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How to do the lightning protection of steel structure buildings? Zhengzhou Leidi Electronic Engineering Co., Ltd. technical personnel today to share with you your own experience, according to the characteristics of steel structures, it is clear that tall and heavy lightning rods are not suitable for installation on such buildings, and "buildings lightning protection design Section 4.1.4 of the “Specification†(GB50057-94, 2000 edition) gives four requirements for metal roofing as lightning protection devices for buildings (except for the first type of lightning protection structures).
The specification addresses the different conditions of flammable materials below the metal plate. Different requirements have been made for the thickness of the metal plate. It is stipulated that "the thickness of the metal plate should not be less than 0.5 mm when there is no flammable material." Let us take a look at the physical properties of the four insulation cores. Hard polyurethane is a Class B1 building material, thermal conductivity of 0.016 ~ 0.025, is a flame retardant; polystyrene is a flame-retardant material, the oxygen index of not less than 30, the thermal conductivity of 0.029, a flame-retardant self-extinguishing type; rock Cotton is an incombustible material with a thermal conductivity of 0.044; glass wool is a Class A building material and has a thermal conductivity of 0.038 to 0.042, which is non-burning. In addition, the adhesive used for the insulating core material is also a flame-retardant type. Therefore, the enclosure system of a steel structure building is non-combustible. When using a metal plate as a lightning receptor, the thickness should not be less than 0.5 mm. The third article of the four requirements of the specification is no longer considered.
From the structural professional perspective, the thickness of the roof panel is generally considered three factors: the first is the wind load; the second is the snow load; the third is the pitch. Therefore, the thickness of roof panels that may be selected in different regions is not the same. Electrical designers need to communicate with the structural professional in a timely manner. When the thickness meets the specification requirements, other conditions are evaluated. For example, in Xinjiang, when the radon distance is about 1.5m, the thickness of the roof panel is generally 0.6mm, and the floor thickness is generally 0.5mm, which is to meet the specification thickness requirements. If the thickness does not meet the requirements, then reference should be made to the National Standard Atlas "Pressed profile steel plate, sandwich panel roof and wall construction structure" (01J925-1) as a lightning protection zone. Details of the lightning protection zone of the profiled steel plate roof shall be referred to For details on the 48-page, sandwich panel roof lightning protection, see page 66. This atlas is a building atlas of professional construction, with less contact with electrical designers, and the national standard atlas “Installation of Lightning Protection Facilities for Buildings†(99D501-2) and “Using Metallic Buildings as Lightning Protection and Grounding Device Installation†( 03D501-3) There are no detailed practices for lightning protection of steel roofing. Therefore, electrical designers should pay attention to standard practices. The grid size of the lightning protection zone shall be in strict accordance with the requirements of the specification and the lightning protection category of all types of buildings. The construction drawings shall be accurately marked according to the standards of the standardization.
The connection method of the enclosure system of the steel structure building is generally occlusal or overlapped. Whether it is pressed steel plate or sandwich panel, its appearance is corrugated. In construction, the overlap length when using lap joints must reach at least one crest or trough, and exceeding 100 mm fully meets the requirements of the specification.
In addition, the specification note mentions that "thin paint protection layer" is not an insulating coating. Therefore, it can be considered that the colored coated steel plate has no insulating coating layer, and the galvanized steel plate is a good conductor of electricity. Therefore, the author believes that the fourth requirement of Section 4.1.4 of the "Code for the design of lightning protection in buildings" (GB50057-94, 2000 edition) is also satisfied.
In summary, I believe that the roof sandwich panel (or profiled steel plate) of a steel structure building with a thickness of 0.5 mm can be used as a lightning receptor.
