In the construction industry, as the use of steel structure workshops has become more and more popular, the manufacturing, transportation and installation process technology of steel structure workshops has been paid more and more attention, and it has also been rapidly developed and continuously improved. How to further improve the production and installation accuracy of the steel structure workshop and reduce the cost is a subject in front of the steel structure workshop industry. Now the relevant national regulations and industry standards have made a lot of provisions in this regard, and have put forward requirements for every step from the parts unloading to completion.
From the perspective of improving the installation accuracy of the steel structure workshop, some problems and specific control methods that must be highly valued in the main links of production, transportation, and installation are analyzed and summarized. Now throwing bricks and introducing jade to communicate with peers.
1. The control of production and transportation of the steel structure workshop The precise size of the steel structure workshop is the basic and prerequisite for ensuring the accuracy of the overall structure size and the smooth installation of the steel structure workshop. Therefore, it is necessary to accurately grasp such as the straightness of the steel column and the Twist, distance from the connection hole of the column and beam to the bottom plate of the column, the processing accuracy of the connection hole itself, the straightness of the roof beam and the processing accuracy of the column and beam connection plate, the tie bar or support connection plate on the beam and column relative to the beam and column itself The size of the position, the size of the purlin board, etc.
If the middle column of the steel structure workshop is made of off-the-shelf H-shaped steel, the production accuracy of the column is easy to control; if it is assembled from plates, the steel column should be shaped after assembly and welding 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 pieces.
Roof beams are generally assembled from plates made by the manufacturer, and the webs of the beams are often irregular quadrilaterals. Manufacturers with strong technical capabilities can accurately control the lofting and blanking of the web, while manufacturers with weak technical capabilities can loft the webs. The size is sometimes biased.
Since the external dimensions of the roof beam are related to the tightness of the connection between the beam and the column, the size of the web directly affects the external dimensions of the beam, so it is particularly important. In the design of general steel structure workshops, roof beams often have certain arching requirements. 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 it just reaches the installation size.
The height of the arch is determined by the design. In order to ensure the degree of arching, the external dimensions of the roof beams must be adjusted. From this perspective, the difficulty of making beams is much greater than the difficulty of making columns. During the on-site inspection, we will focus on the external dimensions of the beam and the beam end connection plate. The purpose is to ensure the overall effect after installation and ensure the tightness between the beam and the column.
We have found that after installation, there is a wedge-shaped gap between the beam and the column. At this time, the large hexagon head bolts have lost the most important role proposed by the original design and only assume the supporting role. There is no between the beam and the column. Friction. In order to eliminate this hidden danger, we later added a shear key on each column close to the lower side of the beam connection plate to improve the support capacity of the roofing system. Practice has proved that the effect is very good. In actual construction, due to various factors, the beam and the column are often not tightly connected, some seem to be combined, but in fact fail to meet the requirements, resulting in the relative weakening of the friction between the joint surfaces. In view of this, we hope that when designing the steel structure workshop, it is recommended to add a shear key on the lower edge of the beam connection plate on the column panel to ensure the column's ability to support the roof. Although the shear bond is small, it has a great effect.
In order to avoid and reduce the deformation of columns, beams, tie rods and other connecting parts during transportation, the transportation company should be required to add more support points throughout the length when tying the members, and use wood pads between the components as much as possible In fact, the outer banding should be firm to minimize the deformation of the component due to vibration or heavy pressure during transportation; two points of lifting are used during loading and unloading. If the component is too long, a pole should be used and the lifting point should be appropriately increased; When stacking, the number of stacked layers should be reduced as much as possible, generally no more than 3 layers, at the same time, support points should be appropriately increased to prevent compression deformation of components. Do not relax the control of transportation, lifting, stacking, etc., otherwise, even if the components of the steel structure workshop are made accurately, there will be problems in the transportation and other links, which will cause big troubles in the installation of the steel structure workshop.
Second, the quality control of the installation process of the steel structure workshop Before the installation of the steel structure workshop, it is necessary to do all the preparatory work. For example, before hoisting, the installer should re-test the component, and only when the component is not deformed and the installation size is correct, can the hoisting be performed. In addition, under the premise of confirming that the strength of the foundation concrete meets the requirements of the specification, the installer should also test the embedded bolts or cup openings of the steel column foundation. 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 select the part of the workshop that has inter-column support, tie rods and roof support to install first.
