Holeless Curtain Wall Mullion Connection

Abstract

A mullion connection system for resisting wind load reactions using a connection clip structurally engaged with a mullion without a hole or a fastener penetrating into the mullion surface. The connection clip can undergo stress-free vertical sliding relative to the mullion along the entire length of the mullion without impairing the structural connection strength; therefore, the building construction tolerance in the vertical direction is eliminated as a design consideration of the curtain wall system. The design also eliminates the need for pre-fabricating mullion holes for the connection locations. The design does not require the pre-determination of the elevation of the connecting point and thus is most beneficial for a curtain wall renovation project where the available locations in the building structure for structural connection cannot be determined prior to the demolition of the existing wall. The uninterrupted mullion tube cavities can be conveniently utilized for inter-floor distribution of utility lines.

Description

FIELD OF THE INVENTION[0001]This invention relates to exterior curtain wall connection design. The design is applicable to either a solid mullion or a split mullion condition.BACKGROUND OF THE INVENTION[0002]An exterior curtain wall system consists of three major components, namely, wall panels providing weather protection, mullions providing structural support to the wall panels, and mullion connection systems providing a structural connection between the mullions and a building structural element. Due to the fact that there is a gap between the acceptable construction tolerance for the curtain wall and the acceptable construction tolerance for the building structural element, the mullion connection system must be designed to absorb the construction tolerance of the building structural element in all three directions (i.e., up / down, in / out and left / right). The most difficult adjustment is in the up / down direction due to the following factors: (a) tolerance due to dead load deflecti...

AI Technical Summary

Benefits of technology

The patent is for a connection system that can handle large construction mistakes without weakening the connection. This makes it easier to build and modify structures using the mullion connection system.

Problems solved by technology

Out of tolerance conditions experienced in the field often result in structurally compromising modifications being employed without the approval of a structural engineer.

If the out of tolerance condition is still erectable but leaves inadequate room for inter-floor deflection, the condition would be unchecked and the structural integrity in the service condition would be compromised.

In addition, depending on the condition of the contacting surface, being too tight on the mullion bolt might disable the sliding function required for the inter-floor deflection while being too loose might impair the structural integrity of the connection system due to the danger of walking and loosening of the bolt nut.

Therefore, a proper torque for tightening the bolt is normally specified for the design, but it is difficult to police the execution in the field.

In conclusion, the proper installation of the slotted hole design is almost impossible to police and ensure in the field.

Existing mullion connection systems are incapable of making such a large tolerance adjustment without impairing structural integrity and the curtain wall erection has to ignore the sloping tolerance by following the slope.

Designing for a higher adjustability would either impair structural integrity or become too expensive.

However, the above slab thickness tolerance is considered to be too tight to execute by the slab contractor and the above floor height tolerance is considered to be too tight to execute by the building frame contractor.

Therefore, an out of tolerance condition becomes unavoidable.

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