I. Introduction to the Project Compared with developed countries, China's super-high-rise steel structure buildings started late and there are not many mature experiences to learn from. Since the reform and opening up, many "tall, big, new and sharp" modern buildings have sprung up, which has become an important symbol of the rapid development of the national economy. Steel structure is widely used in high-rise buildings, especially super-high-rise buildings, because of its advantages and characteristics such as light weight, short construction period and strong earthquake resistance. With the enterprise spirit of "Dare to be the first in the world and strive for first-class" and the courage and strength to undertake the "high, big, new and cutting-edge" project, China Construction Third Bureau aimed at this fertile soil to be reclaimed and took the lead in building the first super-high-rise steel structure in Datong at 1986 by taking advantage of the technology and equipment of large enterprises. Shenzhen Development Center Building, with a height of 165.3m, completed the construction task of the main steel structure 1 1000 tons in only 130mm month, with a maximum vertical deviation of 25mm, which improved the standard of American AISC code. Firstly, a new semi-automatic welding technology of CO2 gas shielded welding for ultra-thick steel plate is applied. After painstaking research and repeated research, it is finally successfully solved. It fills the blank of welding ultra-thick steel plate in our factory. The welding quality of the whole project 10O%% and 100% are qualified, reaching the international first-class level. The successful application of this complete set of construction technology in this project has made the installation and construction technology of super-high-rise steel structure, which started late in China, take a big step forward. Therefore, the complete set of steel structure installation technology of Shenzhen Development Center Building won the first prize of scientific and technological progress of China Construction Corporation and the third prize of national scientific and technological progress in 1988 and 1989 respectively.
Due to the great success of the installation of the super-high-rise steel structure in Shenzhen Development Center, 1987 won the bid to build the first all-steel super-high-rise building in China-the Shanghai International Trade Center Building with a height of 146.5 meters. The construction task of the main steel structure 10470 tons was completed in only 7.5 months. The verticality deviation of the main body of the steel structure is only 17mm, which improves the JASS standard of Japan. The welding 100% is qualified, and 100% is well received by the owners and all walks of life. The project won the highest award for building quality in Shanghai. "Magnolia Award" and the highest award in the national construction industry; Luban College Award. Since then, we have built Shanghai Taiping Model Hotel, New Jinqiao Building and ① Boundary Square, and other steel structure projects with high reputation in China, especially Shenzhen Wang Di Building with a height of 383.95 meters, which was capped at/kloc-0 on June 9, 1995. Our bureau completed 24,500 projects safely, with high quality and high speed in only 1 year and 12 days (more than two months ahead of the contract period). The total deviation of the verticality of the main body is 17mm outward and 25mm inward, which improves the accuracy and is only 1/3 (5 1mm outward and 76 mm inward) of the allowable error of American AISC code. The weld length is 600,000 meters (including vertical welding and oblique vertical welding, accounting for 1/7), the inspection is 100%, the qualification is 100%, and the excellent and good rate is 94%. It has created a miracle of no component falling and no casualties in the whole construction process, and it is a two-and-a-half-story 90-year "Shenzhen New Speed". Rare construction period, first-class quality and safety.
It has been highly praised by the owner, the general contractor and all walks of life.
In August last year, the installation and construction technology of super high-rise steel structure in the main building of Shenzhen Wang Di Building passed the national appraisal. Experts attending the meeting agreed that Wang Di Tower is a masterpiece of super-high-rise steel structure engineering started in China in recent ten years, which indicates that the construction technology of high-rise steel structure in China has made great progress on the basis of previous success, and the installation and construction technology of super-high-rise steel structure in Wang Di Tower has reached the domestic leading and international level.
From Shenzhen Development Center to Shanghai International Trade Center, and from Shanghai International Trade Center to Shenzhen Wang Di Building, it is a milestone in the history of the installation and development of super-high-rise steel structures in China. The construction technology from weak to strong represents a glorious course of three innings and ten years in the history of the development of super-high-rise steel structures.
