Page 38 of Wood Construction Connectors 2006 Catalog by Simpson Strong-Tie

39 Anchors HDA/HD Holdowns Model No. Material Dimensions Fasteners Body Ga Base Ga HB 4 SB W H B SO CL Anchor Dia 5 Stud Machine Bolts Qty Dia HD2A 7 12 4 2 2 8 2 1 2 HD5A 3 10 5 3 3 9 3 2 2 HD6A 7 6 3 3 11 3 2 2 HD8A 7 6 3 3 14 3 2 3 HD10A 7 6 3 3 18 3 2 4 HD14A 3 7 4 3 20 3 2 1 4 1 HD15 3 7 4 3 24 4 3 2 1 5 1 Model No. HD2A HD5A HD6A HD8A HD10A HD14A HD15 Code Ref. Wood Member Thickness 1 2 2 3 3 5 1320 1740 2165 2570 2565 2550 0.058 1585 2110 2625 3130 3645 3680 0.067 1870 2470 3065 3680 4280 5020 0.041 2710 3655 4530 5480 6350 7330 0.111 3275 4600 5745 7045 8160 9195 0.269 9495 12485 0.215 13810 0.082 0.077 0.117 0.125 0.121 0.269 0.282 0.082 40, 105, 122 Holdown 9 Deflection at Highest Allowable Design Load Holdown 9 Deflection at Highest Allowable Design Load Raised Wood Member Thickness 1 2 2 3 3 5 1555 2055 2565 2775 2775 2760 1870 2485 3095 3705 4010 3980 2275 2980 3685 4405 5105 5510 3220 4350 5415 6465 7460 7910 3945 5540 6935 8310 9540 9900 11080 13380 15305 Allowable Tension Loads DF/SP (133/160) Allowable Tension Loads SPF/HF (133/160) 8. See page 13-15 for testing and other important information. 9. Deflection at Highest Allowable Design Load: The deflection of a holdown measured between the anchor bolt and the strap portion of the holdown when loaded to the highest allowable load listed in the catalog table. This movement is strictly due to the holdown deformation under a static load test conducted on a steel jig. All other sources of deflection shall be in addition. 10. When using structural composite lumber columns, bolts must be applied to the wide face of the column. 11. The Designer shall reduce the allowable loads shown per NDS requirements when bolt threads are in the shear plane. 12. HDA and HD allowable loads are based on the lower of the 2001 NDS fastener values or the ultimate load on a steel test jig divided by 2.5. 13. Post design shall be by Designer. 1. Allowable loads have been increased for earthquake or wind load durations with no further increase allowed; reduce where other load durations govern. 2. HD15 requires a minimum 4x8 (in a 3 wide shearwall) or a 6x6 nominal post to ensure the tension load carrying capacity of the critical net section meets the holdown capacity. 3. Use a minimum 4x6 nominal post for the HD14A. Minimum post size is required to ensure the tension load carrying capacity of the critical net section meets the holdown capacity. 4. HB is the required minimum distance from the end of the stud to the center of the first stud bolt hole. End distance may be increased as necessary for installation. 5. The designer must specify anchor bolt type, length and embedment. See SSTB Anchor Bolts (page 33-34) and Additional Anchor Designs (page 34). 6. See page 21 and 29 for anchor bolt retrofit. 7. Lag bolts will not develop the listed loads. See notes below. A B and F do not apply to the PHD and HDQ. A. Bolt slip can occur at holdown stud bolts. B. Increased bolt slip can occur if oversized holes are drilled through the stud for holdown stud bolts (oversized holes are when the hole diameter is greater than the bolt diameter plus per 2001 NDS 11.1.2). C. When a holdown is installed on only one side of the stud, an eccentricity exists during loading which can cause more movement in the shearwall system. D. Unrestrained anchor bolt nuts can spin loose during cyclic loading; using steel nylon locking nuts or thread adhesive may prevent nut spin. E. Movement can occur when nuts are not tightened enough. Retightening bolts before covering wall may prevent this. F. Deflection can occur in the holdown under load caused by stresses due to earthquake or high wind. G. Lateral displacement at the top of the wall rotates the stud around its base causing the holdown base plate to displace vertically. H. Wood shrinkage can occur due to drying of the sill plate, rim joist, and/or top plate; nuts may require retightening. I. Uplift forces on the bolts can cause localized wood crushing at bolt bearing locations. Using larger bearing plates may prevent this. J. Wood at the end of the studs (sill plates, rim joists, etc.) may crush under normal dead and live loading; additional compressive forces due to overturning during earthquake and high wind loads add to the deflection. BPs are required by the City of Los Angeles. Check with your local building code on usage. (NDS Section 11.1.2.3 requires a metal plate, metal strap, or minimum of a standard cut washer.) Available with additional corrosion protection. Check with factory. SOURCES OF DEFLECTION AT SHEARWALL HOLDOWN CONNECTIONS

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