Hello, I have one question about your parameters for the design of the main girder. Why didn't you use additional nodal supports (with locked uy) in points where three secondary beams are connected? You did this for beams around the silo hole buy not for the main girder.
Hi, Julia! You are right, one could consider also a horizontal bracing for the main girder, but on the safe side the design can be done without this bracing.
@@DlubalEN what exactly do you mean by being on the safer side? As I understand, the perpendicular beams are those that control the lateral torsional bucking. So, without considering the intermediate beams, doesn't it increase the member size?
Hi, akhil! I depends which check is controlling. If lateral torsional buckling is controlling then ignoring the intermediate beams will lead to increased member size. The design is then on the safe side. It is up to the user to decide if he wants to include or ignore the lateral bracing.
Hi, akhil! We do all the checks eg for stress, buckling, lateral torsional buckling or deformation. The one that has the highest utilization ratio is the controlling check and is listed first in the output tables with all details.
Hi, In RF-Stability, I cannot import axial forces from result combinations. I can see all the combinations individually but not RC1 nor RC2. How do I solve that problem? Also, you didn't show the differences between RSBUCK and RF STABILITY like you said you would in the 1st webinar. Or if you did, I missed it.
Hi, brittager! You are correct and you cannot assign Result Combination in RF-STABILITY for an import of the axial forces. You have to pick one that is controlling in your opinion. I suggest to take one that has the biggest axial forces in the part of the structure you want to check. Result Combinations are an envelope of all max and min internal forces. Therefore, those forces can come from a different Load Combination at every member or every location. They do not reflect a force distribution that actually comes from one real load. Therefore, result combinations are not the best choice to select for a buckling case. In RFEM it is even a more complex situation because there are surfaces and solids additionally to just 1D members. RSBUCK and RF-STABILITY are in principle very similar. RF-STABILITY covers also surfaces and solids. Further due to different solvers it has more options to set. But both programs give the buckling modes and critical load factors for a given axial force distribution. I hope this explains your questions.
Hi, Tito! Thank you for this idea. We will add it to the wishlist. Meanwhile you may find valuable information to the topic at www.dlubal.com/en/solutions/industries/other/analysis-and-design-software-for-scaffolding-and-rack-structures. If you have a specific question let us know.
Maybe I'll be wrong again but for columns in the module rf-steel in the menu "Detail" the tab "Stability" for this calculation scheme had to put a check box "Sway y-y [Cmy=0.9]).
Hello. Are both sections "intermediate lateral restrains" and "Nodal supports" used to analyse the lateral-torsional (or warping torsion) buckling ? So I have to define parameters only in one section (whether I'm analysing single members or set of members) ? And at 21:08 it's said that intermediate supports should be defined if they aren't modeled in scheme. But even if they are modeled, I also have to define its type, don't I ?
Hi, Alejandro! Yes they are. Nodal supports are only available if you have a set of member, while intermediate lateral supports are also available for members. If you analyze single members you most likely will use intermediate lateral supports. When designing set of members you most likely will work with nodal supports. Yes it is also true that the support types have to be defined also even if the lateral supporting member is modeled in RFEM.
hey @ 43.10 of the video , when the channel member was by elastic analysis , you then decide to use its plastic resitance and then changed to seetiing for plastic naalysis for that member . is it allowed as per Eurocode to combine both elastic and pastic analysis of member in a model
If the members forming the set of members were modeled in such a way that they weren't divided at the nodes, in other words if the girders between the columns remained single members, would the analysis of those members generate the same results or do we still have to make those single members into set of members? I hope my question is clear enough.
Hi, brittager! RFEM can mesh such un-divided models if the ending node of a member is placed exactly on the line of the main girder. The results for the internal forces will be the same. The design then will take into account the entire girder length as a buckling length by default. You may get by without set of members in such case. It is up to you which way you go.
Hello. At 40:19 when imperfections are set when calculating the ltb, the buckling curve is assigned according to table 6.2 of EN 1993-1-1. It is right? When calculating ltb according to en 1993-1-1, you need to use tables 6.4 or 6.5.
Hi, Vasiliy! in the example we analyze the structures internal forces including imperfections and do a stress analysis. For this method we use the imperfections of chapter 5.3.2. We are not using the simplified equivalent member procedure in RF-STEEL Warping Torsion. So the assignment of the buckling curve should be correct.
Thank. Earlier, I thought that the LTP buckling curve should be assigned according to table 6.5. Clause 5.3.4 (3) states that e0 "... imperfection of the weak axis of the profile ..." means table 6.2 is meant.
