KF Controls

The KF3200C front-discharge mixer by Kimble Mfg. uses CAN bus technology to enable operators fingertip controls of all functions. More

I recently read a technical paper that provides exhaustive data for engineered design and detailing of "relief" angles. However, the article does not discuss when – if ever – it is a good idea to incorporate relief angles into a structure, except to acknowledge in the conclusion that states: "Severe damage can result from the improper design, construction, and maintenance of shelf angle details."Since maintenance, and to a large extent construction, are beyond the control of even the most conscientious engineer, I was wondering if you or any of your peers have written a paper with rational criteria for the incorporation of steel relief angles into masonry structures with, hopefully, some considerations for designing the veneer to resist wind loading at interruptions and discontinuities.I have BIA technical note 28B (1980) which recommends: "In order to alleviate the many problems associated with the use of shelf or relief angles at each floor, it is suggested that the brick veneer may be designed to support its own dead weight on the foundation, unless heights (in excess of 100 feet) or number and location of openings in the veneer make it mandatory that walls be vertically supported by the structural frame."We have been happily following this rule of thumb for many years by reinforcing the perimeter of veneer openings and providing lateral anchorage consistent with the UBC wind load requirements. Recently we discovered that our approach was considered "unorthodox" and "unconventional" in some engineering circles. We were shocked to discover the aesthetic, cost, and detailing implications of trying to inject relief angles at every floor of a four-story institutional buildings which we had previously been designing successfully without a single relief angle. I reviewed more recent BIA documents and found that the language I quoted had been deleted. Is something going on in academic and/or professional circles to squelch relief angle free veneers? More