Key points of safety control in hanging basket construction?

1 Ordinary hanging basket is the main equipment in cantilever construction. According to the structural form, it can be divided into truss type (including flat chord unbalanced weight type, rhombic type, triangular type, bowstring type and so on). ), cable-stayed type (including triangle cable-stayed type and prestressed cable-stayed type) and steel-concrete type. At present, rhombic hanging baskets and triangular hanging baskets are mainly used in engineering. 2 Composition and design principles of hanging basket The main components of hanging basket are: main truss, suspension system, anchoring system, walking system and bottom formwork. The design principles of hanging basket: light weight, simple structure, firmness and stability, convenient moving forward and disassembling, strong reusability, small deformation after stress, etc. Sufficient space under the hanging basket can provide a larger construction surface, which is beneficial to the construction of steel formwork. 3. Safety control measures for hanging basket construction 3. 1 Organization and management measures 3. 1. 1 Hanging basket users should set up special organizations, clarify the responsibilities of institutions and personnel, be responsible for the management of all aspects of hanging basket design, installation, use and demolition, and implement the responsibility of on-site card control for key processes. 3. 1.2 The project leader is responsible for the overall organization of continuous beam construction, and with the assistance of the project technical leader, organize the project managers such as site leader and safety leader to perform their respective duties to ensure the normal implementation and work safety of the hanging basket construction process. 3.2 Design management measures 3.2. 1 Hanging basket design (including the old hanging basket reconstruction design) can be carried out in the following two ways: one is to entrust units with corresponding design qualifications and capabilities and professional hanging basket manufacturers to design, and the other is to design by units with design capabilities. For outsourcing design, when selecting a design unit, it is necessary to conduct on-the-spot investigation on the relevant qualifications and design capabilities of the design unit to ensure the intrinsic safety of equipment design. 3.2.2 Whether it is self-designed or outsourced, the detailed design drawings, calculation data and special safety scheme for crossing existing facilities and navigable rivers of the hanging basket can only be implemented after being reviewed and approved by the technical director of the hanging basket using unit. 3.2.3 The hanging basket design must be carried out in strict accordance with the relevant requirements of the current technical specifications for railway, highway or municipal bridge construction and technical specifications for steel structure design and construction. The hanging basket design document consists of three parts: design specification, design drawings and design calculation data. The design specification of the hanging basket shall include the technical indicators, structural composition and use steps of the hanging basket, as well as the specific requirements and precautions in the process of manufacturing, assembling, disassembling, preloading and hanging irrigation of the hanging basket; The design part should include the overall design and detailed design of key structures; The calculation data should include the general situation of bridge structure design, calculation conditions, load distribution and combination, strength, stiffness and stability calculation of hanging basket overall structure and key detail structure. 3.2.4 When the hanging basket construction crosses existing facilities such as roads, railways, pipelines or navigable rivers, the project should adopt measures such as enclosed hanging basket protection or setting safety protective scaffolding under the bridge according to the site construction conditions and the requirements of existing facilities or river management units, and formulate special plans to meet the safety of vehicles or ships under the bridge and ensure the safety of existing facilities under the bridge. The special plan should be strictly examined and approved, and at the same time, it should be reported to the relevant property management unit for approval, and the construction permit procedures should be handled. 3.3 Management Measures for Processing Process 3.3. 1 Hanging basket processing is entrusted to a professional manufacturer with corresponding qualifications for processing in the factory. If on-site processing is needed for special reasons, the on-site processing plant should be specially planned, and the performance of processing equipment should meet the requirements of hanging basket processing accuracy and quality. 3.3.2 The special treatment plan for hanging basket shall be compiled and reviewed by the technical director of the project. 3.3.3 During the processing of hanging basket, users should send professionals to the processing site for a long time to supervise the quality throughout the process to ensure the processing quality. 3.3.4 Hanging basket processing should form complete technical documents, including construction organization design and process plan, raw material factory certificate and material report, welding quality inspection and processing quality inspection report. 3.3.5 After the hanging basket is processed, it should be pre-assembled according to the main truss (including the walking system), bottom formwork platform, internal formwork system and external formwork system, and it can only be transported to the bridge site for installation after passing the inspection by professional and technical personnel. 3.4 Management measures for on-site installation and acceptance of hanging basket 3.4. 1 Special plan shall be prepared for on-site installation of hanging basket, which shall be implemented after being reviewed by the technical director of the project. The special scheme for on-site installation of hanging basket should include the general situation of the project, on-site operation conditions, personnel organization, general situation of hanging basket structure, selection and arrangement of hoisting machinery, installation steps and quality requirements of hanging basket, hoisting operation, aerial work and safety protection measures for existing line operation, etc. 3.4.2 Before the hanging basket is installed on site, the technical director of the project shall organize other relevant personnel to attend, and provide all personnel involved in hanging basket installation with a special plan for hanging basket installation. The technical director is responsible for the disclosure of technical contents such as the general situation of the project, site operation conditions, hanging basket structure, hoisting operation, hanging basket installation steps and quality requirements, the site director is responsible for the disclosure of construction organization and personnel requirements, the safety director is responsible for the corresponding construction safety disclosure, and the project engineering department is responsible for forming a complete disclosure record. 3.4.3 On-site installation of hanging basket shall be carried out in strict accordance with the requirements of Special Plan for On-site Installation of Hanging Basket under the guidance of technicians from the hanging basket design and processing unit and under the on-site supervision of professional technicians and full-time security personnel of the project. Operators of all special types of work installed on the hanging basket site must hold relevant certificates. 