Using a fire-resistance tool in RF-STEEL EC3 I have noticed that design ratio doesn't change according to the change of required fire resistance time (no matter I put 15 minutes or 120). And I can't find any fire-resistance analysis data in details for members.Where can I find it?
Hi, Alejandro! Are you sure you added some load cases or load combinations for design in 1.1 General Data. Only then the checks are done. In the result tables you should find then all details about the design. Note that the maximum design ration may not be affected if fired design is not controlling.
Yes, I have added load combination for design and the checks are done. The point is that I can’t find any checks of fire design in the result table (for example checks according to formulas 4.3… 4.5; 4.8…4.11 of EN 1993-1-2)
Hi, Alejandro! I checked it on an own example and it seems all to work. Would you be so kind to send it in using the form on your website bit.ly/2LF9q48. Thank you!
You were right in your first reply - I haven't add load combinations to the fire resistance design into the inset bottom. I just haven't noticed it( Sorry and thank you
For the wind loads on the columns, did you assume there were claddings or some kind of envelope on the columns? I think it wouldn't make sense to have such wind loads on stand-alone columns (without claddings for wind to apply on). Am I wrong here?
Hi, brittager! This example is not about the cladding. The cladding must be designed additionally. Here we demonstrate only the design of the main steel structure (frames, columns, girders).
Dlubal Software EN I understand it's not about the claddings. What I was referring to is the fact that if there is no envelope on the frame, the wind loads may not be present or very small since there is nothing for the wind to 'push' on. Thanks again for the reply. The wevinars were very interesting. I learned a lot.
Hi, brittager! The wind generator is assuming the area between the girders is filled and it calculates the loads as if there would be a tight roof. So no worries. If you would calculate only one frame in a 2D model you would do manually the same loading procedure.
@@DlubalEN what you mean it wind generator automatically detects the projected area of the steel frames and applies to structural frames . Am I right ? I also want to to know whether the wind load gets automatically updates if member profiles are changed when we change any profile later ?
Hello, I have one question about your parameters for the design of the main girder. Why didn't you use additional nodal supports (with locked uy) in points where three secondary beams are connected? You did this for beams around the silo hole buy not for the main girder.
Hi, Julia!
You are right, one could consider also a horizontal bracing for the main girder, but on the safe side the design can be done without this bracing.
@@DlubalEN what exactly do you mean by being on the safer side?
As I understand, the perpendicular beams are those that control the lateral torsional bucking. So, without considering the intermediate beams, doesn't it increase the member size?
Hi, akhil!
I depends which check is controlling. If lateral torsional buckling is controlling then ignoring the intermediate beams will lead to increased member size. The design is then on the safe side. It is up to the user to decide if he wants to include or ignore the lateral bracing.
@@DlubalEN Can you explain how exactly does the software identy the controlling factor?
Hi, akhil!
We do all the checks eg for stress, buckling, lateral torsional buckling or deformation. The one that has the highest utilization ratio is the controlling check and is listed first in the output tables with all details.
Hi,
In RF-Stability, I cannot import axial forces from result combinations. I can see all the combinations individually but not RC1 nor RC2. How do I solve that problem?
Also, you didn't show the differences between RSBUCK and RF STABILITY like you said you would in the 1st webinar. Or if you did, I missed it.
Hi, brittager!
You are correct and you cannot assign Result Combination in RF-STABILITY for an import of the axial forces. You have to pick one that is controlling in your opinion. I suggest to take one that has the biggest axial forces in the part of the structure you want to check. Result Combinations are an envelope of all max and min internal forces. Therefore, those forces can come from a different Load Combination at every member or every location. They do not reflect a force distribution that actually comes from one real load. Therefore, result combinations are not the best choice to select for a buckling case. In RFEM it is even a more complex situation because there are surfaces and solids additionally to just 1D members.
RSBUCK and RF-STABILITY are in principle very similar. RF-STABILITY covers also surfaces and solids. Further due to different solvers it has more options to set. But both programs give the buckling modes and critical load factors for a given axial force distribution. I hope this explains your questions.
Dlubal Software EN
Yes, it explains perfectly.
Thanks for your quick and very detailed reply.
What's the criteria for defining the nodal supports in the y-direction? You only defined nodal supports for certain members (timestamp 27:37)
Hi, @yousefzam2328!
There are only 2 intermediate members that support the beam only in the y direction.
@DlubalEN what about the secondary beams themselves? Why not consider them as intermediate supports?
I would like to see videos relared to scaffolding structural analysis.
Hi, Tito!
Thank you for this idea. We will add it to the wishlist. Meanwhile you may find valuable information to the topic at www.dlubal.com/en/solutions/industries/other/analysis-and-design-software-for-scaffolding-and-rack-structures. If you have a specific question let us know.
