Selection of steel structure and other structural schemes

Selection of steel structure and other structural schemes

  • 20 Nov 2020
  • steel structure

Selection of steel structure and other structural schemes

1. Steel frame reinforced concrete shear wall hybrid structure

Since it was originally a reinforced concrete structure, the reinforced concrete shear wall was retained. The advantage of this structure is that the cost is lower than that of an all-steel structure. The wall of the elevator is both a bearing and a dividing wall, The disadvantage is that the construction is complicated, especially because of the construction plan characteristics of the project, the concrete wall cannot be constructed before the steel structure, which affects the progress of the steel structure. Under the structural layout conditions of the original concrete structure, using the characteristics of the steel structure large column network, the four rows of columns on the 1, 3, and 4 axes are changed to three rows of columns. Only one column on the G axis remains on the 1/4 axis,The number of columns is reduced, the cross-section of the column is reduced, and the advantages of the steel structure are used to create favorable conditions for renting and selling buildings.

2. Pure steel structure scheme of steel frame brace system

This plan can also better meet the requirements of the architectural plan. The advantages of the structure are light weight, small earthquake action, reduced rigidity eccentricity of the steel concrete shear wall structure plane, and good ductility. The disadvantage is the high cost of concrete mixed structure.

The use of steel reinforced concrete shear wall:

1. Why are steel reinforced concrete shear walls used in the project:

1) Reasonable construction flow operation to speed up the construction period. The shear wall in the building plan does not form an independent cylindrical structure, and it is impossible to construct in advance. Many steel-concrete mixed structures are tube-in-tube structures. The tube body can be poured into the concrete wall for 6-10 floors before the steel structure, and then the steel structure is installed. If a general concrete shear wall is used, the steel structure and each layer of the wall need to be constructed simultaneously, which will inevitably affect the progress of the steel structure and lose the advantage of the steel structure. Therefore, steel column beams and diagonal braces are installed in the concrete shear wall to form a temporary stable structure, which is installed at the same time as the steel frame to form an overall frame brace structure. After installation, the reinforced concrete wall is poured layer by layer. In this way, the installation of the steel structure and the concrete work are carried out separately, without mutual influence.

2) In the construction of the steel-concrete hybrid structure, the installation error of the steel beam and the construction error of the concrete wall are nearly ten times different. Due to the deflection of the concrete wall, it is difficult to place the steel beam in place. After the steel frame is installed in the wall, the embedded parts connected with the steel beam are connected to the steel frame column in the wall, and the steel beam can be accurately positioned within the error of the steel structure, and the problem of difficult installation of the steel beam will no longer occur.

3) The parking garage is below the 10th floor of a project. As it needs to meet 200 parking spaces, the area is very tight. According to the vehicle layout requirements, the 1-axis shear wall cannot penetrate up and down, and the structure needs to be partially converted. The steel frame in the upper wall is in lower part forms a steel-reinforced concrete column as one of the supporting members, which better meets the requirements of the up-down conversion structure.

4) The installation of steel frame improves the bearing capacity and ductility of the steel reinforced concrete shear wall. The addition of steel-reinforced columns can reduce the concrete cross-section and vertical steel bars, and improve the bearing capacity of the wall against compression and bending.

2. Construction of steel-reinforced concrete shear wall: The steel frame is set at the wall end and corner, and the steel corbel is picked out from the external steel frame beam and connected to the embedded parts, and then the connecting plate and the steel frame beam web are welded on the top High-strength bolt connection.  Because the steel columns and beams in the wall are small, they are used as temporary supporting structures. In this state, the 6-story steel frame supporting structure is calculated to withstand wind and conventional loads, which can meet the lateral displacement limit requirements. Therefore, during construction, it is required that the difference between the installation of the steel structure and the pouring concrete should not exceed 6 layers. Practice has proved that the construction of steel-reinforced concrete walls has achieved the expected results.

Small discussion

1. The general high-rise building structure has obvious characteristics in terms of structural calculation and analysis. Due to the building plan, the shear wall is stronger, so the shear wall basically bears the horizontal force. The deformation performance of the structure has obvious characteristics of the shear wall structure. The steel frame mainly bears vertical loads. Can not assume the role of the second line of defense. Therefore, it is very important to ensure the good seismic performance of the shear wall in the design.

2.The height-to-width ratio of the building is 6, which is just the limit. The floor area is small, the shear wall is eccentric, and the plane and vertical shapes are unfavorable for earthquake resistance. If the steel frame support system of pure steel structure is used, it is more beneficial to strengthen the seismic performance.

3. Compared with structural calculation and analysis, the selection of structure, connection nodes, welding quality and materials is more important. It is an important link to ensure structural safety and construction quality progress. In the design, full attention has been given to these aspects, and corresponding measures have been taken.

4. The steel frame part adopts large column net, the number of components is small, and the standard floor has only 9 columns. For narrow construction sites, reducing component hoisting times can improve installation efficiency.

5. The steel-reinforced concrete shear wall is used in the steel-concrete mixed structure or the steel frame is placed in the concrete wall. For the construction of steel-concrete mixed structures, it is beneficial to increase the bearing capacity and increase the ductility.

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