The seismic support code for "Seismic Design Code for Construction Mechanical and Electrical Engineering" GB50981-2014 has been in place for several years now. On December 28, 2018, the National Standardization Committee also officially released the second industry national standard GB/T 37267-2018 "General Technical Conditions for Building Seismic Support Hanging," but despite this, I still feel there are many unclear aspects. Today, the editor has compiled the issues that everyone is concerned about:
1. What exactly is a seismic bracket?
Definition: A seismic support facility firmly connected to the building structure and primarily loaded with seismic force. It consists of an anchor, reinforced boom, seismic connection member, and seismic diagonal brace.
2. Which systems need to be equipped with seismic supports?
According to the relevant standards and regulations of the seismic design specifications for construction mechanical and electrical engineering:
Article 1.0.4 (Strength Strategy) stipulates that construction mechanical and electrical engineering projects in areas with seismic design intensity of 6 degrees or above must undergo seismic design.
Article 3.1.6 specifies the content that needs to be seismically reinforced: â‘ Equipment with a gravity greater than 1.8kN in suspended pipelines; â‘¡ Domestic water supply and fire protection pipeline systems with DN65 or above; â‘¢ Air duct systems with a rectangular cross-sectional area greater than or equal to 0.38 square meters and circular air duct systems with a circular diameter greater than or equal to 0.7 meters; â‘£ Electrical conduits with an inner diameter greater than or equal to 60mm and cable ladder frames, cable duct boxes, and bus ducts with a gravity greater than or equal to 150N/m.
Article 3.1.8 states that building electromechanical engineering pipelines passing through the seismic insulation layer should adopt flexible connections or other methods, and seismic supports should be installed on both sides of the seismic insulation layer.
Article 4.1.2.1 specifies that when the straight length of water supply and drainage pipes in high-rise buildings in 8 degrees and 9 degrees exceeds 50 meters, anti-vibration measures should be taken; when the straight length exceeds 100 meters, anti-vibration measures should be taken.
Article 4.1.2.3 specifies that when indoor water supply, hot water, and horizontal pipes with diameters greater than or equal to DN65 need to be welded, when they are fixed with hangers, brackets or supports, seismic supports should be installed as required.
Article 5.1.2.4 specifies that the pipelines in boiler rooms, refrigeration machine rooms, and heat exchange stations should have reliable lateral and longitudinal seismic supports. For multiple pipelines, a portal seismic support frame or a single pipe support frame with a pipe diameter of more than or equal to 300mm should be used.
Article 5.1.3.3 specifies that air ducts with a rectangular cross-sectional area greater than or equal to 0.38 square meters and a circular diameter greater than or equal to 0.70 meters can use a seismic support hanger.
Article 5.1.4 (Strong Article) specifies that smoke exhaust ducts, accident ventilation ducts, and related equipment should use seismic support and suspension frames.
Article 5.1.5.4 specifies that air conditioning units, fans, and other equipment with a gravity greater than 1.8kN should not be lifted and installed. When lifting is necessary, it should be avoided above the positions of personnel activities and evacuation passages, but seismic support hangers should be installed.
Article 6.1.1 specifies that gas pipelines with an inner diameter greater than or equal to 25mm should be designed for earthquake resistance, and the installation of pipeline earthquake resistance supports and suspension frames should comply with regulations.
Article 6.2.8 specifies that in buildings with a building height greater than 50m, gas pipelines should be equipped with seismic supports at appropriate intervals according to the building's seismic requirements.
Article 7.1.2 specifies that electrical conduits with an inner diameter of not less than 60mm and cable ladder frames, cable duct boxes, and bus ducts with a gravity of not less than 150N/m should be seismically protected.
3. What are the materials of the seismic brackets themselves? What are the advantages and disadvantages?
Q235B is generally used on the market, including cold galvanizing (electroplating), hot-dip galvanizing, and dacro. The thickness of the cold galvanized layer is relatively thin, while the thickness of the hot galvanized layer is relatively thick. Currently, most brackets are hot-dip galvanized (with a galvanized layer thickness generally around 70~80μm). The lifespan of hot-dip galvanized in a general environment can exceed 30 years. The neutral salt spray test is between 300-500 hours, and its price is much higher than cold galvanizing, which also has certain environmental pollution. Dacro is a zinc-chromium coating process with a film thickness of only 4-8μm, but its rustproof effect is 5-10 times that of traditional electro-galvanized galvanized, hot zinc, or paint. The neutral salt spray test is more than 1,200 hours, and it has no pollution to the environment. Fanzu's VZ-MASK super anti-corrosion coating has super anti-corrosion properties, and its rustproof effect is more than 10-20 times that of traditional electro-galvanizing or coating methods. The support hanger treated with the Musk coating process can withstand neutral salt spray tests for more than 3,000 hours without red rust, and its service life can reach more than 100 years, being pollution-free to the environment.
4. How to install seismic brackets?
The seismic support and hanger system consists of C-shaped finished channel steel, special seismic connectors, pipe clamps, and rear-end expansion anchor bolts for cracked concrete. The seismic connectors and channel steel can be mechanically connected to the size and height of the seismic support and hanger. The seismic support and hanger should not be welded on-site, and the anchor bolts should be reliably connected to the original concrete structure. The steel structure is fixed by pre-assembled bolts or beam clamping clamps.
