General Instructions to the Designer
These general instructions to the designer are provided to ensure proper selection and installation of Simpson Strong-Tie Company Inc. products and must be followed carefully. These general instructions are in addition to the specific design and installation instructions and notes provided for each particular product, all of which should be consulted prior to and during the design process.
- Allowable loads are determined per the AISI S100 unless otherwise specified. Other code agencies may use different methodologies.
- The allowable load is typically limited to an average test load at 1/8" deflection, or an average or lowest test value (nominal load) divided by a safety factor or the calculation value. The safety factor is prescribed by Section F1 of the AISI S100.
- To achieve the loads shown in this catalog, the designer must verify that the self-drilling screws used for connector installation have Pss/Ω and Pts /Ω values greater than or equal to the values given in the table, Minimum ASD Loads for Screws (lb.), per this page.
- Allowable simultaneous loads in more than one direction on a single connector must be evaluated as follows:
Design Uplift/Allowable Uplift + Design Lateral Parallel to Track/ Allowable Lateral Parallel to Track + Design Lateral Perpendicular to Track/Allowable Lateral Perpendicular to Track ≥ 1.0.
The three terms in the unity equation are due to the three possible directions that exist to generate force on a connector. The number of terms that must be considered for simultaneous loading is at the sole discretion of the designer and is dependent on their method of calculating wind forces and the utilization of the connector within the structural system.
- The term "designer" used throughout this catalog is intended to mean a licensed/certified building design professional, a licensed professional engineer, or a licensed architect.
- All connected members and related elements shall be designed by the designer.
- Unless otherwise noted, member strength is not considered in the loads given and, therefore, one should reduce allowable loads when member strength is limiting.
- The average ultimate breaking strength for some models is listed under "nominal tension load."
- Simpson Strong‑Tie strongly recommends the following addition to construction drawings and specifications: "Simpson Strong‑Tie connectors and fasteners are specifically required to meet the structural calculations of plan. Before substituting another brand, confirm load capacity based on reliable published testing data or calculations. The designer or Engineer of Record should evaluate and give written approval for substitution prior to installation."
- Verify that the dimensions of the supporting member are sufficient to receive the specified fasteners, and develop the top flange bearing length.
- Simpson Strong‑Tie will provide, upon request, code testing data on all products that have been code tested.
- 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.
- All steel-to-steel connector screws must comply with ASTM C1513.
- Screw strength shall be calculated in accordance to AISI S100 Section E4 or shall be based upon the manufacturer’s design capacity determined from testing.
- Simpson Strong‑Tie recommends that hanger height be at least 60% of joist height for stability against rotation while under construction prior to sheathing install.
- Local and/or regional building codes may require meeting special conditions. Building codes often require special inspection of anchors installed in concrete and masonry. For compliance with these requirements, it is necessary to contact the local and/or regional building authority. Except where mandated by code, Simpson Strong-Tie products do not require special inspection.
- When connectors are attached to two CFS members of different thicknesses, the designer shall use the thinner of the two members for selecting allowable loads.