Maybe I'll be wrong again but for columns in the module rf-steel in the menu "Detail" the tab "Stability" for this calculation scheme had to put a check box "Sway y-y [Cmy=0.9]).
Hi, Vasiliy!
This is an optional parameter and you are free to use it. In the code it says that it "should be used". You are right.
Hello.
Are both sections "intermediate lateral restrains" and "Nodal supports" used to analyse the lateral-torsional (or warping torsion) buckling ? So I have to define parameters only in one section (whether I'm analysing single members or set of members) ?
And at 21:08 it's said that intermediate supports should be defined if they aren't modeled in scheme. But even if they are modeled, I also have to define its type, don't I ?
Hi, Alejandro!
Yes they are. Nodal supports are only available if you have a set of member, while intermediate lateral supports are also available for members. If you analyze single members you most likely will use intermediate lateral supports. When designing set of members you most likely will work with nodal supports. Yes it is also true that the support types have to be defined also even if the lateral supporting member is modeled in RFEM.
hey @ 43.10 of the video , when the channel member was by elastic analysis , you then decide to use its plastic resitance and then changed to seetiing for plastic naalysis for that member . is it allowed as per Eurocode to combine both elastic and pastic analysis of member in a model
Hi, ALEX!
yes, the combination of elastic and plastic analysis is allowed.
If the members forming the set of members were modeled in such a way that they weren't divided at the nodes, in other words if the girders between the columns remained single members, would the analysis of those members generate the same results or do we still have to make those single members into set of members? I hope my question is clear enough.
Hi, brittager!
RFEM can mesh such un-divided models if the ending node of a member is placed exactly on the line of the main girder. The results for the internal forces will be the same. The design then will take into account the entire girder length as a buckling length by default. You may get by without set of members in such case. It is up to you which way you go.
Hello. At 40:19 when imperfections are set when calculating the ltb, the buckling curve is assigned according to table 6.2 of EN 1993-1-1. It is right? When calculating ltb according to en 1993-1-1, you need to use tables 6.4 or 6.5.
Hi, Vasiliy!
in the example we analyze the structures internal forces including imperfections and do a stress analysis. For this method we use the imperfections of chapter 5.3.2. We are not using the simplified equivalent member procedure in RF-STEEL Warping Torsion. So the assignment of the buckling curve should be correct.
Thank. Earlier, I thought that the LTP buckling curve should be assigned according to table 6.5. Clause 5.3.4 (3) states that e0 "... imperfection of the
weak axis of the profile ..." means table 6.2 is meant.
Using a fire-resistance tool in RF-STEEL EC3 I have noticed that design ratio doesn't change according to the change of required fire resistance time (no matter I put 15 minutes or 120). And I can't find any fire-resistance analysis data in details for members.Where can I find it?
Hi, Alejandro!
Are you sure you added some load cases or load combinations for design in 1.1 General Data. Only then the checks are done. In the result tables you should find then all details about the design. Note that the maximum design ration may not be affected if fired design is not controlling.
Yes, I have added load combination for design and the checks are done.
The point is that I can’t find any checks of fire design in the result table (for example checks according to formulas 4.3… 4.5; 4.8…4.11 of EN 1993-1-2)
Hi, Alejandro!
I checked it on an own example and it seems all to work. Would you be so kind to send it in using the form on your website bit.ly/2LF9q48.
Thank you!
You were right in your first reply - I haven't add load combinations to the fire resistance design into the inset bottom. I just haven't noticed it(
Sorry and thank you
For the wind loads on the columns, did you assume there were claddings or some kind of envelope on the columns? I think it wouldn't make sense to have such wind loads on stand-alone columns (without claddings for wind to apply on). Am I wrong here?
Hi, brittager!
This example is not about the cladding. The cladding must be designed additionally. Here we demonstrate only the design of the main steel structure (frames, columns, girders).
Dlubal Software EN
I understand it's not about the claddings. What I was referring to is the fact that if there is no envelope on the frame, the wind loads may not be present or very small since there is nothing for the wind to 'push' on.
Thanks again for the reply.
The wevinars were very interesting. I learned a lot.
Hi, brittager!
The wind generator is assuming the area between the girders is filled and it calculates the loads as if there would be a tight roof. So no worries. If you would calculate only one frame in a 2D model you would do manually the same loading procedure.
@@DlubalEN what you mean it wind generator automatically detects the projected area of the steel frames and applies to structural frames . Am I right ? I also want to to know whether the wind load gets automatically updates if member profiles are changed when we change any profile later ?
Hi, ALEX!
You're right. The load area depends on the corner nodes. The generated wind loads automatically update after the member adjustments.