Space Frame Rubber Bearing: Function, Types And Selection Guide

Space frame rubber bearings, also known as elastomeric rubber bearing pads, are essential structural components for steel grid and truss roof systems. Installed between the space frame lower chord ball nodes and concrete foundation embedded plates, these bearings serve as flexible structural buffers. They effectively transfer vertical loads, release thermal deformation, adapt to foundation settlement, and provide seismic isolation for long-span steel structures. Widely used in modern civil engineering, they are core accessories compliant with international space frame structure design standards.

Manufactured through high-temperature vulcanization of multi-layer high-elastic rubber and thin steel plates, space frame rubber bearings integrate the advantages of rigid steel and flexible rubber. Internal steel plates enhance vertical stiffness and compressive bearing capacity to stably support upper structural loads. The rubber layers allow flexible shear deformation, absorbing structural displacement and vibration that rigid steel connections cannot tolerate. This unique composite structure solves the common structural problems of rigid connection stress concentration and insufficient flexible deformation capacity.

Core Functions of Space Frame Rubber Bearings

High-performance space frame rubber bearings deliver four key functions for long-span steel space frame structures. First,stable load transmission. They evenly transfer vertical dead loads, live loads and wind loads from the steel frame to the concrete foundation, avoiding local pressure overload and foundation damage.

Second, thermal stress relief. Long-span steel structures expand and contract significantly with temperature changes. The rubber's shear deformation freely releases horizontal displacement, eliminating additional internal temperature stress and preventing structural deformation or cracking.

Third, adaptation to structural displacement and rotation. The bearings accommodate minor foundation uneven settlement and node rotation, protecting the overall structural stability. Fourth, seismic isolation and shock absorption. During earthquakes, the rubber layers dissipate seismic energy, reduce structural vibration response, and greatly improve the earthquake resistance of space frame buildings.

Main Types of Space Frame Rubber Bearings

According to structural design and bearing capacity, space frame rubber bearings are mainly divided into two categories to meet different engineering demands.

1. Plate Type Rubber Bearing Pads

This is the basic and cost-effective type, designed as square or rectangular integral rubber-steel composite pads with reserved bolt holes. It features simple structure, convenient installation and low maintenance cost. With a bearing capacity ranging from 100kN to 2000kN, it allows small horizontal displacement and rotational deformation. It is widely applied to medium and small-span factory roofs, light steel space frames and conventional canopy structures. However, this type cannot bear vertical tension force, limiting its use in super-large-span projects.

2. Spherical Rubber Seismic Bearings (GKQZ/GJQZ Series)

As an upgraded composite product, this bearing combines steel spherical hinge structure and high-elastic rubber layers. It is classified into fixed type, unidirectional sliding type and bidirectional sliding type. Breaking the limitations of ordinary plate bearings, it supports large horizontal displacement, flexible node rotation, and bears vertical tension and horizontal shear force simultaneously. Its maximum bearing capacity reaches 10000kN. Ideal for large and super-large-span key projects such as stadiums, exhibition centers, airport terminals and high-speed railway canopies, it provides superior seismic isolation and structural stability.

Material Options and Technical Performance

Different rubber materials are selected based on service environments to ensure long-term durability. NR natural rubber offers excellent elasticity and cost performance for normal temperature indoor projects. CR neoprene rubber features outstanding aging and oil resistance for humid environments. EPDM rubber adapts to extreme high and low temperatures and coastal salt fog corrosion, suitable for harsh outdoor and marine engineering scenarios.

Standard technical parameters include: design rotation angle of 0.08rad, horizontal displacement range of ±20mm to ±100mm, and friction coefficient below 0.03 for PTFE sliding types. The horizontal bearing capacity can reach 20% of vertical bearing capacity, and tension-resistant spherical bearings achieve 20%-30% vertical tension resistance of the rated load.

Engineering Selection and Installation Tips

Proper bearing selection is critical to structural safety. Engineers shall confirm vertical reaction force to match bearing capacity, and calculate temperature deformation and wind-induced displacement to select fixed or sliding types. For wind suction and high seismic zone projects, tension-resistant spherical bearings must replace ordinary plate pads.

During installation, keep the bearing center aligned with the space frame ball node, and control the foundation levelness with four-corner height difference within 1mm. Avoid high-temperature continuous welding to prevent rubber aging and damage. Final locking and welding should be completed after the entire space frame and enclosure structure construction to reserve sufficient deformation space.