ES-Consult has since its establishment completed several tasks related to important civil and structural works and has also carried out many special assignments in the category of applied sience. A very important part of the activities of the firm has been assistance and technical consultances to building- and infrastructure owners.
Here follows descriptions of a series of ES-Consult's special services.
Stability of Structures
Staff members of ES-Consult have many years of experience in solving complicated stability problems related to structures. The problems have included flexural buckling of elements, lateral torsional buckling of beams, plate buckling and combinations of these forms of instability phenomena.
Some problems have been solved as genuine research or development projects and the results have been published in distinguished international journals. Other problems have been related to specific structures where a deeper analysis has led to optimum and economic solutions.
In connection with the design of buildings for power plants a special type of column was needed to transfer the very high loads from the boiler girders. This column required a high load-carrying capacity with respect to plane and torsional buckling combined with good material economy and the possibility of simple connections with the other structural elements. The solution was a column with a cruciform cross section for which the load bearing capacity with respect to torsional buckling was markedly improved by an arrangement of battens providing a "vierendeel effect".
Similarly, a method has been developed for restraining compression elements in triangulated bracing structures in connection with the design of buildings for power plants. Instead of using secondary lattice elements, a simple connection between tension and compression members resulted in simpler detailing.
In connection with the design of pipelines, an evaluation has been made of the stability of the tubes under longitudinal compression due to a rise of the temperature. The tubes are regarded as beam-columns in an elastic medium. The assessment had to take into account the fact that the elastic restraint only acted for downward deflections. For upward deflection the transverse load stems from the self-weight and the overlying earth masses.
As another example of a stability problem that the firm has investigated, we mention a research project dealing with the improvement of the capacity of beams with respect to lateral-torsional buckling. The solution suggested was to weld tube-shaped transverse stiffeners to the web of the beam. The torsional rigidity of the tubes decisively reduces the tendency of the beam cross section to warp and thus increases the critical buckling load. The method has been made operational by developing a computer programme for solving the resulting differential equations. In a cooperation with The Technical University of Denmark the method has been verified by laboratory tests. The tests showed good agreement with the theory and thereby verified the applicability of the method.