In the realm of theatrical productions and event staging, trusses form an integral part of the structural framework. But one key question we encounter is, “When assembling a truss, should the cross members meet at a triangle where bolted or pinned?” The short answer is yes, particularly when we’re dealing with widely used truss systems like Tomcat or James Thomas truss.
The main reason lies in the inherent strength of triangular shapes. According to the American Society of Civil Engineers (ASCE), a triangle is the only geometric shape that retains its shape when force is applied on its sides (ASCE, 2020). This property, known as structural rigidity, ensures that the truss system, made of numerous interconnected triangles, can effectively distribute the loads and resist deformation.
Moreover, the American National Standards Institute’s ANSI E1.2-2012 – Entertainment Technology: Design, Manufacture and Use of Aluminum Trusses and Towers specifically highlights the role of diagonals, often forming a triangular shape with the chords, in the overall truss design. It states that these members “provide the primary resistance to axial compression and buckling” (ANSI, 2012, p. 8).
When dealing with standard 2” box truss structures, whether constructed from aluminum or steel, adhering to this assembly pattern becomes essential. These materials, despite their robustness, can buckle under extreme stress if not correctly configured. By ensuring the cross members meet in a triangular formation at their bolted or pinned connections, the strength of the truss system is optimised, and potential safety hazards are minimised.
However, while understanding the geometric fundamentals is crucial, the assembly of truss systems should always follow the manufacturer’s specific guidelines. The James Thomas Engineering Ltd., for instance, provides clear instructions in their General Purpose Truss Assembly Guide, emphasising the need for professional installation and correct alignment of components (James Thomas Engineering Ltd., 2015).
In conclusion, the triangular configuration in truss assembly is not merely a design preference but a structural necessity. It ensures strength, stability, and safety, enabling the truss system to perform its duty reliably in various entertainment setups.
References:
American National Standards Institute. (2012). ANSI E1.2-2012 – Entertainment Technology: Design, Manufacture and Use of Aluminum Trusses and Towers. https://webstore.ansi.org/standards/esta/ansie12012
American Society of Civil Engineers. (2020). Understanding Structural Analysis. https://www.asce.org/publications-and-standards/
James Thomas Engineering Ltd. (2015). General Purpose Truss Assembly Guide. http://www.jthomaseng.com/uploads/files/general_purpose_truss_assembly_guide.pdf
