1. Pay attention to the waterproof seal of the joint.

In traditional buildings, the size of the wall and roof components are not large, along the same edge of the joint can be better waterproof. However, with the diversification of building materials, the thickness of components decreases gradually, the size of openings and building glass curtain wall increases, and the displacement of joints increases, especially the height and span of modern buildings obviously increases. Precast members are widely used in walls and floors, and the requirements for joint treatment and sealing are becoming increasingly prominent.

However, the old concept has limited attention to the size of the seam reserve and the choice of sealing material. Some designs often do not calculate the displacement of the seam, do not know the ability of the sealing material to withstand the displacement, directly marked“Seam elastomeric sealant”, think as long as there is no leakage of glue. The concept also appears in individual specifications and standards, indicating a lack of joint structure and detailed material selection.

In the construction engineering, the glass curtain wall of the building curtain wall is an industry that pays attention to the joint seal, especially for the structure bonding, the joint stress analysis, the bonding width and the thickness calculation, strict quality control of sealant construction process. But the waterproof seal of the joint is not fine, only the silicone sealant is needed. After the project put into use, in the construction, inspection, maintenance, rarely take similar structural glue measures. The sealing strip should be placed in an important position in the center of the curtain wall system.

2. Analysis of waterproof sealing joint of glass daylighting roof of building curtain wall.

(1)The joints of daylighting roof are mainly located between glass panels of building curtain wall. Because of the small thickness, slot width and relative size of the panel, the temperature change, dead weight deflection and local concentrated load may cause larger tension-compression displacement. For example, 18mm thick safety building curtain wall glass is used in daylighting roof, and the surface layer is heat reflection building curtain wall glass (heat absorption coefficient 0.83, heat capacity constant 56) . The ambient temperature range is -16 ° C ~ -33 ° C, the length of long side is 2000 mn, and the length of short side is 1500 mm. When the edge of the panel is unrestrained, the large temperature difference displacement (L) of the glass joint of the building curtain wall can be calculated as follows:

Considering wind load, snow load, earthquake, deflection of self-weight (calculated on the basis of 160) , 1.20 mm displacement of seam edge, 2.93 mm displacement of temperature difference in consideration of error and other factors, set the Factor of safety above 1.1, the displacement of seam was 3.22 mm.

(2)The displacement of the joint will inevitably lead to the deformation of the sealant, which can only change the shape but not the volume (cross-sectional area) . It should be noted that the deformation stress of the sealant may be localized. With the specific product hardness changes, the corner stress with the increase of hardness and concentration; there will be peeling phenomenon.

(3)Environmental corrosion and the potential for accidental damage from sealants are also worth considering.