This argument is practically my structural design concept. I define that frames or elements would function as fuses (dissipating energy through damage or plastic hinges), ensuring that the other elements are capable of transmitting forces to these elements (elastically) and thus ensuring that...
Yes, I completely agree, the tie beam, no matter how small it is, will assume some moment, but obviously the reinforcement that one has (minimum), must be able to assume that demand for forces, or that is what I have been able to deduce from the times I have modeled such elements.
In the ACI318...
That is exactly what I did... but as I mentioned, ACI 318 18.2.2.3 states the following: "any element below the base required to transmit seismic forces must comply with the provisions of Chapter 18" which means that I must comply with seismic detailing and design loads. In other words, detail a...
It's not that I'm magically declaring something rigid just because I want to. There's an aspect ratio that defines whether an element behaves rigidly or flexibly. I'm not saying that it won't fail magically; I'm literally using a multiplier factor of 2.0 to ensure that the element behaves...
When a column reaches its plastic hinge, it means that it loses its flexural capacity, causing lateral displacements to increase and making it susceptible to geometric instability (buckling). This condition favors the appearance of more plastic hinges and, consequently, greater energy...
The models are fine, I would model with the condition that the pedestal has a higher stiffness, or that the tie beam is very flexible compared to the pedestal, thus I would obtain results more similar to those I show you in the image.
However, the model does not answer my question, because it...
No, precisely... the failure mechanism has a structurally favorable hierarchy: the beams plastify first, and then the columns plastify... however, columns in high seismic threat zones should be highly ductile, meaning they should be able to develop a double plastic hinge. In order for the...
You're absolutely right. I generally associate the ductility of an element with its ability to dissipate energy, in other words, the ability of an element to achieve a plastic hinge, or for the steel to yield. A double plastic hinge is structurally desirable and is likely to occur in a slender...
First, thanks for the reply
I agree that everything deforms, and perhaps I am mistaken in expressing it in words, what I tried to say is that a rigid element does not buckle, it is not likely to fail by buckling, much less achieve a condition in which plastic hinges are generated at its ends...
Thank you for your response, I will try to provide information or observations about it.
You are correct, the seismic resistance system above the tie beam level (buried beam) is a ductile moment-resisting frame system.
I understand your point, but from a structural analysis perspective, I...
Hi everyone, if anyone has any new thoughts on my problem, I'd really appreciate your input. Even if it means telling me I'm wrong, just that I don't know how haha. I'm all ears!.
- Regarding the info, I created new figures in response to your request. However, I believe they might not be essential for your understanding.
- Regarding the pedestal, the elements shown are pedestals to me. While their primary function is to resist axial loads, they can also transmit...
I have a moment-resisting concrete frame structure located in a high seismic hazard zone. At the base or ground level, I will place a tie beam that will be connected to pedestals (or fully buried column sections that allow the foundation level to be reached) (see attached image).
Considering...
