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STHD Strap-Tie Holdown

STHD

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Holdowns and Tension Ties

This product's information may differ depending on the category of use. You are currently viewing details related to Holdowns and Tension Ties. You can also view product information related to the category: Strap-Tie Holdowns

The STHD is an embedded strap-tie holdown offering high loads in both wood and cold-formed steel construction. When installed on the forms with the StrapMate® strap holder or other holding device, the unique design of this cast-in-place strap-tie holdown delivers enhanced stability before and during the pour to help prevent both parallel and perpendicular movement.

Key Features

  • The fastener pattern allows for fasteners to the edges of back-to-back studs
  • Rim joists models accommodate up to 17” clear span without any loss of strap fastening
  • The slots below the embedment line enable increased front-to-back concrete bond and help to reduce spalling

Material

  • 12 gauge

Finish

  • Galvanized

Installation

  • See General Notes for Holdowns and Tension Ties.
  • Use all specified fasteners; see General Notes.
  • Use tables for both standard concrete and post-tension slab installations.
  • Install before concrete pour with a StrapMate, or other holding device.
  • Fasten strap from the bottom up. Install strap plumb.
  • Strap may be bent one full cycle (bent horizontal 90° then bent vertical) to aid wall placement, but may cause spalling behind the strap. If the spall is 1" or less, measured from the embedment line to the bottom of the spall, full loads apply. STHD10 and STHD14 achieve full load for spalls less than 4". Any portion of the strap left exposed should be protected against corrosion.
  • Other than where noted in the two-pour detail, do not install where: (a) a horizontal cold joint exists within the embedment depth between the slab and foundation wall or footing beneath, unless provisions are made to transfer the load, or the slab is designed to resist the load imposed by the anchor; or (b) slabs are poured over concrete block foundation walls.
  • Additional studs attached to the shearwall studs or post may be required by the designer for wall sheathing fastening.
  • For installations in severe corrosion environments, refer to General Corrosion Risks for additional considerations.
  • See installation illustrations in the image gallery for rebar information.

For Two-Pour Installation for Downturn Footings

  • For STHD10 installed through a 4"-thick slab, use the equivalent 8" stem wall loads of the LSTHD8
  • For STHD14 installed through a 4"-thick slab, use the equivalent 8" stem wall loads of the STHD10
  • For STHD14 installed through a 6"-thick slab, use the equivalent 8" stem wall loads of the LSTHD8

Related Literature

Connectors for Cold-Formed Steel Construction Catalog
C-CF-2020
A catalog for Connectors for Cold-Formed Steel Construction products and solutions.
Catalog
Wood Construction Connectors 2021-2023
C-C-2021
A catalog including new product information as well as any applicable specification and installation instructions for wood-to-wood and wood-to-concrete structural connectors.
Catalog
Conectores para la construcción con madera 2021–2023
C-C-2021SP
El catálogo incluye información sobre nuevos productos, así como especificaciones e instrucciones de instalación aplicables para conectores estructurales de madera a madera y de madera a concreto.
Catalog
High Wind Guide
F-C-HWG20
A comprehensive guide to help Designers select the most appropriate connections for challenging, high-wind regions.
Product Guide
Connector Solutions to Meet the Wall Bracing Requirements of the International Residential Code®
T-C-WALLBRACE21
A technical bulletin providing technical information about wall bracing methods and code sections that require connectors (e.g., holdowns or straps) and anchors.
Technical Bulletin
Connectors Installed on SCL Columns
T-C-SCLCLM21
A technical bulletin discussing the structural properties of the two different surface sides of SCL columns.
Technical Bulletin
Connectors Installed on SCL Columns
T-C-SCLCLMCAN20
A Canadian Limit States technical bulletin addressing typical installations of Simpson Strong-Tie® connectors on SCL columns as well as reduction factors for narrow-face SCL installations.
Technical Bulletin
STHD in PFH Wall Bracing Assembly
L-C-STHDPFH421
Simpson Strong-Tie® STHD holdowns with Method PFH Wall Bracing on 4-inch Wide Concrete Garage Curb.
Engineering Letter

Product Information Table

Fastener Production Information and Stuff & Things
Model No. Ga. W (in.) L (in.) Coating/Material Packaging Qty.
STHD10 12 3 24 5/8 Zinc Galvanized, G90 1
STHD10RJ 12 3 38 1/8 Zinc Galvanized, G90 1
STHD14 12 3 26 1/8 Zinc Galvanized, G90 1
STHD14RJ 12 3 39 5/8 Zinc Galvanized, G90 1

Load Tables

Allowable Stress Design (ASD) Loads for STHD Strap Style Holdowns on CFS — 2,500 psi Concrete

Wind and SDC A & B — Allowable Tension Loads (lbs.) — 33 mil (20 ga.) Studs
Min. Stem Wall (in.) Model No. Strap Length (L) le (in.) Non-Cracked Cracked
Standard Rim Joist Standard (in.) Rim Joist (in.) Req'd Screws Midwall Corner Endwall Req'd Screws Midwall Corner Endwall
6 STHD10 STHD10RJ 24 5/8 38 1/8 10 24 -#10 3,535 3,535 1,960 22 -#10 2,910 2,910 1,635
STHD14 STHD14RJ 26 1/8 39 5/8 14 30 -#10 4,935 4,935 3,065 30 -#10 4,935 4,935 3,065
8 STHD10 STHD10RJ 24 5/8 38 1/8 10 28 -#10 4,755 4,075 3,015 22 -#10 4,020 3,350 2,480
STHD14 STHD14RJ 26 1/8 39 5/8 14 30 -#10 5,285 5,285 4,410 30 -#10 5,285 5,285 4,410
SDC C-F — Allowable Tension Loads (lbs.) — 33 mil (20 ga.) Studs
Min. Stem Wall (in.) Model No. Strap Length (L) le (in.) Non-Cracked Cracked
Standard Rim Joist Standard (in.) Rim Joist (in.) Req'd Screws Midwall Corner Endwall Req'd Screws Midwall Corner Endwall
  1. Deflection at highest allowable loads for install over CFS double studs are as follows: STHD10=0.096" and STHD14=0.115".
  2. Multiply Seismic and Wind ASD load values by 1.4 or 1.67 respectively to obtain LRFD capacities.
  3. Per 2012, 2015 and 2018 IBC Section 1613, detached one- and two- family dwellings assigned to Seismic Design Category (SDC) A, B or C are exempt from the seismic design provisions of IBC Section 1613. For this case, the allowable wind loads apply.
  4. Minimum center-to-center spacing is 3 times the required embedment (Smin=3xle) for STHD’s acting in tension simultaneously. Midwall install is based on 1.5xle end distance.
  5. See Fastening Systems for more information on Simpson Strong-Tie fasteners.
6 STHD10 STHD10RJ 24 5/8 38 1/8 10 18 -#10 2,750 2,750 1,615 18 -#10 2,550 2,550 1,435
STHD14 STHD14RJ 26 1/8 39 5/8 14 22 -#10 3,695 3,695 2,685 22 -#10 3,695 3,695 2,685
8 STHD10 STHD10RJ 24 5/8 38 1/8 10 20 -#10 3,400 2,940 2,295 20 -#10 3,400 2,940 2,175
STHD14 STHD14RJ 26 1/8 39 5/8 14 24 -#10 3,815 3,815 3,500 24 -#10 3,815 3,815 3,500

Code Reports & Compliance

Drawings

PDF DWG DXF RFA IFC SAT

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