Steel structure space frame engineering difficult guarantee measures(I)

Steel space frame structure, the structure type commonly used at home and abroad mainly includes bolt ball space frame and welded ball space frame, there is a big difference between the two structural types, bolt ball space frame structure usually uses less steel, fast construction speed; The amount of steel used by the welded ball mesh is higher than that of the bolt ball mesh, the construction speed is slow, the construction site environment and the welding quality are relatively high, but the load bearing capacity is strong. Because the construction method of distribution space frame structure is used more and more widely, there are many difficulties in the construction process, which seriously threatens the actual service life and personal safety of distribution space frame structure. Steel structure space frame is a kind of three-dimensional network structure, which is widely used in large-span roofing structure, and its characteristics are mainly manifested as light weight, large span and large variable strength. The structural types generally include orthogonal and oblique. Among them, the orthogonal structure refers to the formation of a “well” space frame structure, the construction method is more convenient, so the orthogonal structure has a wide range of use in the construction of steel structure space frame, and the oblique component refers to the span of 60-80 meters between the bidirectional truss truss interlaced truss components. In the process of design and construction, it must be simply supported on the supports that no longer exist around, and the structural principle is that the stress acting on it can evenly distribute the intersecting steel truss members to different angles, so that the structure of the truss beam is all stressed, and effectively reduce its tensile stiffness. At this stage, the generally used forms of steel distribution space frame structure are mainly three-cone and four-cone types, but because these types of geometric figures have great stability, in the process of specific use, the superior performance shown by these two forms is also well known. Because of the common advantages of the two types, in the process of long-term design and application, people have gradually established two kinds of systems. In addition to the above two more common types of steel space frame, there are many geometric patterns of structural coordination, in the specific use of the stage, to be scientifically and reasonably selected. According to the overall size, shape and stress state of the project, starting from the overall aspect, it is beneficial to determine the effectiveness of the project, but also to fully consider the overall investment of the project. In the final stage of the selection of steel space frame structure types, several sets of options were developed in advance for customers to screen. It is necessary to take into account the amount of materials, as well as the use of installation personnel and machinery, but also to make a detailed accounting of the materials used in various types of steel space frame structure in order to formulate the best design scheme. According to the principle of material saving, the material application of the inclined square cone is usually the smallest, and the material amount of the normal square cone is followed. It can be investigated from the specific use of the square conical structure to adapt to the large amount of production, and the range of use is quite wide, for the plane of the rectangular structure, the inclined square conical structure and the board square conical structure as the main use of the space frame structure. There are many cross-working processes, limited assembly sites, and discontinuous installation because the space frame steel columns of the coal-fired workshop and smoke exhaust treatment workshop must be lifted by the steel frame at the tail of the boiler, so the roof space frame must also be arranged in accordance with the equipment order of the three lower coal-fired boilers before it can be completed. In addition, the unloading hall, garbage pond roof space frame and other structures must also be cement frames to the roof behind the construction, resulting in the site of concrete pouring, high-pressure boilers, equipment and other multiple stations staggered operation. High altitude operation risk, high installation accuracy requirements due to the roof space frame length is too large, the maximum length of 49.65 meters; The total length of the single lattice column is 45.9 meters, the length of the main limb is about 4.0 meters, and the maximum single weight is about 80t. Because the lattice column is super long, super wide, and the self-weight is large, the production of the lattice column uses a complete set of processing technology and technology to ensure the processing accuracy of the component and product quality. The construction site is small, and the construction organization is difficult. The factory in Zone 1 and 2 is symmetrical, and the central part is separated by the concrete structure of the turbine building, the chimney and the main control plant. In addition, the design of the four working areas of the discharge hall, the garbage pond, the incineration workshop and the flue gas purification workshop is also a problem.

There is no construction site in the direction of the long axis, only two construction channels straddling the end of the short axis, so that the garbage pond, incineration workshop and flue gas purification workshop in the middle are very difficult to build the space frame in accordance with the traditional Chinese way. The whole hoisting method is suitable for any kind of steel structure space frame, especially in the welding and connection process of the space frame, which has a wider application space. When using this construction method, the overall structure of the ground must be lifted first until the hoisting frame is lifted to the installation position. The biggest drawback of this method is that it requires a large lifting force. High-altitude bulk method High-altitude bulk method is mainly the use of steel structure and the leverage of the space frame system and the distance between the nodes to be reasonably connected, among which, the full support method is the node assembly method of the size of the transverse bar carried out in the upper part of the support column, generally the steel space frame structure is divided into several parts and then the assembly frame construction. However, the full overhang rule is a completely overhung part of the structural space frame, which can not only effectively reduce the construction cost, but also improve the economic benefits of enterprises, and this method is also a common method in the construction of steel frame space frame. High-altitude slip method The high-altitude slip method is to divide the steel structure space frame into several strip structures, and then transfer the segmented strip structures from one side of the building to the other side, until all the strip structures are transferred to the designated position before it can be spliced into a whole. It is important to note that during the sliding process of the small strip structure, the construction personnel need to ensure that it must maintain the original form, and this method is more suitable for the installation of the variable space frame structure. Strip or block installation method: The distribution space frame of steel components is cut into some strip or block units and then assembled on the ground, and then the assembled steel structure space frame is hoisted to the designated position by the hoisting machine, so that it forms a whole. Generally, because the construction enterprise in the construction of the space frame structure system is mostly steel structure engineering system, the material used is also mostly steel, so in order to increase the stability and robustness of the steel structure of the space frame, in the construction should choose the correct construction method to be used, and to do the corresponding management of the process. The construction of the urban distribution network and the construction of the steel structure project should be strictly implemented in accordance with the relevant national engineering standards, because in the construction of the current regional soil structure, climate conditions, and construction technology level and other factors will affect the use of construction materials, so the construction party must “adapt to local conditions”, according to the actual situation of the current region for local materials. To reduce the cost of construction, and improve the quality of the space frame. In the building, the most important distribution space frame structure can be divided into many kinds, mainly including: single-layer, double-layer, three-layer, multi-layer and other distribution space frame structure, single-layer space frame structure and three-layer distribution space frame is usually used in buildings with a span of less than 30 m or a span of more than 100 m. The selection of the space frame structure should refer to the mesh size, span size, support, load capacity, structural requirements and other factors, the height span ratio of the space frame should be in the range of 1/18-1/10, the number of short-span space frames of the space frame should be higher than 5, the mesh size should be accurate, and the Angle between the adjacent rods should be ensured to be between 30°-45°. Bolt Before the installation of the ball node space frame, it is usually necessary to set the string first, adjust the size of the lower string according to the axis, and then tighten the sound to fix the screw, and play a positioning effect. In the separate installation, after the installation of the three columns of the upper string ball, the first two plants should be copied on the central axis, which can also be carried out by adjusting the height of the reinforcing bar pad of the lower string ball, and finally fixed to the two ends of the first row of cones and anchor the original position, and tighten all the fixing bolts of the first row of cones. Follow the cycle above.