post tension slabs software

[quatermain]

Dear Pinkto,

I am not really understood your conclusion.
If you say cedrus is better for irregular slabs, why not to regular?

Is it possible to design beams with cedrus?
is it possible to use 2d (Equivalent frame method) with cedrus?

We are not going to purchase a software for every element type.

Very important to me is the ability of the software to deal with ribbed and waffle slabs.

please advice.

Regards

[Pinkto]

Quatermain,

Sorry about being slightly misleading in the previous post.

To answer your question,
Yes, Cedrus perform better in PT slabs design (this includes Regular and Irregular Slabs)
You can still use Cedrus to design a PT beam but the result is not as detail when you use RAPT. For an instance, RAPT allows you to do adjustment for Tendon centroid distance "e", Duct wall thickness, Anchor friction... etc

However, the only thing i found out limitation of Cedrus compared to Safe and RAM is, Safe and RAM allows you to input the column ABOVE and Below (taking account into its stiffness) whereas Cedrus only allows you to input the Column Below.

If you want to do equivalent frame method, stick with RAPT.

To be frank with you i have not tried using any of them to design ribbed and waffle slab but if you are dealing with highly irregular Slabs, go for Cedrus.

Safe's limitation is, even though it provides (wizard/typical design/initial model) but once you get out of the Regular Slabs module, you will have more trouble, adjusting the Tendons profiles and defining the design strips than doing a complete new module in Cedrus.

[amaranu]

Dear Mr. Pinkto,
Thnakyou very uch for your information on CEDRUS, but what i found the difference between CEDRUS and all other softwares mentioned above is Serviceability limit state. All softwares give the tension and Compresson stress values where are CEDRUS doesnot. How do you account for this Tension and compression stress in CEDRUS ?

Regards,
Amaranu

[Pinkto]

Dear Amaranu,

I'm not sure why you ask this question. In Cedrus, you can check the top and bottom fibre stresses, in X and Y direction. The results can be shown on either a contour form, numerical mode on the plate you model (showing Tension or Compression), or more precisely u can define a strip and show its stresses at each point on the strip you defined.

Load combination is self defined, either in SLS or ULS state based on the design codes chosen. Or you can also define your own Load Combination.

To be able to see these result of PT stresses in Cedrus, you need to have the Base Module (0), Prestressed Concrete (V), AND also the Wall, Slabs with NORMAL Forces (S) package.

I think this answer your question pretty well

Regards,
Ms. Pinkto

[kkpp]

Hi all,
I am regular user of both Rapt and Ram concpt. In my opinion Rapt is a great software for regular slabs &beams and quick. Ram concept is good for irregular shaped slabs & beams and more flexible & user friendly than other PT softwares in the idustry.

thanks
kkpp

[deadlord]

Dear Deadlord

First, I am currently using Ram Concept version 3.1.1. I am wondering whether the current version support otherwise compared to the above mentioned version.

Secondly, as far I know, ram concept only allow for vertical static loads input not for dynamic seismic loads as well lateral loads

Thirdly, there is no option to import/export between Ram Concept and Etabs.

Fourth, Ram concept recommended not to model upper structures to the current slab design ==> ignore the stiffness of these elements

Fifth, To calculate the long term effects, we need to modify in Etabs in model analysis such as modulus, then do the different way to the Ram Concept as the different default values.

Sixth, the way of strip definition in Ram Concept is different to Etabs or Safe leading the different slab behaviour under actions.

Correct me if is am wrong.

Can't really compare myself to some1 who's used to using Ram concept as I'm still new at it,and I mostly learned how to use Ram Concept from it's manual and the help of some engineers.
have read a definition of seismic load and wind load in the manual of the software but it's not discussed throughout(manual of version 3.3).
why would u need the export/import between the Ram Concept and Etabs?(asking here for not knowing)can't we just use Etabs for designing the columns and walls including the lateral effects,and if we use finite element instead of strip method the behavior should be the same?,then use Ram Concept for the slabs.
you've got a point on lateral loads ,don't have much experience in the deformation of slabs due to lateral loads,what I know is that if the slab is a rigid diaphram it shouldn't deform under lateral loads.

now,since you are more experienced than me,what softwares do u recommend to use so that importing/exporting from Ram Concept can be done?

your effort and time writing back is highly appreciated.
Husam.

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[skyscraper]

Dear Deadlord

You're right. Lateral loads do not contribute much in the slab as assigned as rigid diaphragm except for shear thus if there is large slab slot or recess, it will transfer the significant shear from the lateral loads at this sensitive zone.

I am little concerns to analysis slab as FEM rather than define the strip due to difficulty to layout reinforcement based on FEM results (reo should be simplified of installation)

As using Ram concept ver3.1.1, the only software to support for the software interaction is Ram Structural System which is not well known to everybody yet.

One problem sitll concerns to me is significant moment at the wall and slab leading to call up a lot reinforcement. It looks not seem right. So you need to release this connection. Any other advises to solve this problem.

Regards

Cheer

[deadlord]

well that's a nice point u just mentioned,but doesn't Etabs take measurement of this recess or slot in the slab geometry into account one the columns,as I've told you I really don't have much knowledge about that,but I guess large changes in geometry exceeding the code limit could cause some serious shears and moments in the slab,I think that's where dynamic analysis interferes(please someone correct me if I'm wrong) I think ACI limits this sudden change in geometry for the statical force method as it may not exceed 50% of the section through the slab in that region(also correct me if I'm wrong please,I'm not sure about the 50%).
maybe the layout of steel using the strip method is better but the results of finite element should be more realistic if done properly,then the strip method doesn't give accurate results in some cases,right?
don't know much about ram structural system,but I think I've read something about that it isn't as capable as Etabs.

To tell you the truth sir,in the company I'm training in,the other day Ram Concept gave me that I should put 59(10mm dia.) bars(rebar not punching) at a small spacing above the column,so I was shocked by the number and it's clearly wrong,so I've asked an Engineer in the company and he told me that if this happens it's clearly not right,the column was near a wall somehow,so he told me to check it manually and then it would be ok.

[skyscraper]

Dear Deadlord

Call up a lot of reo in such small area around column adjacent to the lift shaft is common sense. To avoid that

1) Release that column
2) Delete all columns adjacent to the core due to encountering problem of the diffrential shortening in high rise building.

50% you have mentioned is right. That's a rule of thump. However, do not need to follow as you can provide the tie beam or thickening the slot.

Define Strip design is considered the most difficult part of slab design. It is required experience.

[deadlord]

Dear skyscraper,
See the difference in experience and knowledge?
Don't know why it would need alot of reinforcement near the lift shaft,I think if it's an opening In the slab then u are certainly right but if the lift(elevator,you mean?) shaft is a core of Reinforced walls why would we need alot of reinforcement except for the common stresses Developed by the interaction between the wall and the slab,don't know what "differential Shortening is really and don't know alot about the requirements of high rise buildings design.

Unfortunately,In our college they courage us to use finite element.
Regards,
Husam