Lateral seismic support hangers are used to resist the action of lateral horizontal seismic forces.
Longitudinal seismic support hangers are used to resist longitudinal horizontal seismic forces.
Single-pipe (rod) seismic support hangers are seismic support hangers consisting of a load-bearing hanger and a seismic diagonal brace.
5. Will seismic supports affect net height? How to deepen cooperation and optimize projects on-site?
Looking at the installation diagram above, everyone feels that the height of the pipeline layout will definitely affect the comprehensive pipeline. If the on-site construction units act independently, the net height in the later stage will not be controlled, so early seismic support must be deepened and optimized, especially for the comprehensive pipeline, comprehensive seismic support should be used.
How to cooperate on-site and when will the seismic support deepening be launched? Currently, many sections are placed under the general contractor of electromechanical and electrical conscription, or in the sections of professional subcontracting. The general contractor of electromechanical and electrical conscription requires the unified arrangement of comprehensive pipelines and considers the deepening of seismic support.
Given that everyone does not fully understand the design concepts of seismic brackets and particularly lacks strict review standards, it is impossible for Party A, consultants, and design institutes to professionally judge whether the deepening design is reasonable based solely on the calculation book. If you want to win the bid, the number of seismic supports will be reduced; and if you deepen the bid after winning the bid, you need to add more supports, etc. How to control this? Personally, I think we can discuss a model of reference intelligent design. Seismic support is divided into design standards and supply sections. During the construction drawing design stage, seismic support design will intervene and cooperate with the construction drawings to optimize the pipeline, so that the net height can be actively controlled in the early stage.
6. How to check the correctness of design calculations? How to investigate and deal with the tricks in calculations?
As mentioned earlier, current seismic brackets are generally deepened by the manufacturer. There may be tricks in deepening, which are beneficial to them, or more or less designed. For those who are not very professional, how can you judge its basic rationality?
Generally, during bidding, the manufacturer of seismic brackets needs to have their own copyrighted professional seismic bracket calculation software. The software needs to be certified by a third-party authoritative organization to ensure the rationality and correctness of the calculation. The load value of seismic bracket accessories requires a third-party inspection report, etc.
7. How deeply have manufacturers achieved? Is there a charge for cooperation?
Before the general bid, the project quotation and preliminary design plan are provided; after winning the bid, detailed construction drawings are provided, including seismic support position diagrams, seismic support node details, seismic support material lists, seismic support calculation books, and on-site installation guidance.
Under normal circumstances, the winning bidder does not charge a fee, but the wool comes from the sheep, so the quotation should be comprehensively considered.
8. How to distinguish between products that are mixed in the market?
Due to the short execution time required by seismic brackets, developers and consulting companies do not have a clear brand library. In the early stage, some brands from standardized compilation units were mainly used, which also led to the extremely high prices of these domestic brands. Many manufacturers in the market have seen business opportunities and have joined the production and supply of seismic brackets. How to identify products that are mixed in the market?
You can refer to the basic ideas of consultant brand inventories.
*Step: Product communication. Provide exclusive computing software, testing reports, third-party certification materials, and appropriate project cases, etc., to understand and verify the basic situation of the brand.
Step 2: Factory inspection. Understand production processes, factory management, and annual output to ensure product quality and supply capacity.
Step 3: Project inspection. Conduct on-site inspections of implemented projects to inspect on-site installation quality and on-site feedback.
Fanzu not only participated in the drafting and editing of the National Building Standard Design Drawing Collection 16D707-1 and the seismic installation industry standards of building electrical facilities, but also specially set up a new product model research and development center, a new material mechanics development center, and introduced special earthquake testing instruments and mechanical performance experimental instruments to continuously make breakthroughs and innovate, and provide you with the best support and hanger system products.
9. Which department is responsible for the acceptance of seismic brackets in various places? What is the acceptance method? Which systems should be done?
Currently, the acceptance department is a quality inspection station!
Acceptance method: Compare the design drawings with the actual installation situation on-site. Individual projects will require destructive testing. Currently, most projects actually do systems: ventilation, water supply, fire hydrants, sprinklers, and electrical systems for smoke exhaust emergencies. (Gas is generally made by gas companies).
Among them, the smoke exhaust ventilation is bold. Previously, there were projects that only did this part, but there were also feedbacks that other systems were added to the later acceptance site. The specific requirements shall be subject to local requirements.
Architecture is a business card of the city. "Safety, wisdom, and energy saving" are the direction and future of architectural design. Guangzhou Fanzu Construction Technology Co., Ltd., as a high-tech enterprise integrating the design, production, research and development, and sales of installed seismic supports and hangers, will rely on its industry's best production and R&D technology to ensure the safety of people's lives and property with its excellent product quality.
Black Bond Tile,Bond For Tile,Black Base Tile
Shandong Yahong New Materials Technology Co., Ltd , https://www.okrooftile.com