1.Structural Principles and Figurative Analogies
Steel pipe truss structure: Like a "hollow bridge" or a "three-dimensional beam."
You can clearly distinguish its "upper edge" (upper chord), "lower edge" (lower chord), and the "support rods" (web members) connecting the two. Its force distribution logic is similar to that of an I-beam: the upper chord is under compression, the lower chord is under tension, and the web members resist shear force. Multiple trusses combined can form a large spatial structure.
Space frame structure: Like a "metal woven mat" or a "spatial plate."
It consists of a large number of standard members and nodes, regularly woven together using triangles or quadrangular pyramids as basic units. Loads applied at any point are quickly distributed throughout the entire structure through the grid, similar to the force distribution in a shell structure.
2. Fundamental Differences in Nodes
Steel pipe truss (intersecting nodes): Rigid nodes. Members are directly welded, capable of transmitting bending moment, shear force, and axial force. The nodes have strong constraints, resulting in high structural rigidity and good stability.
Space frame (bolted ball joints): Approximates hinged joints. Members are connected to steel balls via bolts, primarily transmitting axial force. This design means that space frame members are mainly subjected to tension or compression, resulting in a clear calculation model, but the nodes have weaker rotational constraints on the members.
Design Logic and Application Focus
When is a steel pipe truss more suitable?
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When a clear force transmission path is required: For example, the canopy above the stands of a stadium, where the load needs to be clearly transmitted to several supports at the back.
When pursuing iconic architectural shapes: The arrangement of its members can flexibly follow curved shapes, achieving complex forms such as wings or waves.
For ultra-large spans and when steel consumption is a concern: The force distribution is direct, resulting in high material efficiency, and it offers significant economic advantages in large-span projects (such as those exceeding 150 meters).
When is a space frame more suitable?
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For large-area coverage of rectangular or regular planes: Such as large industrial plants, warehouses, and standard station halls of railway stations.
When rapid construction and standardization are desired: Members and ball joints can be mass-produced in factories, and on-site assembly is as efficient as "building with blocks."
When loads are uniformly distributed: Such as when the roof is covered with lightweight materials, requiring evenly distributed forces.
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