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Good Frame Analysis Software? 7
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I have never used ETABS, why is it so good? I am based in the UK and had never even heard of it before using these forums (same can be said for RISA3D). The common ones in the UK seem to be STAAD, SFRAME, PROKON, Masterseries, CADS.
I looked at the ETABS website and it does design to British Standards and Eurocodes. I guess it can also work in SI units with European section sizes. How come I had never heard of it?
I looked at the ETABS website and it does design to British Standards and Eurocodes. I guess it can also work in SI units with European section sizes. How come I had never heard of it?
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As a first hand testament to ETABS, my company has designed some of the world's tallest buildings (Petronas Towers, Taipei 101 etc.) with ETABS. I am currently designing a 4 million sf tower with ETABS.
You have the option of importing a basic DXF, and I think version 9 is compatible with Revit. Speaking of Revit (again, personal experience) I think it has great value with structural design. We are always constantly fighting floor penetrations and in-slab conduits with flat plate PT designs. With Revit (getting it very soon, so I don't have any first hand experience with it) I understand you can assign "off-limits" areas to the unified/all encompassing model. Structural Off limits in my opinion would be punching shear zones at a PT slab and holes bigger than 4" anywhere without approval. The possibilities are endless- and if as an office a standard set of limitations were developed (I assume you can define standard limits, maybe even import them from a base file [how cool!]) you really improve the chances of not missing something that can inadvertently compromise the integrity of the structural design.
Anyway, back on topic.. I'll just give a quick rundown of how I use ETABS day to day.
The way I typically use ETABS is define the grids and stick to it. You can have as many uniquely oriented and defined grid systems, radial and/or cartesian, as you want. For instance, a colleague of mine is designing a building with a standard grid and a multi-contour radial end of the building attached. He spent the time to define the grid system, and it really made his life easy. Then you define story levels. If your building splits off into more than one tower with different intrastory heights (you guessed it- I've come across this limitation in practice..) the new version of ETABS (9) can handle it.
From there you define materials and sections. ETABS can handle exotic situations like non-linear properties, links, springs, dampers (dashpots), gap elements, plastic hinges, base isolators, etc.. (infact, ETABS' sister product SAP2000 is very good at handling funky stuff and all sorts of non-linear crazy stuff- we have both in our office. I use SAP2000 for everything that is not a building; a truss or independent frame for example; SAP2000 very effectively models cables and tendons with drape and the whole 9 yards [meters]
) ETABS and SAP2000 utilize a sub-program called CSI Section Designer. If you for instance have a crazy column (for instance a 10'x12' triangle superimposed over a 72" circle, out of 10 ksi concrete), you can define it as a SD section- and it will accurately be represented and checked within the analysis software. The software obviously has built-in databases that include all of the standard shapes and sections. What I use ALOT are the shell elements for shear walls. You can define within ETABS different behaviors for different area elements. For instance, I use a membrane element (no in-plane stiffness) in conjunction with a rigid diaphram to model a flat PT plate with gravity loads only (applied as pounds per square foot) in my shear wall (lateral analysis) model. Then I use shell elements to model the walls (no out of plane stiffness- I think I got those right..). And if you want all degrees of freedom/stiffness, you can specify a plate element. Finally, there are multiple ways to assign section property modifiers- for instance modified gross section properties due to cracked sections.
So you then go thru and "build" your building in the GUI.
Next, you apply loads. Surface loads to area elements, line loads, point loads, temperature loads etc are all possible. ETABS Version 9 has really refined the automatic load generation capabilities. For instance- wind loads are automatically calculated very well according to IBC 2003 on the one simple model that I recently spot checked the software on.
Earthquake loads are a bit of a black science, especially on a very large, extremely irregular model (again- it's waiting in the office for me
) But ETABS is very good for "standard" buildings in "automatic mode". You can specify a time-history, excitement function, or response spectra. (Among I'm sure dozens of other earthquake related permutations.) Within this, you can specify all of the special seismic provisions, and it will scale everything and consider everything without a hitch. If you want me to go more in depth on this, let me know- earthquake loading is going to drive me to drinkin' before too long 
ETABS performs SRSS and CQC combinations- which by the nature of the theory loses the sign on reactions- not a good thing when you are trying to design a foundation; different topic though. Finally, it will automatically generate all of the load combinations for you depending on your desired design code- i.e. all of the various allowable stress or LRFD codes.
It's actually pretty sophisticated; if you have a steel frame in conjunction with a concrete frame in the same building, it will associate the different codes with different elements- so if you want to use ACI-02 for your concrete frame and ASD for the steel elements it keeps track of it (or whatever combination you want- it has codes for cold-formed framing, shear walls, concrete frames, steel frames etc.)
