Types of Flexible Support Structures

Types of Flexible Support Structures

1) Single-Layer Suspension Structure

The single-layer suspension structure generally consists of a main steel frame made of beams and columns, stay cables, and the cable body. The cable body includes two parallel cables aligned with the component plane, replacing the usual tensile members. After tensioning the support cables, they are anchored at the ends of the steel beams using anchors, providing the cables with stress rigidity to support the components. This forms a self-balancing system through the end stay cables.

• Advantages: Simple form, single-force mode, strong adaptability to terrain, and high construction efficiency.

• Disadvantages: Being a fully flexible system, the overall structural rigidity is weak, making it prone to significant deformation under wind pressure or suction, limiting its ability to achieve larger spans.

• Applicable Conditions:

• Span: ≤ 20m

• Basic Wind Pressure: ≤ 0.5kN/m². If the wind pressure exceeds 0.5kN/m², windproof devices should be installed.

• Application Scenarios:

1. Flat areas such as deserts, fish ponds, agricultural sheds, and parking lots.

2. Steep slopes in mountainous regions.

   
   

2) Double-Layer Cable Truss Structure

The double-layer cable truss structure consists of a main steel frame made of beams and columns, stay cables, the cable body, and rigid braces between the cables. The cable body comprises two parallel upper chord cables and a lower chord cable with an upward curvature. Compared to the single-layer suspension structure, it includes an additional load-bearing cable and rigid braces, forming a self-balancing system by tensioning the cable body to achieve stress rigidity.

• Advantages: After tensioning, the cable body is anchored to the supporting structure, with support cables for supporting components and load-bearing cables resisting downward vertical loads, providing significant rigidity and deformation resistance.

• Disadvantages: Without stabilizing cables, the structure is sensitive to wind suction, making it unsuitable for large-span structures or areas with high basic wind pressure.

• Applicable Conditions:

• Span: 20m ~ 30m

• Basic Wind Pressure: ≤ 0.5kN/m².

• Application Scenarios:

1. Flat areas such as riverbeds, fish ponds, and parking lots.

2. Gently sloping mountainous areas with significant elevation differences. Due to its larger span, the cable truss structure is typically arranged in parallel rows with out-of-plane stabilizing cables to prevent out-of-plane instability.

   
   

3) Triple-Layer Cable Truss Structure

The triple-layer cable truss structure consists of a main steel frame made of beams and columns, stay cables, the cable body, and rigid braces between the cables. Compared to the double-layer cable truss, the cable body includes stabilizing cables, forming an upper and lower chord structure with opposite curvature. The stabilizing cables are used to resist wind suction.

• Advantages: The load-bearing cables resist downward vertical loads, while the stabilizing cables resist upward vertical loads. The rigidity and shape stability within and outside the plane are provided by the pre-tensioning, ensuring good structural rigidity and stability.

• Disadvantages: The structural form is more complex, requiring pre-tensioning for all three layers of cables. The tensioning process is complicated, and construction processes and quality must be strictly controlled to avoid excessive bending moments and deformations in the supporting members during pre-tensioning.

• Applicable Conditions:

• Span: 20m ~ 60m

• Basic Wind Pressure: Suitable for a wide range of conditions.

• Application Scenarios:

1. Large flat areas such as sewage treatment plants, reservoirs, and tidal flats.

2. Gently sloping mountainous areas with significant elevation differences and large spans.

   
   

4) Tensile String Structure

The tensile string structure consists of a main steel frame made of beams and columns, stay cables, a rigid upper chord, the cable body, and rigid braces. The cable body acts as a load-bearing cable, and unlike the triple-layer cable truss, it does not include stabilizing cables. The upper chord is rigid, and the lower chord is a flexible cable. Under the action of prestress, the braces provide elastic support to the upper chord, improving the stress state of the upper structure and forming a self-balancing system.

• Advantages: By connecting the upper compression members with the lower tension members using braces and applying pre-tensioning, the upper structure gains reverse curvature, enhancing its load-bearing capacity and deformation resistance.

• Disadvantages: Compared to other flexible systems, the overall steel consumption of the structure is relatively high. It is a planar force system with potential out-of-plane instability issues.

• Applicable Conditions:

• Span: Over 30m

• Basic Wind Pressure: Suitable for a wide range of conditions.

• Application Scenarios:

• Flat areas such as sewage treatment plants, factories, and mines.