Beams

This multitab dialog box enables to perform checks of beams made of rolled or welded I-beams, rolled channels and rectangular pipes? welded boxes. The dialog contains five tabs: General Properties, Section, Restraints, Loads, and Web Stiffeners.

The following checks are performed for the beams:

Check	SNiP II-23-81*	SNiP RK5.04-23-2002	SP 53-102-2004	SP 16.13330	DBN B.2.6-163:2010	DBN B.2.6-198:2014	ShNK 2.03.05-13
Stability of bearing stiffener	Sec. 7.12	Sec. 7.12	Sec. 9.5.13	Sec. 8.5.17	Sec. 1.5.5.13	Sec. 9.5.13	Sec. 9.13
Bearing stiffener in bearing	Sec. 7.12	Sec. 7.12	Sec. 9.5.13	Sec. 8.5.17	Sec. 1.5.5.13	Sec. 9.5.13	Sec. 9.13
Strength of girth weld	Sec. 11.5	Sec. 11.5	Sec. 15.1.19	Sec. 14.1.19	Sec. 1.12.1.19	Sec. 16.1.19	Sec. 13.5
Strength of bearing stiffener weld	Sec. 11.5	Sec. 11.5	Sec. 15.1.19	Sec. 14.1.19	Sec. 1.12.1.19	Sec. 16.1.19	Sec. 13.5
Strength under lateral force	Sec. 5.12	Sec. 5.12	Sec. 9.2.1	Sec. 8.2.1	Sec. 1.5.2.1	Sec. 9.2.1	Sec. 7.12
Strength under bending moment	Sec. 5.12	Sec. 5.12	Sec. 9.2.1	Sec. 8.2.1	Sec. 1.5.2.1	Sec. 9.2.1	Sec. 7.12
Bending strength taking into account plastic deformation	Sec. 5.18*	Sec. 5.18	Sec. 9.2.3	Sec. 8.2.3	Sec. 1.5.2.3	Sec. 9.2.3	Sec. 7.18
Stability of in-plane bending under moment	Sec. 5.15	Sec. 5.15	Sec. 9.4.1	Sec. 8.4.1	Sec. 1.5.4.1	Sec. 9.4.1	Sec. 7.15
Lateral-torsional buckling taking into account plastic deformation			Sec. 9.4.6	Sec. 8.4.6	Sec. 1.5.4.6	Sec. 9.4.6
Web slenderness based on local stability constraint	Sec. 7.1. 7.2, 7.3, 7.4-7.6*, 7.9, 7.10	Sec. 7.1. 7.2, 7.3, 7.4–7.6, 7.9, 7.10	Sec. 9.5.1–9.5.9	Sec. 8.5.1–8.5.9	Sec. 1.5.5.1–1.5.5.9	Sec. 9.5.1–9.5.9	Sec. 9.1 –9.6; Sec. 9.10, 9.11
Flange overhang (flange plate) slenderness based on local stability constraint	Sec. 7.24, Table 30	Sec. 7.34	Sec. 9.5.14	Sec. 8.5.18	Sec. 1.5.5.14	Sec. 9.5.14	Sec. 9.24
Height to thickness ration of the beam web	Sec. 7.4*	Sec. 7.4	Sec. 9.5.3	Sec. 8.5.3	Sec. 1.5.5.3	Sec. 9.5.3	Sec. 9.5
Strength for reduced stresses at the simultaneous action of the bending moment and the lateral force	Sec. 5.14*	Sec. 5.14	Sec. 9.2.1	Sec. 8.2.1	Sec. 1.5.2.1	Sec. 9.2.1	Sec. 7.14
Strength for local normal stresses under the concentrated force	Sec. 5.13	Sec. 5.13	Sec. 9.2.2	Sec. 8.2.2	Sec. 1.5.2.2	Sec. 9.2.2	Sec. 7.13
Deflection of beam

In the case when the maximal normal stresses in the beam section exceed the design strength of steel, the local stability check of the beam webs and flanges is performed allowing for the development of plastic deformations.

If the web has such a slenderness that the element can be classified as an element with a flexible web, the application outputs the Ratio between height and width of the web factor with a value greater than 1,0. The calculation of elements with a flexible web is not implemented in the program due to the extremely limited scope of the method for calculating such structures (only for continuous beams bearing the static load).

Limitations

There is no analysis of welds attaching the web stiffeners and no check of minimum sizes of the welds for compliance with Table 38* of SNiP II-23-81* (Table 35 of SP 53-102-2004, Table 38 of SP 16.13330, Table 1.12.1 of DBN B.2.6-163:2010, Table 16.1 of DBN B.2.6-198:2014).