From the introduction of the building system of the steel structure building in the front, it can be seen that the main steel frame, the sub-components and the containment system have been reliably connected in the construction and have formed a long-lasting electrical path. Therefore, as long as a reliable grounding device is provided, the steel column can be used as a down conductor in a span. This point has been stipulated in Section 4.2.3 of the Code for Design of Lightning Protection in Buildings (GB50057-94, 2000 edition). Of course, the specification makes requirements for the downhole spacing of various types of lightning protection structures. However, when the civil works are constructed, as long as all the steel columns, lightning receptors, and grounding devices are reliably connected, they are all deflected. The actual effect exceeds the normative standards.
According to the provisions of Article 4.2.5 of the “Code for Design of Buildings for Lightning Protection†(GB50057-94, 2000 edition), that is, whether or not protective measures are taken for a steel column that is used as a downhole from 1.7 m above ground to 0.3 m below ground. No need. First, there is no worry that steel columns are subject to mechanical damage. Second, from the perspective of the steel structure building system, there are 1.2m high brick walls or aerated concrete blocks, which have certain protection against personal contact. Third, The steel column itself has been treated with anti-corrosion treatment and contains insulating coating, which also plays a protective role. In addition, the provisions of the provisions of this article indicate that it is appropriate to set off the case of the clip, and according to the norms of Article 4.2.4, when the use of steel column as the lead off the same time when using the basic grounding body can not be set off the card.
In the current design, the basic rebar is generally used as the natural grounding body, and it is connected with a 40×4 galvanized flat steel and a total equipotential bonding is performed. In this way, the grounding resistance is small and it is generally easy to meet the design requirements. In the design, it should be noted that a ground connection plate should be reserved in an appropriate outdoor location. For the practice, reference can be made to the National Standard Atlas “Earthing Device Installation†(03D501-4). In this way, when the grounding resistance value does not meet the requirements, the construction unit can conveniently connect the artificial grounding body and test the grounding resistance value, which should be reflected in the design drawings.
In addition, in the design drawings, it can not be generalized and talk about "the use of building steel bar as a natural grounding body." It has already been mentioned that the steel structure buildings need to be embedded with anchor bolts during the foundation construction, and the spacers can be connected with the steel columns. Notice: There is no electrical connection between the embedded grounding bolt itself and the foundation steel! Therefore, the civil steel construction and the round steel can be used for reliable welding of the foundation steel and the grounding bolt. Therefore, please refer to the National Standard Atlas for the use of buildings. Metal body for lightning protection and grounding device installation" (03D501-3) 17 pages. In this way, lightning currents have complete discharge channels from the air receptor to the down conductor to the grounding device. This is not enough. We should also use a short steel bar and a basic steel bar for reliable welding, and lead out of the foundation for the connection of the grounding ring network, in order to reduce the grounding resistance of the natural grounding body and to implement an effective equipotential bonding. This point is particularly important for steel structures with independent foundations, so it is necessary to clarify them in the design drawings.
If the particularity of the grounding device of the steel structure building is neglected, that is, the fact that the basic steel bar and the grounding bolt itself are not electrically connected, the consequence is that the entire building does not have a reliable grounding grid. The remedial measures taken are to use 40X4 galvanized flat steel for equipotential ring network. When galvanized flat steel is passed through the steel column, reliable welding should be performed with the underside of the column foot plate. In this way, the galvanized flat steel acts as a grounding electrode and grounding wire. Dual role.
In addition to the equipotential grounding ring network laid along the periphery of the building for one week, a pressure equalizing grid should be set across the span in the building to not only reduce the step voltage and protect personal safety, but also help the industrial plant production equipment to implement equipotential on-site. Coupling shortens the length of the equipotential bonding line.
The above is a summary of measures to prevent direct lightning strikes on steel structures. The conclusion is that the roof sandwich panel (or profiled steel plate) of a steel structure building with a thickness of 0.5 mm can be used as a lightning receptor, using the steel column as a down conductor, using the basic steel bar as a natural grounding body and passing through the galvanized flat steel. Connect to a reliable equipotential ground ring network.
For more information on the lightning protection of steel structures, please visit Zhengzhou Leidi Electronic Engineering Co., Ltd. or directly contact technical personnel!!!