Second, the super high-rise steel structure self-assembly construction technology
I have the honor to participate in the construction organization and management of three epoch-making super-high-rise steel structure projects in the history of steel structure development in China: Shenchuang Development Center Building, Shanghai International Trade Center and Shenzhen Wang Di Commercial Building, combined with the technological process and characteristics of high-rise steel structures: (component acceptance → hoisting → quality control → high-strength bolts → welding and testing → profiled steel plates and welding studs). The installation and construction technology of super high-rise steel structure is mainly embodied in the following seven aspects:
1, component mobilization, acceptance and stacking
2, tower crane selection, layout and installation
Step 3 promote
4, measurement control
Step 5 weld
6, time limit for a project and quality control
7. Safe construction
Based on the construction of the super-high-rise steel structure in the main building of Shenzhen Wang Di Mansion, we will exchange our experiences with experts and colleagues on these issues.
1, component mobilization, acceptance and stacking
Narrow site and poor construction conditions are common difficulties in current construction projects. For high-rise steel structure engineering, under the condition of relatively tight construction period, the requirements for component yard are higher and stricter. If this problem is not handled well, it will definitely have a serious impact on hoisting and the whole project construction. At the initial stage of the construction of Wang Di Building, due to the large number of component yards and the large number of steel structures entering the site, 2-3 floors need to be stacked. If there is no careful mobilization plan, it will inevitably lead to confusion in the mobilization order of on-site components. In this way, the needed parts are pressed below and the unused parts are placed above, which not only hinders the acceptance work, but also leads to a lot of repetitive work such as turning over materials and finding materials. Later, on the basis of strengthening site management and component mobilization plan, the yard layout and stacking order of components were emphatically studied. Besides carefully arranging the entry components according to the hoisting sequence and the characteristics of yard planning, we also arrange the entry components in an orderly manner, which not only ensures the normal acceptance work, but also creates good external conditions for hoisting.
Ensuring the acceptance of components is our previous experience in the construction of super high-rise steel structures. There are 65,438+04,860 steel members in the main building of Shenzhen Wang Di Building. In the process of manufacturing and transportation, problems of one kind or another will inevitably occur. If these problems are not eliminated on the ground, hanging on it will definitely increase the installation progress and have a serious impact on the quality control of the whole job.
2, tower crane selection, layout and installation
Tower crane is the core equipment in the construction of super high-rise steel structure. Its selection and layout should be comprehensively considered according to the layout of the building, site conditions and the weight of the steel structure, and ensure the safety, convenience and reliability of installation and disassembly.
According to the geographical location, structural shape and a large number of special components of Wang Di Building (such as the large A-shaped inclined column with a weight of 47.5t and the box column with a cross section of 37 t), we chose two Australian M440D large internal climbing tower cranes, which were arranged in the core wall # 1 and #5 hoistways, which not only satisfied the vertical transportation of all components, but also created conditions for the double-machine lifting of a large number of overweight, super-high and eccentric components.
M440 internal climbing tower crane is used for the first time in China, and there is not much mature experience for reference. In the construction, we changed the traditional climbing scheme of mutual hoisting of tower cranes, and adopted a set of auxiliary system of "winch+shoulder pole", which solved the climbing problem of two tower cranes, greatly improved the use efficiency of tower cranes, accelerated the lifting speed, and played a decisive role in advancing the construction period; However, the demolition of large-scale internal climbing tower crane is a work with complex technology and difficult construction. We adopted the method of "taking the big ones as the small ones and breaking the whole into parts", which solved the demolition problem of the large internal climbing tower crane, which was regarded as a difficult problem in China, and provided an example for similar projects in China to use the internal climbing tower crane.
Step 3 promote
Hoisting is the leading process of steel structure construction, and the speed and quality of hoisting play a vital role in the whole project. In the construction of the main super-high-rise steel structure of Shenzhen Wang Di Mansion, the technology of "regional hoisting" and "multiple hoisting by one machine" was adopted to solve the contradiction of tight construction period and large engineering quantity.
Using "double cranes" and gantry, not only the hoisting problem of a large "A" cable-stayed crane with a height of 53.79m, a length of 63.20m, a span of 32. 1m and a weight of 232t was solved, but also two cranes in the main workshop with a length of 85.6 1m and a weight of 85.5/kloc-0 were solved.
