Dapeng Town Industrial Park, Tongshan District, Xuzhou City, Jiangsu Province, China
With the continuous development of the construction industry, the number of large buildings is increasing, new building technology, building materials by the construction industry attention, of which the fastest developing, the most widely used technology is steel structure installation technology, in some large infrastructure, public works and high-rise buildings, steel structure installation technology has been widely used. China’s overall national strength has been significantly improved, the people’s living environment and quality of life has been greatly improved. The construction of steel structure requires a large space, and there are a variety of structures and forms, requiring the construction personnel to have a certain technical level, for the steel structure installation and construction technology to conduct in-depth research, has important practical significance.
The following takes the construction of a high-rise building as an example to discuss the installation and construction technology of steel structure. This building project is a large electronic products exhibition and sales mall, a collection of residential, high-end office buildings, entertainment, catering and other functions, the project land area of about 35,325 square meters, the building covers a total area of about 281,520 square meters. The above-ground building consists of a 40-story office building consisting of two towers and a five-story commercial podium, while the underground building is mainly a parking garage and equipment room. The two towers are designed with a steel structure, the podium between the two towers is also a steel frame structure, and the outer part of the tower is a reinforced concrete structure.
The installation and construction of the building steel structure is to transport the steel components made by the factory to the construction site, use lifting equipment to lift the components in order according to the design drawings and construction plans, and connect each component after fixing. The construction process is very different from the traditional reinforced concrete construction. Steel structure construction has the characteristics of large amount of construction, complicated construction procedures, etc., and requires high construction precision. For this project, the installation and construction of steel structure are mainly three parts: podium, tower and basement, and need to install steel beams, steel columns, conversion steel trusses and steel supports. After the investigation of the construction site, the construction site is relatively small, so the mechanical equipment can not enter the construction site, the loading and unloading of the steel structure must use the tower crane of the construction site to complete. For the selection of lifting equipment, in addition to considering the weight and size of the steel components, but also consider the actual situation of the project, such as the material loading and unloading site and the distance between the installation location of the steel components, comprehensive consideration of many factors, for this project, the use of two K50 tower cranes. The project uses a variety of steel components, such as steel columns, embedded parts, conversion trusses, etc., the types and quantities of components are large, and the weight and size of different components are very different, and the requirements for lifting equipment are different. Before the specific construction, it is necessary to classify the steel components used, and formulate the appropriate steel component installation plan according to the actual situation, which is conducive to the construction organization.
Installation and construction technology of steel structure embedded parts. For the two towers in this project, the embedded parts used are composite structures composed of steel plates, embedded anchors and rectangular short columns. The largest embedded parts weigh about 10 tons and are about 6 meters long. There are three kinds of elevations of steel structure embedded parts in this project, which are -14.05 meters, -16.20 meters and -11.90 meters respectively. The weight and size of some embedded parts are large, so it is necessary to use the already set K50 tower crane to complete the loading and unloading, installation and adjustment construction of steel structure embedded parts. Before the embedded parts enter the construction site, it is necessary to ensure that the K50 tower crane works normally.
During the installation of steel structure embedded parts, several measures need to be taken to ensure the construction quality: before hoisting steel columns, it is necessary to carefully check the elevation, axis and extension length of the embedded anchor bolt that has been completed, so as to ensure the buried accuracy to ensure the smooth installation of steel columns and ensure the installation quality; If the anchor bolt has been deformed, it needs to be corrected before normal use. Clean the thread of the anchor bolt. If the screw is damaged, it also needs to be repaired. The concrete vibration mode and pouring direction will directly affect the horizontal deviation of the anchor bolt, so the concrete pouring should be layered, reducing the flow of concrete can improve the embedment accuracy of the anchor bolt, and the vibrator cannot be stuck on the steel bar when vibrating the concrete.
