Uglass Installation Technology
1. Preface
U-shaped glass, also known as channel glass, is continuously produced through a calendering process. It is named for its U-shaped cross-section, and when tempered, it is called tempered U-shaped glass. There are various types of U-shaped glass: classified by surface treatment, they include embossed glass and colored glass; by color, they are divided into tinted and colorless; by surface state, they are smooth or patterned; and by strength, they are tempered or non-tempered.
U-shaped glass is a typical material that allows light transmission without full transparency. Due to its U-shaped cross-section, it functions similarly to channel steel in use, providing high load-bearing capacity and strength. Curtain walls constructed with U-shaped glass offer excellent light transmission, heat insulation, thermal retention, and high mechanical strength. They are versatile, easy to install, and feature unique architectural and decorative effects, while also saving significant amounts of light metal profiles. As a result, they are widely adopted in buildings worldwide, suitable for both interior partitions and external walls.
U-shaped glass curtain walls are favored by owners and architects for the following reasons:
They combine the stability and solidity of non-transparent curtain walls with the delicacy and agility of glass curtain walls, achieving exceptional decorative effects.
They are non-combustible, offering excellent fire resistance; they have almost no radioactivity, reducing light pollution and demonstrating strong environmental friendliness.
They have no color difference and come in various colors, providing a distinct advantage over natural stone or metal curtain walls.
They can form all-glass curtain walls. With extremely low water absorption, U-shaped glass curtain walls avoid the common issues of dust, water, and oil absorption associated with natural stone, maintaining a clean surface and remarkable decorative performance.
2. Structural Requirements
U-shaped glass can be used both indoors and outdoors. For U-shaped glass used in building envelope structures, its appearance quality must meet the standards for "top-grade products" specified in industry regulations, and it must undergo tempering treatment. Industry standards classify U-shaped glass into "qualified products," "first-class products," and "top-grade products" based on appearance quality, with top-grade products being the highest quality. In accordance with the safety glass usage regulations issued by four ministries, glass used in curtain walls must be safety glass; therefore, U-shaped glass for curtain walls must be tempered. Like flat glass, tempered U-shaped glass may experience spontaneous breakage, but using top-grade U-shaped glass for tempering minimizes the breakage rate, enhancing the safety of the curtain wall.
U-shaped glass curtain walls can be constructed in single-row or double-row configurations. Single-row structures have lower costs but poorer sound insulation and thermal performance. Thus, for walls requiring higher thermal or sound insulation, a double-row U-shaped glass configuration is recommended. Since U-shaped glass transmits light without full transparency, installing PC sunboards or silica aerogels between the double rows can improve thermal and sound insulation while retaining light transmission. Double-row U-shaped glass can be arranged with aligned joints or staggered joints.
When constructing curved walls with U-shaped glass:
For U-shaped glass with a bottom width of 260mm, the wall radius should not be less than 2000mm;
For 330mm bottom width, the radius should not be less than 3200mm;
For 500mm bottom width, the radius should not be less than 7500mm.
Curved U-shaped glass walls are essentially polygonal surfaces with larger gaps on one side, which must be filled with flexible materials before applying silicone sealant (see Figure 9 for details).
For U-shaped glass walls exceeding 4.5m in height, structural stability must be considered, and corresponding measures should be taken. Here, structural stability primarily refers to the frame supporting the U-shaped glass, which must be securely fixed to the building's main structure.
3. Installation of U-shaped Glass
The surrounding structural frames of U-shaped glass walls can be made of aluminum or steel profiles and must be reliably fixed to the main structure. The lower ends of U-shaped glass panels should each be independently supported on evenly elastic pads. There should be no rigid contact between U-shaped glass and surrounding metal components, concrete, or masonry. A gap of no less than 25mm must be left between the upper ends of U-shaped glass and building components. Joints between U-shaped glass panels and around the perimeter of the glass wall should be sealed with elastic sealing materials.
While U-shaped glass is not a newly developed product, its application in curtain walls is a relatively new field.In recent years, an increasing number of buildings have adopted U-shaped glass curtain walls. The inclusion of a dedicated chapter on U-shaped glass in Technical Specification for Application of Building Glass (JGJ113) has provided clear guidelines for the design and construction of U-shaped glass curtain walls, which is expected to greatly promote their application.
