Beam properties

Tekla Structural Designer
2021
Tekla Structural Designer

Beam properties

General
Name The automatically generated name.
User Name Can be used to override the automatically generated name if required.
Group The name of the group to which the member belongs.

See: Concrete beam and column groups , Steel member design groups

Plane Indicates the level or frame within which the member is placed.
Characteristic Beam
Active Clearing this option makes single span beams inactive in the analysis.

See: Inactive members

Note: Only displayed for single span members
Material type
  • Steel
  • Concrete
  • Timber
  • General
  • Cold formed
  • Cold rolled

Construction,

Fabrication

The available construction and fabrication options depend on the characteristic and material type selected, see Member characteristic, construction and fabrication properties
Autodesign

See: Concrete member autodesign, Steel member autodesign

Design section order

(steel only)

The design order file from which a section size will be selected.
Note: Only displayed for Autodesign
For details of managing order files, see: Manage design section orders
Select bars starting from

(concrete only)

This option controls the starting point for auto-design procedures and is therefore only displayed if Automatic design is ‘on’. It applies to both longitudinal bars and links.

• Minima (default) - removes the current arrangement and begins with the minimum allowed bar size.

• Current - the auto design commences from the current bar arrangement.

See: Concrete member autodesign, Steel member autodesign

Gravity only Controls whether the member is defined for gravity combinations only, or gravity plus lateral:
  • On = designed for gravity combinations only
  • Off = designed for gravity and lateral combinations

See: Designing individual members for gravity only

Rotation

Rotation of the member about its local x axis.

The default (Degrees0) aligns the major properties with the global Z axis, (provided that the member has not been specifically defined within an incline plane).

Global offset end 1,

end 2

Can be used to model a physical offset with respect to the global axes at one or both ends of the member, (exceptions apply).

See: Member global offsets

Major snap level,

Minor snap level

(not concrete)

Defines the major and minor alignment of the member relative to the insertion point.
Major offset,

Minor offset

(not concrete)

Used to offset the member from the snap point in the major and minor axis.
Allow automatic join end 1,

end 2

(concrete only)

When this checkbox is selected - the end in question will be automatically joined to a suitable connecting concrete beam end during design process or when the ‘Beam Lines’ command is run, (providing the Beam Lines limiting criteria specified in Model Settings are met.)
All spans
Section The section size
Concrete type,

Grade/Class

While you can apply both normal and lightweight concrete, wall design using lightweight concrete is currently beyond scope.
Linearity
  • Straight
  • Curved Major
  • Curved Minor
Chord height This property is only displayed when ‘Linearity’ is curved major or curved minor. It is the perpendicular distance from the mid point of the chord baseline to the curve itself.
Maximum facet error This property is only displayed when ‘Linearity’ is curved major or curved minor. It controls number of straight line elements that replace the curved member in the solver model.

See: Analysis Model settings

Top flange cont. rest.

(steel and composite beams only)

Define if the top flange is continuously restrained.
Alignment (concrete only)
Major snap level,

Minor snap level,

Define the major and minor alignment of the member relative to the insertion point.
Major offset,

Minor offset

Used to offset the member from the snap point in the major and minor axis.
Releases
Free end 1,

end 2

When this checkbox is selected - defines a cantilever end.

Fixity end 1,

end 2

  • Moment
  • Pin
  • Fully fixed

See: Beam end releases and partial fixity

Axial load release end 1,

end 2

Check one end only to define an axial release.
Torsional load release end 1,

end 2

Check one end only to define a torsional release.
My stiffness end 1, end 2 This property controls end fixity in the Major direction. It is only displayed when ‘Fixity’ is Fully fixed, or Moment. The choices are:
  • Fixed (default)
  • Spring linear
  • Partially fixed
Stiffness y end 1, end 2

When ‘My stiffness’ is set to Spring linear, this property allows you to specify the major direction stiffness in terms of a linear spring value.

When ‘My stiffness’ is set to Partially fixed, this property allows you to specify the major direction stiffness as a percentage of a fully fixed connection. (% of 4EI/L).

Mz stiffness end 1, end 2 This property controls end fixity in the Minor direction. It is only displayed when ‘Fixity’ is Fully fixed. The choices are:
  • Fixed (default)
  • Spring linear
  • Partially fixed
Stiffness z end 1, end 2

When ‘Mz stiffness’ is set to Spring linear, this property allows you to specify the minor direction stiffness in terms of a linear spring value.

When ‘Mz stiffness’ is set to Partially fixed, this property allows you to specify the minor direction stiffness as a percentage of a fully fixed connection. (% of 4EI/L).

Wind loading
Apply open structure wind load

Select this flag if you want open structure wind loads to be calculated.

