Why do high-rise buildings need curtain walls?

1. Curtain walls are required to resist temperature changes

When the outside temperature changes, the structure will shrink and expand in cold and hot expansion. If measures are not taken, the structure will be bent and crushed in the summer; Winter will tear and break the structure. Therefore, the long pavement should be divided into joints, and the long building should also be divided into several sections with temperature joints, so as to reduce the impact of temperature changes.

Long buildings can be divided into several sections with vertical temperature seams; However, it is not possible to cut a tall building into several sections with horizontal seams, because the horizontally divided floors cannot be hung up.

Since it is impossible to solve the problem of temperature change of high-rise buildings by using a segmented method, there is only one way out: encapsulate the entire structure with the building curtain wall, so that the structure is indoors, the temperature will no longer change, and there will be no damage to the structure and ensure the safety of the main structure. This is one of the main reasons why high-rise buildings must adopt building curtain walls.

The traditional brick walls and block walls are filled in the plane of the beams and columns, and the beams and columns are partially exposed to the outdoor atmosphere and are directly affected by temperature changes. Therefore, infill walls cannot solve the problem of temperature changes, and it is difficult to apply them in tall buildings.

2. Curtain walls are needed to resist earthquake disasters

In the 1995 Hanshin earthquake in Japan and the 1999 Jiji earthquake in Taiwan, the epicenter intensity was above 11 degrees, and the masonry filling wall and conventional glass windows were damaged in large quantities, and the curtain wall, even if it was a glass curtain wall, there were few reports of earthquake damage, and most of them were well preserved after the earthquake.

The shaking table tests of seven types of building curtain walls have been carried out by the Institute of Structures of China Academy of Building Research, and the results show that even when the input acceleration of the table reaches 0.9g (equivalent to a 10-degree earthquake) and the structural displacement reaches more than 1/60, the curtain wall is not damaged and maintains good performance.

The masonry infill wall cracks at 1/1000 displacement and fails at 1/300 displacement, and it will be damaged even under a small earthquake and severely damaged under a medium earthquake. The reason is that it has a very poor deformation ability in its own plane, and it is filled in the main structure, so it cannot have relative displacement, and is forced to vibrate together, which eventually leads to destruction. Conventional glass windows are more or less the same. Therefore, the seismic damage in an earthquake is very severe.

The wide joints of the building curtain wall and the special connection structure make it resistant to large displacement and deformation of 1/100~1/60. Similar to the leaves relative to the branches, the curtain relative to the entrance, no matter how the main structure shakes, the curtain wall can be safe and sound.

High-rise buildings soar into the sky, and the earthquake swings strongly, and only the curtain wall can ensure the safety of earthquake resistance, prevent collapse and fall, and prevent casualties.

3. The curtain wall saves the cost of structure and foundation

Building materials, such as steel and cement, are materials with high energy consumption and high cost.

The weight of the glass curtain wall is only 1/10 of the brick wall and 1/7 of the concrete wall panel, and the aluminum panel curtain wall is lighter: 370mm brick wall is 760Kg/㎡, 200mm hollow brick wall is 250Kg/㎡, while the glass curtain wall is only 35~40Kg/㎡, and the aluminum curtain wall is only 20~25Kg/㎡. A high-rise building with a height of 150m and an external wall of 20,000 square meters, the curtain wall can reduce the weight of the wall by 5,000t~12,000t. This greatly reduces the amount of material used in the main structure, also reduces the load of the foundation, and saves the cost of the foundation. The construction of super high-rise buildings on weak foundations such as Shanghai and Tianjin played a decisive role.

4. The existing problems can be solved

Everything is divided into two, and it is the right attitude to promote the good and eliminate the disadvantages.

If a glass curtain wall is coated with glass over a large area, it may reflect sunlight and cause disturbance to surrounding buildings and streets. At present, it has been stipulated that the glass reflectivity is controlled below 30%, and the low-rise part can be made of aluminum panels, stone and glass combined curtain walls to reduce the interference of sunlight reflection. According to CCTV, 200,000 people were killed in car accidents nationwide in 2004. However, we have not heard any reports of people dying due to the reflection of the curtain wall, so there is no need to overestimate the risk of reflection on the curtain wall.

On July 1, 2005, the "Energy Saving Design Standards for Public Buildings" came into force. Aluminum curtain wall and slate curtain wall can fully meet the requirements of the standard because of the insulation layer on the back. As long as the glass curtain wall is reasonably designed, it can also meet the requirements of the standard. The promotion and use of Low-E insulating glass curtain wall is a powerful measure. The thermal insulation performance of double-layer ventilated curtain wall and vacuum glass curtain wall is better than that of traditional wall materials. Whether it is energy-saving or not, it is not whether it is glass or not. The selection of suitable glass and the use of reasonable structure can fully meet the standard of energy saving. The statement that "glass curtain walls are not energy-saving" is too arbitrary and general, and the technical basis is not sufficient.