Designing RC Columns in Autodesk Robot Structural Analysis
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- เผยแพร่เมื่อ 30 ก.ค. 2024
- Welcome to our tutorial on Designing RC Columns in Autodesk Robot Structural Analysis. In this video, we'll show you how to design reinforced concrete columns using Autodesk Robot Structural Analysis and how to analyze their behavior under different loads and supports.
Whether you're an engineer, architect, or student, this video will help you understand the basics of RC column design and how to apply them to your projects. We'll cover topics such as modeling techniques, defining properties, and analyzing the results.
We'll show you how to analyze the results, such as the axial force, bending moment, and shear force. We'll also cover how to design the RC column using the ACI 318 code and how to check the reinforcement requirements.
By the end of this video, you'll have a better understanding of how to design RC columns using Autodesk Robot Structural Analysis and how to analyze their behavior under different loads and supports. Don't forget to like, comment, and subscribe for more tutorials like this one!
(CLARIFICATION to a Question by our dear subscriber @Nii Sarpai)
The modification factor was applied to all inertias. This is visible during a split second before applying the cross section. The full input of those modifications was - by mistake - cut during video editting.
Some more details:
ACI code requires you to modify the bending stiffness of the beams and columns with corresponding factors.
Technically speaking, members can bend around yy and zz.
So those two Inertias should be modified, which I did (but was shown for a split second only).
Further proof to this is when looking at the K factor calculation of the column. The Inertias are reduced.
I still agree with your concern about Ixx. ACI code says nothing about it. It is the torsional stiffness of the beam.
Now first off, Ixx will not affect anything in our calculations. There is nothing causing torsion on the beam.
Still, my logic behind reducing it is based on the theoretical part.
You see, for a perfect cylinder, Ixx = Iyy + Izz
for rectangles, it is different.
Still, I thought that:
if Iyy is reduced
and Izz is reduced,
it stands to reason to reduce Ixx.
and that is the logic behind reducing all inertias by the same amount.
Timestamps:
0:00 Introduction
0:27 Frame Definition
4:20 Required Reinforcements
6:34 Provided Reinforcements
7:15 Calculations and Results
9:40 Improvements
12:41 Effective Column Length
16:03 Outro
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Great job, I really find your tutorials very helpful and interesting. I want to ask, if you can provide a video related to the design of Box culvert and pipe culvert using Robot structural analysis. Thank you again for your efforts.
Hi there,
Sure thing, but I need to finish the warehouse design series first.
Stay tuned for more content,
CEE
Great one
thnx a lot. Stay tuned for more content.
alhamdulillah
thank civil engineering essentials
Most welcome. It is really good to know that this video helped you, stay tuned for more content.
In steel columns, is the a video explaining in details the process of designing base plates with anchors with concrete columns with or without stirrups? Does Robot details graphic loads distribution in those situations?
I still have no detailed video about it, but I might add it to my ToDo list.
Stay tuned for more content.
I have a question about the buckling model: Suppose the column (25X25) with a masonry wall and is subjected to wind loads in the Y direction of its local axis, resulting in a moment MZ on the column. Should we turn off the Y direction and let the Z direction be on, because MZ is much greater than MY? Is that correct? I hope you understand me, if there any way to send you a picture of my robot model
I do not agree in turning of any direction in the buckling check.
I understand that your point is:
There is no My, so buckling around y is not an issue.
However, buckling can happen even if no moments are present around y. It can happen solely due to the Axial Forces.
Now, if you are an ACI318 user, then you would think:
Why do I care about buckling y? there is no moment to be "amplified".
(For non ACI users: Moment amplification is a method of including buckling effects by increasing the moment using a factor).
Now here is the plot-twist: the ACI318 code specifies a minimum moment you have to apply.
So in that case, if you were to "hand-calculate" your column, and your column is slender around Y, then you would have to apply M2min on Y and even perform moment amplification.
I hope my words made sense. Also, sorry for the late reply, we are at the end of the academic year, so a lot of paper work.
Regards,
CEE
@@CivilEngineeringEssentials Thank you so much CEE, very good explanation
Great content Sir.
However I realized you applied a stiffness modification factors to your frame according to ACI recommendation.
That is for beam 0.35 to Iyy
and for columns 0.7 to Ixx ( instead of Iyy and Izz)
Please clarify. Thanks
I agree, there was a slight video editting mistake I did.
if you check the input section a split second before I apply, you will see that the modification factor for all stiffnesses (Ix Iy and Iz) was modified.
The input process of those modifications was -however- cut during editting.
To clarify:
ACI code requires you to modify the bending stiffness of the beams and columns with corresponding factors.
Technically speaking, members can bend around yy and zz.
So those two Inertias should be modified, which I did (but was shown for a split second only).
Further proof to this is when looking at the K factor calculation of the column. The Inertias are reduced.
I still agree with your concern about Ixx. ACI code says nothing about it. It is the torsional stiffness of the beam.
Now first off, Ixx will not affect anything in our calculations. There is nothing causing torsion on the beam.
Still, my logic behind reducing it is based on the theoretical part.
You see, for a perfect cylinder, Ixx = Iyy + Izz
for rectangles, it is different.
Still, I thought that:
if Iyy is reduced
and Izz is reduced,
it stands to reason to reduce Ixx.
and that is the logic behind reducing all inertias by the same amount.
Still, you are right. it is only visible a split second before hitting the apply button. My video editting was not on point at that position.
Hope that clarifies the issue.
I will add this clarification to the description.
All the best,
CEE
@@CivilEngineeringEssentials you are right sir.
in a full building model with vertical and horizontal loads applied, stiffness values in all directions is reduced according to code requirements.
I realized in the column design, the columns has a reduced stiffness values but was confused abit in inputting during column section definition and the video editing.
Thank you for the clarification.
I really understand it now.
@@niisarpei3676 Most welcome. I am glad you liked it.
In tems of foundations You pinned the columns why you didn't fixed them?
That is a very good question. You see, fixed vs pinned is determined by the engineer. To explain what I mean, here is the theoretical background:
Fixed supports mean that the support is strong enough to stop any rotation
Pinned supports mean that the support might allow some rotation.
In reality, supports are neither fixed nor pinned, but somewhere in between. Some people like to put a "ground elasticity" by adding springs to the foundation.
So, the decision of pinning vs fixing is left to the engineer's discretion.
Here is what I usually have in mind:
Pinned supports mean that:
1) The moment would be higher
2) the moment would be a single curvature moment
So, it is a little bit more conservative when designing columns.
Hope it helped,
Regards,
CEE
was the column braced or unbraced? How does robot handle these two situations?
Hi there
I do not remember my inputs back then to be honest but:
Autodesk robot always calculates the effective length factor k and as per ACI code calculates the klu/r factor and compares it to decide wether it us long or short.
If you refer about if the atructure itself is braces or not, this is an input that can be provided by the user
@@CivilEngineeringEssentials okay 👍
the rebars in this column are absurd
I respectfully disagree. The controling case was dominated by bending moment.