Analysis of key points in the design of the base of a steel structure house

The base design of a steel structure house is the core link to ensure the overall safety and seismic performance of the building. Combining current specifications, technological innovations and actual cases, the following is a detailed discussion from the dimensions of structural design principles, seismic technology applications, and interpretation of material and process requirements

1. Core principles and structural layout of base design

Bearing capacity and stability requirements

The base needs to bear all the loads of the building (including structural deadweight, equipment load, use load, etc.), and its bearing capacity design should be at least 1.5 times the calculated load to ensure that it can remain stable under extreme conditions. For example, in a magnitude 7 earthquake case, a high-rise steel structure building successfully resisted the impact of the earthquake through the base reinforcement design, and its bearing capacity far exceeded the conventional standard.

Foundation adaptability: The foundation type (shallow foundation such as extended foundation or deep foundation such as pile foundation) needs to be selected according to geological exploration data to avoid foundation settlement or lateral displacement problems. For example, the buried depth of the pile foundation should not be less than 1/20 of the total height of the house, and the buried depth of the natural foundation should be greater than 1/15

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Structural symmetry and integrity

The base and superstructure should be arranged symmetrically to reduce the torsion effect and improve the seismic performance by balancing the load distribution. For example, the layout of the support frame should be basically symmetrical, and the length-to-width ratio of the floor should not exceed 3 to prevent local stress concentration.

Seismic support system design

Support type selection: Central support (such as cross support and herringbone support) is recommended for buildings below 12 floors. Eccentric support or cylinder structure can be combined with more than 12 floors to form multiple seismic lines. K-shaped support should be avoided because it is easy to cause additional bending moment.

Node structure: The angle between the support diagonal rod and the horizontal plane should not exceed 55°, the thickness of the node plate should not be less than 10mm, the inter-column support should be made of whole material or equal strength splicing, and the connection strength should not be less than 1.2 times the plastic bearing capacity of the support rod.

2. Innovation and application of seismic technology

Seismic isolation and energy dissipation and shock absorption technology

Seismic isolation bearings: such as ball joint bearings and pot-type rubber bearings, which can absorb seismic energy and reduce structural vibration. Beijing Daxing Airport uses seismic isolation bearings to achieve 8-degree seismic fortification.

Energy dissipation support: By setting up viscous dampers or metal energy dissipators, seismic energy is converted into heat dissipation. Chongqing Raffles Square uses a damper combination to reduce wind vibration and seismic response.

Patented technology for seismic mechanism

A patented technology uses a U-shaped seat and a torsion spring to buffer and offset the vibration of the X/Y axis. Its base is equipped with a symmetrical seismic mechanism, which achieves multi-directional shock absorption through elastic deformation and improves seismic performance.

Collaborative design of seismic wall and frame

In the bottom frame-seismic wall structure, the thickness of the seismic wall is not less than 160mm, the distributed steel bar reinforcement ratio is not less than 0.25%, and the wall panel opening forms a wall section with a height-width ratio ≥2 to enhance the ability to resist lateral displacement. The transition layer bottom plate needs to use cast-in-place reinforced concrete slabs (thickness ≥120mm) and reduce openings.

3. Material and construction process requirements

Application of high-strength steel

Use high-strength steel of grade Q355 or above to replace traditional Q235 steel to improve the tensile strength and ductility of the base. For example, the application rate of hot-rolled H-shaped steel is increased to 50%, achieving a combination of lightweight and high bearing capacity.

Key node reinforcement measures

Column foot design: high-rise buildings use rigid joints (inserted or exposed column feet), and low-rise store frames can use hinged column feet

Wall beam structure: section width ≥300mm, height ≥1/10 of the span, stirrup spacing ≤100mm, waist reinforcement number ≥2φ14, anchored in the column.

Fire protection and durability guarantee

Steel components need to be treated with fireproof coating, and the fire resistance limit is not less than 1.5 hours. Without protection, steel loses its bearing capacity within 15-20 minutes in a fire, so it needs to be combined with fireproof board or concrete wrapping