Application of the hottest cast-in-place concrete

2022-07-23
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Application of cast-in-place concrete hollow beamless floor technology in buildings

cast in place concrete hollow beamless floor technology is a new floor construction technology based on GBF high-strength thin-walled tubes, and is a major innovation in the field of building structures at present. It has good performance, good price and great social and economic value

gbf high-strength thin-walled pipes are divided into prestressed (span ≤ 25m) and non prestressed (span ≤ 15m) thin-walled pipes for cast-in-place perforated floor slab; According to the cross-section shape of the pipe, it can be divided into square, round, trapezoid and special-shaped. At present, this technology has been gradually used in construction practice. This new technology of cast-in-situ concrete hollow (GBF high-strength thin-walled tube) beamless floor was adopted by our company in the construction of the engineering laboratory building in the North Campus of Suzhou University

the engineering laboratory building in the North Campus of Suzhou University consists of a North University laboratory building with 12 floors above the ground and a South University teaching building with 5 floors. In the middle, there is a single storey auxiliary room and a 5-storey corridor. The plane shape is "back" and the middle is an inner courtyard. The total building area is 38159.6m2 facing severe energy and environmental challenges, including the roof of the multi-function hall on the first floor (19.9 × 17.1m) the technology of cast-in-place concrete hollow (GBF high-strength thin-walled tube) beamless floor is adopted, and the floor structure thickness is 500mm. The φ 400 round prestressed cast-in-place perforated floor slab with thin-walled pipe, 1200mm long, 50mm thick and 40% hollow ratio

during construction, the total construction load of the hollow slab shall be checked for formwork support and erected firmly. After the formwork is installed and accepted, the concealed beam, thin-wall pipe, embedded parts, holes, etc. shall be set out and positioned in detail before the next process. After the complex internal interaction between the reinforcement matrix and fiber of the concealed beam and the installation of the reinforcement at the bottom floor of the floor, the steel tape shall measure the space size of the GBF pipe actually laid. The separation points shall be scribed on the beam reinforcement with a stone pen, and the steel wire shall be used to straighten the pipe. After a column is arranged, it shall be fixed by spot welding after it is clamped with a sizing die, so as to ensure that the welding is firm, but the reinforcement cannot be burned. In order to ensure that the GBF high-strength thin-walled pipe does not float during the concrete pouring process, 12 iron wires are required to be buckled at the intersection of the bottom reinforcement every 1000mm and anchored on the steel pipe through the formwork. In particular, it should be noted during construction that the GBF pipe should be discharged by comprehensively considering the reserved hole position of the floor, and the principle of less cutting off the main reinforcement of the plate at the GBF pipe; The on-site formwork hardness tester must be arched, and the arched range is 3/1000 of the long span; At the same time, the slump of the concrete shall not be greater than 14cm. After the concrete is poured, it shall be covered with film. After 24 hours, it shall be watered for curing every 4 hours. The formwork can be removed only after the age reaches 28 days and the concrete strength reaches 100%; It is not allowed to open holes on the slab surface afterwards. When installing expansion bolts at the bottom of the slab, the reinforcement shall be avoided and shall not be interrupted

from the actual application effect, compared with the general beam slab structure system, the cast-in-place concrete hollow beamless floor technology can reduce the cost of reinforced concrete by 5%, the loss of formwork by 50%, the decoration cost by 10%-15% and the comprehensive cost by about 10%. At the same time, the construction is convenient. Using this technology can directly reduce the workload of formwork erection and removal, and shorten the construction period by nearly 1/3. From the use function, compared with the ordinary frame structure, this technology makes the space more open and beautiful, without column caps and protruding parts, and realizes the real flat plate. At the same time, the hollow floor has large rigidity, small deformation and good seismic performance. At the same time, the sound insulation effect is excellent. The closed cavity technology of the floor greatly reduces the transmission of noise, overcomes the impact noise interference between the upper and lower floors, and improves the sound insulation effect of the floor by decibels. Similarly, the closed cavity structure reduces the heat transfer, significantly improves the heat insulation and thermal insulation performance, and greatly reduces the cost of air conditioning for buildings with air conditioning

due to the use of cast-in-place concrete hollow beamless floor technology in the multifunctional hall project of Suzhou University, the direct economic benefit of 32000 yuan has been obtained. At the same time, the gb/t 6395 ⑵ 000 experimental method for decadent crack growth rate of metal materials has also obtained extensive social benefits. It can be seen that the cast-in-place concrete hollow beamless floor technology has a good development prospect. It is a new technology integrating aesthetics, economy and practicality, which is worthy of reference and promotion

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