Thank you Josh for replying, using a cruciform would be less critical than the beam moment splice. I will see what the contractor is comfortable with. I also found the connection Kootk was talking about, the flange plate would also double as a stiffner for the moment frame, but I will have to...
I will have to dig deeper for that.
Moments from the moment frame are not that much less than the gravity moments any way. the plate bearing the beam and the one below the first column will still have to work a lot to transfer the moments to the top of lower column I will also have to dig...
Do you mean continuing the beam over the column? Gravity moments are larger than wind moments so it accrued to me if I should be splicing my column rather than my beam. I might leave it to the contractor to choose. Having columns with different lengths might be tricky.
Gravity moments for the...
I will just do the connection suggested by HTURKAK. Its more like making a beam moment splice through the column web. Providing a moment splice at maximum beam moment is not ideal but its okay. The column web will see some moment, will look out for it.
Thank you HTURKAK and JAE for replying. In steel I am used to doing the basics so this is new to me.
Having moment connection on both sides of a column web is interesting thank you for providing that document. I guess since the column net moment will be almost zero its doable.
Yes JAE your...
I have a two story building as the provided sketch. The ground floor will be completely open car park (no wind pressure) with only a stair case.
I can have vertical bracing along the 17 meters direction. In the short direction I am limited to using moment frames.
The problem is that I have a...
Thank you Retrograde for replying.
Yeah I did it that way. His equations don't address the case where the column length is more than twice the width ( like slender concrete walls ). In that case I can get significant increase in Ise, as the software results agree.
It's just that the...
Concrete column buckling load (Pc) decreases significantly as the rigidity (EI) increases. The rigidity (EI) increases as the section stiffness (Ig) increases and as the reinforcement moment of inertia about the centroidal cross section (Ise) increases.
My question is, how to calculate the...
Thank you Kootk for replying.
Both great approaches. With the first one I can reduce uplift by (40-50) percent without having to assume gravity is not present [bigsmile]. I just need to pay attention that the smaller section is not over reinforced.
Also, I think applying the first approach...
Thank you everyone for replying.
I think it's not a good detail, but withstanding the explicit code requirements, I have seen some plans where the beams were assumed and designed to act as simple beams. This is done by designing each span as simply supported and provide one third the bottom...
In reinforced concrete continuous beams with unequal spans similar to the attached sketch. Under gravity loading Column (A) has an uplift reaction. How would you detail the beam to column joint to transfer this uplift force ?
Also since this uplift force causes an increase in the reaction at...
Thank you Kootk and TLHS for replying. I am currently not working on a similar situation, I was just wondering about the concept. I plan on taking the time to study this situation with different loading cases on each column and experiment with it.
Thank you Tom for replying, I would not consider the height halved, but I do agree with JAE that it will help if one column was loaded more than the other. Still, it won't be enough to decrease the heavily loaded column dimension significantly maybe by ( 5 to 10 percent ). I think it's better to...
Thank you 3DDave and JAE for replying. So this configuration is helpful to increase the capacity of the heavily loaded column but at the expense of the lighter ones. In concrete we calculate the buckling load for a column based on it's height, reinforcement and section to determine the...
Thank you BAretired for replying,
Yeah the four columns are all connected with concrete beams, I agree that it's not a good detail.
Still, it is interesting to know to what extent they will help each other.
In situations similar to the attached sketch, where one of the stories is higher than the other stories. Looking at the elevator columns. As a concept, I am wondering whether adding concrete beams connecting all of the columns in the middle of the floor height, would be sufficient in reducing...
Interesting, it's weird that the local building code doesn't require a minimum. I never thought contractors would try to save money on a couple of anchor bolts.