4, measurement control
In the construction of super high-rise steel structure, the deviation of verticality, axis and elevation is an important index to measure the engineering quality. As the control stage of engineering quality, measurement must provide basis for construction inspection.
From the construction process of steel structure, it can be seen that each process is interrelated and restricted, and the choice of measurement control method directly affects the progress and measurement of the project. At the initial stage of steel structure construction of Wang Di Mansion in Shenzhen, the survey supervision engineer of the general contractor put forward the method of "integral correction", that is, after the column installation is completed, it will be tracked and corrected. When the beam cannot be installed, it will be temporarily hoisted or placed on it, and the integral correction will be carried out after the whole column, beam and diagonal brace are all installed. Because there are some errors in the fabrication of components and the construction of the core, this correction method is very blind, which not only leads to a large number of secondary installations, but also the structure itself has a certain stiffness after the installation of the column beam, which greatly increases the difficulty of correction. Later, we changed the "integral correction" to "tracking correction" in time, that is, the column was initially corrected before the column-beam frame was formed and corrected in time, which greatly reduced the difficulty of correction, and the correction time of each section was shortened from about 10d to 2-3d, which could be handed over to the next working procedure, thus achieving the goal of a virtuous cycle between regional construction procedures.
In order to make the steel structure construction of the main building of Wang Di Tower reach the first-class level in the world, the project has also formulated stricter quality control indicators than AISC standards: 25mm inward and 20mm outward, and explored a new method of "double system review control" by laser direct discussion, which has played a very important role in ensuring the realization of the project quality control objectives.
Step 5 weld
High-rise steel structure has the characteristics of tight construction period, complex structure, large engineering quantity and high quality requirements. As an important process of steel structure construction, the selection of welding technology and welding level have great influence on the completion of the project "safety, high quality and high speed".
Because of its rare height-width ratio of 1: 9, a large number of diagonal braces and large "A"-shaped diagonal columns are used in the design of Shenzhen Wang Di Building. Among the total 600,000 m extension joints, vertical welding and oblique welding are about 86,000 m long, with 848 joints, accounting for 1/7 of the total welding amount. This kind of structure is not only in the important parts of the structure, but also in the outward, oblique and suspended parts, so it is difficult to operate safely and protect the construction. In particular, the contradiction between the relatively urgent construction period and the huge amount of welding makes us face a severe test from the beginning. Although in the construction of steel structures such as Shenzhen Development Center Building and Shanghai World Trade Center Building, we adopt the new technology of CO2 semi-automatic welding applied to vertical welding, oblique vertical welding and fillet welding, which can fundamentally solve the needs of welding construction.
After the process is selected, it is urgent to work out a set of feasible CO2 gas shielded semi-automatic welding process and method suitable for the characteristics of this project. Driven by the project team, the welding QC team made a difficult attempt and carried out a series of fruitful work.
First of all, we have determined the target of tackling key problems, found out the reasons that affect the quality by using correlation diagram, and made a series of analysis by using 0 1 analysis method, and found out the corresponding countermeasures for these problems; An effective quality assurance system has been established and a perfect process instruction has been formulated. After repeated experiments, the process parameters of vertical welding and oblique vertical welding are determined. A set of operating essentials of "pushing and dragging" has been formed by repeatedly exploring the extension length of welding wire, the cleaning of weld layer and the welding angle of welding torch. In order to make the welding environment in a relatively stable state, the construction protection measures and auxiliary measures have been strengthened. Through the unremitting efforts of all the staff of the project team and the welding QC team, after half a month of failure and summary, the research results are very small; Great achievements have been made. After consolidation, maturity and repeated tests, the technical topic of CO2 gas shielded welding applied to vertical and oblique welding heads of ultra-thick parts has been successfully solved (it has obtained national patents). Through technical research and process improvement, the welding quality has been gradually improved, and the construction period has been greatly advanced, which has been well received by the general contractor and the owner, resulting in good social and economic benefits and enjoying a good reputation in the society.
6, quality and time limit for a project control
The remarkable characteristics of super-high-rise steel structure different from ordinary concrete buildings are: high quality and tight construction period. The guarantee of quality and construction period depends on scientific management, strict construction organization and bold application of new technologies, new processes and new equipment.