So, then you analyze your system.
Obviously you can point and click and get all sorts of typical info- deflections, drift ratios, forces, mode shapes etc. You can also display deformed shapes, animate modes and deformed shapes (great for debugging), and it does a really good job of displaying stress plots. One really good example is say you want to figure out where you should assign cracked section properties. Set the display shell stresses to a range of say 0 psi to 424 psi (tension). If the area is above 424 psi it will be a certain color and you will know that the section(s) are cracked.
Finally (well- I'm getting tired; hardly the full extent of ETABS) you have the design module. What a truly GREAT piece of software. Here's my example- in my current building, I have something like 5000 column 'segments' (column lines x floors). I've assigned the actual section with specified reinforcing as it is on our column schedule to the line elements within the ETABS model. I am not using this for actual design in this instance- but an accurate way of backchecking our drawings and schedules, of which had columns calculated by hand because the ETABS model was not ready yet when the columns were scheduled. (and yes, it took some time to input all of them). Sure enough, I found 5! +/- individual sections that were inadequate (out of 5000). And they showed up as bright red.
Next example is shear wall design. I have over a hundred unique wall segments in 3 cores and independent regions (in all, including manually meshed floor slabs, I have well over 60,000 shell (area) elements in my model). After tweaking the ETABS model and making various assignments, the wall are completely and accurately designed automatically. This includes boundary zones, required reinforcement ratio etc. The final step in my instance was to boil down all of this wonderful information into a simple spreadsheet that tabulated the 3 or 4 values for each wall that I needed to take care of my scheduling and shear wall plans. This was accomplished by importing the ETABS output .txt file into Excel and working out a pretty cool spreadsheet.
In a 'normal' building, you just click on the wall and it comes up with the controlling combos and resulting design. ETABS will also do all sorts of material takeoffs and produce a bunch of summary output that is great for representative calculations.
There are so many valuable features and aspects of ETABS (and SAP2000) that would take all night(s) to explain. Bottom line, in the words of the CSI help/tech support guy -> ETABS is like a Ferrari, anyone can drive it; but it takes practice and skill to master it. I think it is quite possibly the best "building" design software out there- precisely what a Ferrari driver would say about substituting a Lamborghini for his favorite car )
You have the option of importing a basic DXF, and I think version 9 is compatible with Revit. Speaking of Revit (again, personal experience) I think it has great value with structural design. We are always constantly fighting floor penetrations and in-slab conduits with flat plate PT designs. With Revit (getting it very soon, so I don't have any first hand experience with it) I understand you can assign "off-limits" areas to the unified/all encompassing model. Structural Off limits in my opinion would be punching shear zones at a PT slab and holes bigger than 4" anywhere without approval. The possibilities are endless- and if as an office a standard set of limitations were developed (I assume you can define standard limits, maybe even import them from a base file [how cool!]) you really improve the chances of not missing something that can inadvertently compromise the integrity of the structural design.
Anyway, back on topic.. I'll just give a quick rundown of how I use ETABS day to day.
The way I typically use ETABS is define the grids and stick to it. You can have as many uniquely oriented and defined grid systems, radial and/or cartesian, as you want. For instance, a colleague of mine is designing a building with a standard grid and a multi-contour radial end of the building attached. He spent the time to define the grid system, and it really made his life easy. Then you define story levels. If your building splits off into more than one tower with different intrastory heights (you guessed it- I've come across this limitation in practice..) the new version of ETABS (9) can handle it.
From there you define materials and sections. ETABS can handle exotic situations like non-linear properties, links, springs, dampers (dashpots), gap elements, plastic hinges, base isolators, etc.. (infact, ETABS' sister product SAP2000 is very good at handling funky stuff and all sorts of non-linear crazy stuff- we have both in our office. I use SAP2000 for everything that is not a building; a truss or independent frame for example; SAP2000 very effectively models cables and tendons with drape and the whole 9 yards [meters]
) ETABS and SAP2000 utilize a sub-program called CSI Section Designer. If you for instance have a crazy column (for instance a 10'x12' triangle superimposed over a 72" circle, out of 10 ksi concrete), you can define it as a SD section- and it will accurately be represented and checked within the analysis software. The software obviously has built-in databases that include all of the standard shapes and sections. What I use ALOT are the shell elements for shear walls. You can define within ETABS different behaviors for different area elements. For instance, I use a membrane element (no in-plane stiffness) in conjunction with a rigid diaphram to model a flat PT plate with gravity loads only (applied as pounds per square foot) in my shear wall (lateral analysis) model. Then I use shell elements to model the walls (no out of plane stiffness- I think I got those right..). And if you want all degrees of freedom/stiffness, you can specify a plate element. Finally, there are multiple ways to assign section property modifiers- for instance modified gross section properties due to cracked sections. So you then go thru and "build" your building in the GUI.
