05-03-2010, 08:59 AM
Hi,
If somebody familiar with midas Civil please try to help me :\. I’m analysing a composite plate girder bridge and when I check the beam forces/moments and stresses of the structure I found some anomaly.
My question is: How does midas Civil calculate the primary and secondary effect of shrinkage and creep?(the general methods of calculating these phenomena are clear) I checked the online manual, the analysis reference, the verification examples and a pdf file named CS_Load_Cases and now I’m a little bit confused. I quote from the before-mentioned document (CS_Load_Cases):
“CS: Shrinkage Primary
Reactions: Results are of no significance and unaccounted for in CS Summation.
Deformations: Deformations due to Shrinkage (includes the secondary effect results)
Forces: Fictitious member forces required to cause the Shrinkage strain, therefore,
unaccounted for in CS Summation
Stresses: Fictitious stresses required to cause the Shrinkage strain, therefore,
unaccounted for in CS Summation”
In case of a composite section the primary effect of shrinkage will develop stresses in all of the parts, or at least as I know. Because the steel girder restrains the deformation of concrete, it results self-balanced internal stresses in the whole cross-section.
stresses from primary effect of shrinkage
However the software doesn’t give me stresses in the steel part from the primary effect.
“CS: Shrinkage Secondary
Reactions: Reactions due to Shrinkage resulting from the effects of support constraints
Forces: Member forces due to Shrinkage resulting from the effects of support constraints
Stresses: Stresses due to Shrinkage resulting from the effects of support constraints”
here is the SC_Load_Cases document:
The secondary effect is clear, and it appears only if I have statically indeterminate structure, so it doesn’t contain the effect of the restrain of the steel girder.(I checked with a simply supported beam)
Please let me know if I’m wrong or how midas calculates the primary effect of shrinkage in the case of composite structures.(I checked the Steel I-girder Bridge tutorial too which gives the same result)
Thank you in advance.
Best regards,
rusty
If somebody familiar with midas Civil please try to help me :\. I’m analysing a composite plate girder bridge and when I check the beam forces/moments and stresses of the structure I found some anomaly.
My question is: How does midas Civil calculate the primary and secondary effect of shrinkage and creep?(the general methods of calculating these phenomena are clear) I checked the online manual, the analysis reference, the verification examples and a pdf file named CS_Load_Cases and now I’m a little bit confused. I quote from the before-mentioned document (CS_Load_Cases):
“CS: Shrinkage Primary
Reactions: Results are of no significance and unaccounted for in CS Summation.
Deformations: Deformations due to Shrinkage (includes the secondary effect results)
Forces: Fictitious member forces required to cause the Shrinkage strain, therefore,
unaccounted for in CS Summation
Stresses: Fictitious stresses required to cause the Shrinkage strain, therefore,
unaccounted for in CS Summation”
In case of a composite section the primary effect of shrinkage will develop stresses in all of the parts, or at least as I know. Because the steel girder restrains the deformation of concrete, it results self-balanced internal stresses in the whole cross-section.
stresses from primary effect of shrinkage
However the software doesn’t give me stresses in the steel part from the primary effect.
“CS: Shrinkage Secondary
Reactions: Reactions due to Shrinkage resulting from the effects of support constraints
Forces: Member forces due to Shrinkage resulting from the effects of support constraints
Stresses: Stresses due to Shrinkage resulting from the effects of support constraints”
here is the SC_Load_Cases document:
Code:
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The secondary effect is clear, and it appears only if I have statically indeterminate structure, so it doesn’t contain the effect of the restrain of the steel girder.(I checked with a simply supported beam)
Please let me know if I’m wrong or how midas calculates the primary effect of shrinkage in the case of composite structures.(I checked the Steel I-girder Bridge tutorial too which gives the same result)
Thank you in advance.
Best regards,
rusty
Engineering - the Art of Neglection