How to improve the fire resistance limit of glass curtain wall of high-rise building

The glass curtain wall is favored by architects for its magnificent appearance, good lighting, exquisite texture and other advantages. It is widely used in various buildings and has become a beautiful urban landscape. However, the complex and beautiful building curtain wall design will also have a negative impact on fire protection.

Fire blocking, which belongs to the category of passive fire protection, corresponds to the more common active fire protection (including sprinklers, detectors, etc.). It refers to the use of fire blocking materials (products) to protect the firewall and pipelines of buildings, especially high-rise buildings. Wells, strong and weak electric bridges, etc., need to have a certain fire-proof time effect or gaps (including the interlayer gaps of curtain walls or the head gaps of firewalls, etc.) that are likely to form a chimney to be blocked during a fire, so that the fire source does not pass through Fire zoning or other floors to achieve the purpose of controlling the fire and reducing fire losses. Generally speaking, it includes the detailed structure of various penetrating objects through walls and floors, and the treatment of various structural joints.

How to improve the fire resistance limit of the curtain wall, extend the time the curtain wall resists fire, and minimize the loss caused by the fire are issues that must be considered in the design and application of the curtain wall. However, which kind of structural plan is more reasonable and how long the fire protection aging period can be achieved is not subjectively estimated or calculated. The design must be based on the relevant data obtained from the relevant tests.

1. STI glass curtain wall fireproof sealing method

STI (Specified Technologies Inc.) has been paying attention to and devoting itself to the development of fire-proof sealing technology, and is in a leading position in the industry. It has proposed and passed UL testing of more than 1,700 fire-proof sealing methods (solutions), which can solve all the problems in the building. Fire-proof sealing of penetrations, especially the structural solutions for the interlayer seams of glass curtain walls, is the majority in the industry.

STI's fire-proof sealing method for the gap between glass curtain walls is mainly through squeezing mineral wool to fill the gap and spraying glue to cover the mineral wool to form a system with high smoke tightness and fire resistance. Its fire resistance performance lies in:

1. The total width of the density is 64kg/m3 as the gap width of 125%~150% of the gap width of several mineral wool slivers tightly packed, so that the mineral wool in the gap has sufficient pre-pressure, on the one hand, to offset the thermal expansion of the mineral wool during fire. External expansion force that causes looseness and shedding. On the other hand, the squeeze packing makes the mineral wool itself more dense; for larger gaps (≥250mm), angles or fasteners can be added to improve the tightness of the mineral wool and the floor;

2. The specially formulated spray glue is carbonized into fine particles in the fire, and covered on the mineral wool, filling the small holes on the surface of the mineral wool, so that the sprayed carbonized layer and the mineral wool form a smoke and fire barrier; this is different from the traditional The sealing principle of the galvanized steel plate as the supporting plate is completely different, and the traditional galvanized steel plate will expand after being fired, causing more openings and causing smoke diffusion;

3. The separation belt of the relevant construction method is fixed on the backing plate or angle steel independent of the curtain wall structure by setting anchors (Impaling Pin), so even if the lower curtain wall frame is fused, the separation belt can still maintain its integrity to avoid the fire going up.

2. Project examples

A super high-rise building in Zhengzhou has 56 floors above ground and 2 floors underground. It is 280 meters high. In the original design plan of curtain wall structure, the interlayer seam structure of the curtain wall structure and floor slab is consistent with the traditional design plan. The mineral wool is supported by galvanized steel plate. However, because the building is a new landmark of Zhengzhou City, the outer structure of the structure is unique, and the construction quality requirements are high. All the galvanized steel sheets used for the interlayer seams of the curtain walls need to be prefabricated by the factory according to the design drawings, which greatly increases the cost of the construction unit. As mentioned above, the fire protection performance of the traditional design scheme cannot be guaranteed. Therefore, STI related engineering and technical personnel put forward suggestions for fire prevention and blockage modification of the original scheme. By filling mineral wool and spraying glue, the joints between each floor are greatly reduced. The construction cost of the fire-proof sealing project has been approved by the owner, consulting company and curtain wall construction unit. According to the actual progress of the project, the construction of the STI curtain wall interlayer fire-proof sealing demonstration layer has been carried out recently on the 15th and 16th floor of the project. And passed the inspection of the local fire and quality inspection department.

3. Discussion

With the launch of my country’s “Twelfth Five-Year Plan”, there are about 135 cities across the country that are going to be among the international cities. CBDs in all regions are under planning or have begun to take shape. Super high-rise buildings as a CBD symbol will inevitably be in the future. The emergence of continuous emergence in the past five years, the ensuing safety issues should be paid attention to by the industry, especially how to reasonably implement the fire-proof sealing measures for the interlayer joints of the curtain wall is worthy of our joint discussion. In view of this, the author has the following three ideas:

1. Seriously study foreign advanced technology. Since the methods of packing mineral wool and spraying glue have been widely used in foreign countries, and it has been proved by tests and actual fire cases that its fire resistance is good and can effectively control the spread of fire, we should consider correcting it in future curtain wall design and construction. Make adjustments to the traditional scheme, or combine the advantages of the two schemes;

2. Relevant regulations should be adjusted in due course. Including the current test basis for fire protection products, the aspect of fire protection and sealing still lags behind the needs of actual engineering development. There can be no more serious fires, so that we can truly consider the shortcomings of traditional design solutions.

3. The inspection and acceptance of fire protection shall further strengthen the monitoring of the construction quality of the fire protection seal in the building, and shall refer to the practices of other countries or regions and require the relevant construction unit of the fire protection seal to provide construction reports.