Q. Is there any way to use additional reinforcing bars to increase the capacity of anchors designed according to Appendix D of ACI 318-081? A. The answer to your question depends on the particular failure mode that is controlling the strength of the anchor group you are designing. SUPPLEMENTARY REINFORCEMENT The first way that reinforcing bars can be used to increase calculated anchor group capacity is by allowing the use of a higher strength reduction factor (-factor) for determining side-face blowout strength and concrete breakout strength in tension or shear.
increasing anchor Capacity with reinforcement Q. Is there any way to use additional reinforcing bars to increase the capacity of anchors designed according to Appendix D of ACI 318-081? used. The increase in φ-factor for post-installed anchors is larger, but the use of supplementary reinforcement is often limited to cast-in anchors because the exact location and orientation of the reinforcement in an existing A. The answer to your question depends on the particular failure mode that is controlling the strength of the anchor group you are designing. When member is often not known to a sufficient level of detail. The anchor capacity is calculated using the same equations whether supplementary reinforcement is used or not, but the controlling failure mode is the steel strength of the the φ-factor in some of the equations is higher. The area anchor in either tension or shear, additional reinforcement of supplementary reinforcement provided is not directly will not affect the calculated strength of the anchor group. used to calculate the anchor capacity. Also, for the concrete failure modes of pullout and pryout, Supplementary reinforcement is defined in Appendix D additional reinforcement does not affect the calculated as “Reinforcement that acts to restrain the potential capacity. For the remaining failure modes of concrete concrete breakout but is not designed to transfer the breakout in tension, concrete breakout in shear, and side- full design load from the anchors into the structural face blowout in tension, there are two ways that additional member.”1 The commentary for this definition explains reinforcement may increase the anchor group capacity. that “Supplementary reinforcement has a configuration and placement similar to anchor reinforcement but is not Supplementary reinforCement specifically designed to transfer loads from the anchors The first way that reinforcing bars can be used to into the structural member.”1 We’ll discuss anchor increase calculated anchor group capacity is by allo
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