions, which consider various possible anchor failure modes rather than designing the bars to yield. This article expands the discussion of a design concept introduced in an ACI Structural Journal article by Charney et al. in which anchoring-to-concrete provisions could be used to design post-installed reinforcing bars specifically for yielding.
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Erratum
Figure 2(b) and Figure 3(b) in the article incorrectly show the bearing area (Aef,sl) as a T-shaped configuration. This configuration is only relevant when stiffeners are used.
Since the shear lug in these illustrations does not include stiffeners, the bearing area (Aef,sl) should be shown as a rectangular configuration. If stiffeners are installed, the leading edge of the stiffener and the area of the shear lug extending 2tsl on either side of the stiffener would be included in Aef,sl. The author apologizes for any confusion this may have caused. (This Erratum has been added to the online version of the article, www.STRUCTUREmag.org.)
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Anchoring-to-concrete provisions in the American Concrete Institute’s Building Code Requirements for Structural Concrete (ACI 318) are used to calculate anchor design strengths that consider possible anchor failure modes. These design strengths are checked against calculated factored loads acting on anchors. ACI 318 anchoring-to-concrete parameters for calculating anchor design strengths are derived from testing and analysis that includes the use of a rigid fixture to apply tension load to anchors. Therefore, ACI 318 provisions for anchor design can be considered relevant if the fixture being attached can be considered “rigid.” …
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Base plate design” is a frequently misunderstood term, particularly when discussing attachments for post-installed anchoring applications. This article explains how the concept of base plate design, which is typically understood in the context of “column base plate design,” is not necessarily relevant to fixture attachment for post-installed anchoring applications. …
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Post-installed expansion anchors are used to attach fixtures to concrete and masonry. Expansion anchor types include torque-controlled anchors, which must be torqued to expand wedges, and displacement-controlled anchors, which require impact forces on a sleeve or plug to expand wedges. Expansion anchors that rely on torque to expand wedges are referred to as torque-controlled expansion anchors. This article discusses the importance of torque on the installation and performance of torque-controlled expansion anchors installed into concrete. …
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Anchor channel systems are cast into a concrete member. They are used to attach both structural and nonstructural components. Attachment of nonstructural components, such as curtain wall, is a typical anchor channel system application. Traditionally, anchor channel systems have been designed using manufacturer’s data and allowable stress design. Anchor channel systems can now receive recognition under the International Building Code (IBC) for design with strength design provisions. …
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The American Concrete Institute (ACI) Building Code Requirements for Structural Concrete (ACI 318) includes provisions for anchoring to concrete in Appendix D (ACI 318-02 through ACI 318-11) and Chapter 17 (ACI 318-14). Anchorages designed to resist seismic load conditions require special consideration. This article discusses the changes between ACI 318-08 Appendix D seismic provisions and ACI 318-11 Appendix D/ACI 318-14 Chapter 17 seismic provisions, and includes a brief discussion about the International Building Code (IBC) seismic anchoring provisions. …
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Provisions for the design of cast-in-place and post-installed anchors were introduced into the American Concrete Institute (ACI) publication Building Code Requirements for Structural Concrete (ACI 318) in 2002 (ACI 318-02) via Appendix D – Anchoring to Concrete. Since ACI 318 is referenced in the International Building Code (IBC), these provisions are thereby incorporated into IBC Chapter 19 – CONCRETE. …
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Design Using Adhesive Anchor Systems
Reinforced concrete is a construction method that relies on widely understood and historically validated concepts. Traditionally, reinforcing bars are placed in formwork prior to concrete placement. However, many applications require reinforcement to be added to existing structures by means of reinforcing bars grouted into drilled holes, usually with injectable adhesives. …