Unit curtain Wall design experience
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, which 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. The design principles of hanging points should be mastered :(1) the hanging strength should meet the requirements of force transmission; (2) 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.
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 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.
The internal panel and curtain wall frame 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 modern curtain wall design.
The sealing effect of unit curtain wall system with rubber strip butt and rubber strip plug is not good. This kind of system has higher requirements on curtain wall construction quality :(1) it is more accurate when it needs to be installed; (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.