Photovoltaic New Energy Basketball Courts (BIPV): Which Is More Cost-Effective, Truss Structures or Portal Frame Structures?

    How much does it cost to build a photovoltaic basketball court structure like this? Which structural option is both economical and better looking?

Project Overview

    Taking a standard basketball court 28 m × 15 m for an example, if adopting steel structure plan, it is 30 m (length) × 21 m (width), with a total installed PV capacity of 136 kW.

    Design load follows 0.4 kN/m² wind load and 0.4 kN/m² snow load. The column spacing is 6 m, and the height is 7.8 m.

Truss Structure Calculation Model

    Load-transfer: In a truss, loads are transferred through the joints. Horizontal roof loads such as dead load and snow load are transmitted through the purlins to the joints, then converted into axial forces in the members. 

    The members themselves generally undergo little bending deformation. In most cases, the top chord is in compression, the bottom chord is in tension, and the web members alternate between tension and compression.

    Joint spacing: The spacing of the top-chord joints is related to the purlin distance. If the purlins are arranged at 1.5 m intervals, then the joint spacing is generally also taken as 1.5 m. During structural modeling, the horizontal roof loads need to be converted into concentrated joint loads.

    Out-of-plane and in-plane effective length: Section 5.3 of the China Steel Structure Code provides explicit requirements for the effective length coefficients of chord members and web members.

Portal-Frame Structure Calculation Model

    In a portal-frame structure, the horizontal roof loads are transferred through the purlins and converted into bending moments and shear forces in the steel beams, causing beam bending deformation. The purlin spacing can be adjusted more freely and is not limited by joint spacing.

    The out-of-plane effective length of the steel beam is determined according to the out-of-plane bracing conditions and is generally taken as the spacing of the rigid tie members, which ensures the beam's out-of-plane stability.

Cost Comparison

    Steel Consumption of the Truss Structure

    The steel consumption for each truss is approximately 1,000 kg, with a total of 6 trusses.

    Total steel for 6 trusses: 1,000 × 6 = 6,000 kg.

    Tie members and bracing: 1,200 kg; purlins and sag rods: 2,500 kg.

    Total steel consumption for the truss scheme: 6,000 + 1,200 + 2,500 = 9,700 kg.

    Steel Consumption of the Rigid-Frame Structure

    The steel consumption for each rigid frame is approximately 1,500 kg, with a total of 6 frames.

    Total steel for 6 frames: 1,500 × 6 = 9,000 kg.

    Tie members and bracing: 1,200 kg; purlins and sag rods: 2,500 kg.

    Total steel consumption for the rigid-frame plan: 9,000 + 1,200 + 2,500 = 12,700 kg.

    Comparison: 12,700 − 9,700 = 3,000 kg. Therefore, the rigid-frame scheme uses 3,000 / 12,700 = 23% more steel than the truss plan.

Economic Span and Steel Intensity

    The economical span of a portal frame is generally 18–24 m, while the economical span of a truss structure is 30–40 m.

    The economical column spacing is generally 7.5–9 m. If the spacing is too small, the steel consumption of beams, columns, and foundations increases. If the spacing is too large, although the number of frames is reduced, the steel consumption of the purlins increases and the steel beam sections also become larger, making the solution uneconomical.

    Unit steel consumption of the truss structure: 9,700 kg / 630 m² = 15.39 kg/m².

    Unit steel consumption of the rigid-frame structure: 12,700 kg / 630 m² = 20.16 kg/m².

Conclusion

    For conventional steel-structure sports venues with spans of 18–24 m, the truss structure is superior to the rigid frame in terms of unit steel consumption. However, because truss structures have many welded joints and higher labor costs, their ex-factory steel price is generally significantly higher than that of standardized portal frame structures. 

    As a result, truss structures do not show a major advantage in overall cost under these span conditions.

    When the structural span exceeds 24 m, and especially when it reaches 30 m or more, the steel consumption of a rigid-frame structure increases significantly, and the advantages of the truss structure become more apparent.

    In addition, wind loads and snow loads vary by region, so the steel consumption for the same span can differ from one location to another. Large-span structures are particularly sensitive to snow load, and in regions with high snow loads, snow load has a much greater impact on the required steel quantity.

    For a standard photovoltaic basketball court measuring 28 m × 15 m, the total project cost is roughly around RMB 400,000. Depending on factors such as material price fluctuations, span, and region, the final cost may vary by approximately 10% to 15%.