ETABS

[Yasir]

Dear All

How many of you have developed a worksheet or any helping material on composite design?

[concreteok]

Yasir,

Never really into composite or steel design but i have seen demo of csc fastrak. Its seems to me, giving much better control on the designing part. Since its shared here, maybe u can try it out.

Secondly, i am much of a manual designer. For concrete design, why should we use multiplier to the reinforced concrete frames' stiffnesses when we carry out elastic analysis? Unless we are performing non linear analysis. Pls advise.

[juice]

yasir,

Never really into composite or steel design but i have seen demo of csc fastrak. Its seems to me, giving much better control on the designing part. Since its shared here, maybe u can try it out.

Secondly, i am much of a manual designer. For concrete design, why should we use multiplier to the reinforced concrete frames' stiffnesses when we carry out elastic analysis? Unless we are performing non linear analysis. Pls advise.

concreteok, the modifier is required to estimate the effective stiffness of your frames at ultimate limit state--drifts are checked at ULS in accordance to code (drift at ULS ~ disp. ductility * drift from linear analysis). The preceding approximation of drift at ULS is based on equal displacement hypothesis--may not be actually true but still acceptable within the present codes' concept of force-based design methodology.

regards,
juice

[oanm2000]

I agree as much with JUNAID as with YUCAPAREJA too.
Personally I have not had reliable experiences in designs of composed beams with ETABS. In a previous project, where I totally trusted of the obtained results, a discussion appeared on the design that I emitted, because some results were not consistent, if they were compared by hand with results displayed with the STAAD or another software.
I try to recheck ever with another software first
oanm2000

[tarugo]

it is possible to assign boundary elements in wall design. the easiest way to do that is thru the shea wall design overwrites. you should choose simplified T & C instead of uniform reinforcing. in T & C option u can input the dimensions of the boundary elements. for better understanding you should consult the etabs manual also...

[vati]

I am trying to use this link but it is not working and i cant find the problem.
Does any one use this link?

[aslam]

* COLUMN DESIGN:
As i know, etabs only gives column steel area requirement and not the arrangement of steel bars with dia. Actually, capacity of column section depends on arrangement of steel bars (Interaction diagrams).
Checking section for given bar dia and arrangement is OK, but how it calculates steel area without having arrangement of steel.

*BEAM DESIGN :
ETABS gives steel area requirement at beam mid span and at beam support, but how we can know upto which distance this steel is required.
Also, distance upto which given shear reinforcement is required, is not mentioned. I think distance shall be mentioned for steel area and shear rein. in BRACKET.

*COMPOSITE BEAM & COLUMN:
I use ATIR STRAP for this purpose and i am getting satisfactorily results from that.

Presently i use ETABS only for Analysis purpose. I have prepared EXCEL sheets for RC componets design for design purpose.

[piscesa]

@ Column Design
As far as I'm experienced in using ETABS, it is true that ETABS only gives column steel reinforcement if option of reinforcement to be design was selected. How it calculates steel area without having arrangement of steel ? I had implement a program which is similar to PCACOL and the way it design the reinforcement is quite different than PCACOL whereas the PCACOL use steel area arrangement in design. The way it design is using a lot of steel area arrangement (i.e 100 steel bars, So it is more like a steel strip in the concrete), but the diameter of bars is a variable needs to be found according to the axial and moment load. After the diameter is found then the area of steel reinforcement could be found by multiplying the area with sum of the total bar (100) and it only says that it requires xxxx mm2 of reinforcement not the number of steel reinforcement with its area (i.e 4-D25). I think the ETABS had done the same way, it could be using a lot of reinforcement or using a steel strip.

Since ETABS didn't show any value in interaction curve so it will be more difficult in seeing whether the load is satisfied or there could be error in the interaction curve (Based on experience) I would prefer PCACOL or CSICOL in designing concrete columns as a cross check in ETABS design.

@ Beam Design
How do we know which the distance required ? By checking the inflection point of the moment. For example the simple ways is if the moments in the support is negative we should check the location where the moments is began to change into positive it is the point where the steel area requirement in the support should stop theoritically, but since the steel reinforcement in the support and midspan should connect each other, the location of the inflection point should be extended according to the development length required (Usually 40 db is satisfied). By this way the continuity of steel reinforcement in beams is satisfied.

@ Composite Beam and Column
I had never design this type of element in ETABS, I think using manual calculation or other RC design component such as CSICOL will be more wise. For this case ETABS just for analysis.

CMIIW,
regards
piscesa

[iceman84]

Regarding the slab modelling in ETABS I use shell elements for slab analysis and membrane elements for frame analysis (no mesh). I saw that there are quite some differences in beam efforts if you use shell compared to membrane (smaller efforts in case of shell).

[gacella]

Dear all
*BEAM DESIGN :
ETABS gives steel area requirement at beam mid span and at beam support, but how we can know upto which distance this steel is required.
Also, distance upto which given shear reinforcement is required, is not mentioned

ETABS report steel area al every station, usual divide in 10 piece, right click in beam and you have every location or prin tables and copy on excel

@ Column Design

it calculates steel area based on uniform steel, its better having arrangement of steel and check column Etabs calcule the interaction curve. In define frame you can see interaction curve.