Check simple connection resistance

Added September 16, 2020 by Tekla User Assistance tekla.documentation@trimble.com

Software version: 
Tekla Structural Designer 2020

Check simple connection resistance

Check simple connection resistance

Tekla Structural Designer provides a quick and simple way of checking the shear capacity of simple beam connections, and the axial capacity of brace connections.

Overview

Tekla Structural Designer has a Connection Resistance database for simple beams and braces. For simple beams the database contains pre-defined types with pre-defined resistances to Eurocode and US head codes.

You can add user-defined connection types and user-defined resistances to the database for any head code, for steel and cold formed materials. Once defined, these can then be used across all projects.

Each resistance value in the database has an 'active' flag which must be 'on' for the resistance to be considered. (Simple beams and braces in the model that have no active resistances are not checked.)

Having configured the active resisistances in the database as required, the checks are then performed in the model as follows:

  • For each simple beam the active shear resistances for each available connection type are read from the database.
  • These resistances are compared to the maximum shear force at the connection (determined from a 3D analysis)
  • The connection configuration is optimized accordingly for each connection type.
  • A similar process is then followed for each brace, by comparing the active axial resistances to the maximum applied axial force.

Results can be displayed in a review data table, or output via a connection resistance report.

Specify 'active' connection resistances (Eurocodes)

Since only active resistances are considered in the check, you can deactivate resistances for those connection configurations you do not want to be considered.

The active status of resistances can be set on or off directly (by ticking or unticking a checkbox in the Active column) but a quicker way of changing the active status is with the Activate/Deactivate dialog.
  1. In the Connection Resistance dialog, click Activate/Deactivate...
  2. Set the filters in the dialog, then set either Activate or Deactivate, as required.
  3. Click Apply if you want to change further Active settings, or click Apply & Close to finish.

Example: From the pre-defined connection types you want only Fin Plates to be active, only for S355 Universal Beams, and only those Fin Plates with 1 line of bolts. There are a number of ways to achieve this using Activate/Deactivate but one way would be as follows:

  1. Click Activate/Deactivate...
  2. Deactivate everything - select ‘All’ in each of the Activate/Deactivate filters, select ‘Deactivate matching resistance values’, then Apply

  3. To activate only Fin Plates for S355 Universal Beams with 1 line of bolts
    1. select Fin Plate in the Connection Type filter,
    2. select S355 in the Grade filter,
    3. select 1 in the # Bolt Lines filter,
    4. select Universal Beams in the Section List filter,
    5. select ‘All’ in the other filters (# Notches, # Bolt Rows),
    6. select ‘Activate matching resistance values’,
    7. click Apply & Close



Following step 3, you will find ticks in the Active column only for Fin Plates with S355 Universal Beams with 1 line of bolts, but note these changes are not saved to the database, and do not become active in Reports or in Tabular Data, until clicking OK in the main dialog.

Specify 'active' connection resistances (US)

Since only active resistances are considered in the check, you can deactivate resistances for those connection configurations you do not want to be considered.

The active status of resistances can be set on or off directly (by ticking or unticking a checkbox in the Active column) but a quicker way of changing the active status is with the Activate/Deactivate dialog.
  1. In the Connection Resistance dialog, click Activate/Deactivate...
  2. Set the filters in the dialog, then set either Activate or Deactivate, as required.
  3. Click Apply if you want to change further Active settings, or click Apply & Close to finish.

