Shear failure

[yasser_goldstone]

hi
I know that seismostruct does not account for shear deformation in analysis, However is there any other way to predict shear failure in analysis of RC frames?
I read a paper at which the author has predicted the shear failure using ADAPTIC program by comparing shear demand by shear capacity, but i don't know how to do this. does anyone have any idea how to do this?
the name of paper is:
"Importance of shear assessment of concrete structures detailed to different capacity design requirements"

[seismosoft]

You can use the shear performance criterion to get notified about the shear failure of the structural elements. In v6.5 you will need to calculate yourself the shear capacity, in the upcoming v7 release the shear capacity is automatically calculated. SeismoStruct v7 will be released on September 8 (next Monday).

Seismosoft Support

[fakharifar.mostafa]

I've been successfully implementing the time-dependent element to simulate new elements introduced at any desired time-step into my frame models. The models run fine, and the obtained results upon introducing the new element to the existing element, are satisfactory/correct, however, something regarding the shear performance criteria does not seem right to me. It seems SStruct v7.0, when it introduces the new member in the analyses, however, it does not update the member shear capacity of the member which it is assigned to. I know I have defined it for one frame element. But I need to obtain the shear capacity of the updated column (existing column + repair jacket) while only the existing column cross section gets considered. Should I introduce another performance criteria, which is not really appropriate I guess, as I am summing to shear capacities, which in turn should be treated as one. Thanks.

[z.gronti]

Dear fakharifar.mostafa,

I checked what you say with a Reinforced Concrete Rectangular Column Section(rcrs) and a Reinforced Concrete Jacketed Rectangular Section(rcjrs), but the shear capacity performance criteria worked fine for me. At the beggining, when the rcrs section was activated, i got shear values only for this section, and from the load step that the rcjrs was activated i got shear values only for the rcjrs section. In addition, in the Condition column, in the Performance Criteria molude, i got different values for the shear capacity of the two sections. Perhaps i haven't understood your point, so if i don't cover you with my answer, you may send me your model.

[fakharifar.mostafa]

Thanks for the reply. Sorry I was not clear enough. You are correct, however, my question was not replacing an element with another element (in your case rcrs cross section replaced by rcjrs). I was concerned about addition a new element to an existing element, let's say you have Reinforced concrete circular section (rccs) and later on the Circular hollow section (chs) is added to the same nodes of the same element (chs element encloses the rccs). That was my concern, as I guess the shear capacity is still considered for the original section.

[fakharifar.mostafa]

The frame element shear capacity performance criterion is a fantastic addition to SStruct. However, I have a question on how SStruct automatically computes the shear capacity of the member. Is it like Priestley model that includes the variation in shear capacity according to the curvature ductility factor, or is it assumed constant for the whole analysis, irrespective of the member inelastic flexural deformation. (reason for question as I don't know/no access to Eurocode 8, part 3). Thanks for your clarification.

[z.gronti]

From what i understand you have two different elements. The Shear Capacity Output is per element. In addition, SeismoStruct doesn't calculates shear capacity for hollow sections.

[z.gronti]

quote:The frame element shear capacity performance criterion is a fantastic addition to SStruct. However, I have a question on how SStruct automatically computes the shear capacity of the member. Is it like Priestley model that includes the variation in shear capacity according to the curvature ductility factor, or is it assumed constant for the whole analysis, irrespective of the member inelastic flexural deformation. (reason for question as I don't know/no access to Eurocode 8, part 3). Thanks for your clarification.
The shear capacity is computed at the end of every load step according to the Eurocode 8-Part 3. You may see it by inserting a static pushover analysis wizard model with a shear capacity performance criterion. At every load step it computes a different value for the shear capacity.

[fakharifar.mostafa]

Thanks for clarifying response.

[huffte]

I have a 3-column bridge pier on which I am performing a simple pushover analysis. I am also employing shear capacity check performance criteria. I define the circular column sections and SeismoStruct computes a reported contribution to capacity due the transverse reinforcement of 317 kips. I calculate a number by hand and get 335 kips, so that is close - my number is based on the UCSD model. I may be mistaken, but I believe EC8 may be similar to the UCSD model.

I check the post-processed performance criteria. At time 0, no lateral load, the 3 columns have shear capacities of 305 kips (exterior columns) and 256 kips (interior column). At time step 24, column 3 (the leeward column) is reported to have reached its shear capacity (256 kips). At the axial load level and ductility level in column 3 at time step 24, I hand calculate a total capacity of 582 kips, including concrete and axial load contributions.

I expected the initial shear capacities to include the effects of concrete contribution and axial load contribution to the shear capacity.

It appears that something in my settings is telling SeismoStruct to ignore the contributions of concrete and axial load to shear capacity. Or perhaps I am missing another aspect of the shear capacity theory.

I will e-mail the model. I thank you very much for a stellar line of products. - Tim