The metal skeleton of the building curtain wall is a good conductor. The lightning protection measures of the curtain wall are improper. It may also be damaged by the side impact of lightning. Seriously, it may attract fire. At the same time, for some high-rise buildings, due to the large number of metal components on the curtain wall, it is easy to generate static electricity. The role, when the sky thundercloud and the earth form an electric field, the metal rod of the curtain wall will accumulate a large amount of induced charges opposite to the thundercloud polarity. When the thundercloud is instantaneously discharged, the electric field of the thundercloud and the earth suddenly disappears. The induced charge of the metal rod cannot be dissipated at the corresponding speed, and will generate a ground potential of more than 10,000 volts. This electrostatic induction voltage will cause great harm to people and equipment. Therefore, the lightning protection of the curtain wall must also be strictly in accordance with the relevant Standard design and construction.
The glass curtain wall is attached to the main building. The metal frame of the curtain wall is not used for lightning protection and grounding. Instead, it uses the lightning protection system of the main structure to combine with the lightning protection design of the building itself. Therefore, the requirements should be related to the main structure. The lightning protection system is reliably connected and keeps the electricity conductive. Therefore, in the case of a curtain wall embedded part, and the embedded parts and the lightning protection system of the building have been reliably connected, the lightning protection measures of the curtain wall can generally be processed as follows: the vertical metal column between the curtain wall of the same plane position is used A copper flexible wire or an aluminum connecting piece with a root cross-sectional area of not less than 25 mm2 is connected up and down as a vertical down-conducting line of the curtain wall lightning protection system, and a floor of the main building having a water pressure ring, corresponding to the pre-conductive column The embedded or fixed parts are φ12 galvanized steel bar and the water pressure ring is reliably overlapped by welding. The lap length is not less than 120mm to make the connection resistance ≤1Ω, forming a lightning protection path, but in the actual design and construction process, we also Still need to pay attention to the following points:
(1) Defining the lightning protection classification of buildings:
The lightning protection classification of a building is classified according to its importance, the nature of its use, the likelihood of a lightning accident and its consequences, rather than the height of the building.
(2) When connecting the curtain wall metal pillars
If the protective film layer of the metal column is not electrically conductive, when the copper flexible wire or the aluminum connecting piece is connected up and down, the protective film layer needs to be scraped off at the connection position.
(3) If the civil construction process
If the embedded part is not considered, or the embedded part is considered but the embedded part is not reliably connected with the lightning protection system of the building, it is necessary to additionally arrange the pressure equalizing ring of the curtain wall lightning protection system according to the lightning protection classification of the building, the curtain wall The vertical down conductor needs to be reliably connected to this equalizing ring.
(4) There are many important sensitive electronic systems
For buildings with modern equipment such as communication equipment, electronic computers, electronic control systems, etc., in order to increase the shielding effect, anti-side lightning and equipotential measures can be started from the ground floor, that is, the building curtain wall on the outer wall above the first floor, Large metal objects such as aluminum and gold doors and windows and metal railings are connected to lightning protection devices.
(5) The lightning protection of the top of the curtain wall can be used as a lightning protection belt or a lightning rod.
When the building curtain wall is located outside the parapet wall, a lightning protection belt can be arranged along the roof. The installation position is slightly protruding from the top of the top of the parapet wall. Other roofing metal objects can be used as the lightning receptor. There is also a direct use between the building curtain wall and the parapet wall. The metal plate is used as a lightning receptor. At this time, the thickness of the metal plate is required to be greater than 0.5 mm, and the overlap length between the plate and the plate is greater than 100 mm. The metal plate has no insulating cover layer, and the metal plate is connected with the steel bar in the parapet wall to form an electrical passage. The connection node between the curtain wall structure and the lightning protection belt device at the parapet wall should be exposed.
(6) Equipotential requirements shall be met when the curtain wall lightning conductor is connected to the aluminum alloy material.
When copper material is used to connect with aluminum alloy material, the outer surface of the copper material shall be hot-dip galvanized. The wire connection contact surface should be tight and reliable and not loose.
(7) Connection of curtain wall metal frame and lightning protection device
It should be tight and reliable, and should be welded or mechanically connected to form a conductive path. The horizontal spacing of the connection points shall not be greater than the spacing of the lightning protection down conductors, and the vertical spacing shall not be greater than the spacing of the voltage equalization rings.
(8) Selection of aluminum panel curtain wall for high-rise buildings
It is advisable to use a single-layer aluminum plate instead of an aluminum-plastic composite board, because the polyhexene plastic sandwiched between the composite plates is not electrically conductive, so that the composite panel curtain wall cannot be grounded, and it is impossible to prevent the damage of lightning to the building tempered glass supplier. The curtain wall made of material is not durable. The single-layer aluminum plate is not only deformed for several decades, but also has a long service life. More importantly, its conductive performance is good, and it is easy to be grounded together with the curtain wall to prevent lightning strikes.
(9) The grounding resistance of the curtain wall lightning protection should be less than 10 ohms.
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