Event Sequences

Select Event Sequences to show a summary of the model event sequence and any custom event sequences that have been defined.

When this page is active you can:

• Add a Custom Load Event Sequence.
• Remove a selected Custom Load Event Sequence.
• Review which Event Sequences are used in submodels

Model Event Sequence

Select Model Event Sequence to display the various event sequence parameters for editing.

Custom Event Sequences

Pages for custom event sequences are only displayed if they have been added from the Event Sequences page.

Load Event sub-pages

Load Event sub-pages are displayed under the Model Event Sequence, and any custom Event Sequences pages. Each Load Event has a separate sub-page which is used to define the loadcases included in the Load Event.

The [>>] and [<<] buttons are used to add or remove loadcases from the Included Loadcases list.

On submodel specifies the percentage of each included loadcase on the submodel.

Submodels

Select Submodels to assign a custom event sequence to a submodel if required.

The input parameters required for each event are:

• Event Number - Automatic

• Event Name - A user defined name to help explain the event

• Load Start time - The time at which the event takes place

• Beta - a coefficient to take account of the influence of the duration of loading. (See: EC2 Clause 7.4.3) This coefficient is used to account for the fact that tension stiffening effects reduce over time.

  Tension stiffening is the phenomenon that when the concrete is not fully cracked, there is still concrete in the tension zone that transfers some tensile forces, so the stiffness is greater than that of the fully cracked stiffness (and less than the uncracked stiffness). Since this effect reduces over time, to model loads with a longer duration, you want to model a lower stiffness, which means setting beta = 0.5.

  In Tekla Structural Designer, Beta defaults to 1.0 where the start event time is ≤ 30 days and 0.5 if >30 days, but may be changed for any event.

  Tension stiffening reduces over time because of increased cracking and bond failure between the steel reinforcement and concrete.

  These phenomena cannot be reversed, so reduced tension stiffening cannot be recovered.

  For this reason, if Beta is set to 0.5, and then in a later event set to 1.0, a warning flag is shown.

• Temperature - Used in the calculation of the Composite Modulus. The effective age of concrete is adjusted to account for the defined temperature.

• Relative Humidity - Used in the calculation of creep.

• Number of Exposed Faces - Used for the calculation of creep.

• Construction load - The construction load you wish to allow for at the chosen load event.

• Loadcase - You select the load cases you wish to be included in the event.

• On submodel - The % of load to apply to the slab, applied directly to the sub-model.

• From chasedown - The % of load to apply to the slab, from the reactions established in analysis of the sub-models above.

The input parameters required for each event are:

• Event Number - Automatic

• Event Name - A user defined name to help explain the event

• Load Start time - The time at which the event takes place

• Ultimate Creep Coefficient

• Aging Coefficient

• Number of Exposed Faces - Used for the calculation of creep.

• Construction load - The construction load you wish to allow for at the chosen load event.

• Loadcase - You select the load cases you wish to be included in the event.

• On submodel - The % of load to apply to the slab, applied directly to the sub-model.

• From chasedown - The % of load to apply to the slab, from the reactions established in analysis of the sub-models above.

If you select the Update custom event sequences option, changes made to the Event in the Model Event Sequence are also replicated in custom event sequences.