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HDU8-SDS2.5 Simpson Heavy Duty Holdown 75x420x90mm Includes 20 – SDS 6.4x64mm screws

$49.00 inc. GST

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Availability: 1515 in stock (can be backordered)

SKU: 707392934608 Categories: ,
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HDU Heavy Duty Holdown https://strongtie.co.nz/products/hdu-heavy-duty-holdown

BASE WIDE 75MM X HEIGHT 420 MM X BASE DEPTH 90MM

INCLUDE 20 SDS 6.4X64MM SCREWS

The HDU is designed for use in shearwalls and braced-wall panels, as well as other lateral applications in wood construction. The HDU uses Strong-Drive® SDS Heavy-Duty Connector screws which install easily, reduce fastener slip and provide a greater net section than bolts.

Key Features

  • Strong-Drive SDS Heavy-Duty Connector screws are supplied with the holdown to ensure proper fasteners are used
  • Predeflected seat eliminating deflection under load
  • No stud bolts to countersink at openings

Material

  • See table

Finish

  • Galvanized

Installation

  • See General Notes for Holdowns and Tension Ties.
  • The HDU requires no additional washer.
  • Strong-Drive SDS Heavy-Duty Connector screws install best with a low-speed, high-torque drill equipped with a 3/8″ hex-head driver.
  • Fasteners and crescent washer are included with the holdowns. For replacements, order part no. SDS25212-HDU_. (Fill in the size needed, e.g., HDU2.)

Simpson Strong‑Tie offers a wide variety of holdown devices engineered and tested to perform and manufactured to the highest quality standards. The HDU Holdown is pre‑deflected during the manufacturing process, virtually eliminating deflection under load due to material stretch. This super heavy duty HDU is suitable for residential and commercial projects, sub diaphragm floor, seismic upgrades, mid floor vertical connection applications. 

The HDU installs with Simpson Strong‑Tie® Strong‑Drive® SDS Heavy‑Duty Connector screws which install easily, reduce fastener slip and provide a greater net section when compared to bolts. The HDU is also ideal for retrofit or new construction projects. They provide high-strength, post-pour, concrete-to-steel connections.

Please check Corrosion Information if it is suitable for your application.

Material

Carbon Steel 3.5mm thick

Finish

Z275 Galvanised

Features & Benefits
  • Pre-deflected body virtually eliminates deflection due to material stretch
  • Uses Strong-Drive® SDS Heavy-Duty Connector screws which install easily, reduce fastener slip and provide a greater net section area of the post compared to bolts
  • Strong-Drive SDS Heavy-Duty Connector screws are supplied with the holdowns to ensure proper fasteners are used (HDU8-SDS2.5 includes 20 – SDS 6.4mm x 64mm screws)
  • Easy to install
  • No stud bolts to countersink at openings
Installation
  • Use all specified fasteners 
  • The HDU requires no additional washer
  • Strong‑Drive SDS Heavy‑Duty Connector screws install best with a low speed high torque drill with a 3/8” hex head driver
Model No. Table

Model No.

Dimensions (mm)

Fasteners

Minimum Timber Member Size (Depth x Breadth, mm)

Country

Design Tension Capacity (kN)

Strap
Thickness

W

H

B

CL

Anchor Hole Dia (mm)

Post (Nails: No. – Length x Dia., Screws: No. – Dia. x Length, mm)

HDU8-SDS2.5

3.5

75

420

90

35

20

20 – SDS6.4 x 64

90 x 75

AU

k1 = 1.14

32.58

NZ

k1 = 1.0

26.83

90 x 90

AU

k1 = 1.14

36.20

NZ

k1 = 1.0

29.81

115 x 90

AU

k1 = 1.14

38.85

NZ

k1 = 1.0

32.00
  1. Design Capacity is the lesser of (1) the Characteristic Capacity multiplied by the Australian Capacity Factor, or the NZ Strength Reduction Factor (φ), and applicable the k modification factors following AS 1720.1 and NZS 3603 and (2) the Serviceability Capacity which is the load at 6.4mm joint slip, which includes fastener slip, anchor elongation and holdown deformation. Design Capacity is the minimum of test data and structural joint calculation.
  2. For Australia, the Capacity Factor (φ) is 0.85 for nails and screws for structural joints in a Category 1 application. Reduce tabulated values where other Category applications govern. For NZ, the Strength Reduction Factor (φ) is 0.80 for nails in lateral load and 0.70 for other fasteners.
  3. Duration of Load Factor (k1) is as shown. Reduce Duration of Load Factor where applicable. Capacities may not be increased.
  4. Timber species for joint design is seasoned Radiata Pine, which is Australia Joint Group JD4 per AS 1720.1 Table H2.4 and New Zealand Joint Group J5 per NZS 3603 Table 4.1.
  5. Simpson Strong-Tie Strong-Drive SDS Heavy Duty Connector screws are HDU8.
  6. The Designer must specify anchor bolt type, length and embedment.
  7. Anchor bolt nut should be finger tight plus 1/3 to 1/2 turn with a hand wrench. Care should be taken not to over-tighten the nut.
  8. Post or beam design by Designer. Posts may consist of multiple members provided they are connected independently of the holdown fasteners.
  9. Structural composite timber columns have sides that either show the wide face or the edges of the timber strands/ veneers, known as the narrow face.
  10. Simpson Strong-Tie stainless-steel connectors require stainless-steel fasteners.
  11. Values in the table reflect installation into the wide face.
  12. Holdowns and tension ties are for use in vertical or horizontal applications.
  13. Holdowns and tension ties may be installed raised up to 460mm above the top of the concrete with no load reduction, provided that additional elongation of the anchor rod is taked into account.

Model No.

H
(mm)

Fasteners

Stud
Quantity

Stud
Member Thickness (mm)

LRFD Tension Load

(kN)

Deflection at LRFD Load4 (mm)

Nominal Tension Load5 (kN)

Anchor Hole Diameter (mm)

Stud Fasteners

S/HDU9

327

22

18 – 14g

2

0.75

49.5

4.8

58.6

2

0.95

68.9

6.4

97.0

2

1.15

71.0

5.7

108.9

Steel Fixture

4.76

91.2

4.5

139.9
  1. Designer shall specify the foundation anchor material type, length, embedment and configuration.
  2. Stud design by Specifier. Tabulated loads are based on a minimum stud thickness for fastener connection.
  3. Self-drilling tapping screws of 6.35 mm diameter can be substituted for 14g.
  4. Deflection at LRFD Loads includes fastener slip, holdown elongation and anchor bolt elongation (L=102mm).
  5. Nominal Tension Load is based on the average ultimate (peak) load from tests. AISI Lateral Design standard requires holdowns to have nominal strength to resist the lesser of the amplified seismic load or the maximum force the system can deliver.
Dimensions 90 × 75 × 420 cm

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