Next, you apply loads. Surface loads to area elements, line loads, point loads, temperature loads etc are all possible. ETABS Version 9 has really refined the automatic load generation capabilities. For instance- wind loads are automatically calculated very well according to IBC 2003 on the one simple model that I recently spot checked the software on.
Earthquake loads are a bit of a black science, especially on a very large, extremely irregular model (again- it's waiting in the office for me
) But ETABS is very good for "standard" buildings in "automatic mode". You can specify a time-history, excitement function, or response spectra. (Among I'm sure dozens of other earthquake related permutations.) Within this, you can specify all of the special seismic provisions, and it will scale everything and consider everything without a hitch. If you want me to go more in depth on this, let me know- earthquake loading is going to drive me to drinkin' before too long ETABS performs SRSS and CQC combinations- which by the nature of the theory loses the sign on reactions- not a good thing when you are trying to design a foundation; different topic though. Finally, it will automatically generate all of the load combinations for you depending on your desired design code- i.e. all of the various allowable stress or LRFD codes. It's actually pretty sophisticated; if you have a steel frame in conjunction with a concrete frame in the same building, it will associate the different codes with different elements- so if you want to use ACI-02 for your concrete frame and ASD for the steel elements it keeps track of it (or whatever combination you want- it has codes for cold-formed framing, shear walls, concrete frames, steel frames etc.)
So, then you analyze your system.
Obviously you can point and click and get all sorts of typical info- deflections, drift ratios, forces, mode shapes etc. You can also display deformed shapes, animate modes and deformed shapes (great for debugging), and it does a really good job of displaying stress plots. One really good example is say you want to figure out where you should assign cracked section properties. Set the display shell stresses to a range of say 0 psi to 424 psi (tension). If the area is above 424 psi it will be a certain color and you will know that the section(s) are cracked.
Finally (well- I'm getting tired; hardly the full extent of ETABS) you have the design module. What a truly GREAT piece of software. Here's my example- in my current building, I have something like 5000 column 'segments' (column lines x floors). I've assigned the actual section with specified reinforcing as it is on our column schedule to the line elements within the ETABS model. I am not using this for actual design in this instance- but an accurate way of backchecking our drawings and schedules, of which had columns calculated by hand because the ETABS model was not ready yet when the columns were scheduled. (and yes, it took some time to input all of them). Sure enough, I found 5! +/- individual sections that were inadequate (out of 5000). And they showed up as bright red.
Next example is shear wall design. I have over a hundred unique wall segments in 3 cores and independent regions (in all, including manually meshed floor slabs, I have well over 60,000 shell (area) elements in my model). After tweaking the ETABS model and making various assignments, the wall are completely and accurately designed automatically. This includes boundary zones, required reinforcement ratio etc. The final step in my instance was to boil down all of this wonderful information into a simple spreadsheet that tabulated the 3 or 4 values for each wall that I needed to take care of my scheduling and shear wall plans. This was accomplished by importing the ETABS output .txt file into Excel and working out a pretty cool spreadsheet.
In a 'normal' building, you just click on the wall and it comes up with the controlling combos and resulting design. ETABS will also do all sorts of material takeoffs and produce a bunch of summary output that is great for representative calculations.
There are so many valuable features and aspects of ETABS (and SAP2000) that would take all night(s) to explain. Bottom line, in the words of the CSI help/tech support guy -> ETABS is like a Ferrari, anyone can drive it; but it takes practice and skill to master it. I think it is quite possibly the best "building" design software out there- precisely what a Ferrari driver would say about substituting a Lamborghini for his favorite car
)WillisV is right - From ETABS Help:
A wall or slab section can have shell, membrane or plate-type behavior.
Shell-type behavior means that both in-plane membrane stiffness and out-of-plane plate bending stiffness are provided for the section.
Membrane-type behavior means that only in-plane membrane stiffness is provided for the section.
Plate-type behavior means that only out-of-plane plate bending stiffness is provided for the section.
A wall or slab section can have shell, membrane or plate-type behavior.
Shell-type behavior means that both in-plane membrane stiffness and out-of-plane plate bending stiffness are provided for the section.
Membrane-type behavior means that only in-plane membrane stiffness is provided for the section.
Plate-type behavior means that only out-of-plane plate bending stiffness is provided for the section.
apetr26542
Structural
I've used Risa 3d from 1 story to a 10 story building, It does give you much design freedom.
