Causes and Analysis of Aluminium Curtain Wall Damages
1、Causes and analysis of falling off while opening sashes
Sash is the easiest damaged position of a whole curtain wall system in typhoon. Typhoon causes different damages due to sashes are different in sizes and structures.
The open sash is hooked on the beam of curtain wall and adjusted with an open-angle. The gravity of sash is on the beam that has two modes split type and integrated type.
The open window of hook-type curtain wall is designed by using hook or hinges to connect sashes with frames. It has the advantages of heavy load-bearing for big open windows. However, due to its direct installed and hook-type design, it has safety issue that may fall off while opening under strong wind. It needs to install security devices to ensure normal use.
The sash is free to move when the hook-type curtain wall lock site is damaged or opened. The wind bracing may break down when wind pressure stresses the curtain wall. If two wind braces are broken down, the sash will be flipped. The angle assembly is used compression and pin point, when stress on sash reaching the limit, the turning force in frame will be extreme. The pin point will lose efficacy and the duct corner will be pulled out. The glue is no longer in force and the sash will be falling off.
Although there are some anti-falling off devices installed, when high wind pressure stress on sash, connection parts require a high level of structural stability and hardness. As time goes by, the hook's fair wear and tear may also lose efficacy.
（2）Four bar links hinges damages
This open model is fixed with two sashes by friction hinges and curtain wall frames. Big sashes opening angles are limited by hinges and wind braces.
In the early years, curtain wall sashes are usually small. They are controlled by friction hinges and will not fall off even it is unlocked. Nowadays, buildings desire ventilation and bright. Glass units are bigger and bigger. It can increase the risk of being damaged by and wind pressure and falling off.
Under strong wind pressure, there is still possibility to damage the curtain wall even it is closed.
Therefore, for those widescreen sashes, it requires satisfied locks quantity and distance, specified install location and quality control.
2、Curtain wall unit falling off
Unit curtain wall designs are important. For super high-level buildings, curtain wall must have security devices to prevent falling off especially in hazardous weather.
（1）Wind speed increase in a narrow space between two buildings
From the research, damages and falling off are not usually happened in the front side, but back and sides. This unexpected phenomenon is also happening in house windows. Harbourfront in Hung Hom twenty level of glasses is damaged by the typhoon. The typhoon came from south-east, all the damages are in backsides, (north sides, west sides).
We could find out that all the glasses are in the narrow space between two buildings when we understand the principles and environment. Narrow space increase the typhoon power in term of speed and pressure and then causing damages.
（2）Scraps damages in typhoon
Scraps brought by typhoon may cause damages to glass, that also one of the common glass plate damages. Scraps in high speed typhoon are powerful and dangers. The scraps brought by typhoon impacts on glass where the weakest place of building. Then, the glass scraps splashed and caused damages to other properties and dangers to people. Also, the strong wind may blow in the house and cause dangers indoor.