Loads

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

 

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.

  • 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. 
  • 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.