Improve the installation accuracy of Dongguan steel structure plant
In the construction industry, with the increasing popularity of steel structure plants, the production, transportation and installation technology of steel structure plants has received more and more attention, and it has also been rapidly developed and continuously improved. How to further improve the production and installation accuracy of steel structure workshops and reduce costs is a topic facing the steel structure factory industry. At present, the relevant national norms and industry standards have made many provisions in this regard, and every step has been made from the cutting of parts and components to completion.
From the consideration of improving the installation accuracy of steel structure workshops, some problems and specific control methods that must be highly valued in the main aspects of production, transportation and installation are analyzed and summarized. Now he is using bricks to attract jade and communicate with his peers.
I. Control of the production and transportation of steel structure workshops
The precise size of the steel structure is the basic and precondition for ensuring the accuracy of the overall structure and the smooth installation of the steel structure. Therefore, it is necessary to accurately grasp the straightness and distortion of the steel column, the connection hole of the column and the beam to the column. The distance of the bottom plate, the machining accuracy of the connecting hole itself, the straightness of the roof beam and the machining accuracy of the column beam connecting plate, the position of the tie rod or the supporting connecting plate on the beam column relative to the beam column itself, and the position and size of the stern plate Wait.
At present, the middle column of steel structure factory building is assembled by outsourcing H steel processing or sheet metal. If it is ready-made H-beam steel processing, the production precision of the column is easy to control; if it is assembled from sheet metal, it must be assembled and welded. Be careful to shape the steel column to ensure the straightness of the steel column and prevent distortion. Most of the roof beams are herringbone structures, often assembled from 2 or 4 inches. The roof beam is generally assembled by the manufacturer's plate, and the web of the beam is often irregular quadrilateral. The manufacturers with strong technical ability can accurately grasp the blanking and unloading of the web, while the manufacturers with weak technical ability lay out the web. The size is subject to deviation. Due to the size of the roof beam, which is related to the tightness of the beam-to-column connection, the size of the web directly affects the dimensions of the beam and is therefore particularly important. In the design of general steel structure workshops, there is often a certain arching requirement for the roof beams. The purpose is to offset the lower deflection of the beam body due to its own and roof load after the overall installation, so that the installation dimensions are achieved. The height of the arch is determined by the design. In order to ensure the degree of arching, the outer dimensions of the roof beam must be adjusted. From this aspect, the difficulty of making the beam is much greater than the difficulty of making the column. When inspecting the site, we will focus on the beam dimensions and beam end joints. The purpose is to ensure the overall effect after installation and to ensure the tightness between the beam and the column.
We have found such a situation, there is a meandering gap between the beam and the column after installation. At this time, the large hexagon bolt has lost the most important function proposed by the original design, and only bears the supporting effect. There is no bridge between the beam and the column. Friction. In order to eliminate this hidden danger, we added the anti-shearing key on each pillar to the lower side of the beam connecting plate to improve the supporting ability of the roofing system. It has been proved that the effect is very good. In actual construction, due to various factors, the beam and the column often cannot be tightly combined, and some seem to be combined, but in fact, the requirement is not met, and the friction between the joint faces is relatively weakened. In view of this, we hope that when designing the steel structure plant, it is recommended to increase the shear key on the column panel against the lower edge of the beam connection plate to ensure the support capacity of the column to the roof. Although the shear bond is small, it has a great effect.
In order to avoid and reduce the deformation of the columns, beams, tie rods and other connecting parts during transportation, the transportation company should be required to increase the support points within the full length range when tying the components, and use wooden mats between the parts as much as possible. In fact, the peripheral tying should be firm to minimize the deformation of the component caused by vibration or heavy pressure during transportation; two points of hoisting should be used during loading and unloading. If the component is too long, the sling can be used and the lifting point can be appropriately increased; the component is at the installation site. When stacking, the number of stacking layers should be reduced as much as possible, generally no more than 3 layers, and the supporting points should be appropriately increased to prevent the members from being deformed under pressure. Do not relax the control of transportation, lifting, stacking, etc. Otherwise, even if the steel structure plant components are made more precise, there will be problems in the transportation and other links, resulting in major troubles in the installation of steel structure plants.