See: Open structure wind loads

Shape factor, Cf The default shape factor varies according to the entity type and is taken from Model Settings > Loading > Wind Loading
Note: Default Cf factors are taken from the document ‘Wind Loads For Petrochemical And Other Industrial Facilities’ published by ASCE.
Effective area XY
Formula The default effective area formula varies according to the entity type and is taken from Model Settings > Loading > Wind Loading
Factor The factor used in the above formula can be edited if required.
Effective area XZ
Formula The default effective area formula varies according to the entity type and is taken from Model Settings > Loading > Wind Loading
Factor The factor used in the above formula can be edited if required.
Load reductions

KLL

(Head Code ACI/AISC)

Specify the KLL factor in accordance with Table 4-2 in ASCE 7-05/ASCE 7-10.

See: Overview of live or imposed load reductions

Reduce imposed loads by

(All other Head Codes)

This property is particularly applicable to the design of transfer beams.

Although the percentage of imposed load reduction is not determined automatically for beams, this property allows you to specify the percentage manually.

It can be applied to all, or individual spans.
  • reducible loadcases are reduced
  • combinations incorporating reducible loadcases are reduced

The reduced results are used in concrete beam design.

See: Overview of live or imposed load reductions

Deflection limits (steel only)

Apply span\factor

With this option checked, the limit can be defined as a Relative span/factor.
Apply abs. limit With this option checked, the limit can be defined as absolut value.
Limit for immediate live load deflection,

Limit for total deflection affecting sensitive finishes

Calculate total deflection at design time

Calculate deflection after installation of finishes

(ACI only)
These options control how the deflection is calculated.
Torsion (steel only)
Check for torsion,

Apply rotational limit

Used to specify if the member should be checked for torsion, and also to apply a rotational limit if required.

See: Torsion

Camber (steel only)
Apply camber Used to specify a camber to the beam if required.

See: Camber

Natural frequency (non-composite and composite beams only)
Calculate natural frequency For composite beams this is fixed to on (for EC and BS head codes only) and is utilized during autodesign. The calculated natural frequency is displayed in the results viewer.
Check natural frequency against minimum

For composite beams this is fixed to on (for EC and BS head codes only). For non-composite beams it can be used in conjunction with the 'Calculate natural frequency' property to impose an optional 2-step control, ‘calculate’ and ‘check’, which allows for the natural frequency value to be calculated (and displayed in Results Viewer) with or without the check. While the US head code has no requirement for this check, it can still be requested if required.

When performed, a simple (design model) approach is taken based on uniform loading and pin supports. This fairly simple calculation is provided to the designer for information only. The calculation can be too coarse particularly for long span beams and does not consider the response side of the behavior i.e. the reaction of the building occupants to any particular limiting value for the floor system under consideration. In such cases the designer has the option to perform a 1st Order Modal Analysis.

See:

Minimum natural frequency The minimum value against which the natural frequency is checked (default 4Hz).

Include self weight (beam & slab)

Include other dead loads

Include live loads (US)

Include imposed loads (other head codes)

The engineer can specify the percentages of each of these loads to be included in the calculation of the maximum static instantaneous deflection, δ
Factor for increased dynamic stiffness of the concrete flange For composite beams this factor is applied to the beam's short term modular ratio

Effective width

Calculate effective width

For composite beams the effective width can either be entered directly or calculated from the geometry.

See:

Size constraints (steel only)
Max depth,

Min depth,

Max width,

Min width

Size Constraints are only applicable when Autodesign is checked. They allow you to ensure that the sections that Tekla Structural Designer proposes match any particular size constraints you may have. For instance for a composite beam you may want to ensure a minimum flange width of 150mm (6in). If so you would simply enter this value as the Minimum width, and Tekla Structural Designer would not consider sections with flanges less than this width for the design of this beam.

See: Size constraints

Apply max span/depth ratio

Max span/depth ratio

After setting a max span/depth ratio you can check the 'Apply' button for it to be considered by auto-design. During design, only sections which satisfy the maximum ratio limit will be selected.

The setting can also be reviewed and/ or copied via Review View > Show/Alter State.

See: Size constraints

Instability factor (steel only)
Prevent out of plane instability Define if out of plane stability is prevented.

See: Instability factor

Analysis & design control (concrete only)
Structure supporting sensitive finishes (ACI and Eurocode only)

Any beam that supports or is attached to partitions or other constructions likely be damaged by large deflections should be identified as such by selecting this property.

ACI - The deflection method applied to the beam depends on this setting as follows:
  • beams not required to support sensitive finishes adopt the simplified method.

  • beams required to support sensitive finishes adopt the rigorous method.

Eurocode - The f2 parameter used in the deflection check depends on this parameter as follows:
  • When selected: f2 is calculated as MIN[1,7/Leff]

  • When unselected: f2 will be taken as 1.0.

