In the steel structure is increasingly complex, the more important it is to deepen the design of steel structure. China's steel structure engineering design uses two stage design method, the first stage is by the unit of construction and engineering design and structure design, given component section size, general typical member nodes, under various conditions structure internal force. The second stage is the construction and production of steel structure units to deepen the design according to the design drawings provided by the design units, and the preparation of deepening design drawings.
The depth of construction design documentation requirements, steel structure engineering design graphics also have clear demarcation, the owners commissioned units in the design and structural design, if in the contract did not specifically on the deepening of the design requirements, the design of steel structure only design drawing of steel structure. Therefore, the design development of the steel structure in more time required by the processing and installation unit to complete, it also put forward higher requirements of processing and installation units, especially for complex steel structure. Due to deepening design personnel lack of understanding of the structure design, in processing and construction experience is lacking, so of joints and members in the deepening design expression in drawings, design of node structure is not reasonable.
Deepen the design content
Steel structure deepening design component cutting, processing and installation of the basis, to design the content of deepening should contain at least the following: list of drawings, to deepen the design of steel structure description, component layout, component machining drawings, installation details.
Steel structure deepening design, design in general as a factory processing and on-site installation guide, described in general should contain: according to the design, engineering survey, the material description (steel, welding materials, bolts), blanking and processing requirements, component assembling requirements, weld connection, plate groove, hole making requirements, quality requirements for welding, shot blasting, coating requirements, member number, size label instructions, installation sequence and installation requirements, component processing and installation process should pay attention to the matters etc.. Through the development of the steel structure design specification summary, the basic requirements of the project to show the processing and installation personnel.
Component layout design, component layout mainly as a field installation, design personnel according to the component structure diagram component section size, member length, different uses merge, classification, component numbers to reflect the actual location of the building structure to, expressed by the layout drawing, section map, index and different ways, the positioning component should be according to the positioning axis, elevation, size of the details, text description and express them to meet the on-site installation requirements. When the manual merge sort of structural member, pay special attention to the relevance of the component, it is very easy to cause error coding component assembling error. The shape of components can be used coarse single or simple shape to represent the component with a map or a map should not use the same number. For details or holes of different beams should be individually numbered. On the contrary the relationship between component installation, numbers can be used to differentiate the suffix.
Component detail drawing design, component detail mainly as a production and processing workshop assembly, according to the steel structure design diagram and component layout using a larger proportion to draw, the composition component of all kinds of large and small parts are should have detailed the number, size, location hole, groove, plate assembly drawings, weld detail and should be in the component details provide material parts list and the components of the processing instructions, in the material list should contain at least part number, thickness, specifications, quantity, weight, material etc.. In the way of expression can be used to view, side view, side of the drawings, sections, details, index parts details etc.. Each member shall be numbered corresponding to the component layout, parts should be numbered in sequence according to the primary and secondary components. Position detail size, elevation control and positioning parts, components of gravity position etc.. Component drawing should be according to the actual size of the drawing, the elongated member, in the direction of length and width can be used in different scale. The size should be indicated for oblique slope, when the component is multi arc segment, the curvature radius and arc height should be specified. In short, the component detail design drawings expression depth should be to meet the fabrication of members is a minimum requirement, in the drawing expression should as far as possible to do the detailed.
Install the joint detail design -- when there is joint detail structural construction drawings and in the deepening of the design, does not take into account the node design, drawing. But when the node graph structure design diagram node is unknown or belonging to deepen the design stage increased, installed in the node details should also express, to meet the on-site installation. Node detail should be able to articulate member connection way, number of bolts, welds practice, connecting plate number, picture index. A bolt hole, specifications, aperture in the node should be unified and in detail.
To deepen the design of steel structure is a cost a lot of manpower and material resources work. At present, there are the following several ways to deepen the design of steel structure: professional software of AutoCAD, struCAD, Xsteel etc., greatly improve the steel structure designed to deepen the efficiency.
