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2024-07-09Overview of prefabricated steel construction
1.1 Basic composition of prefabricated steel structure building
Prefabricated steel structure building by the structure system, equipment and pipe space frame system, internal system, peripheral protection system integrated building; The structural system mainly takes steel members as the main skeleton, which are transported to the construction site for assembly and hoisting after processing in the factory. The components are connected by high-strength bolt connection, bolt connection and welding.
1.2 Characteristics of prefabricated steel structures
(1)Steel components can be produced in the processing plant, such as blanking, drilling, assembly, welding, ultrasonic flaw detection, sand blasting, rust removal, painting and other processes, components can be directly assembled and installed after production to the construction site, convenient and fast, greatly improving the construction speed. For example, when the novel coronavirus epidemic broke out in early 2020, the “Huoshenshan” Hospital and “Leishenshan” Hospital in Wuhan adopted the prefabricated construction technology, which was completed within 10 days from the start of construction to the delivery of the hospital.
(2) The main components of the building components are processed in the factory. According to the construction drawings, BIM technology is adopted to build 3D models or sample turning models. Equipped with advanced equipment for production, material consumption can be reduced and the utilization rate of materials can be greatly improved. On-site cast-in-situ work to reduce health and not disturbing the public, farewell to the “gray Meng” construction site.
(3) After the components are assembled on site, they are hoisted and installed by lifting equipment. The components of the prefabricated steel structure are connected with high-strength bolts and anchors. The bolt connection is not required to be painted on site, and the painting is carried out in the factory.
1.3 Advantages of prefabricated steel construction
(1)Steel structure is a natural prefabricated steel structure building, which has the characteristics of green building. After careful design of the prefabricated steel structure building has the following advantages: light silt weight, high bearing capacity: steel structure used by the material has the characteristics of light and high strength, low steel, low cost. In the realization of mechanization and professional production, shorten the construction period: component factory processing, installation site no or a small number of cast-in-place nodes, speed up the construction progress, improve the quality of the project. The arrangement of the vase space is flexible: the section of the beam column is smaller, and more use area can be obtained. Elm windproof seismic, excellent quality: steel is elastic deformation material, its good ductility, high strength characteristics with strong elasticity and windproof seismic resistance. Yu environmental protection beautiful, sustainable development: plastic modeling, insulation board as the enclosure structure instead of cement, sand non-renewable resources, more green environmental protection; The material can be disassembled and recycled. Modern function, sound insulation effect is very good: wall system, ceiling system with Europine board, extruded board, thermal insulation rock wool, with waterproof, moisture-proof, fire prevention, high temperature resistance, sound insulation effect.
(2)Bill of quantities valuation mode of construction engineering cost by the division of the project cost, measures of project cost, non-competitive fee, other project fees, taxes, including the division of the project cost of the quota labor fee, quota machinery fee, comprehensive fee; Non-competitive expenses include safety construction expenses, environmental protection expenses, civilized construction expenses, and temporary facility expenses. The cost of the subdivision project is the main part of the construction cost and the calculation basis of the cost of the project. How is it applied in practical engineering? The following takes the compilation of the maximum bid limit price of a project as an example to explain the composition of the construction cost of prefabricated steel structure:
(3)A beverage production base engineering beverage warehouse, the main structure is steel structure. Solid belly steel column 86.4 tons, steel beam 190.9 tons, floor bearing plate 206.7 square meters, steel wall panel 2874 square meters, roof color plate 14960 square meters, pull, stay bar, brace, corner support 19.4 tons, tie rod, roof support, horizontal support 22.9 tons, roof purlin 122.8 tons, wall purlin 23.7 tons, steel ladder 2.1 tons, 6.23 tons of steel gutter, 0.83 tons of scattered steel components, 2540 sets of high-strength bolts M20, 7632 sets of bolts with a Φ16*100, 17,860 square meters of metal components brush fireproof paint, the project discharge fee of 1000 yuan, the general contract service fee of 30000 Yuan, According to the above, according to “construction engineering bill of quantities valuation code” (GB50500-2013), 2018 edition of “Anhui Province construction engineering valuation basis”, “prefabricated steel structure building technical standards” GB/ T512-2016, “steel structure design code”, “steel structure engineering construction quality acceptance code” GB50017-2003, GB 50205-2001, “Prefabricated Building Engineering Load Reduction Quota” TY01-01 (01) -2016 and other relevant materials.
- Cost control measures for prefabricated steel structure construction
The cost of prefabricated steel structure is mainly related to the amount of steel. There are the following ways to reduce the cost of steel:
(1) Select professional steel structure designers, reduce the amount of steel and reduce the cost under the premise of ensuring the quality, so as to maximize the cost performance. Steel varieties and material selection, in view of more steel varieties, the form of the design component is more. Such as: steel column can be designed into solid belly steel column, hollow steel column, steel frame, steel pipe column, solid belly steel column usually choose hot rolled steel or welded steel column; The steel beam form can be designed to be variable section or equal section; The material can be ordinary carbon structural steel Q235 or low alloy structural steel Q355, etc., usually the design of low alloy high strength structural steel, because low alloy high strength structural steel has comprehensive properties such as light, high strength, impact resistance, corrosion resistance, can save steel, high economic benefit.
(2)The varieties and brands of different materials are highly differentiated in price, so we should try our best to purchase optimized and selected materials under the condition of ensuring quality and function. For example, the floor plate is only used as a permanent template, and the galvanized thickness and refractory time limit are not high. Ordinary galvanized pressed steel plate can be purchased, and the procurement cost is relatively low; If the floor bearing plate is not only used as a template in the construction phase, but also used as a tensile steel bar in the structure, the galvanized thickness and fire resistance time are required to be higher. When designing the floor bearing plate, the service life of the floor bearing plate and the service life of the main structure should be considered, so the floor bearing plate needs to purchase hot dip galvanized laminated steel plate with good comprehensive performance.
(3)Do a good job in the detailed design of steel structure. Usually, there are node samples in the steel structure design drawing, but no parts processing drawing. Detailed design personnel deepen the design according to the actual situation of the project, processing plant conditions, transportation conditions and other professional requirements. Use BIM technology to build 3D models or use computer sample drawing, provide parts processing drawings and component lists; According to the list of components, the amount of raw materials can be accurately measured to avoid the waste phenomenon of purchasing more steel or the repeated procurement of less steel, increasing the procurement cost, and fully minimizing the cost of material procurement.
(4) To purchase materials and equipment, at least three inquiries should be made to determine the optimal supplier, so as to directly purchase materials from manufacturers in bulk, reduce intermediary agents and reduce procurement costs.
(5) Set the optimal ordering point quantity of materials, reduce storage costs, limited material acquisition during construction, reduce material waste, so as to reduce the cost.
(6) Do a good job of material acceptance, quality and quantity inspection. Try to complete the quality acceptance at the origin of raw materials or semi-finished products to reduce the scrap rate of materials.
(7) Do a good job of material measurement, complete the work, clean the site, reasonable recycling, reduce the consumption of raw materials.