3.4.4 After the installation of hanging basket is completed, comprehensive inspection and acceptance shall be conducted. The work is organized by the technical director of the project, with the participation of the project director, site director and safety director, as well as the technical personnel of the hanging basket design and processing unit, relevant personnel of the project department and site installation personnel. Inspection and acceptance include raw material quality and arrival inspection report, welding quality, fastener connection quality, parts processing quality, hanging basket assembly quality and steel structure painting quality. Inspection data of hanging basket shall be signed by experienced personnel, and whether the quality of hanging basket meets the requirements shall be confirmed by the technical director of the project. 3.5 Control measures for hanging basket loading test 3.5. 1 A special plan must be prepared for hanging basket loading test. The hanging basket loading test scheme should include test steps, personnel organization, machine material configuration, grading load size and distribution, stress and strain observation point layout, observation method, observation frequency, theoretical value of stress and strain and safety measures. 3.5.2 Before the hanging basket loading test, the technical director of the project shall organize all personnel involved in the hanging basket installation to make disclosure of the special scheme for the hanging basket loading test. The project engineering department is responsible for forming a complete disclosure record. 3.5.3 The hanging basket loading test shall be carried out after the hanging basket installation is completed and passed the inspection and acceptance, and shall be organized by the technical director of the project and attended by the professional bridge engineer. 3.5.4 The loading test of hanging basket should simulate the actual construction state of cantilever casting of beam body as much as possible, and be carried out according to the most unfavorable working conditions of hanging basket. 3.5.5 After the hanging basket loading test is completed, a special file shall be formed to provide reference for the hanging basket loading test of similar projects in the future. 3.6 Management measures for hanging basket construction 3.6. 1 The project leader shall specify the specific work responsibilities, authorities and division of labor of management personnel and professional technicians at all levels, and arrange special management personnel and professional technicians for on-site management, including at least two professional technicians, to ensure that the hanging basket walking and anchoring operators are relatively fixed. All construction personnel should be trained and qualified before taking up their posts. 3.6.2 The technical director of the project shall organize the formulation of strict operation procedures for hanging basket construction, and make disclosure to all operators and managers at the site, and be responsible for checking the on-site implementation of the technical scheme. If it is necessary to adjust the scheme due to changes in conditions, it should be reported to the scheme approval unit in time and handled according to the reply. 3.6.3 The person in charge of project safety shall conduct daily inspection of the safety protection facilities on the bridge deck, hanging basket and under the bridge, and require immediate rectification if problems are found. If there are serious problems that directly affect the safety of operation, it is necessary to stop work and rectify. 3.6.4 The hanging basket operation area shall be provided with corresponding identification plates, clearly indicating the operation steps, construction technical requirements and safety precautions of the hanging basket. , clear the relevant inspection responsible person, formulate the inspection content table, and sign the on-site inspection content. 3.6.5 Hanging basket walking should be carried out under the command of the designated management personnel of the project. Hanging basket walking should be slow and steady, and the hanging basket walking at the two cantilever ends should be symmetrical and synchronous. Before the hanging basket walks, professional and technical personnel should check whether the hanging basket is in a safe walking state. In order to ensure the walking safety of the hanging basket, the chain should be set at the end of the hanging basket, and the limit device should be set at the front end of the hanging basket walking track. Before and during the walking of the hanging basket, professional and technical personnel should check the anchoring quality of the track to prevent anchor leakage or virtual anchor. 3.6.6 After the hanging basket is in place, it should be anchored in strict accordance with the design requirements of the hanging basket. The hanging basket should be anchored by hydraulic jack as far as possible to accurately control the tightness of each boom. After the anchoring work is completed, on-site professional and technical personnel are responsible for inspecting the key parts, and can be put into use only after confirming the complete state. 3.6.7 Beam concrete pouring can only be carried out after the hanging basket is inspected and accepted by on-site professional and technical personnel, who are responsible for checking the stress state of key structures of hanging basket during pouring. 3.6.8 When using fine-rolled threaded steel bars as hanging baskets of suspenders, the suspenders must be protected by PVC pipes or sacks. It is forbidden to use suspenders and anchors for electric welding, such as ignition, neutral wire and current path. It is necessary to strengthen the usual inspection, and the derrick damaged or with quality problems should be replaced immediately. All suspenders and anchor rods shall adopt double nuts, and the person in charge of project safety shall be responsible for daily inspection and rectification. 3.6.9 Pre-reserved holes of hanging basket anchor rod on the beam section must be accurately embedded according to the design drawings, so as to prevent leakage or excessive embedded error, and prevent the anchor rod from bending. On-site professional engineers are responsible for the quality inspection of holes and report the problems to the technical person in charge of the project for handling. Before the requirements are met, the construction shall not be continued to prevent accidents. 4 Summary 4. 1 With the popularization of hanging basket construction, the construction technology level has been continuously improved, but there are still some safety risks and quality control difficulties in hanging basket construction. First of all, we should start from the aspects of organization and management, pay attention to details, implement the responsible person, implement the system of checking and signing at different levels, rectify problems in time when they are found, and better avoid safety and quality accidents. 4.2 Pay special attention to the implementation of design, scheme, disclosure and training, first consider the essential safety control link, and then pay special attention to the implementation from disclosure training and other aspects, so that every manager and operator can clearly define the key control points of safety and quality, give full play to the collective strength, and ensure the construction safety. 4.3 Strengthen the identification and evaluation of hazard sources, formulate countermeasures and emergency plans in strict accordance with the evaluation results, and organize drills in time, which should be targeted. 4.4 Strengthen the setting and inspection of on-site protective facilities to ensure the safety of the working environment. 4.5 The key to ensure the safety of hanging basket construction is to ensure that the responsibilities of personnel at all levels are fulfilled in place, all safety measures are put in place and all links are controlled in place. As long as the above points are achieved, the hanging basket construction will be safe, stable and controllable.

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