Structural optimization of nodes
With the development of science and technology, construction steel structure more and more complex, how to achieve safe and reasonable structure and node structure complex become the emphasis and difficulty of deepening design, this design of steel structure and manufacturing personnel to deepen the manufacturers put forward higher requirements, not only requires the designer to have rich professional knowledge, but also to install processing technology and process of comprehensive understanding, therefore requires not only the deepening of the design personnel are familiar with the deepening of the design program, how to carry out the detail drawing according to the design, but also integrated manufacturing and installation, a combination of factors, discover and solve problems in the development of the steel structure design process, keep good relationship with the structure designer, continue to improve and adjust the structure, to create a better condition for the processing and installation. In order to meet the reasonable structure, deepening the design to provide convenience for the processing and installation component.
Structural design of structure design is not reasonable, box beam column rigid connection of steel structure, usually adopts 01SG519 Atlas of high-rise buildings on page 17 of node 2, but sometimes the box beam is narrow and high (such as the width of 500 mm, 1200 mm high), if still using the graph it will, in the actual operation is difficult, due to the high and narrow beam, welded box girder bottom flange welding workers at the scene, no space, even if the welding but the quality is difficult to guarantee, so we must consider other connections, such as the practice, through many engineering verification, the node is feasible the weld quality, and stress can meet the requirements.
After perforation plug weld reinforcement and the column base bottom plate as a whole embedded pre embedding and then circular column and buried in welding, and the column steel and round steel column is welded on the inner wall, according to the requirements of the practice of the joints, are also encounter many problems in the actual operation, buried in the elevation of the top there will be construction error, steel column installation column bottom elevation can not adjust and is not easy to locate, the pipe diameter is 600 mm to 800 mm, reinforced and tubular column wall site didn't method of welding. According to the practice of the joints, after repeated communication and design, finally reached the following practices and pre embedded anchor bolt, steel column installation by anchor bolt elevation adjustment, the adjustment of steel column in place will be reinforced and column is welded on the inner wall, due to the reinforcement in the column has been lengthened to about 1100 mm, from the round tube at the upper end of the column of steel bar and column is welded on the inner wall. In general, both reached the foot force requirements, also reached the purpose of convenient installation.
Component production, processing is difficult to achieve, weld intensive, stress concentration, a multi-storey steel box and steel beam column connection rigid diaphragm beam flange through corresponding beam columns, steel beams and columns connected because not identical (some of Liang Gao only 50 mm or 100 mm), so some diaphragms are very close the steel column, are the diaphragm into a short, because the steel column is 40 mm thick above the plate, so when the diaphragm spacing in 100 ~ 300 mm, steel column connection weld very much, the stress concentration is obvious, in order to ensure the node transfer, also to reduce the weld. We suggest that the design unit will instead of the following practices, baffle spacing less than 150 mm, which is connected with the steel column steel beam with variable cross section, when the baffle spacing of not less than 150 mm above, clapboard in welding box column This way, the stress is reasonable, and convenient processing and production, reduce the amount of welding. Transportation and installation technology of special requirements, deepen the components, finished just finished a part of the whole project, a lot of work still need to accomplish in the field, can not successfully complete the installation, it also shows that deepen design is reasonable, the processing of the component meets the accuracy requirements. Due to the transportation and installation requirements, such as: member subsection point selection, determination of component transport unit length, component in the assembly plant or site bulk, crane installation position and practices identified, determine the maximum weight of component, tool screw of the implementation of the minimum space considerations, complex steel structure in the deepening of the design stage of pre arching considerations and so on, all these work to completely in the deepening of the design phase to consider.
A successful completion of the project, is the result of efforts. Is to have a precise theoretical calculations of the structure, but also the guidance of practical engineering experience, in this process, the deepening of steel structure design plays a role of intermediate link, deepen design and structure design must interact constantly improve the design, ensure the project quality and efficiency. Therefore, deepening training of qualified design personnel is a long-term work, need to accumulate gradually in the level of design and construction experience. Deepening of the design is not only according to the structure design of "gander", but in understanding the structure designers intent, deepen design not only satisfy the requirements of structural strength, and convenient processing and installation.