The Application for Major Contribution

Compared to traditional steel and aluminum assemblies, this new generation of steel frames provides certain basic design benefits such as narrower frames; sharp edges versus rounded profiles; corner joints without any visible weld beads or fasteners; and flexibility to use back mullions of different shapes and sizes. Since framing establishes the base for a curtain wall assembly’s performance, systems employing this new forming methodology can effectively satisfy demanding design and performance criteria. Moreover, cold roll-formed and laser-welded steel bar processes can capitalize on steel’s obvious strength over more conventional materials like aluminum. Steel has a modulus of elasticity nearly three times of aluminum by applying new forming methodologies, this can translate into a smaller system frame profile and component parts than aluminum without decreasing end-use performance. Consider long steel or extruded aluminum mullion with the same cross-sectional properties, using as the design load discounting allowable deflection limits momentarily. An aluminum mullion deflects whereas a steel mullion deflects allows the designer to do one, or all of the following when using steel as the primary framing material.

Using a smaller system shapes while meeting the same deflection criteria, thus translating to larger, uninterrupted views of the outside environment and greater illuminance for interior occupied spaces to support larger lite of glass or other glazing infills than the aluminum cousins or the span larger heights without the need for reinforcing or more frequent connections to the steel bar in building structure. Despite the many benefits associated with these new steel bar forming methodologies, myths continue to circulate around steel’s limitations in curtain wall systems. These steel bar framing processes are well understood and used but they are still new to other markets in accounting for much of this confusion. To help set the record straight, it will address three relevant inaccuracies as they relate to laden winters, subarctic temperatures, and in energy and environmental design goals. Among the most common misconceptions about steel is the carbon alloy is unsuitable for use as a primary framing material due to corrosion because early steel curtain walls were vulnerable to rust, and the industry turned to more corrosion-resistant materials, such as aluminum.

In a country largely subjected to freezing winters with heavy snowfall, those in the design-build sector are rightfully wary of building materials that cannot stand up to moisture and air, two of the main catalysts for corrosion. They have led the way in developing systems that eliminate much of the water and steel bar contact in glazing systems is typically present in the glazing pockets, where the glass is captured along its edges, to hold it onto the framing. The means of capture employs gaskets since metal to glass contact would not create the necessary air and water seals required by the specification. Pioneering a solution took the gasket at the face of the primary framing member, which forms the interior portion of the glazing pocket, and entirely covered the face of that steel with the gasket, completely removing any possibility of water coming into contact with the steel. Water from other portions of the façade, such as the perimeter interface with surrounding construction or from the surrounding construction itself, is precluded by intelligent detailing and execution of those conditions to the governing principle is water should not come in contact with the steel, and the systems themselves address water isolation from steel internally.