As an important part of lightning protection engineering, the design and construction of roof lightning strip is very important
.
So, how can the roof lightning strip be standardized? This paper summarizes for your reference
.
The first design code 1 is based on the design of roof lightning strip according to the code for design of lightning protection of buildings (GB 50057)
.
The lightning protection measures for the first, second and third types of lightning protection buildings are implemented according to the provisions of 4.2, 4.3 and 4.4 respectively
.
If the height of the second type of lightning protection building is more than 45m, the lightning strip laid along the periphery of the roof shall be set on the external surface of the external wall or the vertical surface of the eaves, or it can be set on the external surface of the external wall or the vertical surface of the eaves, as shown in the figure below
.
2
.
Process key points: the lightning belt bracket is made of galvanized angle steel (L25 * 3) or galvanized flat steel (- 25 × 3) in actual construction, and can be installed with special clamp or wire rope clamp
.
The upper opening of the fixing clip on the bracket cannot be closed with the angle steel of the bracket
.
The lightning strip shall be smooth and straight, the distance between fixed point supports shall be uniform and fixed reliably, and each support shall be able to follow the vertical tensile force greater than 49n (5kg)
.
The connection of galvanized round steel lightning strip adopts single Z-shaped lap joint (it is recommended to use self-made mold), the lap length is 6 times of the diameter of round steel, and the lap joint is up and down
.
The semicircle of the telescopic compensation is vertical or parallel to the sky
.
The distance between supports of lightning strip in straight section should be evenly divided, and the distance should be controlled within 0.5-1.5m, generally 1m
.
The lightning strip shall be straight and of the same height, and the deviation of flatness in every 2m inspection section shall not be greater than 3 / 1000
.
3 precautions 1) the metal pipes protruding from the roof shall comply with the provisions of code for design of lightning protection of buildings (GB 50057), “when the size of isolated metal objects on the roof not protected by air termination does not exceed the following values, additional protection measures are not required: the height above the roof plane is not more than 0.3m, the total area of the upper surface is not more than 1.0m2 and the length of the upper surface is not more than 2.0m” The lightning device is connected
.
See the description of protection area in the figure below for details
.
In special cases, metal pipes and accessories in accordance with code for design of lightning protection of buildings (GB 50057) shall be provided with lightning receiving devices separately
.
2) According to the provisions of code for design of lightning protection of buildings (GB 50057), “when the non-conductive roof object is not within the protection scope of air termination, when it does not protrude more than 0.5m above the plane formed by air termination, additional protective measures of air termination are not required.” Non metallic pipes shall be provided with separate air termination
.
3) For high-rise buildings, if the first class building exceeds 30m, the second class building exceeds 45m, and the third class building exceeds 60m, it is necessary to prevent side lightning strike
.
To prevent direct lightning strike on the roof of high-rise building, lightning strip should be set along the periphery of the roof, and its installation position slightly protrudes from the outer edge of the roof, as shown in the figure
.
Special cases are handled (see Atlas 03d501-3p54)
.
II
.
Construction specification: the construction of roof lightning strip shall be in accordance with GB 50303 code for acceptance of construction quality of building electrical engineering: the lightning rod and lightning strip shall be in correct position, the welding seam fixed by welding shall be full without omission, the anti loosening parts fixed by bolts shall be complete, and the anti-corrosion paint applied on the welding part shall be complete
.
The lightning strip shall be smooth and straight, the distance between fixed point supports shall be uniform and fixed reliably, and each support shall be able to have a vertical tensile force greater than 49n (5kg)
.
When there is no requirement in the design, the distance between supports should be 0.5-1.5m for the horizontal straight part and 0.3-0.5m for the bending part
.
The installation of downlead and support frame of lightning strip shall be planned and set in the magnetic sheet joint or in the magnetic sheet
.
When the lightning strip passes through the expansion joint, the “Ω” bend downlead shall be brushed with green / yellow to make eye-catching mark, and the downlead signboard shall be uniformly made
.
The third construction example of lightning strip stereotyped support frame is summarized by country garden project department based on the engineering example, so as to provide reference for construction We can refer to the guidelines for implementation
.
1
.
Key points of lightning protection construction control 1
.
The lightning protection grounding down lead shall be constructed in strict accordance with the lightning protection grounding plan
.
2
.
Strictly control the construction materials to meet the requirements of the drawings
.
3
.
The distance between fixed supports is less than 1000mm, the distance between corner supports is less than 500mm, and the specific distance should be adjusted appropriately
.
4
.
The overlap length of lightning strip (net) and down lead meets the specification requirements, and the welding quality meets the requirements
.
5
.
The lightning strip shall be 150-200 mm higher than the finished surface of parapet or roof
.
2
.
Construction process of lightning strip: ① setting out and positioning; 1
.
The snapping line is straight without distortion
.
2
.
The spacing of support positioning points is uniform
.
3
.
The hole is located in the middle without collapse
.
② Support installation 1, accurate positioning, vertical without tilt
.
2
.
Firm without looseness, consistent height
.
3
.
The horizontal spacing is not more than 1000mm, the vertical spacing is not more than 1500mm, and the turning spacing is 300-500mm
.
③ Installation of lightning strip 1
.
It is smooth and straight, beautiful and without distortion
.
2
.
The height from the finished surface of the building is 150 mm
.
3
.
The turning is smooth without sharp water chestnut
.
④ Lead down spot welding 1
.
The weld is full without slag inclusion, undercut, crack, air hole, etc
.
2
.
The lap length of down lead and lightning strip shall not be less than 6D (d galvanized round steel diameter), and welding shall be carried out on both sides
.
3
.
The overlap length of lightning strip and lightning strip shall not be less than 6D (d galvanized round steel diameter), and welding shall be carried out on both sides
.
⑤ Welding antirust treatment 1
.
Before painting antirust paint, clean the welding slag coating; if there is rust, remove the rust to the round steel primary color
.
2
.
The paint must be antirust paint, and the color is generally silver
.
3
.
The antirust paint is applied evenly without omission
.
3
.
Common quality problems 1
.
The material does not meet the requirements, and the galvanized round steel is replaced by rebar
.
2
.
The height of the lightning strip is inconsistent, and the bending is not smooth
.
3
.
The distance between supports is not consistent, and the distance at the turning is more than 500mm
.
4
.
The sharp angle is formed at the corner, which is easy to discharge
.
5
.
The overlap length of the lightning strip is not enough, the welding seam is not full, and there is false welding
.
6
.
The galvanized round steel is seriously rusted and is not derusted and coated with antirust paint
.
。
.