Installation and construction technology of steel column. The project has two towers, the main body is an all-steel structure. Since the two towers are symmetrical, the method and process of installing steel columns are the same. The tower steel column is installed with three elevations, and the K50 tower crane is used for segmented construction. Before construction, the performance of the tower crane and the specific conditions of construction should be carefully analyzed, and the steel column can be segmented to ensure that the tower crane can successfully lift the steel column to complete the installation and construction. After the steel column enters the construction site, the tower crane is used to remove and install the steel column, or the K50 tower crane can be used to transport the steel column to the location closest to the installation position.
The installation of steel beams requires attention to the following aspects: when correcting the elevation and axis, it is necessary to protect the steel structure frame that has been installed to prevent deviation; After installing the steel beam, check the fitting direction of the connecting plate and the steel beam; If there is a deviation in the bolt hole, do not use the gas cutting method to expand the hole, only use the hole cutter to expand the hole, after the installation is completed, hang a safety rope, so that the construction personnel can use the safety belt in the subsequent construction, and improve the construction safety.
At present, the construction technology of steel structure connection mainly includes full bolt connection, welding and bolt welding connection. Among them, welding is the most common application, the technology is simple, and the scope of application is wide, but the construction environment, construction materials and the technical level of construction personnel will have a greater impact on the quality of welding, requiring higher welding process and steel quality; There are two kinds of bolts, high-strength bolts and ordinary bolts, in large construction projects generally use high-strength bolts, strength and toughness, can withstand dynamic load, superior performance, so in recent years in the construction of building steel structure more applications, but the use of high-strength bolts need to be processed and processed on the contact surface of the connection.
Welding overview. Due to the high construction of this project, it is necessary to high-altitude welding, and the number of steel structure joints and rods used in the project are large, so it is very important to do a good job of welding construction quality control. The main methods of on-site welding are vertical welding, horizontal and horizontal welding, support butt vertical welding, etc. In order to reduce the difficulty of welding, carbon dioxide gas and semi-automatic welding technology are generally combined, which can effectively solve the problems of large steel plate thickness and welding deformation.
Preparation for welding construction. The construction personnel should have a full understanding of the specific conditions of the construction, do a good job in the preparation of welding construction, such as classifying the materials used in welding construction and cleaning the construction site in time, so as to fully ensure the safety of the construction. The construction is mainly used carbon dioxide gas shielded welding method, should be ready to use welding tools and equipment.
Welding construction technology. (1) Check the work before welding, determine the type of welding machine and the materials used in welding construction are consistent with the construction plan, clean the surface of the welding part, if the welding part is not smooth enough, it must be ground before welding construction; (2) Clean the surface of the welding liner and groove; (3) Assembly plate, arc plate and lead plate, the material of the three plates must be the same as the base material, after the completion of welding construction, you need to use the flame cutting method, the lead plate and arc plate removed, the connection surface grinding flat, but can not use the hammer knock method to prevent the quality of welding.
Welding environment control. In the welding construction site, waterproof and windproof measures should be set up, a professional platform for welding construction can be set up, the foot board is laid around the platform, and the asbestos cloth is spread on it, which can effectively prevent the splash of sparks from scald the construction personnel, and the use of windproof canvas can reduce the impact of wind in the environment on the construction. If the construction environment is not set wind protection measures, if the environmental wind is more than 2 meters/second, can not use carbon dioxide gas welding construction method, if the wind is more than 8 meters/second, can not carry out manual arc welding construction, but also pay attention to the environmental humidity before construction, environmental humidity is too large can not carry out welding construction.
If the hole position of the bolt is smaller than that of the high-strength bolt, it is necessary to use the punch rod or reamer to expand the hole before insertion, and the insertion direction should meet the requirements of the construction scheme; It is strictly forbidden to install high-strength bolts in rain and snow. Clean the dirt and water on the bolt surface and friction surface before installation. It is necessary to tighten the bolt twice, the first pre-tension to reach 80% of the standard requirements, the second time to reach 100%; The final twist of the high-strength bolt is generally completed by using the electric scissors wrench, in the construction to control the strength, generally the use of torque control equipment, when the prestress meets the requirements, the torque control equipment will close the control switch.
