Aluminium Structures in the Entertainment Industry

Reviews

 “I decided that it was but a short jump from a half a dozen articles to a book,” Peter Hind wrote to me in an e-mail message. Writing a book, rather than the series of short articles Peter Hind has done in the past for Protocol, is more like a running leap than a short jump. Hind has managed to do it and land on his feet. Certainly anyone interested in the design and use of aluminum structures in the entertainment industry, and who has a bit of background in high school-level physics should find Aluminium Structures in the Entertainment Industry interesting and informative reading.

Hind’s book offers sixteen chapters covering a variety of topics related to aluminum trusses and aluminum staging systems. He starts with the fundamentals and works up to applications. Chapters one and two are about aluminum: how it’s welded, what alloys are used, how it reacts in weather and under load, and how its strength is affected by heat. Chapter three is about how structures react to forces on them, and it’s applicable to steel or wooden trusses as well as to aluminum ones. Chapter four looks at some of the designs of trusses and towers that are on the market and points out some of their weak points. Hind does this while avoiding turning the chapter into a commercial pitch. Chapters five and six cover design standards and safety factors. Chapters seven through twelve analyze the forces involved in vari-ous truss applications, while chapter thirteen looks at the forces involved in stages, both from the supported load and from wind outdoors. Chapter fourteen covers user information, inspection, and records maintenance. Chapter fifteen, entitled “Safety” is almost devoted to fall arrest systems, but the chapter is less informative about fall arrest than it is about Total Fabrications’ T2 truss system. This is the only chapter in which the balance is off be-tween generic information and commercial interests. The final chapter is a look to the future, where Hind questions if stage structures can get much larger using current technology, but he sees greater professionalism and accep-tance of responsibility by those designing and building temporary aluminum structures.

There’s a lot that is very good about the book. Personally, I found the sections dealing with the fundamental properties of aluminum and dealing with wind loads out-doors most interesting. Intuitively I knew that aluminum bends, yields, and breaks differently than does steel, but Hind’s discussion and graphs in chapter two make the differences clear. I also found the information about aluminum’s loss of strength at elevated temperatures interesting. Hind points out the folly of backing up synthetic roundslings with steel cables to stop a truss from falling in the event of a fire by quoting U.S. OSHA regulations for slings, but a graph in chapter two shows that at 233 degrees C, about the flash point of paper, 6082-T6 aluminum has lost more than half its tensile strength. A truss will fail in a fire, whether the slings hold or not. The sec-tion in chapter twelve on guy ropes and wind loads was also interesting. The technique of using ballast to terminate the guy ropes is discussed in great detail, with lots of trig formulas and coefficients of static friction. It takes a lot of weight to provide a moderate amount of horizontal bracing.

Aluminium Structures in the Entertainment Industry is a good book, but it’s not a great book. It’s not clearly written in some spots and it skips at least one important issue in using trusses. The lack of clarity comes from Hind’s conversational writing style: he starts with a topic and deals with it for a while, then he switches to something else that’s important but tangentially related, and then he moves off, either back to the original topic or off to another one before finally returning. If the reader is unfamiliar with basic concepts such as force vectors, this meandering structure can be confounding. There is also the free exchange in the text of measures of mass for measures of force that is common in practical engineering, but that can get the novice confused.

The topic that I wish Hind had covered in more detail is how one calculates the loading on chain hoists supporting a truss. Calculating this when a straight length of truss is supported by two hoists isn’t hard, but when three or more hoists are used, the structure becomes “a statically indeterminate structure.” According to Hind, these structures have to be analyzed using a computer program or by hand using one of three methods, which he names. However, he refers the reader to “standard engineering text books” to find them. It would have been nice if he had presented at least one of these methods in Aluminium Structures.

In spite of these few complaints, I can recommend Aluminium Structures in the Entertainment Industry to readers of Protocol who are involved in specifying or using trusses. Reading the book won’t turn you into a structural engineer, but it will give you a better understanding of trusses and should help you avoid mistakes that could cause your aluminum structures to fall flat.

Karl Ruling, PROTOCOL magazine

Peter Hind is a renowned engineer within the entertainment business, and has been involved with many publications and regulations, including various British Standards, the 'Pop' code, as well as being an active member of the task group rewriting Temporary Demountable Structures for the Institution of Structural Engineers.

This book is aimed at all those who may be involved in using or designing aluminium structures, from riggers to the owners of such systems. In the book, a quote by Dr Dykes of the Institution of Structural Engineers is worth repeating: "Engineering is

the art of modelling materials we do not wholly understand, into shapes we cannot precisely analyse, so as to withstand forces we cannot properly assess, in such a way that the public has no reason to suspect the extent of our ignorance.

There is, of course, no room for making mistakes as invariably the structures

discussed are in the most dangerous position possible -above our heads. The author realises the significance of ensuring that the designs and implementation of such systems are got right, and first time. Accordingly. the book is not for the mathematically faint-hearted, but for those just wanting to understand more or to care for their investments and spot signs of failure. there are plenty of examples and points to consider when maintaining such systems. In order to design and make use of structural elements, however, the reader is first guided through structural theory and response (e.g. how a structure responds to differing loads by bending or flexing) before taking a look at the elements normally encountered such as trusses and tower sections. Design standards and safety factors are covered before going on to look at the practical applications of structures.

Assessment of loads is a fundamental element of designing a truss system, and the author not only covers those areas one would expect such as static weight loadings due to lamps and such like, but also the less determinate aspects such as possible forces exerted by a person falling off the truss while secured by a safety line. Ground support systems and their foundations are looked at in some detail, and consideration and calculations given to environmental aspects such as wind and rain loading. Finally, the author goes on to look at inspection and testing of trusses and related components, and the safety aspects involved -not only in working at height, but also at ensuring the equipment is fit for purpose. The book, while being necessarily mathematical, is well written, informative and well illustrated throughout. It's well worth reading if you encounter truss or other such structures as part of your work.

Lighting and Sound International magazine, Nov 2002