In the construction industry, as the use of steel structure workshops becomes more and more popular, much more attention is paid to the production, transportation and installation technology of steel structure workshops, and at the same time, rapid development and continuous improvement have been achieved. How to further improve the manufacturing and installation accuracy of steel structure workshops and reduce the costs is significant for the steel structure workshop industry. From the consideration of improving the installation accuracy of steel structure workshops, this article analyzes and summarizes some issues and specific control methods that must be paid attention to in the main links of production such as transportation, installation, and etc.
1. Production and transportation control
Generally speaking, the principle of length greater than width should be followed when arranging column nets, which can reduce the amount of steel used in the rigid frame and reduce the wind load of the column support at the same time, thereby reducing the amount of steel used in support system.
The accuracy of the production size of steel structure factory building is the basic and prerequisite to ensure the accuracy of the overall structure’s dimension and smooth installation. Therefore, it is necessary to accurately grasp the straightness and twist of the steel column, the distance from the connection hole of column and beam to the bottom plate, the processing accuracy of the connecting hole itself, the straightness of the roof beam, the processing accuracy of connecting plate, the position and size of the purlin plate and etc.
At present, most of the H steel beams used in steel structure workshops are assembled from steel plates. After assembly and welding, the steel columns should be reshaped to ensure straightness and prevent distortion. Most of the roof beams are herringbone structures. Roof beams are generally assembled by the steel plates, and the webs of the beams are often irregular quadrilaterals. Manufacturers with strong technical ability can accurately grasp the cutting of web, while those manufacturers with weak technical capabilities, there is a size deviation.
Because the external dimension of the roof beam is related to the tightness of the connection between beam and column, then the size of the web directly affects the external dimension of beam, which is especially important. In the design of general steel structure workshops, there are certain arching requirements for roof beams. The purpose is to offset the downward deflection of the beam body due to the effect of itself and the roof load after the overall installation so that the installation size is just reached. The height of arch is determined by design. In order to ensure the degree of camber, the outer dimensions of the roof beams must be adjusted. From this point of view, the difficulty of making beams is far greater than that of columns. When we inspect on-site, we take the shape and end connecting plate of the beam as the key inspection items to ensure the overall effect after installation and also ensure the tightness between the beam and column.
In order to avoid and reduce the deformation of columns, beams, tie rods, and other connecting parts during transportation, it is necessary to add more support points in the full-length range when lashing the components, and add wood as much as possible between the components. The lashing of the components’ periphery should be firm enough to minimize the deformation due to vibration or heavy pressure during transportation. Two-point lifting should be used during loading and unloading. One pole can be used and the lifting points should be appropriately increased if the component is too long.
Before the steel structure factory building is installed, it is necessary to do all the preliminary work. For example, before hoisting, the installer should retest the components, and hoisting can only be carried out on the premise that the components are not deformed and the installation dimensions are correct. In addition, on the premise of confirming that the strength of the foundation concrete meets the requirements of the specification, the installer should also inspect the embedded bolts or cup openings of the steel column foundation. If the position of the foundation and the elevation size are found to have deviated, then the position should be recorded to adjust the position of the steel column.
In order to improve the installation accuracy of the overall steel structure workshop, it is best to install the part of the workshop with inter-column supports, tie rods and roof supports firstly. After these steel columns are hoisted, the axis and elevation of the steel column must be re-measured. The steel column is temporarily stabilized with a cable wind rope after the deviation is corrected, and then the column supports, roof beams and inter-beam tie rods are installed. This is the so-called rough installation. Before installing the roof beam, it should be assembled on the ground firstly, and then hoisted after passing the measurement. The roof beams are connected with high-strength bolts, and other parts are fixed with corresponding bolts, but all kinds of bolts should not be locked. After the components are fixed, re-measure and correct the steel column axis and elevation again. The axis of the steel column should be re-tested from two directions. After the re-test is qualified, the bolts of each part should be tightened in turn.
During the installation process of the steel structure factory building, each independent frame should form a stable structure as soon as possible. Through the above method, several other parts can be installed in sequence, so that the entire plant has a stable frame structure with intervals, which makes the cumulative error generated during the installation of the entire plant dispersed to each part, and the influence of natural conditions can also be avoided.
All temporary fixing bolt holes that need to be welded on site should be designed with long holes, which is convenient for installation and adjustment, and is more beneficial to ensure the overall installation accuracy. The unilateral connecting holes of the secondary components such as purlins should also be designed with elongated holes, of course, the related gaskets should be enlarged accordingly. Special attention should be paid to the fact that since the installation of the purlin is a high-altitude operation and the plate wall is thin if the installation hole is deviated and sprayed at high altitude, it will indeed bring a lot of inconveniences, danger, and will affect the appearance.
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