- Hoisting trusses is a more dangerous practice than most people think; both individual trusses and bundles of trusses should not be lifted at the peak.
- The recommended industry best practices for hoisting truss bundles are a bit different than those for single trusses, but the same basic concepts apply.
- BCSI and CFSBCSI outline industry best practices for hoisting trusses.
- Based on the recommendations of the IRC, IBC and ASCE 7, truss or rafter uplift connections should be designed for applied wind loads using MWFRS analysis.
- Individual truss and rafter members should be designed using C&C generated wind loads.
- The SBCA Load Guide includes information about uplift connections for structural building components.
- In addition to implementing a QC program and training staff, another good way to increase awareness of quality control issues is by creating QC posters strategically placed throughout the shop floor.
- A QC board can use photos or actual material examples to illustrate common QC dos and don’ts.
- Work is underway to revise and reaffirm Chapter 3 of the ANSI/TPI 1 standard on quality control.
- Two engineers involved in the design of structural building components respond to a previous Technical Q&A on bearing area.
- Both give their perspective on bearing area and ways that component manufacturers and truss designers can help engineers with this issue.
- Each engineer discusses his preferred method for dealing with insufficient bearing area.
- Be proactive and develop a plan to strategize how you might deal with a truss collapse and the subsequent investigation.
- Information is critical; visit the site, take lots of photos and document as much as you can.
- Remember that the only company looking out for your company’s best interests is your own. Take action with this in mind, and ultimately, it will save everyone money and time.
- Only scaffold-grade lumber should be used for erecting scaffolds.
- Scaffold-grade lumber meets strength criteria determined by the grading rules set by a recognized lumber grading agency or independent lumber inspection agency and meet the minimum requirements of OSHA standard 29 CFR 1926.
- The characteristics required for scaffold-grade lumber, such as number and size of knots, slope of grain and juvenile wood, are higher and more stringent than those for construction lumber.
- The Building Designer providing accurate wall or beam/header information in the Construction Documents is essential in order for the Truss Designer to arrive at the correct bearing width.
- There are two key bearing related considerations—bearing capacity of the truss and bearing capacity of what the truss is sitting on; often, the bearing capacity of this material is an unknown and an assumption must be made.
- The options for dealing with insufficient bearing need to be considered and specifically dealt with on a case-by-case basis.
- Plywood and OSB design values are given; those that are doing repairs in your office should have a good feel for the similarities and differences.
- Plywood and OSB generally have similar design properties with a key exception of fastener strength where plywood will require more fasteners to be used.
- If a truss repair specifies only OSB, plywood should not be substituted without written permission from the registered design professional who prepared the truss repair design drawing.
- The strength axis of a structural panel is the direction parallel to the grain of the wood fiber in the face and back surfaces of the panel.
- The strength axis is usually the long dimension of the panel.
- The IBC provides two tables with the allowable spans and loads (psf) for wood structural panel sheathing installed continuous over two or more spans with their strength axis perpendicular and parallel to the supports.
- The Occupancy Category designates the nature of occupancy for a building, which affects the required design loads for the structure.
- There is a direct relationship between the Occupancy Category and the Importance Factor—a low category will result in lower loads and a high category will call for an increase in loads
