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Traditional patterns

The Peiner-Schnittführung (also known as: Litzka-Schnittführung)

Various choices have to be made when dimensioning castellated beams. On the Continent, traditionally, the so-called "Peiner-Schnittführung" is often used for the rack-shaped cut. This pattern is also known as Litzka-Schnittführung. It is characterized by the following three basic assumptions:

  1. the height ratio H/h is set at 1.5 (in other words, the depth of the castellated beam H is one and a half times as great as the depth of the rolled section before cutting, h)
  2. the pitch is assumed to be equal to the depth H of the castellated beam
  3. the angle α is set at 63.5° (to be precise, tan α = 2)

These three assumptions define the entire castellated beam. The weld length at the top of the tooth is h/2; the greatest width of the web opening is h. The depth of the web opening also is h.

Anglo-Saxon castellated beams

In England, America and Canada the traditional design is different. Here the angle α has traditionally been set at 60°. The ratio H/h of the nominal dimensions is taken as 1.5; and the pitch is set at 1.08 times the height of the web opening. The height of the web opening is chosen as in the Peiner-Schnittführung, namely equal to the nominal depth h of the profile before cutting. These assumptions result in a profile with shorter teeth. In the Peiner-Schnittführung, the weld length on a tooth equals 1/3 of the pitch; in the Anglo-Saxon tradition, the weld length on a tooth equals only 1/4 of the pitch. Since the weld length can determine the strength of the beam, the Anglo-Saxon castellated beam is therefore at a disadvantage in this respect.

As an example, we give a castellated beam based on the beam UB-914x419. In Anglo-Saxon countries DIFFERENT rolled sections are used than in Continental Europe, in inch sizes. UB stands for "universal beam" and the actual dimensions of the master beam UB-914x419 are as follows: the nominal depth is 914.4 mm; the actual depth h is 921 mm; breadth over the flanges 420.5 mm; web thickness 21.5 mm and flange thickness 36.6 mm; radius 24.1 mm. The weight is 388 kg/m. The standard castellated beam made from the UB-914x419 is called a "castellated universal beam" 1371x419. The nominal depth of this beam is 1371 mm; the actual depth H is 1377.7 mm.

A comparison?

Is it feasible to compare the traditional Peiner pattern and the traditional Anglo-Saxon pattern? No, not really. Both patterns arose from the limitations of now completely obsolete production methods. With today's computer driven cutting technology there is absolutely no valid reason to hang on to such old-fashioned cutting patterns and designs. Nowadays it is possible to select the cutting pattern and the ratio H/h so that the castellated beam EXACTLY meets all technical requirements (as regards bending strength, deflection, transverse shearing, and buckling of the web). Traditionally, overdimensioning of the beam was unavoidable, but this is no longer necessary. These days we optimize the castellated beam according to economic criteria. Precisely made to measure, at your service!

©  Johann Grünbauer  Tel (+31) (0)20 6990300  E-mail info@grunbauer.nl TOP