Differences Between Space Frame Structures and Steel Trusses

1. Structural Form

Space Frame Structure

A space frame structure is a space truss system formed by numerous members intersecting in space according to specific patterns to create multiple triangular or quadrilateral grids. These interconnected grids constitute a three-dimensional space structural system. It resembles a three-dimensional net-like structure where members crisscross in space to share loads collectively. For instance, common flat-plate space frames can be arranged in various configurations such as two-way orthogonal, two-way orthogonal skew, or three-way space frames. This structure evenly distributes loads across all members and nodes, offering superior spatial load-bearing performance. 

Steel Trusses 

Steel trusses are primarily planar structures. Straight members are connected at their ends through nodes to form triangular or other geometric units, which are then assembled into an integrated structure within a plane. Their shapes are relatively regular, typically functioning within a single plane, such as common parallel-chord trusses or triangular trusses. Trusses primarily bear tensile and compressive forces within the plane but have relatively weak resistance to out-of-plane loads, requiring support systems to enhance stability.

2. Load-bearing Characteristics 

Space Frame Structure

As space structures, space frame structures can transmit forces from multiple directions when bearing loads. For instance, when subjected to roof snow loads or live loads, the forces are dispersed through the members in all directions, resulting in a relatively uniform distribution of internal forces within the structure and avoiding stress concentration. Furthermore, in resisting lateral forces (such as wind loads or seismic loads), the space frame utilizes its spatial stiffness to form an integrated lateral force resistance system, effectively reducing lateral deformation of the structure. 

Steel Trusses 

Steel trusses primarily bear forces within a plane, with internal forces in their members varying based on the truss configuration and applied loads. Under vertical loads, the upper chords typically experience compression, the lower chords tension, and the diagonal members transmit forces according to their position and angle. For horizontal loads, additional bracing or connection systems are required to ensure truss stability, otherwise out-of-plane buckling may occur.

3. Application Scenarios 

Space Frame Structure

Space frame structures are suitable for large-span building roofs, such as those in large stadiums, exhibition halls, and airport terminals. These structures require expansive column-free spaces, which the large-span advantage of space frames can fulfill. Additionally, their form can be flexibly adapted to architectural designs, enabling the realization of various complex curved surfaces. 

Steel Trusses 

Steel trusses see extensive use in industrial plants, bridges, and similar applications. In industrial facilities, they serve as roof trusses or crane girders, leveraging their efficient load-bearing capacity to support roof loads and crane weights. In bridges, steel trusses function as primary truss structures, bearing vehicular loads and their own weight. Through strategic layout and design, they meet bridge span and load-bearing requirements.

4. Material Consumption and Cost Efficiency

Space Frame Structures

Due to their spatial stress characteristics, space frame structures may consume less material than steel trusses under identical span and load conditions. This efficiency stems from their ability to fully utilize material mechanical properties, distributing internal forces more uniformly across members. Consequently, material usage is reduced while maintaining structural safety. However, the relatively complex node construction of space frames may increase fabrication and installation costs.

Steel Trusses

Material consumption for steel trusses is largely determined by span and load magnitude. For shorter spans, steel trusses may be more economical. However, large-span structures often require increased member cross-sections or additional bracing to ensure strength and stability, leading to higher material usage. Furthermore, steel trusses exhibit relatively weaker resistance to lateral forces, potentially necessitating supplementary measures to enhance stability, which also impacts overall cost-effectiveness.