What is a static calculation?#

Often we get the question of what a static calculation (or structural analysis) is and who can create it. This article is intended to give insight into the topic.

A static calculation documents the stability and serviceability of a building.

As a rule, it is divided into the following parts:

• Title page
• Tasks
• Table of Contents
• Preliminary remarks
• Overview drawings, position plans, construction sketches
• Load assumptions
• Calculations and verifications
• Bearing forces (connection force tables)
• Final page with signature
• Appendix

Why do I have to conduct a static calculation?#

In event technology, we are usually dealing with temporary structures that have only a short service life compared to normal buildings.

Building codes include therefore the term flying (or temporary) structures.

(1) Flying structures are structures that are suitable and intended to be repeatedly erected and dismantled at different locations. Construction site equipment and scaffolding are not flying structures.

An application for an execution permit - "model approval" - is required for these structures before they are first erected and put into operation.

There is an exception to this obligation for smaller stages. In Brandenburg (Germany), for example, this applies to stages up to 5m in height, a floor area of up to 100sqm and a floor height of up to 1.5m. In other federal German states, other values may apply.

Simple truss constructions are usually not flying structures, as are not meant to be repeatedly rebuilt. They are therefore not subject to the obligation to obtain an execution permit.

The accident prevention regulation DGUV regulation 17 Event and production venues for scenic representation applies to the stage technology and performance area of event venues as well as production facilities for film, television, radio and photography.

As a rule, truss constructions are built in this context, so the regulation must be applied.

The following paragraphs are of particular interest:

§4 Stability and load-bearing capacity surfaces and superstructures must be designed and constructed in such a way as to be set up, supported, braced, suspended and anchored in such a way that they can absorb and dissipate the static and dynamic loads arising from the intended use. They must also be stable during assembly and dismantling and, when accessed, load-bearing.

§ 9 Load bearing suspensions and slings suspensions and slings must be designed and sufficiently dimensioned in accordance with the particular hazard involved during operation and the loads occurring during operation.

The truss constructions must therefore be dimensioned in such a way that they can withstand the loads. Of course, adherence to this criterion must be demonstrated. The simplest option is through a static calculation. Another possibility would be a test setup with stress tests. This type of proof is usually not common in event technology because it is very cost-intensive.

The static calculation must of course be documented.

If the constructions are set up at a trade fair, the technical rules of the trade fair company must be observed.

What are test statics?#

Who is allowed to conduct a static calculation?#

In principle, a distinction must be made between a testable and a tested static calculation. Tested static calculations can only be made by inspecting structural engineers. Special requirements are placed on them, and among other things, they must be officially recognized as such.

In principle, anyone is allowed to set up verifiable static calculations. These static calculations only have to meet certain requirements in terms of traceability.

Anyone who makes a static calculation is liable for its correctness. Liability can quickly pose a major risk. Inspecting structural engineers therefore usually have insurance that covers these risks.

Usually, event technicians do not have such insurance. So if they create a static calculation, they may incur large personal liability risks.

The calculations that can be created with Production Assist can be used to create a testable static calculation. In any case, however, they are a helpful means of making a principled assessment of the static system.

Requirements for a static calculation#

The following requirements are to be met for a static calculation:

• Each calculation must be self-contained.
• It must be suitable for further use by third parties.
• It must be fully and clearly structured.
• It must be legible and verifiable.
• It must be able to be copied or scanned.
• The structural safety and serviceability must be complete, clear and provable for all components and connections according to their intended structural function.
• It must contain all the necessary information for the connection design and a special connection statics.
• Printouts of computer-aided calculations must be complete, comprehensible and reproducible (see also vpi (2001), para. 4). Authoritative results of the calculations should be highlighted (e.g., the internal forces used for the proofs).

According to Bangert, et al. (2000), Requirements for structural documentation of steel structures

Summary#

In general, in event technology, anyone can create a static calculation from a legal point of view for most areas of application.

However, the person who creates these is usually personally liable for the correctness and completeness. In particular, it is difficult for many event technicians to gain a comprehensive overview for the purpose of completeness. To provide verification for simple truss sections, usually with the manufacturer's specifications, further proofs are often required for complex structures such as raised floor systems and frame constructions.

Such documentation and verifications can also be managed with software such as Production Assist, but you have to know that you need them.

Production Assist are good tools for non-structural engineers to plan a system and to get a rough estimate for the load capacity. But if the required expertise for to conducting a complete assessment is lacking, you should get professional help. File exchange via DSTV export and other interfaces available here enable simple exchanges of information. (We at Production Assist are also working on a special solution for this issue, so stay tuned...)