The specification addresses the different conditions of flammable materials below the metal plate. Different requirements have been made for the thickness of the metal plate. It is stipulated that "the thickness of the metal plate should not be less than 0.5 mm when there is no flammable material." Let us take a look at the physical properties of the four insulation cores. Hard polyurethane is a Class B1 building material, thermal conductivity of 0.016 ~ 0.025, is a flame retardant; polystyrene is a flame-retardant material, the oxygen index of not less than 30, the thermal conductivity of 0.029, a flame-retardant self-extinguishing type; rock Cotton is an incombustible material with a thermal conductivity of 0.044; glass wool is a Class A building material and has a thermal conductivity of 0.038 to 0.042, which is non-burning. In addition, the adhesive used for the insulating core material is also a flame-retardant type. Therefore, the enclosure system of a steel structure building is non-combustible. When using a metal plate as a lightning receptor, the thickness should not be less than 0.5 mm. The third article of the four requirements of the specification is no longer considered.
From the structural professional perspective, the thickness of the roof panel is generally considered three factors: the first is the wind load; the second is the snow load; the third is the pitch. Therefore, the thickness of roof panels that may be selected in different regions is not the same. Electrical designers need to communicate with the structural professional in a timely manner. When the thickness meets the specification requirements, other conditions are evaluated. For example, in Xinjiang, when the radon distance is about 1.5m, the thickness of the roof panel is generally 0.6mm, and the floor thickness is generally 0.5mm, which is to meet the specification thickness requirements. If the thickness does not meet the requirements, then reference should be made to the National Standard Atlas "Pressed profile steel plate, sandwich panel roof and wall construction structure" (01J925-1) as a lightning protection zone. Details of the lightning protection zone of the profiled steel plate roof shall be referred to For details on the 48-page, sandwich panel roof lightning protection, see page 66. This atlas is a building atlas of professional construction, with less contact with electrical designers, and the national standard atlas “Installation of Lightning Protection Facilities for Buildings†(99D501-2) and “Using Metallic Buildings as Lightning Protection and Grounding Device Installation†( 03D501-3) There are no detailed practices for lightning protection of steel roofing. Therefore, electrical designers should pay attention to standard practices. The grid size of the lightning protection zone shall be in strict accordance with the requirements of the specification and the lightning protection category of all types of buildings. The construction drawings shall be accurately marked according to the standards of the standardization.
The connection method of the enclosure system of the steel structure building is generally occlusal or overlapped. Whether it is pressed steel plate or sandwich panel, its appearance is corrugated. In construction, the overlap length when using lap joints must reach at least one crest or trough, and exceeding 100 mm fully meets the requirements of the specification.
In addition, the specification note mentions that "thin paint protection layer" is not an insulating coating. Therefore, it can be considered that the colored coated steel plate has no insulating coating layer, and the galvanized steel plate is a good conductor of electricity. Therefore, the author believes that the fourth requirement of Section 4.1.4 of the "Code for the design of lightning protection in buildings" (GB50057-94, 2000 edition) is also satisfied.
In summary, I believe that the roof sandwich panel (or profiled steel plate) of a steel structure building with a thickness of 0.5 mm can be used as a lightning receptor.
From the introduction of the building system of the steel structure building in the front, it can be seen that the main steel frame, the sub-components and the containment system have been reliably connected in the construction and have formed a long-lasting electrical path. Therefore, as long as a reliable grounding device is provided, the steel column can be used as a down conductor in a span. This point has been stipulated in Section 4.2.3 of the Code for Design of Lightning Protection in Buildings (GB50057-94, 2000 edition). Of course, the specification makes requirements for the downhole spacing of various types of lightning protection structures. However, when the civil works are constructed, as long as all the steel columns, lightning receptors, and grounding devices are reliably connected, they are all deflected. The actual effect exceeds the normative standards.
