Concrete and Timber

This section type provides options to specify regular shaped sections with a particular E (elastic modulus) and G (shear modulus) value. Although this option is most commonly used for modelling concrete and timber sections, it can also be used to model regular shaped sections of any other material by entering the appropriate E and G value.

Section Types

Material Type

This has the effect of setting the appropriate E and G values in the text boxes.

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Note, amending E values will affect the self-weight as specified in 📄 Member Global Density

Default E-value band:

0–20 → treated like timber/lightweight → about 10 kN/m³
20–200 → treated like concrete → about 24 kN/m³
200+ → treated like steel → about 77 kN/m³

If specifying a different E value, the user will need to manually control the self-weight. You'd have to turn this off and use member density specification instead. Read more in 📄 Member Loading Types

Choose a material type from

Steel

Concrete

When a T or flanged L concrete beam is defined

The flange self-weight is not considered and therefore no eccentricity is induced within the section when it comes to analysis
The presence of the flange only contributes to the compressive capacity of the section

Sawn Timber

Planed Timber

Regular Timber

Additional Timber Properties

When a timber material is selected further parameters are available regarding timber grade, no. of pieces and service class. Note that only the rectangular, square and circular section shapes are available in timber.

Flitch Beam

A flitched timber beam can also be specified by giving the number of timber and steel plate members along with the plate grade and size.

Select or enter the section dimensions.
You can enter any dimensions you wish in the white coloured text boxes, or you can select a dimension from the grey coloured drop list. The only difference between the sawn, planed and regular timber property options is the pre-set section dimensions that are available in the drop lists.

L- and T-Section Flanged Concrete Beams

Self Weight and Torsion

From https://files.masterseries.com/documents/DefiningTorsion-in-MasterFrame.pdf

By default, MasterFrame assumes that member loads act through the shear centre of the section and therefore do not induce local torsion unless an explicit torsional eccentricity is applied.

For symmetrical sections, this is usually a reasonable assumption. However, for asymmetrical sections such as L-sections, T-sections, channel-type sections, and built-up members, the centroid and shear centre are not coincident.

In the case of single-junction sections such as L-sections and T-sections, the program does not automatically include torsion arising from the self weight of the flange or leg. Therefore, the self weight of these sections is not treated as an eccentric load that would induce torsion in the analysis.

For these section types, the engineer should review whether torsional effects are likely to be significant and apply engineering judgement where necessary. If torsion due to load eccentricity needs to be considered, the load should be defined with an appropriate torsional eccentricity measured from the shear centre. Example below.

As a guide, for single-junction members such as L- and T-sections, the shear centre lies at the intersection of the centre-lines of the flange and web/leg.

Accordingly, to model an eccentric load on an asymmetrical section correctly, the required eccentricity should be taken as the distance from the shear centre to the line of action of the applied load.

Example Scenario

A concrete 'L' beam is supporting a block wall of 10kN/m run, 1.775m from the shear centre.

The user can input Torq ecc Loads as outlined in the 📄 Member Loading Types

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MasterFrame assumes that loads act through the shear centre and therefore do not induce local torsion unless a torsional eccentricity is specified by the user. For L-sections and T-sections, the program does not automatically account for torsion due to the self weight of the leg or flange, so no torsional effect from self weight is included in the analysis by default.

Because these are asymmetrical sections, the centroid and shear centre do not coincide. Where loading does not act through the shear centre, torsion may arise and should be considered by the engineer using an appropriate torsional eccentricity. For single-junction sections such as L’s and T’s, the shear centre is taken at the intersection of the centre-lines of the flange and web/leg.

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Note: that the MasterSeries (currently) draws the section based on the section being centred on the wire frame line (which is incorrect) but does analyse the frame with the wire frame line representing the Shear Centre, thus no eccentric loads by default.