The main steel structure of Shenzhen Wang Di Mansion 14860, with a weight of 24500t, profiled steel plate140,000m2, 500,000 sets of welded studs and 600,000 linear meters of welds. However, the construction period specified by the owner is only 14.5 months, and the project is accepted according to American codes and standards. The short construction period, large engineering quantity and high construction difficulty are rare at home and abroad.
Establishing a scientific management organization system and strictly following the project management methods are the keys to ensure the "safety, high quality and high speed" of the project. To this end, we set up the Wang Di Project Management Department, and implemented the project manager responsibility system and contract management for all employees. In organizational form, the personnel, posts and responsibilities are fixed, and it is advocated that one expert should do many things, one person should do many things, and the section chief should go to the front with the workers. It not only plays an exemplary role, but also facilitates on-site management. From the project manager to the labor, safety, technology and other functional departments to the site office, timely understand and master the progress of the project and solve related technical, quality and safety problems. In the whole project management, a capable construction team with the project manager as the core and a safety and quality assurance system with the construction organization network, new technology application and QC team as one. At the same time, each bid section has implemented daily contract, defined responsibilities, rights and interests, and implemented risk of mortgage system, which mobilized the enthusiasm and sense of responsibility of front-line workers to the maximum extent, laying a foundation for the rapid development of the project. In order to build the first world-class skyscraper for China people into a cross-century classic, the project not only set stricter quality control targets than American standards, but also actively cooperated with the QC team of hoisting, measuring and welding to tackle key problems. The "Four Innovations" technology was fully applied in the installation and construction of the super-high-rise steel structure in the main building of Wang Di Building. Under the leadership of the project, the hoisting QC team improved the traditional techniques of "one crane with multiple cranes" and "double crane hoisting", which greatly accelerated the hoisting progress; The survey QC team improved the traditional "overall survey" technology, innovated the "tracking survey" and "double system retest control" technology, and successfully controlled the total verticality deviation of the main building at 17mm outward and 25mm inward, which was only 1/3 of American standard. After arduous attempts, the welding QC team finally succeeded in breaking through the forbidden zone of CO2 gas shielded semi-automatic welding applied to vertical welding and oblique vertical welding, which not only improved the work efficiency and ensured the construction period, but also all the welds were tested by an authoritative third party, 100% was qualified and the excellent and good rate reached 94%.
In steel structure engineering, the laying of regional steel plates is a process with heavy workload and high risk. Its laying speed not only directly affects the progress of the project, but also seriously affects the construction safety through a series of processes such as slow correction of hoisting ships, high-strength bolts and welding. For this reason, we imported two internationally advanced Co spot welding machines from Japan, which are not only simple in operation, short in interval, but also smooth and smooth in welding spot, good in quality and five times more efficient than manual welding. Advanced equipment such as M44OD large internal climbing crane from Australia, semi-automatic CO gas shielded welding machine from Japan, fusion welding nailing machine, etc. imported from L process of super high-rise steel structure in the main building of Digong Mansion, have played an important role in this project.
7. Safe construction
Safety construction is an important link in steel structure construction, and the characteristics of super-high-rise steel structure construction are high altitude and many hanging operation points. During the construction of Wang Di Building, there were only 500,000 high-strength bolts. Although these things are small, the consequences can be imagined if they fall from a few hundred meters high. In order to prevent safety accidents, the project set up a safety supervision team, set up full-time safety officers, strictly managed, formulated detailed safety production rules and regulations, conducted regular safety education for employees, and established the idea of "safety first". On the basis of strict management, the project does not hesitate to spend a lot of manpower, material resources and financial resources for strict protection. By adopting new technologies, such as setting up a double-layer safety net and laying profiled steel plates in advance, the miracle of 379-day construction of the main super-high-rise steel structure of Wang Di Building was created, with no casualties and no falling members. At the technical appraisal meeting of the super-high-rise steel structure construction of Shenzhen Digong Industrial and Commercial Building organized by China Construction Corporation, experts reached the international advanced level from the construction technology of the super-high-rise steel structure of Wang Di Commercial Building, and this achievement has won the special prize of scientific and technological achievements of our bureau. China Construction Corporation won the first prize of scientific and technological progress and the third prize of national scientific and technological progress.
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