Steel Building With Block Walls
Low rise steel buildings using rigid frames are typically designed to be relatively flexible for resisting wind force.
When block walls are to be used instead of the more traditional steel panel siding, careful consideration of how steel-frame flexibility affects the block walls must be considered, especially for full-height block walls.
The key issue, to be determined before the design process begins, is selecting person or company to be responsible for overall structural design of the building. All-too-often, this issue is simply neglected.
Unless the steel building manufacturer takes on complete responsibilty for building design, including block walls, the building designer (architect, engineer) must make sure that block walls are designed; (1) To move with the steel frame without damage, or (2) To resist forces from the steel frame.
Of course, if block walls are designed to resist forces from the steel frame, the entire design concept of using steel rigid frames should be reconsidered.
Lateral movement of steel frames can be limited by a properly designed roof diaphragm. However, when standing-seam roof deck is used, careful evaluation is required to determine capacity of the standing-seam roof to act as structural diaphragm.
If block walls are designed to move with the steel frames, vertical reinforcing bars will most likely be required in the block.
Early Design Efforts
While working as a structural engineer for Conrail in the 1980s, this writer addressed the problems with using full-height block walls with flexible rigid frames.
One such project was the new "Tractor Trailer Building" at the Intermodal Facility built in Columbus Ohio in 1986.
In-house architects responsible for overall design of the building specified full-height block walls with a "pre-engineered" steel rigid frame building.
Prior to this project, the architectural department had been specifying steel buildings made by Armco. Architectural design plans were developed for an Armco building.
However, the design and construction process was modified to allow the contractor to provide a steel building by any qualified manufacturer. American Buildings, in Alabama, was selected by the contractor.
The architects had not considered how lateral movement of a flexible steel frame might interact with full-height block walls.
During review of fabrication drawings submitted by American Buildings, this writer brought the issue to the attention of architects, building designer and contractor.
Design requirements were discussed with technical staff of NCMA (National Concrete Masonry Association). At the time, NCMA was developing standards for proper design of block walls with low-rise steel rigid-frame buildings.
The following files contain letters and design details produced by this writer in 1986 to address the problem. Note that letters are all hand-written. Although the Design & Construction Department had started to use PCs, there were only a few available. Also, office assistant positions had been reduced dramatically throughout the company.
Initial letter raising the issue.
Detailed report describing problems to be addressed (page 1 - 8)
Detailed report (pages 9 - 18)
Design details; Set 1
Design details; Set 2