Structural Design of Airport Terminal Building (Part 1)

1. Project overview

Fortification of degree 7 (0.10g) of the airport terminal building, design earthquake group 3, design service life of 100 years, design length 185m, width 82.5m, reinforced concrete columns, horizontal column spacing 15m, 15m, 20m, longitudinal column The distance is 12m, the highest point of the main body is 21.5m, the structure adopts Q3 5 5B, and the roof is metal roof. The safety level of the building structure of this project is Class II, the structural design reference period and service life are 50 years, the seismic fortification category of the building is Class C, the foundation design class is Class C, the seismic fortification intensity is 7 degrees (0.10g), and the design earthquake Group 3, construction site category II.

2. Roof scheme analysis

The roof of the airport terminal building adopts a light steel roof with a large span. At present, in this kind of long-span roof, the fasting space structure is often used, which has the advantages of space force, high rigidity, light weight, low cost, beautiful appearance, and good seismic performance. In this project, two spatial structures, space frame and truss, are selected for comparative analysis.

2.1 Space frame scheme

The biggest feature of the space frame structure is the mutual support between the rods. It has good integrity, relatively large rigidity, and strong earthquake resistance. Therefore, this project uses the space frame for comparative analysis. Generally, the height of the space frame with a large span usually 1/14 to 1/20 of the short span. The span of this project is 82.5m. According to engineering experience, a three-layer space frame is often used, with a minimum height of 4.1m. Due to the decision of the building shape, the middle part of the project is a two-layer space frame with a height of 2.7m. There are 4-layer space frames in the surrounding area, and 2-layer space frames at both ends. In order to meet the requirements of the included angle of the web, the space frame’s size is 3m×3m, and the quadrangular pyramid space frames are used.

2.2 Truss scheme

The truss structure has a simple shape, smooth and beautiful effect. This project adopts the horizontal truss as the main truss with a spacing of 6m, the vertical truss as the secondary truss, and the truss members as square steel pipes and rectangular steel pipes. The height of each truss is 2.7m. The purlins are placed on the upper part of the transverse truss, the distance between the purlins is 1.5m, and the corner braces are set at a distance of 3m. Since the lateral force caused by the instability of the upper chord is very small, the purlins can restrain the upper chord, and the corner braces can restrain the lower chord. Therefore, when modeling this project, the The calculation length of the top chord and the bottom chord outside the plane can be set to 3m to consider their effects to reduce the amount of steel used. In order to enhance the horizontal stiffness of the structure, a horizontal support is set at an interval of 36m, and the support is made of round steel. The length of the branch pipe and the height of the section are greater than 24, and the web bar can be set as a hinge.

3. Mechanical performance analysis

3.1 Load Statistics Roof

The load consists of roof dead load, live load and wind load.

• Roof dead load, except that the self-weight of the steel structure is automatically included by the calculation program according to the cross-section, and the roof panel is an aluminum-magnesium-manganese alloy plate, taking 1.0KN/㎡into consideration for insulation cotton, suction cotton, purlin self-weight, and etc.
• Roof live load is 5KN/m² for this project according to Article 5.3.1 of the “Load Code” .
• Ceiling live load is 0.8KN/m 2 .
• Wind load is 1.0KN/m 2 .

3.2 Structural design methods and standards

This project adopts 3D3S modeling, and conducts internal force and displacement analysis of various engineering combinations. According to the requirements of the code, the horizontal and vertical seismic effects may not be considered in the 7-degree zone. This project is a long-span structure, only the horizontal seismic effects are considered, and the The temperature load effect, the temperature effect is -28 to 37°C, which mainly meets the strength, stiffness (slenderness ratio), stability and deflection requirements of the components, as well as the deflection of the structure and the horizontal displacement requirements of the column top .

3.3 Calculation results

3.3.1 Modal analysis

For a terminal building with a truss roof, the first mode of vibration is X-direction translation with a period of 2.08s. The mass participation coefficients of the vibration modes are all greater than 90%, and the period ratio is 0.75, which meets the specifications. The terminal building with a space frame roof, the first vibration mode is X-direction translation, the period is 2.05s, and the second vibration mode is Y-direction translation, the period is 1.51s, the third period is torsion in the Y direction, the period is 1.47s, the mass participation coefficients of the x-direction and Y-direction modes are both greater than 90%, and the period ratio is 0.72, which meets the specification. From the modal analysis data, it can be seen that the torsional vibration mode of the terminal building with a space frame roof appears in the high-order mode, which reflects the good torsional stiffness of the structure, which is related to the good integrity of the space frame structure and the large space rigidity. The natural vibration frequency and mode shape of the structure are inherent properties of the structure, which are only related to the mass and stiffness distribution of the structure. This shows that the structural mass and stiffness distribution of the terminal building with a space frame roof is relatively reasonable.