After hoisting this part of the steel column, the axis and elevation of the steel column must be re-measured. After correction, the steel column is temporarily stabilized with the cable wind rope, and then the inter-column support, roof beam and inter-beam tie rod are installed. Rough installation. Before installing the roof beam, it should be assembled on the ground first, and then hoisted after passing the measurement. After the beam is in place, it is connected with high-strength bolts, and other parts are fixed with corresponding bolts, but all kinds of bolts should not be locked.
After each component is fixed, re-measure and correct the axis and elevation of the steel column, that is, fine-tune. The axis of the steel column should be re-tested from two directions. After the re-test, the bolts in each part should be tightened in turn. The high-strength bolts must be first tightened. During the tightening process, the axis of the steel column should be dynamically tracked. If the axis changes exceed the allowable value, it should be adjusted immediately.
The entire tightening process should be from the beam-column contact to the support and tie-bar contact, using the symmetrical method for both ends of the same component to reduce the cumulative error on one side. This ensures that the steel column is installed correctly.
If, during this process, it is found that the mounting part and the mounted part do not cooperate, the mounted part cannot be adjusted, but the mounting part is adjusted or other remedial measures are taken.
For example, if the steel beam and the steel column do not match, the steel column cannot be adjusted, only the steel beam. In the entire installation process of the rack, the correct installation of the steel column is a necessary condition for the correct installation of everything else.
In the installation process of the steel structure workshop, each independent bent part should form a stable structure as soon as possible. Through the above method, several other parts can be installed separately in sequence, so that the whole workshop has a stable and stable shelf structure, so that the cumulative error generated during the installation of the entire workshop can be distributed to each part, and it can also avoid the influence of natural conditions. To deform or fall off even the overturned steel members.
When installing the steel columns and steel beams between other bents, they should also be measured and corrected independently, instead of using the adjacent bent as a reference. During the installation of the main body structure, after the partial bent structure is installed in place and corrected, the high-strength bolts must be final-tightened. The final torque value must meet the requirements of the specifications. The inspector should measure and record.
All the temporary fixing bolt holes that need to be welded on site should be designed with elongated holes, which is easy to install and adjust, and is also more beneficial to ensure the overall installation accuracy.
The unilateral connection holes of purlins and other sub-components should also be designed with elongated holes. Of course, the relevant gaskets should also be increased accordingly. Special attention should be paid to the fact that purlin installation is done at height, and the wall is thin. If the spraying is cut at high altitude due to deviations in the installation holes, it will indeed cause a lot of inconvenience, it is also dangerous, and it also affects the appearance. Therefore, it may be more reasonable to design the connecting holes at both ends of the purlin and the steel beam and steel column to be elongated, or at least unilaterally.
When installing the roof steel frame system, sometimes the roof support and roof purlin installation often conflict. If the roof support is installed first, the roof purlin cannot be lifted; if the roof purlin is installed first, the roof support is not easy to lift. Our usual practice is to first hang the roof purlins in batches and hang them on the roof beams to fix them. The purlins in the same span can be divided into 4 batches or 5 batches, and they must be fixed after they are stacked.
The construction sequence is very important to allow the crane boom to protrude from the gap between the purlins of the batches, hoist and fix the roof support, and then spread the roof purlins. Considering that the installation of the enclosure and the main structure is often not the same construction unit, it must be unifiedly commanded and coordinated by an experienced manager.
In this way, not only can the mutual interference between the construction units be avoided, but also the safety of the high-altitude operation process can be improved. In the above installation process, it should be reminded that if there is a crane beam system in the workshop, and the space between the crane beam and the roof is not enough for the crane arm, the crane beam should be installed before installing the roof support; if the crane The beam has a larger distance from the roof space and can be installed later. In general, it is best to hoist the crane beam as early as possible, which is also beneficial to the stability of the entire bent.
Qingdao Yili Steel Structure Engineering Co., Ltd. specializes in designing and producing steel structures, budgeting, disassembling drawings and renderings. Steel structure workshop, steel structure warehouse, steel frame structure. For more questions, please consult the customer service of steel structure for consultation.