Save time and money with type statics
If you want to erect a structure, you often need an official permit. The prerequisite for this is usually static calculations, also called proof of stability or structural analysis for short. While simple or subordinate building projects often only require a simple proof of stability, buildings in the public sector and commercially used or larger buildings require a special proof of stability, which must be verified by a second, independent authority. However, when it comes to building law in particular, the details are regulated by the building ordinances of the states and municipalities, and their regulations often differ considerably from one another and change over time. In North Rhine-Westphalia, for example, roofs for bicycle parking spaces of up to 100 square meters do not currently require a permit, while elsewhere they do.
For customers who place an order for a roofing system to be used as a bus shelter, bicycle parking shelter or smoking shelter, the structural calculations that need to be performed mean a delay in the delivery process of up to three weeks. In addition, there is the time required for their review, and this can take months, depending on the workload of the reviewing engineering firm or agency. Finally, structural analyses and their testing are also a cost factor: in the case of bus shelters, they account for an average of around 30 percent of the actual construction costs.
One for all: type statics
Time and costs that can easily be avoided: structural analyses for standard structures can be prepared independently of the building application and checked by an independent institute. These type tests or type statics then apply nationwide. If a building permit is applied for, the issuing authority only has to check whether the structure applied for complies with the type statics. Usually a formality.
Although type statics are practical, their importance has decreased in recent years. Experts cite several reasons for this: Many builders want to design and build more and more individually, and at the same time the cost of type statics is becoming ever greater. Finally, there are only a few organizations that perform the independent type static tests, namely the State Office for Construction and Transport in Thuringia, the State Trade Office of Baden-Württemberg, the State Trade Office of Bavaria, and the German Institute for Structural Engineering DIBt in Berlin.
On the safe side
But what does a structural analysis actually mean, and how does a structural engineer go about his work? The aim of structural analysis of building structures is to ensure their safety and reliability. To determine possible hazards, the forces acting on a structure and their mutual effects are calculated.
The basis for every structural calculation is the determination of the framework conditions. Shelter systems, for example, have different profiles and material thicknesses, materials used, dimensions and a building grid, structures, materials for the fillings such as a sheet metal roof or glass side panels. In their interaction, these elements must safely support all occurring loads and the various loads acting from the outside at all times.
Since these loads are site-dependent, acceptable limits are specified for wind and snow loads in type structural analyses. Many factors have to be taken into account: In the North German Lowlands, for example, increased snow load requirements have been known since 1980. Accordingly, the snow load permitted here was designed as 2.3 times the normal. Wind loads, on the other hand, depend on terrain structures such as the surrounding buildings and are also height-dependent.
In his calculations, the structural engineer must also take into account the type of fastening of the system, for example, a waiting hall. Finally, evidence of the quality of production is required, as well as constant checks on, for example, the welding processes used and permitted, and the qualifications required.
The structural requirements for a structure are nowadays ensured throughout by standards, the same applies to the permissible calculation methods, materials and fastening systems. For a bus shelter, between 20 and 30 of these standards must be observed and met. However, the customer does not have to worry about their compliance. Another advantage for the customer is that compliance with the standard limits have an impact on his liability. Anyone who has done everything right is automatically on the safe side here and also benefits from the guaranteed high manufacturing quality.
The demand for type statics is increasing again, and type statics are also increasingly in demand in areas where building regulations do not even require certified statics. For companies, the aspect of quality assurance certainly plays a role.
Type testing ex works
The numerous advantages were reason enough for WSM - Walter Solbach Metallbau GmbH - to have a type test carried out by the Landesgewerbeanstalt Bayern (LGA) for variants of its popular Shelter systems Köln. These test certificates are valid for halls up to 4,195 mm wide and 2165 mm deep and allow complete freedom of design.
According to type testing, the Köln and Mannheim model series are designed for snow (Sk = 1.9 kN/ m²) and wind loads. The characteristic Sk value in the snowiest zones (3) in Germany is greater-equal to1.10 kN/ m². The constructions are also permissible for wind load zones I - III and are thus approved throughout Germany. Only some coastal sites and other extreme locations are exempt.
The roofing type Köln has a flat roof made of weatherproof profiled sheet. Its supporting frame structure is made of galvanized steel profile tubes, which is coated with freely selectable colors (RAL). The Shelter system includes base plates for dowelling and wall elements made of toughened safety glass (ESG).
The Mannheim model is also covered with weatherproof profiled sheet. As with the Köln variant, an integrated drain directs rainwater through the frame structure, while water spouts drain it away just above ground level. Side elements, such as opaque corrugated metal walls, can be customized. A variety of claddings, including trapezoidal sheet, corrugated aluminum, toughened safety glass, trellis or wood, are available.
The Shelter systems Köln and Mannheim each have an LGA-tested type static and are delivered ready-made by WSM. This minimizes assembly times as well as disturbances due to the installation time quite considerably. Due to their welded construction, both systems can be easily disassembled and reassembled at other locations even after years of use.
Good advice is - free of charge
The building regulations of the federal states and local authorities specify who needs a stability certificate for which structure and what expenditure is to be expected. These are very different and are constantly evolving. "We therefore recommend that our customers first submit a general building application to the relevant authorities for new projects; this provides clarity," explains Christian Mortsiefer of WSM. "However, our customers also receive initial free information and all-round support from planning to testing to installation from us."
Conclusion: Type static analyses save builders time and money in many cases. But even if no independent structural analysis is required, it remains good to know that the structure has been carefully manufactured and tested, and that nothing can go wrong here in terms of structural analysis and quality.