Amongst cable structures, cable mullions achieve optimum transparency from one-way spans. Cables are tensioned vertically or horizontally, and the glass plane can be straight or curved in plan.
This headquarters campus in Seattle includes a vertical cable-mullion system that spans approximately 85 feet.
A dual cable horizontal cable-mullion system is used at Newseum in Washington, D.C. Designs include steel hangar bars to provide mid-span support and reduce cable sag. Note the unique point fixings that tie glass to structure.
Just as with cable-net structures, prestress must be applied to cable-mullion systems in the field via complex hydraulic jacking processes. Narrow glazing grids result in greater densities of cable elements, lowering the prestress requirements of each individual cable (although high prestress forces are sometimes desired to control deflections).