FEA calculations

Will it hold or will it not – there are two ways to settle that question. You can build it and check, or you can calculate first. The second way is cheaper by an entire structure.

We carry out strength calculations using the finite element method, for structures being designed and for structures already standing. FEA makes it possible to determine the utilisation of the whole system and of individual members while the design is still on the drawing board – and, in existing facilities, to identify the cause of a failure and select the method of repair.

What FEA gives you

The finite element method divides a structure into small fragments and calculates how they act on one another. In practice this means that the critical locations – the ones where stresses accumulate – become visible before anyone orders the steel.

The calculations let us define three properties of a structure precisely: strength, stiffness and durability. The gain is twofold – the design comes together faster, because there is no need to go back to the assumptions after every doubt, and the structure itself can be lighter, because there is no need to hedge with surplus material where the calculation shows spare capacity.

Scope of analyses

We run static and dynamic analyses of existing and planned structural systems, elastic-plastic analyses, wind load calculations, thermal studies and calculations for heat exchangers. Fatigue and seismic analyses form a separate group – needed wherever a structure works under variable loading.

For structures with unusual airflow around them we carry out computational wind flow analyses (CFD) – for installations on high-rise buildings, on irregular façades and in the gaps between buildings, where tabulated wind load values stop matching reality.

What we calculate with

We work in DLUBAL/RFEM, IDEA StatiCa and Robot Structural Analysis, supplemented by our own engineering calculators. IDEA StatiCa Connection serves us for steel connections: it determines joint capacity, critical load factors and rotational and shear stiffness, with verification against national standards. RFEM calculates internal and support forces, deformations and soil contact stresses in systems built from plates, walls, shells and bars.

Which tool we choose depends on the question that needs answering. Not every analysis calls for a three-dimensional model of the entire facility – sometimes a single joint, calculated properly, settles the matter.

Structures for photovoltaic installations

This is a separate field, and one where the Eurocodes do not provide a full basis for calculation. For ballasted structures we draw on the Dutch NEN-ISO standards, for wind flow analyses on the German DIN and American ASCE standards, and on the technical literature.

We have developed our own method of ballast selection based on the PN-EN and NEN-ISO guidelines. It takes account of the fact that gusts at the edges of a roof are stronger than in the middle of the slope, so the ballast should not be distributed evenly either. We determine the capacity of thin-walled sections using restrained warping torsion – so that the structure stays light and cheap to manufacture and is nevertheless safe.

We calculate in four areas:

• Static and dynamic analyses of structures
• Fatigue, seismic and thermal analyses
• Computational wind flow analyses (CFD)
• Calculations for photovoltaic support structures