Lightning protection design and construction of high-rise building curtain walls?

The lightning protection design and construction of high-rise building curtain walls is very important. Every detail of the construction must be paid attention to, especially the lightning protection design, which must be done well to prevent problems in the bud. Zhongda Consulting would like to introduce to you the lightning protection design and construction of high-rise building curtain walls.

1 The importance of lightning protection for high-rise building curtain walls

As we all know, lightning is a very destructive natural phenomenon, but the occurrence of this natural phenomenon is uncertain. The voltage can reach up to several million volts, and the instantaneous current far exceeds 100,000 amps. Its main hazards are as follows: (1) The huge energy contained in lightning directly acts on the curtain walls of high-rise buildings, causing damage to the curtain walls and even fires and explosions. , or even casualties; (2) Due to the extremely high voltage of lightning itself, it can breakdown the insulating equipment in the electrical system, causing huge destructive phase-to-phase short circuits; (3) Since most modern electronic products are high-density, low-voltage and low-power products. It is very sensitive to the electrostatic effect and electromagnetic induction effect of lightning products, which can cause equipment data errors or even paralysis. The characteristics of curtain walls as decoration of high-rise buildings and their metal frames are the main causes of lightning strikes, causing huge property losses and personal injuries. Therefore, lightning protection of high-rise building curtain walls has reason to attract people's attention.

2 Design principles of lightning protection for high-rise building curtain walls

Damage forms caused by lightning to building curtain walls can be roughly divided into direct lightning strikes, side lightning strikes and lightning induced damage. Therefore, there are the following three corresponding lightning protection design principles.

(1) Protection against direct lightning strikes. The protection project for direct lightning strikes is generally constructed from the outside: an air-termination device at the top of the curtain wall to attract lightning, a grounding device arranged at a certain depth underground to conduct lightning current, and a down conductor connecting the two located around the high-rise building. This is A complete direct lightning protection system.

(2) Anti-side lightning strike. At locations 30 meters above the curtain wall of a high-rise building, every three floors are taken as a unit, and each unit constructs a pressure equalizing ring and connects the lightning protection systems of the building and the curtain wall. In this way, an equipotential connection is formed, and the potential difference caused by the lightning current is reduced, thereby avoiding the step voltage to prevent side lightning strikes.

(3) Protection against lightning induced damage. The electromagnetic induction caused by lightning strikes acts as a source of interference to affect the operation of electronic equipment and network systems. In order to prevent this damage, a shielding effect must be formed, and a lightning-proof metal hexahedral mesh cage pattern is constructed within the curtain wall. Perform shielding. However, a system built with steel bars within the floor, ceiling and wall panels not only has a good shielding effect, but is also an important measure to solve the problem of equipotential and shunt separation.

3 Matters needing attention when constructing lightning protection for high-rise building curtain walls

Lightning protection for high-rise building curtain walls is a system that requires careful design and strict construction. During the construction process, careful consideration is required, combined with the engineering experience and the actual situation of the building. On the premise of ensuring the construction technology, attention must still be paid to the following links:

(1) Strict Designed according to the lightning protection principle of high-rise building curtain walls. The design should be compared based on the functionality and aesthetics of the curtain wall to determine the interior, structure and materials of the curtain wall. Due to the particularity of high-rise buildings, wind removal factors and other protective functional requirements still need to be considered, such as fire protection, light pollution prevention, etc. In the lightning protection system of high-rise buildings, down conductors need to be evenly distributed around the high-rise building as much as possible, and as many down conductors as possible should be installed so that they can withstand larger currents. Due to the height problem, the down lead is relatively long and the voltage difference is relatively large. A voltage equalizing ring should be constructed strictly according to each unit (every three layers is a unit) to avoid the occurrence of counterattack effect.

(2) Strictly select raw materials according to usage standards. As the material basis for reliable project quality, raw materials also deserve attention in the system structure of lightning protection for high-rise building curtain walls. First of all, the material should be treated with anti-corrosion treatment, and the weight it needs to bear and the tightness of the interface also need to be considered. At the same time, strict verification is carried out on materials such as certificates of quality, quality assurance, and whether the usage standards are in compliance with the standards. Finally, inspection is required during the acceptance process of materials and during construction and use.

(3) Carry out quality control in strict accordance with construction technical standards. Conduct focused inspections on problems that may arise during project implementation, and implement special inspections at key locations in the process.

Management measures that focus on prevention and combine supervision to strictly ensure the construction quality of curtain wall lightning protection projects. Technical designers must convey the design concept, and on-site construction managers must be familiar with the design and building structure, as well as the technical characteristics of construction operators, and construction operations. Personnel need to be familiar with basic electrical operation slogans and strictly follow the established plans. It is also necessary to have professional quality inspection personnel of lightning protection facilities to inspect each item one by one. The resistance value of the grounding must reach the specified standard value.

(4) Strictly follow the connection requirements for curtain walls of high-rise buildings. When building a metal frame structure, it should be consistent with the lightning protection system of the main building. Welding and mechanical connections are generally used to form a good conductive circuit. The contact surfaces are closely matched, with three-sided welding as the main method, and anti-corrosion and anti-electrochemical treatment is done.

(5) Testing should be carried out after the construction is complete. Whether the quality of a project must be tested in practice before a conclusion can be made. Therefore, in order to detect whether the curtain wall lightning protection system can operate normally, an on-site grounding resistance test is required. This experiment must be conducted on a sunny day. If it rains, you must wait until one week after the rain and the sky clears. After the test is completed, the test points must be restored to avoid affecting the test results.

4 Conclusion

Due to the particularity of building curtain walls, lightning protection projects for building curtain walls are generally carried out by professional curtain wall construction units. It is hoped that the construction units will Not only should we pay attention to the structural safety of the curtain wall, but we should also not ignore the installation of the lightning protection system of the curtain wall. While closely integrating with the main structure of the building, we should improve our own lightning protection projects, do a good job in detecting ground resistance, improve various preparation and control materials, and fully ensure the normal lightning protection system of high-rise building curtain walls. Installation to protect people's property and personal safety and completely eliminate the potential safety hazard of lightning.

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