midas Civil 2010 - composite bridge

[rusty]

Hi,

I’m using midas Civil 2010.

1st problem: I have problem with the run of the Composite plate girder design, I click Design and I get the following message: "Load combination data for composite plate girder design has not been entered." where do I have to enter the load combinations for composite girder? I created load combinations with Results>Combinations...>Concrete tab, in the table of load combinations, I made at least one of the combinations as Strength (under Active column). But I still have the same before-mentioned message.

2nd problem: I would like to analyse a steel-concrete composite bridge with double composite action, additional bottom concrete slab in the area of the intermediate supports. I created the cross section with MIDAS/SPC and exported to Midas Civil Composite-General Section Type. My question: Can I handle the time dependent behaviour of the concrete parts as in the case of typical Composite Steel-I section? I linked material to the composite parts in the SPC but I guess this required only for the calculation of the idealized (homogenized) cross section properties.
I created a beam model with only one girder, because from another accurate model (with shell finite elements) I calculated the lateral distribution function.
Here are the midas model files and the SPC composite export file:

Code:

***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:

http://forum.civilea.com/thread-27464.html
***************************************

Code:

***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:

http://forum.civilea.com/thread-27464.html
***************************************

Best regards,
rusty

[rusty]

Problems have been solved, thanks to the very kind midas support team. :JC_cheers:
If somebody has the same (similar) problem send me a mail. Probably further problems will come because I have low priority support.

[Dell_Brett]

Dear rusty,
Consider put your experience here, to share with all Midas users.

Regards

Dell Brett

[rusty]

Dear Dell Bret,

Here are the answers to my problems:

1. Time dependent properties can be considered for the double composite section also. But for that, you have to link the material to composite parts in midas Civil. As noted by you, the material you defined in SPC, was just for the calculation of cross section properties only. So you need to define construction stage for double composite section using “Composite Section for Construction Stage”. There you can assign the concrete material properties to the composite parts.

2. For composite plate girder design, you have to define “SRC” type materials when you define material properties. After that you need to define the Load Combinations in “Steel” tab.

Thank you midas support team.:yes:

Best regards,
rusty

[rusty]

I have some problems again, I will highly appreciate if someone could help to solve these.

1st: I’m using General Type Composite section partially, and I defined SRC material and linked to the elements (the whole structure is a steel-concrete composite bridge with partial double composite action) to perform the Design. But I receive the following message when I click the Perform Analysis button: “If a SRC material is used, the section must be a SRC or a corrugated steel web PC section”(the problem is with the general type section), so I have to change the linked material if I want to perform the analysis, however with this modification I can’t execute the Composite Plate Girder Design (without SRC link I get the before-mentioned message:” Load combination data for composite plate girder design has not been entered.”). Does it mean that I can’t use the Design option if I have General Type Composite section?

2nd: Is there any way to change a section of an element in a specified time? I would like to model the cracking of the upper composite slab due to the fist application of the traffic load.

(I defined an orthotropic material to consider the effect of tension stiffening in cracked zone. So I want to change in a specified age the material properties of the upper concrete slab.)
I attached the composite export and model file.

Code:

***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:

http://forum.civilea.com/thread-27464.html
***************************************

Thank you in advance.

Best regards,

rusty

[rusty]

Hi,

Here are the answers (I asked my questions today during the Midas Civil webinar):

1st: The Composite Plate Girder Design option is only available for cross sections defined in Midas (not working with imported General section).

2nd: With Section Stiffness Scale Factor option I can model the cracking of the concrete (reduce of the flexural stiffness)... however this scale factor is for the whole section and I only want to change the stiffness of the top concrete(I need the stresses of the section). There is an option to add stiffness scale factor to the parts of the composite section but this factor is working immediately after the part becomes active during the construction. My goal: uncracked cross-section till the first application of the traffic load, after it cracked concrete slab. I guess I can’t achieve this aim so I have to neglect this and use only the cracked section. If anybody has any idea please let me know.

Best regards,

rusty

[rusty]

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:

Code:

***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:

http://forum.civilea.com/thread-27464.html
***************************************

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

[rusty]

Problem has been solved.:JC_cheers:
For the first time with the simply supported beam I made a mistake with the link of the shrinkage function so I didn' get stresses, now I fixed it and it works perfectly.
The software handles the restrain of the steel girder as secondary effect!
I learned that the restrain of the steel girder is the primary effect, nevertheless if we consider as a secondary effect is reasonable too, the composite section is like an "inner indetermination".
Thanks for the support midas support team.:JC_handshake:

Welcome to my schizophrenic thread. :prankster:

Regards,

rusty