Once the slab deflection analysis has been run, three deflection types are available for review:
Understanding differential deflections
When looking at differential deflections it is important to appreciate that an event is not a single point in time, it is a time period which has different deflections at the start and the end - so it is logical that there can be a differential deflection for a single event.
To clarify the selections requested in the ribbon:
- Start Event defines the start of the start event
- Event defines the end of the event
Therefore, if you specify the same event as the start and the end event, you will still see a differential deflection.
To clarify further, consider the scenario below:
- Event 1 - Construction loading
- Event 2 - Application of Sensitive Finishes
- Event 3 - Application of Additional Finishes
- Event 4 - Occupation (all loading with live load set at long term factor)
- Event 5 - Final loading event (as above with live load set at 100%)
To determine the maximum differential deflection relevant to the application of sensitive finishes you would define this as the deflection between Events 2 and 5 (Start of Event 2 to End of Event 5). If you opted to pick Events 1 and 5 you would get an un-conservative deflection reported since the effect of construction loading is also considered.