I use SAP, ETABS. But my company buy a new software called S-FRAME and ORION which is cool~
I realised that most of the engineer in the UK are using S-Frame from CSC for analysis. The program can import DXF files easily. If your 3-6 storey building is a concrete building, a totally new program called Orion R14 is really cool. The program can import column and walls from DXF autoomatically and all position and size can be use for design without revising. It output all anaylsis results and it also do reinforcement design and detailing! I use ETABS for lateral load input and use Orion for analysis, design, detailing. All result can export to AutoCAD.
ETABS is good but it can only output result where I need to use conventional hand calc for design and deailting. Orion does all of that!!!
I realised that most of the engineer in the UK are using S-Frame from CSC for analysis. The program can import DXF files easily. If your 3-6 storey building is a concrete building, a totally new program called Orion R14 is really cool. The program can import column and walls from DXF autoomatically and all position and size can be use for design without revising. It output all anaylsis results and it also do reinforcement design and detailing! I use ETABS for lateral load input and use Orion for analysis, design, detailing. All result can export to AutoCAD.
ETABS is good but it can only output result where I need to use conventional hand calc for design and deailting. Orion does all of that!!!
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strangeoddity
Structural
Personally I prefer RAM (including RAM frame) for all structural steel buildings. Very user friendly and the interface between gravity design and lateral analysis continues to get better and better. RAM allows you to import a column grid from an AutoCAD file (although sometimes finiky) or you can export a dxf file from RAM to AutoCAD. Plus RAM has a great customer service department. Quick with responses!
I do have alot of experience with STAAD, which is the first program I turn to for those odd-ball designs. STAAD is a very powerful program.
I also find RISA2D and RISA3D to be very user friendly..although there are distinct limitations to these programs (cable structures for one).
As far as SAP2000, and ETABs, and SAFE (all products from the same company) I just began using these programs...and I miss STAAD. So far SAP2000 has been the most unfriendly piece of software I have ever used. One distinct disadvantage with changing companies...you get stuck with unfamilier software.
I do have alot of experience with STAAD, which is the first program I turn to for those odd-ball designs. STAAD is a very powerful program.
I also find RISA2D and RISA3D to be very user friendly..although there are distinct limitations to these programs (cable structures for one).
As far as SAP2000, and ETABs, and SAFE (all products from the same company) I just began using these programs...and I miss STAAD. So far SAP2000 has been the most unfriendly piece of software I have ever used. One distinct disadvantage with changing companies...you get stuck with unfamilier software.
About two years ago I tried the demos for both SAP2000 and RISA3D. I wanted to like SAP2000 but found that RISA was a little more intuitive. I talked to an engineer that used both and preferred RISA for his use but said SAP was what they used in the analytic department. I ended up not getting anything.
Last year I tried Multiframe and was really surprised at its intuitive interface. I was up and running in just a few hours. I purchased it along with the steel code checker which I don't like but not having tried any others can't really say if it's better or worse than the other programs.
Regards,
-Mike
Last year I tried Multiframe and was really surprised at its intuitive interface. I was up and running in just a few hours. I purchased it along with the steel code checker which I don't like but not having tried any others can't really say if it's better or worse than the other programs.
Regards,
-Mike
slickdeals
Structural
jen4950,
Etabs v9 has a lot of improvements. However, I wanted to ask you if the column import still worked. I have never been able to import a column element (defined as a block) into etabs v9. However it works just fine in 8.5.6.
Nevertheless ETABS rules, just cos it very sequential and schematic with menu driven input capabilities
Etabs v9 has a lot of improvements. However, I wanted to ask you if the column import still worked. I have never been able to import a column element (defined as a block) into etabs v9. However it works just fine in 8.5.6.
Nevertheless ETABS rules, just cos it very sequential and schematic with menu driven input capabilities
I always just import the architectural grid, and build the model from scratch- sure, it's a little more work on the front end, but debugging and related time is usually cut quite significantly.
For instance I modeled a very complex 4 story, 2 million square foot steel/composite deck building with all sorts of radial grids, non-sensical work points and transfers in an afternoon. This framed into my flat plate and conventional concrete tower that I already had modeled. Of course that was just the geometry; spent much longer on assignments etc. but you get the idea.
For instance I modeled a very complex 4 story, 2 million square foot steel/composite deck building with all sorts of radial grids, non-sensical work points and transfers in an afternoon. This framed into my flat plate and conventional concrete tower that I already had modeled. Of course that was just the geometry; spent much longer on assignments etc. but you get the idea.
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