Loads

Truss Blocking Panels

Learn more about a future industry testing concept for the SBC Research Institute.

Moment Resistance: Why Bigger Plates Are a Good Thing

Consider for a moment the basics of manufacturing a truss. Based on SBCA’s 2012 Financial Performance Survey, lumber accounts for roughly 40 percent of the total cost. Plates account for about eight percent of the total cost. Design and production labor account for 30 percent, and delivery, sales and overhead account for the remaining 22 percent (these are rough industry averages). All other things being equal, if you could decrease your lumber costs by a few percentage points while raising your plate costs a small amount, would you take the trade-off?

Sprinkler Loads on Trusses

Building Designers need to account for the dead and live loads of fire sprinkler systems, in addition to the other load requirements imposed under the model building codes. Truss Designers are responsible for incorporating the additional load from the fire sprinkler systems into the truss design. The information in this Research Report is applicable to both floor and roof systems. Only vertical loads from fire sprinkler systems are discussed; lateral loads, where required, should be evaluated separately by a Registered Design Professional. 

Truss Industry Standard of Care Issues: Part 4

Truss industry standard of care items are contained throughout ANSI/TPI 1,* The National Standard for Metal Plate Connected Wood Truss Construction. The focus of this article is ANSI/TPI 1 Chapter 2, Section 2.3.5.1 and companion Section 2.4.5.1, which require a truss designer to prepare truss design drawings (TDD) based on design criteria and requirements set forth in the construction documents. The truss industry should expect to get this information from the building designer (BD), which may include the building owner, contractor or a registered design professional (RDP). Particularly when there is an RDP for the building, the design community expects the truss industry to design components that conform to the truss framing plan and specified design parameters within the construction documents, unless instructed otherwise in writing.

 

Innovative Framing Requires Collaboration

  • Even with its many benefits, innovative framing faces resistance. Prescriptive codes don’t directly promote innovative framing, and markets are slow to adopt for many reasons.
  • The earlier in the process CMs can get in front of building designers, the greater their ability to influence the use of innovative framing techniques to design buildable structural framing. 
  • In order to get innovative framing ideas into the market effectively, you need to have your ducks in a row prior to approaching the building designer.

Seismic Design Coefficients: How they are determined for light-frame components

Why Seismic Design Coefficients (i.e., factors) are important to engineering innovation

Isolated Testing Helps Understanding of Heel Height Load Paths: Downstream Improvements Probable

  • Couple the IRC requirements with energy code requirements that are pushing more buildings to utilize a higher heel, and it is apparent the connection of high heels to walls is a key application issue.
  • The SBC Industry Testing Task Group and the TPI TAC/SBCA E&T Testing Review and Vetting Group has begun to evaluate the needs and priority of testing the performance of assemblies to quantify the effect of heel blocking. 
  • It is clear from the very specific and isolated heel height testing already performed that there is an opportunity to provide revisions to 2009 and 2012 model code blocking requirements to transfer the lateral load resulting from wind and seismic events into braced wall lines.

Connecting Wood Trusses to Braced Wall Panels

  • The 2012 IRC does not provide sufficient details on how to connect wood trusses to braced wall panels.
  • SBCA has developed a couple of details and will continue to develop standard details that provide code-compliant connections between roof/floor trusses and braced wall panels.
  • Component manufacturers can provide framers with specialty or standardized blocking panel products to reduce the time needed to install the blocking between trusses for these connections.

 

Perfect Form: The Value of Engineering & a Well-Executed Plan

Last summer, Superstorm Sandy caused an estimated $65 billion worth of damage in the U.S., a total surpassed only by Hurricane Katrina in American history. Sandy was the largest hurricane on record to hit the Atlantic Coast, at over 1,100 miles in diameter. So while it hit the New Jersey shores the hardest, according to the National Oceanic and Atmospheric Administration, its disastrous effects were felt as far inland as Wisconsin and Michigan.

While the chaos and destruction wrought by this powerful natural force is sobering, it’s hard not to simultaneously focus on the positive stories that came out of such events. One such story is that of Cussewago Truss LLC in Cambridge Springs, PA. It’s a tale of the marvels of wood, the value of engineering and the fruits of a well-executed plan.

The Hidden Costs of Optimization, Part II

  • Understanding how the computer software automatically loads a truss can help designers avoid unintended consequences when optimizing trusses.
  • When fascia loads are missing from a project, there is incorrect loading on the jack trusses, sub girders and the corner girder/hip jack.
  • Missing loads can lead to extensive repairs and may even require that the trusses be revised.