Choosing a structural system for a wide building is not simply a matter of span. A 30 m warehouse, a 50 m industrial building, and a 100 m column-free facility create different demands for stiffness, member depth, connections, transportation, erection, and foundations.
For many steel building projects, portal frames, steel trusses, and space frames are three important options. The best choice depends on span, roof load, building use, geometry, local design conditions, and total installed cost.
What Are the Main Types of Long–Span Structures?
Long-span structural systems create large open areas with few or no internal columns. They are common in warehouses, factories, hangars, exhibition buildings, and sports halls.
Large Span vs Clear Span: What Is the Difference?
Large span describes a structure with a relatively wide distance between major supports. Clear span focuses on the usable interior width without intermediate columns.
A 90 m-wide warehouse may use several structural bays and internal columns, while a 60 m hangar may require a completely column-free opening. The second project can place greater demands on roof depth, deflection control, connections, and erection. For buyers, the key question is not only “How wide is the building?” but also “How much uninterrupted space is required?”
Why Span Alone Does Not Decide the Structural System
Two buildings with the same width can need different solutions. Engineers must also review wind, snow, and seismic loads, cranes, door openings, height, transport limits, erection conditions, and future expansion.
Portal Frame, Steel Truss, and Space Frame: How They Work
Each system carries loads differently, creating a different balance of simplicity, depth, fabrication effort, and long-span efficiency.
Portal Frame: Simple for Regular Industrial Buildings
A portal frame uses rigidly connected columns and rafters repeated along the building length. It is widely used for warehouses and factories because the layout is straightforward and works well with repetitive bays and enclosure systems.
At XINGUANGZHENG, our project experience includes portal-frame warehouses, factories, commercial buildings, and industrial facilities. One auto-parts factory used a portal steel frame with a maximum span of 40 m, while a Thailand warehouse combined a portal frame with internal office floors and overhead cranes.
Our design, production, scheduling, installation, and after-sales teams allow structural decisions to be considered together with fabrication and project execution.
Steel Truss: Efficient for Longer Spans and Heavier Roof Demands
A steel truss uses top and bottom chords connected by web members. Because many members work mainly in tension or compression, trusses can be structurally efficient for longer spans.
They are often suitable for hangars, sports buildings, and industrial roofs where deeper roof zones are acceptable. More members and connections, however, can increase fabrication and erection work.
Space Frame: Three-Dimensional Action for Very Wide Roofs
A space frame is a three-dimensional network of interconnected members and nodes. Instead of carrying load mainly in one plane, it distributes forces in multiple directions.
This makes space frames useful for very wide column-free roofs and complex geometry, including exhibition halls, terminals, and sports facilities.
Portal Frame vs Steel Truss vs Space Frame
The following comparison provides a practical starting point for system selection.
| Factor | Portal Frame | Steel Truss | Space Frame |
| Structural action | Rigid frame | Mainly planar truss action | Three-dimensional action |
| Structural depth | Usually moderate | Deeper | Distributed roof depth |
| Fabrication | Relatively simple | More members and joints | High connection density |
| Best fit | Regular industrial buildings | Longer spans or heavier roof demands | Very wide or complex roofs |
| Erection | Relatively simple | More assembly work | Careful node and sequence control |
Span, Depth, and Total Project Cost
In a portal frame, bending in rafters and columns is central to structural behavior. In a truss, axial forces in chords and webs are more important. A space frame shares loads through a three-dimensional network.
That is why portal frame vs steel truss or space frame vs truss comparisons should not rely on span alone. Connections, shipping dimensions, foundations, and erection can change the economics. The lightest structure is not always the lowest-cost installed solution.
Project Example: One Facility, Two Structural Systems
A 4,587 m² automotive facility in Uruguay used a truss structure for the exhibition hall and a portal steel frame for the workshop.
This shows why there is no universal winner. The open exhibition area and the regular workshop had different functional needs, so different framing systems were used within the same project.
What Is the Best Structure for 30m, 50m, and 100m Spans?
These ranges are preliminary selection guides, not engineering limits.
| Required clear span | Systems to evaluate first |
| Around 30 m | Portal frame or steel truss |
| Around 50 m | Steel truss, engineered portal frame, or space frame |
| Around 100 m | Space frame or another engineered long-span system |
Best Structure for a 30m Span
For a regular warehouse or factory around 30 m clear span, a portal frame is often a strong starting point because of its simple layout and repetitive fabrication. A truss may be preferable when roof loads or geometry change the requirements.
Best Structure for a 50m Span
At around 50 m, selection becomes more project-specific. A steel truss can reduce bending demand by transferring more force axially, while an engineered portal frame may remain feasible under suitable loads and geometry. A space frame may be considered where wider support spacing, two-way action, or roof form justify it.
At this span, total installed cost should be compared instead of steel tonnage alone.
Best Structure for a 100m Span
For a 100 m column-free roof, deflection, structural depth, connection forces, erection strategy, and temporary stability become major design issues.
A space frame is often one of the first systems to evaluate because of its three-dimensional load distribution. The final solution should still follow engineering calculations, functional requirements, local codes, and project logistics.
How to Choose a Large Span Steel Structure
The best long-span system fits the building operation, design conditions, fabrication plan, transport route, and installation method as a complete project.
From Structural Selection to Project Delivery
For a large-span warehouse structural system, racking, automation, and future expansion may drive the layout. For a large-span hangar structure, aircraft clearance, doors, and unobstructed floor space can dominate the design.
At XINGUANGZHENG, we provide customized support from preliminary solutions through design refinement, production planning, delivery planning, and installation assistance. Our technical team includes more than 100 senior technical personnel, and our business has reached more than 100 countries across six continents.
Our aviation-related project in Qingdao included structural laboratories and a UAV assembly test lab; installation from steel-column entry to completion of the space-frame erection was finished within 33 days.
For early evaluation, we recommend providing:
- project location and design standard;
- building dimensions and required clear span;
- building use, crane requirements, and door sizes;
- major roof and environmental loads.
With these inputs, we can compare suitable systems before developing a detailed project solution.
FAQ
Q: Space frame vs truss: which is better for a long-span roof?
A: A steel truss mainly carries loads in one structural plane, while a space frame distributes loads in three dimensions. Space frames are especially useful for very wide or complex roofs.
Q: What is the best structure for a 50m clear span building?
A: Steel trusses, engineered portal frames, and space frames can all be considered. The final choice should compare loads, deflection, roof depth, foundations, transport, erection, and total installed cost.
Q: What is the most economical large span steel structure?
A: There is no single most economical system for every project. The best value comes from balancing steel quantity, connections, fabrication, foundations, shipping, erection, and operational requirements.
