2. Calculation of rolled beams

Analysis of beams is carried out in two groups of limit states. The first limit state leads strength calculation, general and local sustainability, and the second limit state shall calculate the deformations.

Selection section rolled beams can be performed in the following sequence:

1. Defines the type of cells girder step beams span of the beam;

2. Collected by loads per meter beams based on a load from her own weight (of the weight load beam is taken approximately);

3. Determined calculation scheme beams and build epures of shear forces and moments

4. Accept steel and finding it design resistance; establish conditions of work coefficientγ_с.

5. Moment is determined by the maximum required moment resistance

6. Product mix of rolled profiles finds the girders having moment of resistance, which is equal to or somewhat more of the desired. Picked up for the I-beam write out actual values: the moment of resistanceW_x; the moment of inertia I_x; I-beam cross-sectional area А.

7. For the control section chosen to perform a check chosen an I-beam section

8. I-beams made ​​from rolled profiles, under the action of uniformly distributed load cannot count on the strength of the shear stresses. But in the case of exposure to concentrated forces should be checked chosen section.

Calculation is carried out on beams deformation.

If deflection gets more limits should increase cross-section beams and re-perform the scan deflection. Analysis of beams from rolling sills produces similar analysis of beams of rolled I-beams.

Deflection of beams is determined by regulatory action loads, as this calculation refers to the second group of limiting conditions.

3. Girder cells

Girder system cell called cross beams designed for supporting decking at the device of over any area of ​​overlap.

Beams, supported by columns or walls, are called the principal. Rely on the main beams cross beams that are serve as supports for the longitudinal beams. Transverse and longitudinal beams are often called secondary or auxiliary. Longitudinal beams support the deck (concrete or steel). By flooring sometimes even arranged floor. The floors are wood, asphalt, clinker, iron, etc. (depending on the technology).

Girder cells are used very often, for example, in suspended ceiling for intrashop work sites in the roadway bridges, etc. Thefollowingtypesofbeamcells:

a) simple (there are only the main beams);

b) normal (consists of main and cross beams subsidiary);

c) complicated (there are three types of beams).

Load on the any element girder determined by the magnitude of cells corresponds to this element of cargo Square.

Beam loads cells are to: a) proper mass building structures, b) the weight of the payload and stationary equipment, and c) the weight in Mobile Equipment (cranes) and of railway and motor transport.

Conjugation in one level is so called because the top shelf of the main and secondary beams are placed in one level. Advantages of this conjugation - lesser Construction height pairing.

a - simplified girder cell b - girder normal cell, с - complicated girder cell, 1 - the main beams, 2,3 - decking beams.