Concrete beam and column groups

Tekla Structural Designer
2021
Tekla Structural Designer

Concrete beam and column groups

Why use design and detailing groups?

Concrete beams and columns and isolated foundations are put into groups for two reasons:

  1. For editing purposes - individual design groups can be selected and displayed graphically so that their properties can be changed as a group in the properties window.
  2. For design and detailing purposes - to standardise designs, reduce processing time, and reduce the volume of output created.

In a manual process, the Engineer might select a number of sufficiently similar members to form a "design group" to carry out a single design that is sufficient for all members in the group. Using this single set of design results, they would then create sub-groups of the members in the design group to produce a set of output details for each of these sub-groups.

In Tekla Structural Designer, concrete design groups are analogous to the manually created design groups described above. Concrete detailing groups are analogous to the sub-groups.

A fixed set of rules are used to automatically determine member groups: for example beams must be of similar spans, columns must have the same number of stacks, bases must be of similar lengths in X and Y, and similar depths etc. The same rules also constrain manual group editing.

Note: Grouped design and detailing is optional and can be deactivated if required:

From the Design tab, click Settings> Design Groups, then select or unselect the member types to be designed in groups.

What happens in the group design process?

When the option to design a specific concrete member type using groups is checked, for that member type:

  • In each design group the first member to be designed is selected arbitrarily. A full design is carried out on this member and the reinforcement so obtained is copied to all other members in the group.
  • These other members are then checked one by one to verify that the reinforcement is adequate for each and if this proves not to be the case, it is increased as necessary and the revised reinforcement is copied to all members in the group.
  • This process continues until all members in the group have been satisfactorily checked.
  • A final check design is then carried out on each group member. During this process peak and individual utilizations are established.

Design group requirements

Concrete member design groups are formed according to the following rules:

Member type Design group rules
Concrete beam
  • A beam element may be in only one design group.
  • Design groups may be formed from single span or multi-span continuous beams.
  • All beam elements in the group must have an identical number of spans.
  • For each individual span all beam elements in the group must have an identical cross section, including flange width where appropriate, and span length.
  • All beam elements in the group must have identical material properties and nominal cover.
  • All beam elements in the group must be co-linear or be non-co-linear with identical degrees of non-co-linearity between spans.
Concrete column
  • A column element may be in only one design group.
  • All column elements in the group must have an identical number of stacks.
  • For each individual stack all column elements in the group must have an identical cross section, and stack length.
  • All column elements in the group must have identical material properties and nominal cover.
Pad base
  • A pad base may be in only one design group.
  • Each base in the group must have an identical cross section and depth.
  • Each base in the group must have identical eccentricities in X and Y.
  • Each base in the group must have identical material properties and nominal cover.
Pile cap
  • A pile cap may be in only one design group.
  • Each pile cap in the group must have an identical cross section and depth.
  • Each pile cap in the group must have identical eccentricities in X and Y.
  • Each pile cap in the group must have identical material properties and nominal cover

Detailing group requirements

Each parent design group is sub-divided into one or more detailing groups.

Although there can be a "1 to 1" relationship between a design group and a detailing group, in practice there will often be a "1 to many" relationship as each design group is likely to require several detailing groups to allow for differences in the connected geometry.

Detailing groups are formed for the different concrete member types based on the following rules:

Member type Design group rules
Concrete beam
  • A detailing group may be associated with only one parent design group.
  • A beam element may be in only one detailing group.
  • Detailing groups may be formed from single span or multi-span continuous beams.
  • All beam elements in the group must have an identical number of spans.
  • The cross section, including flange width where appropriate, span length and material properties in span
  • "i" of all beam elements in the group must be identical .
  • All beam elements in the group must have identical plan offsets.
  • All beam elements in the group must be co-linear or be non-co-linear with identical degrees of non-co-linearity between spans.
  • All beam elements in the group must have identical inclinations.
  • The support types and sizes, including the attached structure above and below the beam element, must be identical in all beam elements in the group however different support types and sizes in individual multi-span continuous beams are acceptable i.e. support i in beam element j must be identical to support i in all other beam elements in the group but supports i and i+1 in beam element j may be different.
Concrete column
  • A detailing group may be associated with only one parent design group,
  • A column may only be in one detailing group,
  • All columns in the detailing group must have an identical number of stacks,
  • All columns in the group must have an identical cross-section, rotation and alignment/snap levels/offsets in stack 'i'. In a multi-stack column, the cross-section may be different in each stack, i.e. the cross-section in span 'i' may be different to that in span 'j'.
  • Stack 'i' and stack 'i+1' must be co-linear for all columns, OR must be non-co-linear with an identical degree of non-co-linearity for all columns. The exact inclination must be the same for stack 'i' in all columns.
  • At every level each column is considered to be either "internal" or "external" (depending on if it has beams framing into it on all four sides, or not). These settings do not have to be identical for columns to be in the same group, but only if you have selected the option: Provide ties through floor depth for internal columns in Design Options > Concrete > Column > Detailing Options.
Pad base
  • A detailing group may be associated with only one parent design group.
  • A base may be in only one detailing group.
  • The attached column cross-section above the base must be identical for all bases in the group however different support types are acceptable.
Pile cap
  • A detailing group may be associated with only one parent design group.
  • A pile cap may be in only one detailing group.
  • The attached column cross-section above the base must be identical for all pile caps in the group however different support types are acceptable.

Group management

Automatic Grouping

Concrete beams and columns are grouped automatically.

In Model Settings > Grouping the user defined Maximum length variation is used to control whether elements are sufficiently similar to be considered equivalent for grouping purposes.

Manual/Interactive Grouping

After assessing the design efficiency of each group, you are able to review design groups and make adjustments if required from the Groups tab of the Project Workspace.

Detailing groups cannot be edited manually.

Note: When manually adding members to a group, the order in which they are added will incrementally affect the average length within the group, (which is then compared to the maximum length variation). Therefore, if members are not being added as you expect, try adding them in a different order.

Regroup ALL Model Members

If you have made changes in Design Settings that affect grouping, you can update the groups accordingly from the Groups tab of the Project Workspace by clicking Re-group ALL Model Members.

Note: Any manually applied grouping will be lost if you elect to re-group!

Model Editing and Group Validity Checks

When new beam elements are created when a "split" or "join" command is run the resulting beam elements are automatically placed in existing design and detailing groups [or new groups created].

Was this helpful?
Předchozí
Další