According to the provisions of Article 4.2.5 of the “Code for Design of Buildings for Lightning Protection†(GB50057-94, 2000 edition), that is, whether or not protective measures are taken for a steel column that is used as a downhole from 1.7 m above ground to 0.3 m below ground. No need. First, there is no worry that steel columns are subject to mechanical damage. Second, from the perspective of the steel structure building system, there are 1.2m high brick walls or aerated concrete blocks, which have certain protection against personal contact. Third, The steel column itself has been treated with anti-corrosion treatment and contains insulating coating, which also plays a protective role. In addition, the provisions of the provisions of this article indicate that it is appropriate to set off the case of the clip, and according to the norms of Article 4.2.4, when the use of steel column as the lead off the same time when using the basic grounding body can not be set off the card.
In the current design, the basic rebar is generally used as the natural grounding body, and it is connected with a 40×4 galvanized flat steel and a total equipotential bonding is performed. In this way, the grounding resistance is small and it is generally easy to meet the design requirements. In the design, it should be noted that a ground connection plate should be reserved in an appropriate outdoor location. For the practice, reference can be made to the National Standard Atlas “Earthing Device Installation†(03D501-4). In this way, when the grounding resistance value does not meet the requirements, the construction unit can conveniently connect the artificial grounding body and test the grounding resistance value, which should be reflected in the design drawings.
In addition, in the design drawings, it can not be generalized and talk about "the use of building steel bar as a natural grounding body." It has already been mentioned that the steel structure buildings need to be embedded with anchor bolts during the foundation construction, and the spacers can be connected with the steel columns. Notice: There is no electrical connection between the embedded grounding bolt itself and the foundation steel! Therefore, the civil steel construction and the round steel can be used for reliable welding of the foundation steel and the grounding bolt. Therefore, please refer to the National Standard Atlas for the use of buildings. Metal body for lightning protection and grounding device installation" (03D501-3) 17 pages. In this way, lightning currents have complete discharge channels from the air receptor to the down conductor to the grounding device. This is not enough. We should also use a short steel bar and a basic steel bar for reliable welding, and lead out of the foundation for the connection of the grounding ring network, in order to reduce the grounding resistance of the natural grounding body and to implement an effective equipotential bonding. This point is particularly important for steel structures with independent foundations, so it is necessary to clarify them in the design drawings.
If the particularity of the grounding device of the steel structure building is neglected, that is, the fact that the basic steel bar and the grounding bolt itself are not electrically connected, the consequence is that the entire building does not have a reliable grounding grid. The remedial measures taken are to use 40X4 galvanized flat steel for equipotential ring network. When galvanized flat steel is passed through the steel column, reliable welding should be performed with the underside of the column foot plate. In this way, the galvanized flat steel acts as a grounding electrode and grounding wire. Dual role.
In addition to the equipotential grounding ring network laid along the periphery of the building for one week, a pressure equalizing grid should be set across the span in the building to not only reduce the step voltage and protect personal safety, but also help the industrial plant production equipment to implement equipotential on-site. Coupling shortens the length of the equipotential bonding line.
The above is a summary of measures to prevent direct lightning strikes on steel structures. The conclusion is that the roof sandwich panel (or profiled steel plate) of a steel structure building with a thickness of 0.5 mm can be used as a lightning receptor, using the steel column as a down conductor, using the basic steel bar as a natural grounding body and passing through the galvanized flat steel. Connect to a reliable equipotential ground ring network.
For more information on the lightning protection of steel structures, please visit Zhengzhou Leidi Electronic Engineering Co., Ltd. or directly contact technical personnel!!!
| roduct name | Hardware fasteners high strength t bolt wheel studs |
| Brand | QEJ |
| Place of Origin | Hebei, China |
| Finish | Blue-White Zinc Plated or as per require |
| Material | Carbon steel,as per require |
| Non-standards | OEM is available, according to drawing or samples |
| Samples | Samples are free |
| Package | Bulk in master cartons, then on pallets, or according to customers' requirement |
| Payment | T/T, L/C,or as per require |
| Delivery | 30-40 days |
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