How does Midas Civil distinguish between short-term and long-term load and apply the modular ratio accordingly? Does Midas take Creep into account for any loadcase we include in the construction stage?
Answer:
Construction stage analysis is generally used where time-dependent properties (compressive strength gain, creep and shrinkage) are defined. Based on time-dependent properties, the effects of long-term loads are observed.
Post CS stage (after the construction stage), concrete would have gained strength and short-term loads are applied generally after construction stages as the modular ratio is observed accordingly.
But if construction stage analysis is not performed, short-term and long-term modular ratios can be defined while defining the composite section property, as shown below.
Note: These modular ratios are overridden if construction stage analysis is performed.
A separate boundary group will be created, with an updated section stiffness scale factor for the long-term (Es/Ec creep), which needs to be activated for long-term loads in the "boundary Change Assignment" option under Analysis control as shown below.
Kindly refer to the short video attached, where the application of the modular ratio and results for SW using the long-term and short-term modular ratios are compared for the non-construction stage process.
Creep and other time-dependent effects will be handled in the construction stage analysis. We need not define short-term and long-term loading and the corresponding modular ratio in that process. The Midas simulates the whole process and sequence in the construction stage analysis.
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Steel Composite Bridge_Postcs.mcb
long-short term.mp4
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