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Ram Structural System
2

Ram Structural System

Ram Structural System

(OP)
After strong recomendations, our firm finally bought bentley Ram structural System. I have used, staad, etabs, midas gen at various firms, and this is my first time with RAM SS, and i am surprised to learn RAM SS is incapable of assigning a two-way load distribution type floor deck to a simple multistory building model, modeled in RAM modeler. therefore load is not distributed to all four beam but is distributed through One-way, in direction selected when assigning the Deck to the floor slab. Is this correct? or am i missing something ? ?  
 

RE: Ram Structural System

2
Yes. There is no two way deck modeling option in RAM. But you can achieve this by modeling some additional dummy beams and assigning decks oriented at 45 deg and 135 deg.

RE: Ram Structural System

(OP)
well then i model the slab assign it a deck of specified thickness and manually workout two beam loads and apply it to the beams ? would this be correct ?
 

RE: Ram Structural System

RAM's capabilities are very limited in comparison to Etabs, et al.  RAM is a very user-friendly program, but the list of things RAM cannot do is quite long.  It is not a true finite-element solver.  With a few exceptions, you are limited to simply supported, statically determinate structures.  I use RAM for simple buildings but prefer more "powerful" programs for complex situations.

RE: Ram Structural System

RISA all the way!!

RE: Ram Structural System

(OP)
yeah but can RISA calculate center of rigidity ? this is very handy tool in locating shearwalls or bracings in the building.?
(just a question)
 

RE: Ram Structural System

RAM is worthwhile just for the 180 Load combinations it generates for wind seismic and everything else.  Additionally, as pointed out, it gives very refined frame analyses.  Will RISA consider the torsional effects of the center of rigidity not being in line with the center of mass?   

RE: Ram Structural System

Call RAM tech support and they have a document showing how to simulate a 2 way slab action by adding some diagonal dummy beams and changing the deck orientation.

RE: Ram Structural System

The great thing about Ram Structural System is that it will reduce the live load automatically based on the trib area it calculates and member classification.  I guess, this is why it stays away from two-way action and keeps everything determinate.

RE: Ram Structural System

(OP)
prsconsultant

apparently Bentley dont have such document. Can you guide me a litle bit on how i can model two way loading using dummy beams

RE: Ram Structural System

gyroman10:

I could not find the documentation RAM had sent me few years ago. But, you can look at the attached sketch which basically shows how to simulate 2 way action. In a typical bay, model the column strips as beams. Divide the typical bay in to 4 quadrants using 3 dummy beams. Full span dummy beam would be along the shorter of the two spans. Model the flat slab with deck oriented at 45 deg and 135 deg as shown in the attached.

RAM in their documentation had claimed that by doing this way the column loads & moments would be quite accurate.

Let me know how this works for you. I will keep looking for that document and will post it if & when I find it.

RE: Ram Structural System

(OP)
prsconsultant

thankyou so much this helped a lot, now i dont have to calculate loads manualy. However i distribute load on beams via Traingular method of distribution, but strip method is also fine i presume.

Thanks again
 

RE: Ram Structural System

(OP)
By the way there is no dummy beam option in RAM. or is there ?
 

RE: Ram Structural System

I think he means "other" beam.

RE: Ram Structural System

What I mean by dummy beam is that you define a beam with a small section (say 1"x1") with other material.  

RE: Ram Structural System

(OP)
prsconsultant
i have tried your way, it may be good for column design but surely is not good for beams. do you use RAM SS to design complete concrete structures ? columns beams and footing ? if so then how do to you model two load onto the beams

 

RE: Ram Structural System

gyroman10

We use RAM SS for complete concrete design when we have a wide joist module one way system. When we have 2-way slab system, we export the RAM SS model data to RAM CONCEPT and design it there. All columns and foundations are designed in RAM SS / RAM Foundation.

Just curious what kind of problem did you see with beam forces? What did you compare the RAM beam forces to? If properly modeled I would have expected comparable results.

RE: Ram Structural System

(OP)
When suggeted method used, the beams are only transfered half the load they should be transfered to, and remaining load goes to the columns in form of point load, the beams are therefore designed for half the load. and columns recieve half the moment they should be recieving. I wrestled with RAM SS for one long week. Now i am calculating floor loads in form of line loads and applying it to the beams. even though there is a large room of improvement in RAM SS i still tend to like, or may be i have no other option ! this is the only software my company has. Also RAM does not design a beam for Torsion that was too a bit surprising.
 

RE: Ram Structural System

(OP)
what is the difference between gravity beam and lateral beam ?  

RE: Ram Structural System

As the name says, gravity beams carry dead and live loads only. The frame beams are part of the buildings lateral system & carry gravity loads plus additional loads due to wind / seismic.

RE: Ram Structural System

I just finished a series of buildings with concrete moment frames and I did use RAM Concrete for modeling -- however, I did not use it for the beam design.  
I called Bentley to ask about 2-way slabs and they said their solution was to use Concept and then import those results into Concrete.  I did not go this route because I didn't have the time to learn Concept.  
Instead, I modeled a concrete deck at 45 degrees so that each beam would be transferring the appropriate load to the columns. I used the axial loads from the results, as well as the story displacement and building story shear values.  
I then modeled the continuous beams in Enercalc and used those designs.
I love RAM for many reasons but yes it does have it's limitations- they all do in some way.  I just purchased RISA recently and have been disappointed with it thus far.  I have used STAAD and I think it is the worst of them all... Of all the programs, I've been the happiest with RAM and if I had it to do over, I would have purchased RAM Advanse instead of RISA.

 

RE: Ram Structural System

Structure33

Since you are not satisfied, see is RISA will refund your money.

RE: Ram Structural System

I am not being a smart butt, but some of the questions you are asking gyroman10 are a little scary.  I would make sure someone reviews your RAM design

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