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With the continuous development of science and technology, the shape and structure of steel structures are becoming more and more complex, which brings new challenges to the design and construction of steel structures. Such as "Bird's Nest", "Water Cube", as well as influential steel structure projects such as the National Grand Theatre, Guangzhou TV Tower, and Famen Temple, not only innovating and developing in design, but also in steel structure installation technology. New achievements have been made. Many mature and advanced process methods have gradually become the construction method, which has promoted the development of the steel structure industry.
Due to market reasons, steel structure installation accidents and violations have occurred from time to time, causing unnecessary economic losses and social impacts. In order to further improve the overall level of steel structure construction and promote the development of the industry, in addition to strengthening construction site management, steel structure construction should also carry out research and summary in construction organization design, technical measures and other aspects; vigorously promote new technologies and new processes; Choose advanced, reliable and economical construction solutions.
The basic principle of the LED display steel structure lifting scheme
1. Policy: Based on the drawings, with the norms as the guideline, strictly implement the relevant national safety production regulations.
2. Reliability: Adhere to safety first, ensure the feasibility of the implementation of the program, and increase its reliability. Regardless of the method used, first consider whether the program has successful precedents and supporting equipment, otherwise it must be demonstrated. According to the structural characteristics, the construction check is carried out to prove the stability of the structure of the method during the construction phase, and whether the stress and deformation of the rod meet the requirements. Whether the mechanical equipment used can meet the installation requirements. Whether the construction site conditions are met, such as whether the civil construction environment and surrounding structures restrict the implementation of the program.
3. Advancement: With the development of science and technology, new technologies, new technologies and new equipment in the field of structural installation are emerging one after another. For example, the large-tonnage cranes have come out, and the computer's synchronous control of overall lifting and slipping technology has added a new chapter to structural installation. Especially for large steel structure projects, when the site conditions and structural forms allow, new technologies and processes should be promoted and applied; the amount of work at height should be reduced as much as possible, and the installation efficiency of steel structures should be continuously improved.
4. Economical: A good installation plan should be easy to use, proper measures, high efficiency, low construction cost, wide application range, and can withstand review and test. Therefore, we must adhere to the principle of program comparison, conduct technical and economic analysis, and choose a program with short construction period and low cost.
Applicable conditions for LED display steel structure lifting scheme
Due to the inconsistency of architectural shapes and structural forms, the construction site conditions vary widely. It can be said that no method or scheme is applicable to any steel structure project installation, so each installation method has its own support conditions.
The commonly used installation methods for the grid structure are: high-altitude bulk method, strip-and-block installation method, structural slip method, support frame slip method, integral lifting method, and overall lifting method.
1. Consider the process method: understand the characteristics of structural form, structural weight, installation height, span, etc., and use mature and advanced installation techniques as much as possible in combination with the actual situation on site.
2, according to the lifting equipment considerations: first select the own equipment, make full use of the on-site lifting equipment, and secondly rent nearby. General situation: when the number of components is small, more choices are used for truck cranes; for portal frame hoisting, most small and medium-sized truck cranes are used; when the installation period is longer, the installation height and the radius of gyration are larger, the crawler cranes are more economical than the truck cranes; The hoisting and sliding are mostly hydraulic synchronous lifting (pushing); the middle and high-rise steel structures are generally installed with tower cranes; the ordinary bridge installations mostly use gantry cranes and bridge erecting machines.
3, flip-chip construction: flip-chip method is a special installation process first and then down, it is suitable for structures with high aspect ratio, such as steel towers, masts and other structures. In the case where the conventional crane is difficult to approach the hoisting, the flip method is generally used. When adopting this method, it is necessary to consider the overall stability of the structure during installation and the stability of the equipment itself, and it is necessary to have reliable support and stability measures. Structural slip method - The structural slip method has been developed to use hydraulic thrusters and computer synchronous control technology, which is a step further than the previous grid slip method. Its applicable conditions are as follows: First, due to the limitation of the site conditions, the crane and the support frame cannot be installed inside the bridge; secondly, the structural support conditions are favorable for laying the slip track; third, the strength and structure of the slip unit structure determined by calculation The stiffness meets the requirements; fourth, understand the structural support form and fixing method; fifth, the longer the longitudinal slip path, the higher the efficiency. Support frame slip method - its applicable conditions are occupied by the cross-inner site, low installation height, large structural area or long longitudinal length. First, when the installation height is below 15 meters, the ordinary fastener-type steel pipe scaffold or the bowl-type scaffold can be used as the support frame. Secondly, when the frame body is high and the bearing capacity is large, the steel support frame should be selected. Regardless of the solution, in addition to the requirements of the specification, the horizontal dynamic load should be considered in the design calculation, and large diagonal braces should be added if necessary to improve the overall stability.
4. Overall improvement method: The overall improvement method currently uses computer synchronous control and hydraulic lifting equipment developed by Tongji University. This process gradually replaces the through-heart type mobile lifting and jack lifting scheme, and its equipment is light and advanced. Its applicable conditions are: first, occupying the in-situ site; second, the installation height is higher; third, the component is heavier; fourth, limited to vertical lifting, not horizontal displacement. That is, the higher the installation height, the heavier the lifting weight and the better the effect.
5, soil method hoisting: soil hoisting is the use of unicorn bar, herringbone frame, reeling machine, pulley block, etc. as lifting equipment for structural lifting, it is suitable for heavy components, small number, high installation height of the project. Due to the increasing number of large-tonnage lifting equipment and advanced installation processes, there are fewer and fewer hoisting methods.
6. Rotation method construction: This method is mainly used for bridge installation. Due to the influence of railway, highway traffic, and special environment such as Shanchuan River Ditch, when other bridging methods are limited, the rotating method is often used.
7. Overall lifting method: It is basically similar to the overall lifting method, except that the lifting equipment is different, suitable for small and medium-sized structure installation. In the early days, a number of monopod or herringbone frames, hoists, pulley blocks and cable systems were used for large-tonnage hoisting. At present, due to the large number of large-tonnage cranes, small and medium-sized projects are selected for installation in a centralized manner.