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Additional Important Information & General Notes for Hybrid (Steel-to-Wood) Connections

These notes are in addition to the other notes for steel to steel connections and are provided to ensure proper installation of Simpson Strong-Tie® Company Inc. products and must be followed fully.
  1. Unless otherwise noted, allowable loads are for Douglas Fir-Larch under continuously dry conditions. Allowable loads for other species or conditions must be adjusted according to the code. The section from the AC13 criteria indicating the range of specific gravity reads as follows: 3.2.3 The species of lumber used shall have a specific gravity not greater than 0.55 as determined in accordance with the NDS. This chart shows specific gravity and perpendicular to grain compression capacities for the different wood species:

  2. Species Fc Specific Gravity
    Douglas Fir-Larch (DFL) 625 psi 0.50
    Southern Pine (SP) 565 psi 0.55
    Spruce-Pine-Fir (SPF) 425 psi 0.42
    Hem Fir (HF) 405 psi 0.43
    Glulam 560 psi 0.50
    LVL (DF/SP) 750 psi 0.50
    TimberStrand® LSL (E=1.3x106) 680 psi 0.50
    TimberStrand® LSL (E>1.5x106) 880 psi 0.50
    Parallam® PSL 750 psi 0.50
  3. For face-mount hangers & straight straps, use 0.86 of table loads for Spruce-Pine-Fir.
  4. A fastener that splits the wood will not take the design load. Evaluate splits to determine if the connection will perform as required. Dry wood may split more easily and should be evaluated as required. If wood tends to split, consider pre-boring holes with diameters not exceeding 0.75 of the nail diameter (2015 NDS 12.1.5.3).
  5. Wood shrinks and expands as it loses and gains moisture, particularly perpendicular to its grain. Take wood shrinkage into account when designing and installing connections. Simpson Strong-Tie manufactures products to fit common dry lumber dimensions. If you need a connector with dimensions other than those listed in this catalog, Simpson Strong-Tie may be able to vary connector dimensions; contact Simpson Strong-Tie. The effects of wood shrinkage are increased in multiple lumber connections, such as floor-to-floor installations. This may result in the vertical rod nuts becoming loose, requiring post-installation tightening.
  6. Top flange hangers may cause unevenness. Possible remedies should be evaluated by a professional and include using a face mount hanger, and notching the beam or cutting the subfloor to accommodate the top flange thickness.
  7. Built-up lumber (multiple members) must be fastened together to act as one unit to resist the applied load (excluding the connector fasteners). This must be determined by the Designer/Engineer of Record.

Additional Instructions for the Installer for Hybrid (Steel-to-Wood) Connections

  1. Bolt holes into wood members shall be at least a minimum of 1/32" and no more than a maximum of 1/16" larger than the bolt diameter (per the 2015 NDS 12.1.3.2 and AISI S100 Table E3a, if applicable).
  2. Joist shall bear completely on the connector seat, and the gap between the joist end and the header shall not exceed 1/8" per ICC-ES AC261, ASTM D1761 and ASTM D7147 test standards (unless specifically noted otherwise).
  3. For holdowns, anchor bolt nuts should be finger-tight plus 1/3 to 1/2 turn with a hand wrench, with consideration given to possible future wood shrinkage. Care should be taken to not over-torque the nut, impact wrenches should not be used. This may preload the holdown.

Additional Instructions for the Designer for Hybrid (Steel-to-Wood) Connections

  1. Loads are based on the AISI S100 and the 2015 AF National Design Specifications (NDS), unless otherwise specified. Other code agencies may use different methodologies.
    Duration of load adjustments for fasteners into wood as specified by the code are as follows:

    Do not alter installation procedures from those set forth in this catalog.
    “FLOOR” and “DOWN” (100) — no increase for duration of load.
    “SNOW” (115) — 115% of design load for 2 month duration of load.
    “ROOF LOAD” (125) — 125% of design load for 7 day duration of load.
    “EARTHQUAKE/WIND” (160) — 160% of design load for earthquake/wind loading.

  2. Some catalog illustrations show connections that could cause cross-grain tension or bending of the wood during loading if not sufficiently reinforced. In this case, mechanical reinforcement should be considered.
  3. Most of the allowable loads published in this catalog are for use when utilizing the traditional Allowable Stress Design (ASD) methodology. A method for using Load and Resistance Factor Design (LRFD) for cold-formed steel is also included in AISI S100. When designing with LRFD, the nominal connector strength multiplied by the resistance factor must be used. If not listed or noted in a table footnote, contact Simpson Strong-Tie for the LRFD values of products listed in this catalog. A method for using Load and Resistance Factor Design (LRFD) for wood has been published in ASTM D5457. For more information, refer to the 2015 NDS Appendix N, which contains a conversion procedure that can be used to derive LRFD capacities. When designing with LRFD, reference lateral resistances must be used.
  4. Pneumatic or powder-actuated fasteners may deflect and injure the operator or others. Unless otherwise noted, powder-actuated fasteners should not be used to install connectors. Pneumatic nail tools may be used to install connectors, provided the correct quantity and type of fasteners are properly installed in the fastener holes. Tools with fastener hole-locating mechanisms should be used. Follow the manufacturer’s instructions and use the appropriate safety equipment. Over driving fasteners may reduce allowable loads. Contact Simpson Strong-Tie as needed.