Example: From the pre-defined connection types you want only Single Plates to be active, for W & M beams of ‘Any’ Fy, only for 3/4 in bolts, but for all defined thicknesses of plate. There are a number of ways to achieve this using Activate/Deactivate but one way would be as follows:

  1. Click Activate/Deactivate...
  2. Deactivate everything - select ‘All’ in each of the Activate/Deactivate filters, select ‘Deactivate matching resistance values’, then Apply

  3. To activate only Single Plates for W & M Beams of ‘Any’ Fy, with 3/4 in diameter bolts and all plate thickness
    1. select Single Plate in the Connection Type filter,
    2. select Any in the Fy filter, select 3/4 in in the Bolt Diameter filter,
    3. select W & M in the Section List filter,
    4. select ‘All’ in the other filters (Coping, # Bolt Lines, # Bolt Rows, Thickness),
    5. select ‘Activate matching resistance values’,
    6. click Apply & Close



Following step 3, you will find ticks in the Active column only for Single Plates, with Any Fy selected, and W & M Beams with 3/4 in diameter bolts, but note these changes are not saved to the database, and do not become active in Reports or in Tabular Data, until clicking OK in the main dialog.

Run resistance checks

Provided you have an appropriate set of 'active' resistances, the checks are performed automatically, using the current analysis results - you can proceed directly to a review of the check results.

  • If necessary, analyse the model to generate an up-to-date set of analysis results,
  • Review the check results, see: Display connection resistance checks in a review data table below.

The connection optimization process

Tekla Structural Designer carries out an optimization process to find the first passing Active resistance based on the name of the Connection Type and the number of Bolt Lines and Bolt Rows assigned to that name.

For Eurocodes, separate check results are reported for each 'active' connection type and each notch variation.

For US codes, separate check results are reported for each 'active' connection type and each coping variation.

Example: to Eurocode, a Fin Plate for an S355 UB 457x152x52 with 1 and then 2 lines of bolts has pre-defined resistances as shown below. All resistances are indicated as Active.

If an S355 UB 457x152x52 in a model is found to have an applied major shear force of 250 kN then the connection resistance check will report that a Fin Plate with 1 bolt line and 4 bolt rows (resistance 263 kN) is adequate.

If the applied major shear force is 300 kN then the connection resistance check will report that a Fin Plate with 1 bolt line and 5 bolt rows (resistance 352 kN) is adequate.

If the applied major shear force is 355 kN then the connection resistance check will report that a Fin Plate with 2 bolt lines and 5 bolt rows (resistance 450 kN) is adequate.

For each of the applied major shear forces given above only the first passing resistance is reported, by looping through the Active bolt rows for 1 bolt line followed, where necessary, by looping through the Active bolt rows for 2 bolt lines.

If Tekla Structural Designer gets to the end of these loops and still doesn’t find a passing resistance then it reports the last resistance found and a fail status e.g. if the applied major shear force is 455 kN then the connection resistance check will report that a Fin Plate with 2 bolt lines and 5 bolt rows (resistance 450 kN) fails.

Now suppose that the UB 457x152x52 with 1 bolt line and 5 bolt rows (resistance 352 kN) is not Active. The first shear check above (applied force 250 kN) would be unchanged but the second check (applied force 300 kN) would now report that a Fin Plate with 2 bolt lines and 4 bolt rows (resistance 349 kN) is adequate. This illustrates the interplay of the resistance Active status with the optimization process.

Display connection resistance checks in a review data table

  1. If necessary, change the view regime to a Review View
  2. Click Review > Model & Results

    A Review data view opens in a new tab.

  3. Select Connection Resistance from the drop list on the View Type ribbon group.
  4. Make selections from the other groups on the ribbon in order to filter to the specific results required.
A resistance check is provided for the filtered selection for every section where a resistance has been specified in the database.
Note: A resistance check is not provided for beams that do not have simple connections.
Note: If there is uplift in any load combination then the maximum uplift shear force will be displayed, with a warning that connection resistance is not checked for uplift condition.
Note: Each time you re-analyse the building, if you have the Connection Resistance data table open you must close and then re-open it to update the results.

Create and display a connection resistance report

  1. On the Report tab, use the droplist to select the existing Connection Resistance report.
  2. Click Model Report...
  3. Review the report structure and adjust as required.
  4. Click OK to save the report.
  5. Click Show Report
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