design taboo of unit curtain wall

1. The mounting point is not positioned horizontally
Unit curtain wall hanging point is the foundation of curtain wall structure transmission force, so it can not be taken lightly. There are usually three design defects :(1) poor design of hanging point strength, especially the bearing capacity of negative wind pressure can not meet the needs. It is found in the experiment that some pendants break under negative wind pressure, and the bearing capacity can not meet the requirements. (2) All hanging points can slide, and the whole unit has no horizontal positioning; (3) The hanging depth is not enough, and there is a danger of groove. Design principles for hanging points :(1) hanging strength should be able to meet the requirements of force transmission; (2) can be adjusted in three dimensions, adjust a point and the main structure is relatively fixed, another point can slide horizontally, so that there is accurate positioning, but also through sliding expansion absorption structure, temperature and other reasons caused by deformation; (3) The amount of adjustment should be enough, not less than 20mm in each direction; (4) The hanging depth is generally not less than 15mm; (5) It can effectively absorb the deformation during normal operation and does not produce noise.

2. Air tight lines are not coplanar
unitised curtain wall adopts the principle of isobaric design, in the air tight line and water tight line between the cavity, called isobaric cavity. For a unit, the isobaric cavity around it may be interlinked. For individual transverse slip structures, the method of gluing is used to seal the unit horizontally, so at least three isobaric cavities are interlinked. The airtight line is the last line of defense, if the break will cause leakage, therefore, if the horizontal and longitudinal profiles of the unit of the airtight line is not coplanar, there will be permanent holes, is the hidden danger of water and gas leakage.
3. The internal panel of the unit plate is directly bonded with the frame by structural adhesive
The internal panel and frame of the unit curtain wall facade are directly bonded by structural adhesive, which can be completed in an indoor gluing environment with no problem. But if the glass plate needs to be replaced in the project, this structure must be injected with structural adhesive on site. If the environmental conditions such as temperature and humidity are not available, the quality of the adhesive joint can not be guaranteed, so it is necessary to solve this problem from the structural design.
4. Use butt rubber strips for airtight and watertight wires
The sealing unit curtain wall system with rubber strip butt and rubber strip plug has poor sealing effect. This kind of system requires high quality of curtain wall construction: (1) The installation is more accurate; (2) The butt part should be pressed tightly; otherwise, if the pressure is not enough or the civil construction error is too large, the seal will not be realized; The insertion strip should be centered, otherwise it will lead to leakage problems; (3) It is necessary to set up independent force transmission components to transfer loads.