I undergoing the engineering profession since 1978, since 1983 I am a self employee in my study, although I have a degree in civil engineering, for many years I have dedicated myself to the mechanical design, currently I have specialized in the calculation of structural steel, wood, aluminum and reinforced concrete, by a dozen years I have also studied the technique to consolidate the foundations, special foundation and the calculation of micropiles; work often for Enterprise Earth With my friend Paolo Gioda.
The method for the structural dimensioning in recent years there has definitely evolved with the method of finite elements calculation.
Once the calculation of structures was rather empirical, evaluating the stresses acting on a beam or a column based on the diagrams in the engineering manuals and with the method of allowable stress consisting of controlling wheather the section that is presumably more stressed resists the stresses to which it was designed for in the toughest conditions, only very important structures, such as large public works were calculated by laborious programs run by large mechanographic computers.
Currently, following the regulations, all facilities shall be calculated by the finite element and the sections must check with the method known as limit states. The only exceptions are some areas where the land is classified as low seismicity it is still permissible to verify allowable stresses.
The finite element calculation provides that the frame of a structure, subject to the action of different forces (including also the inertial forces induced by the earthquake) is analyzed as a whole by identifying each individual auction component and each individual node in which converge the above auctions.
The rods interact with each other and are determined by successive approximations, in any case of load, the stresses on the same; then with the method limit state occurs that each section of the individual elements is capable of supporting with good safety margin the stresses where each element is subjected, in practice occurs that each section of each element is affected by a lower voltage, with a large safety factor, to that breaking point; in addition to verification of the resistance of the materials and of the sections, we analyze all the deformations and if the vibration of the structure.
As you can imagine, the current method of calculation, which is purely mathematical, it is much more accurate than the previous method engineering, fortunately today's computers enable us to carry out briefly the calculations that once would have required a very long time.
The finite element is therefore very useful for the design of the support of our dear amateur radio antennas.
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