Second, the quality control of the installation process of steel structure plant
Before the installation of the steel structure factory building, it is necessary to do a good job in all the preliminary work. For example, before lifting, the installer should re-test the components, and the lifting can only be carried out under the premise that the components are not deformed and the installation dimensions are correct. In addition, the installer should also check the pre-embedded bolts or cups of the steel column foundation on the premise that the strength of the foundation concrete meets the requirements of the specification. If the position of the foundation and the height of the elevation are found to be deviated, the part should be recorded. In order to adjust the position of the steel column.
In order to improve the installation accuracy of the overall steel structure plant, it is best to select the part of the plant with inter-column support, tie rods and roof support for installation. After the steel column is hoisted, the axis and elevation of the steel column should be re-tested. After the correction, the cable string is temporarily stabilized by the cable rope, and then the inter-column support, the roof beam and the tie between the beams are installed. This is called Rough installation. Before installing the roof beam, it should be assembled on the ground and hoisted after passing the measurement. After the beam is in place, it is connected by high-strength bolts, and other components are fixed with corresponding bolts, but the bolts of various types should not be locked. After the components are fixed, the axis and elevation of the steel column are again re-measured and corrected, that is, fine-tuned. The axis of the steel column should be re-tested from two directions. After the re-test is passed, the bolts of each part are tightened in turn. The high-strength bolts must be firstly screwed. During the tightening process, the axis of the steel column should be dynamically tracked. If the axis change exceeds the allowable value, it should be adjusted immediately. The entire tightening process should be carried out simultaneously from the beam-column joints to the support and tie rod joints, and the two ends of the same part are simultaneously symmetrical to reduce the one-sided cumulative error. This will ensure that the steel column is installed correctly. If, during this process, it is found that the mounting member and the mounted member do not match, the mounted member cannot be adjusted, but the mounting member is adjusted or other remedial measures are taken. For example, if the steel beam and the steel column are not matched, the steel column cannot be adjusted, and only the steel beam can be adjusted. In the entire rack installation process, the correct installation of the steel column is a necessary condition for everything else to be installed correctly.
During the installation process of the steel structure plant, each independent frame part should form a stable structure as soon as possible. Through the above method, the other parts can be separately installed in order, so that the entire plant has a stable and stable frame structure, so that the cumulative error generated during the installation of the entire plant can be dispersed to various parts, and the natural conditions can be avoided. , the steel components that have been installed are deformed or detached or even tipped over. When the steel columns and steel beams between the other rows of racks are installed, they should also be independently measured and corrected, and cannot be benchmarked by the side racks. During the installation process of the main structure, after the partial frame structure is installed and corrected, the high-strength bolts must be finalized. The final torque value must meet the requirements of the specification. The inspectors should sample and record.
All temporary fixing bolt holes that need to be welded on the site should be designed with elongated holes, which is convenient for installation and adjustment, and is more advantageous for ensuring overall installation accuracy. It is also advisable to design a growth hole for the single-sided connection hole of the secondary member of the purlin, and of course the relevant spacer should be correspondingly increased. It is important to note that since the purlins are installed at high altitudes and the slabs are thin, if they are cut at high altitude due to deviations in the mounting holes, it will cause a lot of inconvenience, danger, and appearance. Therefore, it is more reasonable to design the connecting holes of the ends of the stringers and the steel beam steel columns to be elongated, or at least one-side design.
When installing a roof steel frame system, sometimes the installation of roof support and roof rafters tends to be contradictory. If the roof support is installed first, the roof raft can not be lifted; if the roof raft is installed first, the roof support is inconvenient to hoist. Our usual practice is to first hang the roof rafts in a batch and hang them on the roof beams. The rafts in the same span can be divided into 4 batches or 5 batches, which must be fixed after stacking. The construction sequence is important for the crane boom to extend from the gap between the batches of beams to the roof, to hoist and fix the roof support, and then to spread the roof rafters. Considering that the installation of the enclosure and the main structure is often not the same construction unit, it must be unified and commanded by an experienced management. In doing so, not only can mutual interference between construction units be avoided, but also the safety of the aerial work process can be improved. In the above installation process, it should be reminded that if there is a crane beam system in the factory and the space between the crane beam and the roof is not enough for the crane's boom, the crane beam should be installed before installing the roof support; if the crane If the beam is far from the roof space, it can be installed later. In general, the crane beam is best hoisted as early as possible, which is also beneficial for the stability of the entire shelf.
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