2012 Tilt-Up Temporary Wind Bracing Guideline Released
The Tilt-Up Concrete Association is offering it, having decided to endorse ASCE/SEI 7-10, Minimum Design Loads of Buildings and Other Structures, as the standard for temporary bracing of tilt panels during construction.
The Tilt-Up Concrete Association is now offering the 2012 edition of its Guideline for Temporary Wind Bracing of Tilt-Up Concrete Panels During Construction and says it has confirmed that tilt-up bracing systems are sufficiently designed to meet ASCE/SEI 7-10, Minimum Design Loads of Buildings and Other Structures, which is likely to be adopted by many, if not all, local building codes.
TCA, based in Mount Vernon, Iowa, and founded in 1986 by contractors, professionals, and manufacturers interested in improving the quality and acceptance of tilt-up construction, notes that OSHA requires tilt-up concrete panels to be temporarily braced during construction but does not specify how to prevent them from overturning or collapsing. As a result, the association developed a temporary bracing guideline to aid the construction industry.
The 2012 edition bases its design loadings on SEI/ASCE 37-02, but the wind loadings are now based on ASCE 7-10, which uses three wind speed maps based on strength design in conjunction with a wind load factor of 1.0. The prior standard, ASCE 7-05, uses a single wind speed map with an importance factor and a wind load factor of 1.6, according to the Roof Wind Designer, an online tool developed and maintained by the National Roofing Contractors Association with the support of the Midwest Roofing Contractors Association and the North/East Roofing Contractors Association.
TCA explains that many, if not all, local building codes are likely to endorse ACE 7-10, so the association decided to endorse it as the standard for temporary bracing of tilt panels during construction.
"The 2012 edition of the TCA Wind-Bracing Guidelines is a combination of technological progress in this industry and reassurance for the performance of these systems," TCA Technical Director Jim Baty said in a release posted at www.tilt-up.org. "We were challenged as an industry when ASCE 37 identified that it would change to adopt ASCE 7 pressures. This established the concern that bracing schemes may be under-designed for the resulting wind conditions. However, through the diligent work of the engineers leading the way for this revision, we have been able to confirm that Tilt-Up bracing systems are sufficiently designed with today's standards. This permitted us to move forward with recommendations for response design recommendations on slab thickness and integrating helical ground anchor systems to this more robust version."