【HaiChuan Safety Discussion】Is this approach to tower crane foundations safer?

Reliability is important, but how will the tower crane foundation be removed after completion?

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It seems to be specially designed, so it should be more reliable. The construction company is very wealthy, so it can afford to use this amount of reinforced concrete.

Special Plan for the Installation of Tower Cranes I. Project Overview The residential building in **** Community is located to the southeast of ***; it has a brick-concrete structure with a total of 6 floors. The total height of the building is 19.6 meters, and the total construction area is [X] m2. II. Installation of the tower crane and required equipment 1. Placement of the tower crane’s center position: One QTZ40 tower crane (produced by ****** Co., Ltd.) is to be used for the construction work; its center position is 1.4 meters east of axis 2 and 9.314 meters north of axis D (see the diagram showing the location of the construction tower crane for details). Since a high-voltage cable runs westward across the site, only 50 meters of the tower crane’s boom is installed. 2. The foundation for the tower crane is a natural raft foundation; its dimensions are 5000×5000 meters in width and 1.40 meters in height. According to the geological report, the standard bearing capacity of the foundation soil is 230 kPa, which meets the design requirements specified by the manufacturer. For details, please refer to the foundation diagram below. 3. Equipment required for installation: (1) 1 x 45-ton truck crane. (2) 1 x 30-ton jack. (3) 1 theodolite and 1 level. (4) 1 geodetic oscillating meter. (5) 1 set of sleeve wrenches. 4. Installation requirements and sequence: In accordance with the construction requirements, the tower crane foundation is located between Building 1 and Building 2 (see the foundation plan for details). That is, the elevation of the tower crane foundation surface (–3.350 meters) is the same as the elevation of the bottom slab of the main building’s foundation; the future foundation slab can simply be placed on top of the tower crane foundation surface. The concrete used for the tower crane foundation is of grade C30. To accelerate the construction progress, the foundation for the tower crane is constructed first; the installation of the tower crane can only proceed after the concrete strength of its foundation reaches 80%. It is planned to install it at its maximum free height of 37 meters during the first installation. During installation, the reinforced standard sections are placed at the bottom of the tower body first, followed by the installation of the tower crane and the tower crown. The balance arm and the boom are assembled on the ground at the construction site before being lifted into place. The installation sequence is as follows: reinforced standard sections → outer frame → slewing bearing → tower crown → balance arm → power connection → debugging → tie-down brackets. After the entire tower has been installed, the upper standard sections can be raised into place by themselves. According to the design specifications, the first tie-down bracket is positioned 30 meters above the ground, the second one is 25 meters away from the first, and the third one is 20 meters away from the second; thereafter, an additional tie-down bracket is added every time the tower rises by 15 meters. When fixing the attached support brackets, it is necessary to adjust the tower properly; its vertical deviation should not exceed 1%, nor more than 5 cm (the verticality is checked using a theodolite and level). The key installation points and procedures are specified in the installation instructions provided by the manufacturer. 5. Once the tower crane has been installed and is operating properly after testing, it should be thoroughly inspected. The company’s Power Equipment Department and Safety Department shall organize an acceptance check, and only after approval can it be put into use.

Standard sections cannot be used as embedded footings for tower crane foundations. The bearing capacity of the pre-embedded foundation section is greater than that of the standard section, and the manufacturer has applied special treatments to it.