Article Applying Appendix D

5 hef 2 175 effective embedment depth d 55 65 8

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Unformatted text preview: 2.5 3 3.5 2.75 in. e 3.5 4.5 5 4.5 hef 2 1.75 Effective embedment depth d 5.5 6.5 8 Installation torque Tinst ft.-lb. 30 65 cmin in. 1.75 2.5 3 Minimum spacing smin in. 1.75 2.5 3 Minimum concrete thickness hmin in. 1.5hef Critical edge distance @ hmin cac in. yrigh E R 100 Minimum edge distance t Cop Anchor Data 1, 2, or 3 — 2 Yield strength of anchor steel fya psi 55,000 Ultimate strength of anchor steel futa psi 75,000 Effective tensile stress area Aze in. 2 0.0775 Effective shear stress area Aze in.2 0.0775 Effectiveness factor for uncracked concrete kuncr Effectiveness factor for cracked concrete used for ACI 318 design kcr* R T S in cracked concrete ψc, N = kuncr/kcr for ACI 318 design in uncracked concrete 3.5 U T 1.5hef 1.5hef 3.6 4.0 ASTMF 1554 Grade 55 (meets ductile steel element requirements) Category number ψc, N for ACI 318 design 3.5 3.0 C U Anchor material 175 1.5hef 2.1 ® ψc, N* 1 55,000 55,000 75,000 75,000 0.226 0.334 0.142 0.226 0.334 24 24 24 17 17 17 17 — 1.0 1.0 1.0 1.0 — 1.4 1.4 1.4 1.4 55,000 75,000 i z 0.142 a g 24 a — m 1 e n — ψc, N* 2 Np lb. Np hef Np hef Np hef Np 1.75 1,354 2.5 2,312 3 4,469 3.5 5,632 2.75 2,667 3.5 3,830 4.5 8,211 5 9,617 4.5 Pullout or pull-through resistance from tests hef 5,583 5.5 7,544 6.5 14,254 8 19,463 1.75 903 2.5 1,541 3 2,979 3.5 3,755 4.5 3,722 5.5 5,029 6.5 9,503 8 12,975 Tension resistance of single anchor for seismic loads Neq lb. Shear resistance of single anchor for seismic loads Veq lb. 2,906 5,321 8,475 12,543 Axial stiffness in service load range b lb./in. 55,000 57,600 59,200 62,000 Coefficient of variation for axial stiffness in service load range v % 12 11 10 9 *These are values used for kc and ψc, N in ACI 318 for anchors qualified for use only in both cracked and uncracked concrete. Figure 4: Example of Anchor Data Sheet. and the value for ψc,N. This ψ value is used to ascertain the difference between a postinstalled anchor’s performance in cracked and uncracked concrete. Appendix D of ACI 318 provides engineers with design requirements for anchors in concrete. This appendix applies to both cast-in-place and post-installed anchors. By incorporating the CCD method, the design rules in this appendix can cover relatively complex anchoring problems. Understanding the many ψ values used by this design method will assist the designer in proper application of these code provisions.▪ STRUCTURE magazine 23 January 2008 Dr. Peter Carrato, P.E., S.E., is a Principal Civil Engineer and Fellow of the Bechtel Corporation. He has over 30 years of experience in heavy industrial design and has been a member of ACI Committee 355, Anchorage to Concrete for more than 10 years....
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