I'd like to have a discussion about the best way to set up the Load History Parameters and realistic Construction Sequencing.
I tuned into a Bentley Webinar a few months ago and the presenter went through a Load History setup which was more comprehensive than the default file setup. I can't locate that webinar material. Perhaps one of the Support Team can explain/detail it further? I remember it separating the different stages of construction (slab poured, slab backpropped, partitions installed, occupancy etc).
An example of a post-tensioned highrise tower floor plate is below:
Load applied after 7 days (just after the final stressing).
Backpropping loads (say 2.5 kPa average) applied for the next 28 days (say we need to backprop 4 levels and there is a week cycle time).
Construction Loading (1.5 kPa) applied for the next 21 to allow for materials being stacked.
Partitions installed (SDL applied)
Occupancy (SDL + LL) after say 3 months from partitions installed. At this point we can calculate short term deflection.
Then we can go on to calculate Long Term deflections.
What are other people's approach to this? Have you set up your own Load History steps? If so would you like to share them?
PS - Does Concept account for the fact the concrete hasn't reached it's final design Elastic Modulus (E) value when loaded between 0-28 days?
Can I still have an access to that webinar? Thanks
I don't think that one was moved over to new servers.
Learning Path: learn.bentley.com/.../BrowseLearningPaths
YouTube ChannelL www.youtube.com/.../search
Click here for a feature article that discusses load history deflections and may answer some of your questions.
Also, RAM Concept now accounts for reduced Elastic Modulus at early ages. See "Load History Calculations - Strength Adjustments for Time of Loading ACI209R-92 Creep/Shrinkage Model" in the Version 8 Update 2 Release Notes found here. That adjustment is made for other creep/shrinkage models when appropriate. The Load History Deflection chapter in the RAM Concept Manual outlines specific implementation details for each model.