Construction points of large-span galvanized steel warehouse

 

Large-scale public buildings and industrial plants have shadows of large-span steel structures. Large-span structures mainly work under self-weight loads. In order to reduce the self-weight of the structure, steel structures are often suitable as the main structure. According to the problems encountered in the past construction, we mainly summarized into three categories.

1. Design and optimization

Before construction, the construction design scheme of a large-span galvanized steel warehouse should be optimized, especially in terms of calculation and analysis. Many project departments do not calculate, and failure to calculate will lead to poor construction quality or high cost of engineering projects. So what parts do you look at in terms of computational analysis?

1.1 Drawing design

First of all, attention should be paid to the cooperative work of the upper and lower structures, and the effect of multidirectional seismic action should be taken into account. The most reasonable way to consider the synergy of the upper and lower structures is to perform the seismic action calculation according to the overall structural model. The substructure simplification must be based on reliable and dynamic principles, that is, the effectiveness of equivalent stiffness and mass should be considered comprehensively. Key points of construction of large-span steel structure.

Use software to model the design model and perform calculation analysis. During the specific operation, the calculation model should be reasonably determined to ensure that the connection and structure of the roof and other structures and the main supporting parts are consistent. In addition, force analysis should also be considered. In the calculation and analysis, in addition to simulating the stress situation after the overall formation of the structure, the special stress situation during the construction process should also be taken into account, so as to avoid damage due to local stress exceeding the design value before the structure is formed. For the calculation and simulation of the construction process, it is necessary to consider component hoisting, working conditions in different construction stages, structural pre-deformation technology, pre-assembly and unloading of components, etc.

1.2. Structural layout

The structural arrangement should avoid the formation of weak parts due to local weakening or sudden change, resulting in excessive internal force and concentrated deformation. For possible weak parts, measures should be taken to improve the seismic capacity. Therefore, during the structural arrangement, it should be ensured that the mass and stiffness distribution is balanced and the structural integrity and force transmission are clear.

The seismic action of the roof should be effectively transmitted downward through the support; Avoid the concentration of internal forces or large torsion effect of the roof, so the roof, support and the layout of the lower structure should be uniform and symmetrical; To ensure the integrity of the roof structure, spatial force transmission system should be preferred to avoid local weakening or mutation of weak parts; Light roof system should be used, so the unit weight of roof system should be strictly controlled.

2. Steel Structure Construction and installation

Due to the complexity of large-span structures and the diversity of construction methods, construction issues must be comprehensively considered in the process of determining their design. This is also a place that is often overlooked or not fully considered in the design process. The construction mainly involves the following installation technologies

2.1 Fabrication technology of structural components and special-shaped joints

Various large-span and complex space-shaped steel structure buildings require complex local stress and difficult-to-manufacture steel components. Therefore, in the construction of complex engineering projects, it should be considered that the production of structural components and special-shaped nodes should meet the stress conditions to ensure that engineering quality and safety.

2.2 Overall slippage construction technology

The key problem in the construction of large-span steel structures is the stability of the structure before forming a spatial whole. This problem can be better solved by moving the structure divided into several stable bodies horizontally from the assembly position to the design position along a certain track by using the traction equipment that can control synchronization through the sliding construction technology. However, when using it, attention should be paid to the fact that it requires large out-of-plane rigidity of the structure, needs to lay tracks, and is difficult to synchronize control when pulling at multiple points.

2.3 Overall improvement of construction technology

By using hydraulic jacks as power equipment, according to the lifting force requirements of each operation point, a number of hydraulic jacks, hydraulic valve sets, pumping stations are combined into hydraulic jack clusters, and synchronized movement under computer control, to ensure the large structure in the process of lifting or shifting posture stable, load balance.2.4 The high-altitude block expansion unit has no support assembly technology

2.4 High altitude assembly construction technology without support

The construction principle of the assembly technology of the high-altitude block expansion unit without support is that the structure system is reasonably segmented and the lifting sequence is selected, so that the construction process does not need to set up a support platform. The stability unit is formed by using the structure's own stiffness, and the overall structure is finally formed through the continuous expansion of the unit.

3. In terms of quality control, during the construction process, the following issues should be paid attention to

3.1 Installation precision control

The complex space steel structure should be measured and controlled during installation. As the steel structure construction measurement control is a part of the construction technology, the rationality and advancement of the engineering construction plan should be analyzed from a large amount of measurement and control data information and obtained responses and confirmations. For large-span steel structures, since the deformation and stress state of the structure during the construction process are very different from those after forming, it is necessary to use various supporting tire frames to ensure the accuracy of the structure.

3.2 Disassembly control

Because the large-span steel structure has the characteristics of large total unloading tonnage, wide distribution of unloading points, large unloading force at a single point, and large unloading calculation and analysis workload, if the support force is released unreasonably, the structure will be damaged or the scaffolding will gradually become unstable. Therefore, when unloading steel structures, the system conversion scheme must be taken as the principle, the structural calculation and analysis as the basis, the structural safety as the purpose, the deformation coordination as the core, the real-time monitoring as the guarantee, and the operation must be carried out in strict accordance with the requirements of the two unloading methods, the equal ratio method and the equal distance method.

3.3 Hoisting scheme

Large span steel girder hoisting, if not reasonable lifting point calculation, still choose traditional two segments, due to the steel structure is longer, lifting point spacing is bigger, and the factors such as weight and variable load, axial force of the steel beam and wire rope are very big, prone to beam lateral bending, or even more serious deformation. 

On the construction site of large-span steel structures, management should be strengthened, and workers' professional knowledge training should be increased, so that they can have a more concrete understanding of the force characteristics of components and hoisting knowledge. At the same time, the construction organization design is strengthened to carry out a reasonable demonstration of the hoisting scheme, so as to select a more reasonable hoisting scheme.

3.4 Installation sequence

Since the long-span steel structure has high requirements on the installation sequence, if the installation sequence is not reasonably considered and the steel components do not meet the needs of hoisting, the safety of the structure may be affected. When designing the construction organization, the installation sequence should be arranged reasonably, and the factory processing, component transportation, and on-site installation should be coordinated and strictly implemented during the construction process. In addition to carefully formulating the installation sequence suitable for the project, an experienced construction team should also be selected for installation to avoid potential quality hazards.

 Large-span steel structures are widely used in specific engineering projects. In view of various problems in the construction process, the optimization of construction organization design should be strengthened, the red line of safety and quality should be strengthened, and construction technology should be continuously improved.