Steel in the News
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Posted by Tasha Weiss on July 29, 2011 at 9:30 AM.
You may have heard of a staggered truss system - it was developed in the 1960s at MIT and has been used in many multi-story residential projects nationwide - but can you define it? Shown in the above photo, the system consists of story-high trusses that span the entire width of the building. The trusses alternate from floor to floor with the long axis of one truss mid-span between the trusses on the floors immediately above and below. This system has proved to be an efficient structural solution that resists both gravity and lateral loads in the direction of the trusses. Photo: John Cross.
Nearly 50 architects, engineers, contractors, and other construction professionals discovered the steel staggered truss system up close during a recent seminar and site tour of The Ohio State University South High-Rise Residence Halls project in Columbus. You can view the presentation files and more photos from the event on AISC’s website at www.aisc.org/osu.
The system works in harmony with hollow-core precast concrete floor planks, allowing for the desired low floor-to-floor heights. The precast plank spans from the top chord of one truss to the bottom chord of the next, achieving large column free areas on each floor and provides a smooth floor and ceiling.
You’ll notice in the above photo that the only columns are found on the exterior of the structure and the entire ground level can be completely column-free, allowing for tremendous flexibility in room layout and architectural design elements. And fewer columns mean fewer foundations, resulting in reduced foundation costs and schedule.
Additionally, the construction schedule can often be compressed by using staggered truss. Because the steel trusses and precast planks are both off-site fabricated, there are fewer pieces to erect on-site, and the system goes up relatively fast. The dry system also allows for winter construction.
For additional information, see AISC’s Steel Design Guide No. 14, Staggered Truss Framing Systems. It is available as a free download for AISC members and for purchase by non-members at www.aisc.org/dg.