Construction method of hoisting bridge engineering

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Construction method of hoisting bridge works with crane (3)

4 quality and safety measures

during the transportation of precast beams from the stacking site to the installation site, it must be noted that the support positions of precast beams are symmetrical and consistent, and they must be stabilized by diagonal braces or brackets; And steel wire rope shall be used to bind the beam body firmly to the flat car transporting the beam to prevent it from toppling and causing accidents; The length of the carriage of the flatbed trailer should meet the distance requirements between the support points. The components should be placed evenly when loading, so that the vehicle can bear evenly, and the support points should be padded with gunny bags or wooden wedges; A movable turntable shall be added to the beam body at the support to avoid damaging the components when turning. When transporting the beam and turning, it shall be commanded by a specially assigned person and operated carefully

quality problems that should be paid attention to in crane hoisting: before hoisting, a comprehensive quality inspection should be carried out on the precast beam, and the precast beam with defects and deformation during shipping should be corrected and treated to meet the requirements before it can be used; If there is no rule, can it be said that the strength and internal stress of the precast beam with the lifting point be considered when hoisting, so as to avoid deformation and damage of the precast beam. If the lifting point of the precast beam cannot be determined, it should be reported to the designer for approval before hoisting; When the precast beam is in place, a special person must be assigned to align and position to ensure the installation quality; When the precast beam is placed horizontally, its strength is poor. During hoisting, pay attention to the uniform distribution of lifting points to avoid the deformation of the precast beam. Quality requirements for precast beam hoisting: the beam body shall not be twisted and damaged during hoisting; The installation of the beam must be stable, and the fulcrum must be in close contact and stable; Temporary stabilization measures must be taken after the hoisting of precast beams; The expansion joints must be connected with all seamless steel pipes with wall thickness less than 1.2mm, and shall not be blocked or deformed; The movable bearing must be lubricated according to the design requirements; The allowable deviation of beam installation shall meet the requirements of construction specifications. The binding of the beam body is an important guarantee for the smooth and safe transportation and hoisting of the beam. During construction, attention should be paid to: the beam body should be bound firmly, and the smaller beam body can be bound at two points. As far as possible, the force at the two points should be uniform and consistent. The binding point and the center of gravity of the component should be symmetrical with each other, and the center of the binding point should be aligned with the center of gravity of the component and higher than the center of gravity of the component, so that the component can be lifted smoothly and will not overturn, causing accidents. When binding the beam, gunny bags, wooden wedges and anti-skid padding should be laid between the sling and the beam to avoid wearing the sling or pinching the beam. The models and specifications of slings, snap rings, rope buckles and beam body reserved lifting rings used for binding and lifting are determined through calculation, and the safety load regulations are strictly controlled during construction

safety issues that should be paid attention to: crane drivers and welders must receive special training and work with certificates; When commanding the operation, the signal should be unified, clear, correct and timely; Except for the "stop" signal sent by anyone, the crane driver only accepts the unified command of the commander on duty; It is strictly forbidden to enter the hoisting area without operators, and the staff entering the site must wear safety helmets; Work at heights must wear safety belts with additional resources, and the safety belts should be hung in a firm and reliable place; High altitude workers are not allowed to wear hard soled shoes, plastic shoes and slippers; No one is allowed to stand and pass under the jib and within the rotation range of the lifting platform; Personnel working at heights shall take the escalator, and shall not use lifting equipment to lift personnel. Personnel who are not troubleshooting are not allowed to climb the jib; Check the road before operation. If soft ground subsidence is found, take measures before construction; There must be an index rope for lifting the precast beam. The precast beam that has been lifted and tested for 5 test pieces is not allowed to stop in the air for a long time. If the operation must be suspended, the precast beam should be put back to the ground; There must be sufficient lighting for hoisting or transporting precast beams at night; Operations shall be suspended in strong winds, storms and foggy weather above level 6, and all personnel working at heights shall go down to the ground; There shall be no inflammables under electric welding and gas cutting, and special personnel shall be assigned to check the fire prevention. Acetylene tanks and oxygen cylinders shall be placed in a safe place. The wires of electric welding machines shall not touch steel wires and cables to prevent accidents; The aerial work platform must be equipped with guardrails, and the height of the handrails should not be less than 1.2m; It is strictly forbidden to eliminate the computer safety oath system of crane force distance detector during hoisting; "Five no hoisting" shall be achieved in hoisting operation (no hoisting if the command gesture or signal is unclear, no hoisting if the weight and center of gravity are unclear, no hoisting if overloaded, no hoisting if the line of sight is unclear, no hoisting if the binding is not firm or the hook method is wrong); During the construction of the project in rainy season, it is necessary to take full measures to prevent rain, lightning, skid and electricity leakage, so as to ensure safe production

safety measures: strictly implement unified command on the construction site, and unify all kinds of command gestures, flags and whistles; The operators shall have a clear division of labor and position determination, and non construction operators shall not enter the site; All machines, tools and equipment shall be fully loaded for trial operation, overload operation is not allowed, and the operation shall be strictly in accordance with the operating procedures; If the wind force is greater than grade 6 or there is rainstorm and fog, installation is strictly prohibited; During the lifting process, it is strictly forbidden to stand under the boom and lifting parts. Operators must wear safety helmets and work shoes, and safety belts must be worn for high-altitude operations

5 Conclusion

the construction method of hoisting precast beams with cranes has the advantages of simple construction machines and tools, easy operation, low cost, short construction period, easy quality and safety assurance, etc. However, due to the limitation of the lifting capacity of the crane, it is difficult to hoist the precast beam with large weight and length. Therefore, the crane hoisting method is suitable for small and medium-sized bridges with small span. Through the construction practice of this project, it can be seen that crane hoisting is a better construction method for small and medium-sized bridge projects with open construction site and convenient road traffic

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