Before the installation of the steel structure plant, we should do all the preliminary work effectively. For example, before lifting, the installer should retest the components, and only under the premise that the components are not deformed and the correct installation size can be lifted. In addition, the installer should also test the pre-built bolts or cups of the steel column foundation under the premise of confirming the concrete strength of the foundation to meet the specification requirements, and if the location and elevation size of the foundation are found to deviate, the part should be recorded so as to adjust the position of the steel column.
In order to improve the accuracy of the installation of the overall steel structure plant, it is best to choose the part of the plant with inter-column support, ties and roof support to be installed first. After lifting this part of the steel column, the axis and elevation of the steel column should be remeasured first, after correcting the deviation, temporarily stabilize the steel column with cable wind rope, and then install the inter-column support, roof beam and inter-beam tie, which is called coarse installation.
Before installation of roof beams, they should be assembled on the ground first and then lifted after being measured and qualified. After the beam is in place, it is connected with high-strength bolts and each other part is fixed with corresponding bolts, but all kinds of bolts should not be locked. After each component is fixed, the steel column axis and elevation are again remeasured and corrected, i.e. fine-tuned. The axis of the steel column should be retested from two directions, and after passing the retest, then tighten the bolts of each part in turn.
The high-strength bolts should be initially screwed, and the axis of the steel column should be dynamically tracked during the tightening process, and should be adjusted immediately if the axis changes exceed the allowed value. The whole tightening process should be carried out simultaneously from the beam-column joints, then to the support and bollard joints, using the asymmetrical method for both ends of the same part to reduce the accumulated error on one side. This will ensure that the steel column is installed correctly. If in this process, it is found that the installed parts and the installed parts do not cooperate, it is not possible to adjust the installed parts, but to adjust the installed parts or take other compensatory measures.
In the process of steel structure plant installation, each independent row frame part should form a stable structure as soon as possible. Through the above method, several other parts can be installed separately in turn, so that the whole plant first has intervals of stable row frame structure, so that the cumulative error arising from the installation of the whole plant can be dispersed to various parts, but also to avoid the impact of natural conditions, so that the installed steel members deformation or fall off or even overturning, etc..
In the installation of steel columns and beams between the other rows of frames, they should also be independently measured and corrected for deflection, rather than the next row of frames as a benchmark. During the whole main structure installation process, after the local rack structure is installed in position and corrected for deflection, the high-strength bolts should be final screwed, and the final screwing torque value must meet the specification requirements, and the inspectors should sample and record the measurements.
All temporary fixing bolt holes of welded parts in the field should be designed with long holes, so that it is easy to install and adjust, and more beneficial to ensure the overall installation accuracy. The single-sided connection holes of purlins and other sub-components should also be designed with long holes, and of course the related shims should be increased accordingly. Special attention should be paid to the fact that the purlin installation is a high-altitude operation and the wall of the plate is thin, so if the installation hole deviates and the spraying is cut at high altitude, it will indeed bring a lot of inconvenience and danger, and it also has an impact on the appearance. Therefore it may be more reasonable to design the connection holes of purlin ends and steel beam and column as long shape, or at least one side as long shape.
When installing the roof steel frame system, sometimes the installation of roof support and roof purlin often contradict each other. If the roof support is installed first, the roof purlin can't be lifted; if the roof purlin is installed first, the roof support is inconvenient to be lifted. Our usual practice is that the roof purlins are first hoisted onto the roof beam in batches and set aside for fixing, and the purlins within the same span can be divided into 4 or 5 batches, which must be fixed after stacking.
Let the crane boom extend the roof from the gap between each batch of purlins, and then spread the roof purlins after lifting and fixing the roof support, this construction sequence is very important. Considering that the installation of enclosure and the main structure is often not the same construction unit, thus it is necessary to have an experienced manager to unify the command and coordination. By doing so, not only can we avoid mutual interference between construction units, but also improve the safety of the overhead working process.
In the above installation process, it should be reminded that if there is a crane beam system in the plant and the space distance of the crane beam from the roof is not enough for the crane boom, the crane beam should be installed before the installation of the roof support; if the crane beam has a larger space distance from the roof, it can be installed later. In general, it is better to hoist the crane beam as early as possible, which is also beneficial to the stability of the whole row of frames.
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