Increase reinforcement if deflection check fails (Eurocode BS and IS only) Select in order to increase the reinforcement during the auto-design process if the deflection check fails.
Permissible increase in reinforcement Specify the max percentage increase in reinforcement that is allowed in order to satisfy the deflection check.
Consider flanges

Select in order to consider flanges in the concrete beam design calculations - once checked additional fields are displayed for specifying an allowance for openings.

Flange dimensions can only be calculated by editing the beam once it has been positioned and slabs have been defined. (In this case a ‘Calculate flanges’ button is also displayed, this can be clicked in order to automatically calculate the flange dimensions based on the adjoining slabs.)

See: Flanged concrete beams

Include flanges in analysis
Note: This property is only displayed when the ‘Consider flanges’ option has been selected.

Select this checkbox to use flanged beam properties when the analysis is performed.

See: Flanged concrete beams

Isolated beam (ACI only)
Note: This property is only displayed when the ‘Consider flanges’ option has been selected.

Select this checkbox in order to apply ACI 318 clause 8.12.4.

When the check is performed, if the flange geometry does not meet the requirements the flanges are ignored.

See: Flanged concrete beams

User defined flange (left/right)
Note: This property is only displayed when ‘Include flanges in analysis’ has been checked.

If you clear this checkbox the flange depth and the effective flange width are determined automatically.

If you select the checkbox, two new properties are displayed for defining ‘Flange width’ and ‘Flange depth’.

See: Flanged concrete beams

Ignore lateral instability (Eurocode only)
This option allows you to ignore lateral instability for slender spans to EC2 clause 5.9(1).
  • When selected: the slender span check is excluded from design

  • When unselected (default): the slender span check is included.

Assume cracked

Assuming concrete sections are cracked has a direct affect on the analysis; smaller Modification Factors are applied to cracked sections causing an increase in deflection. Indirectly the design can also be affected because the sway/drift sensitivity calculations are also influenced by this assumption.

See: Cracked, partially cracked, and uncracked concrete members

Design parameters (concrete only)

Nominal cover beam top edge,

bottom edge,

section side,

beam ends

The nominal concrete cover is the distance between the surface of the reinforcement closest to the nearest concrete surface (including links and surface reinforcement where relevant) and the nearest concrete surface. Different values of nominal cover can be specified to the beam edges, sides and ends.
Seismic
In a seismic force resisting system

If this is the case, select the checkbox, and then specify the SFRS direction and type.

Note: Design of members in seismic force resisting systems is only supported for the ACI/AISC Head Code in the current release.
Utilization ratio
Apply (to autodesign) On
  • When an Autodesign is performed, the design will be incremented to achieve a utilization ratio less than the ratio limit.
Off
  • When an Autodesign is performed, the design will be incremented to achieve a utilization ratio less than 1.0.

See: Apply user defined utilization ratios

Apply (to check) On
  • When a Check is performed, the check will pass provided the utilization ratio is less than the ratio limit.
Off
  • When a Check is performed, the check will pass provided the utilization ratio is less than 1.0.
Ratio limit The utilization ratio against which the autodesign or check is performed (when applied above).
Fire proofing
Check for fire resistance
Note: This property is only displayed for non-composite, simply supported rolled steel beams to Eurocodes.
On
  • When the check is requested, the additional properties shown below are required.

See: Fire check (Eurocode only)

Off
  • no check is performed
Protected On
  • When members are set as 'Protected', self-weight of the members is increased by the weight of fireproofing.

    See: Fire proofing

  • If 'Check for fire resistance' is also selected, the check is performed using the 'protected' time interval for critical temperature iteration, as specified in Design Settings
Off
  • If 'Check for fire resistance' is also selected, the check is performed using the 'unprotected' time interval for critical temperature iteration, as specified in Design Settings
Fire check (steel only, Eurocode only)
Load reduction factor 0.65, or user input value.
Required time of fire exposure R15, R30, R60, R90, or R120
Exposure Exposed on three, or four sides
UDA

Name

Finish

Class

Phase

Note

File

A customizable list of the attributes that can be applied to individual members and panels.

See: Create and manage user-defined attributes

Reinforcement (concrete beams only)
Rib type - vertical, Class - longitudinal Specifies the longitudinal reinforcement properties
Rib type - link, Class - link Specifies the link properties.
Top longitudinal bar pattern,

Bottom longitudinal bar pattern

Choose from standard patterns (which can be setup in Design Options) to control the top and bottom bar arrangement when the beam is auto-designed.

See: Concrete beam design fundamentals

Span 1, 2, 3 etc.

In a multi-span beam properties can be entered for a specific span, over-riding those defined at the All spans level.

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