The procedure of the stability check of beams (stability of in-plane bending) implemented in SNIP "Steel Structures" requires information on the type of load and its application area (top or bottom chord). The codes provide recommendations only for a few particular cases, when all the loads are applied only to one chord. How to proceed in the cases when there are different loadings and moreover, bending moments are taken from the envelope, rather than from a single specific loading, remains unclear. Therefore, developers of the program (focused on the consideration of the loading in the general case) have assumed that in the calculation of the coefficient $\psi$ we consider the case of a distributed load, without analyzing the particular cases given in Table 77 of SNIP II-23-81* (all further modifications of the codes have not made any changes to this problem). However, a special dialog box can be invoked by clicking the button $image\kristall_74.jpg$ , where you can select one of the rules for calculating this factor provided by the codes (the user is responsible for the consequences of this selection), or use the Default button to return to the standard behavior of the program (described above).

The General Properties tab is used to specify the span of the beam. Moreover, the Structural scheme group contains radio buttons for specifying a system of web stiffeners:

without stiffeners;
bearing stiffeners only;
bearing and intermediate stiffeners.

If a structure with intermediate stiffeners has been selected, you need to specify their spacing in the respective field. It does not have to be an exact submultiple of the beam span; the end segments of the beam will be adjusted to fit.

After checking the respective checkboxes, you can specify limitations of the absolute deflection value (for characteristic and/or characteristic long-term loads) or of the natural oscillation frequency in the Limitations group. In the latter case you can specify the weight of the connected mass which will be added to the own mass of the structure. The deflection limit for the beam is specified in fractions of the span length (it will be compared with the relative deflection under the loads with design values which correspond to the serviceability limit state). You can specify the deflection of the beam in fractions of the span expressed as 1/А where А is one of the most frequently used values (500, 750 etc.).

Note that no special factor is introduced for the deflection in Kristall — the application only calculates and outputs the maximum deflection value.

In cases when the user for some reasons does not want to go beyond the elastic behavior, he can use the Inelasticity is not allowed checkbox provided in this tab.

The Section tab is used to assign a cross-section to the beam.

If the section is a rolled I-beam or a channel then it should be selected from the catalogues. If the beam cross-section is a welded I-beam, then you need to specify the sizes of its constituent sheets. The thickness of the sheets can be either taken from the suggested list (they comply with those in the assortment) or specified by the user.

This tab also contains a text field for specifying the leg of girth welds. This field becomes accessible when a welded I-beam is selected.

The analysis can be performed with the account of corrosion like in the Resistance of Sections mode. The difference is that the built-in corrosion calculation module (invoked with the button $image\calc.png$ ) does not require you to specify the inclination of the member to the horizon.

The Restraints tab contains two groups of buttons for specifying a system of beam restraints in and out of the bending plane. The selection within each group is performed independently by clicking a respective button. If the last model of restraints out of the bending plane is selected, a field for specifying the number of segments of the beam span will appear.

The check of the entered initial data is performed with the help of a table displaying the selected system of restraints.

The Loads tab is used to specify the loads acting on the beam. This tab is nearly identical to that from Envelopes mode. The difference is that an application area (top or bottom chord) of the considered loads has to be specified, which is assumed to be the same for all components of the current load case. Moreover, you have to specify the width of load application for a "concentrated force". It should be noted that if you place the cursor in the window displaying the diagram and click the right mouse button, this will display a beam cross-section with isofields of normal and shear stresses depending on the specified parameters and corresponding to the section defined by the cursor position.

The Web Stiffeners tab, which appears if you select the respective structural scheme, is used to specify the sizes of the bearing stiffener and the leg of the weld that attaches this stiffener to the beam web. If the design of the beam with both bearing and intermediate stiffeners is selected, it necessary to specify the spacing between the intermediate stiffeners in the Spacing of stiffeners tab, define their type, and specify their width and thickness in the respective fields..

The type of intermediate stiffeners (single-sided or double-sided) is selected using the respective buttons. The sizes of the stiffeners specified in milimeters are checked for compliance with the requirements of codes concerning the width and the thickness of the protruding part. It is assumed that the width of the bearing stiffener should be not less than that of the narrowest flange of the I-beam.

The Factors and Find buttons (the latter is available only for the rolled-profile beams) enable you to analyze the calculation results or to perform the search of cross-sections.

It should be noted that the search of sections will be based only on the strength and stability conditions, if you have not specified a deflection limitation in the General Properties tab. The limitation of the natural oscillation frequency does not affect the results of the search.

Moreover, the report document will contain a table with design combinations of support reactions. During the working session, values of the support reactions obtained for their most unfavorable combinations of loadings are displayed in the Support reactions dialog box, which can be invoked by clicking the respective button, $image\kristall_65.jpg$ , in the Loads tab.