Curtain Wall Expansion Joint for ±15mm Deflection
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Solution Overview
Problem
Current curtain wall systems are unable to accommodate the higher deflection limits of modern building floor structures, as they are limited to ±2 millimeters of movement, which is insufficient for newer building designs, and existing systems that can accommodate more movement are costly and not widely implemented.
Innovation Solution
The use of expansion joints formed from compressible materials like polymeric elastomer foam or closed cell ethylene propylene diene monomer (EPDM) foam rubber sponge, which allow for ±15 millimeters of deflection, and pressure plate expansion units made from the same materials to accommodate movement while maintaining a seal with infill panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing curtain wall designs are used, then manufacturing precision and structural integrity are maintained, but the deflection accommodation capability is limited to ±2 millimeters which is insufficient for modern building designs
Solution Approach 1:
The curtain wall system is divided into modular frame units that can independently deflect, with each unit containing expansion joints that segment the overall structure to accommodate floor deflection while maintaining local precision
Solution Approach 2:
The expansion joint geometry is designed with specific dimensional parameters (width, depth, angle) that can be adjusted to accommodate different deflection requirements, allowing the same basic design to adapt to various building types while maintaining manufacturing precision
2Adaptability or versatility
If curtain wall systems allowing for more movement are implemented, then deflection accommodation is improved, but construction costs increase significantly
Solution Approach 1:
The expansion joint design serves multiple functions simultaneously: it accommodates deflection, provides weather sealing, allows thermal expansion, and maintains structural continuity, eliminating the need for separate expensive components for each function
Solution Approach 2:
The expansion joint utilizes flexible gasket materials and thin film seals that can deform to accommodate movement while maintaining their sealing function, providing a cost-effective alternative to rigid mechanical sealing systems
3Ease of manufacture
If lightweight materials are used for curtain wall fabrication, then construction costs are reduced, but the ability to accommodate higher deflection limits without compromising structural integrity is challenged
Solution Approach 1:
The curtain wall system combines lightweight materials (aluminum extrusions, glass panels) with strategically placed stronger components (steel reinforcement in expansion joints, robust anchorage systems) to achieve overall cost-effectiveness while maintaining structural integrity during deflection
Solution Approach 2:
The expansion joints are designed with pre-compressed gaskets and cushioning elements that absorb the forces generated during deflection before they can damage the lightweight curtain wall components, protecting the overall structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables curtain walls to accommodate substantial movement of building floor structures without distorting or losing structural integrity, providing a cost-effective solution compatible with newer building designs by allowing up to ±15 millimeters of movement.
Implementation Method 1
expansion joint formed from a compressible material such as a polymeric elastomer foam
Implementation Method 2
expansion joint formed from a closed cell ethylene propylene diene monomer (EPDM) foam rubber sponge
Data Source
Figure 1
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AI summary
An expansion joint configured to connect first and second vertical mullions of a curtain wall is disclosed. The first and second vertical mullions may each include an elongated body having an inner contour defining a hollow slot, and an inner sleeve may extend through the hollow slot of both of the first and second vertical mullions. The expansion joint may comprise a body, and an inner contour defining a central inner slot configured to receive the inner sleeve therethrough. The expansion joint may further comprise a first raised lip projecting from a lower surface of the body and configured to be inserted inside of the inner contour of the first vertical mullion, and a second raised lip projecting from an upper surface of the body and configured to be inserted inside of the inner contour of the second vertical mullion. The expansion joint may be formed from a polymeric elastomer.