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The elevated slab is modeled with concrete elements and foundation pile cap is composed of rigid plate elements (Plates with very high E value to increase stiffness). If I use concrete elements with their associated stiffness, I would get weird displacements throughout the slab since my boundary...

Interesting as to how different people/companies interpret and incorporate "lessons learned" aspects from their previous projects. Below is the model I have developed for my table top. The top slab is composed of 30" concrete plate elements, with 30" round columns and loads modeled at rotor...

Does this mean they were actually designing for resonance conditions for a certain time function even though this may happen for just a second of time? That would definitely be very conservative. In my case, I have a table top but it is not very high (about 12' to top of slab) so it is not too...

Thanks Josh! I think I'll end up creating a couple of models with loads at the rotor CG and at the anchor locations to verify.

On similar lines, do you typically include a "Ramp Up" and "Coast Down" time within the harmonic load function? I have not yet seen this being applied in all the literature I've read on this topic.

Thanks for the detailed explanation Josh. The dynamic loads I received from the equipment manufacturer occur at the anchor locations (See below), which is the reason I want to model them there. On point 4, you mention "sign" of the loads. Since I have the loads provided by the manufacturer at...

Thanks Josh! In the case of "keeping all the anchor loads from a rotor together regardless of direction", wouldn't this effect the output to compare the maximum response amplitudes?

Thanks Josh. I have my combinations set for in phase and 180 degree out of phase load case. I have two load tags like below. But I am wondering if I need to create different load tags for each direction of loading. For in phase condition, my thoughts are, inserting all the load functions acting...

I have an elevated concrete platform and I am researching on performing a time history analysis for the structure. The equipment manufacturer has provided a set of dynamic loads at the rotor support points for both horizontal and vertical directions. I have assigned sine functions for vertical...

I have an elevated concrete platform modeled in RISA 3D and I am researching on performing a time history analysis for the structure. The equipment manufacturer has provided a set of dynamic loads at the rotor support points for both horizontal and vertical directions. I have assigned sine...

I have seen a lot of architects wanting to push the vertical leg to the face of sheathing and the horizontal leg needs to be 7" to support the brick. They blame it on the energy codes. I am thinking if this is what they want than it has to be a shelf angle with proper structural steel backup...

Hey Guys, I have got a quick question on loose lintels. When designing a loose lintel we assume the loose lintel to be braced at the end points. I am curious as to how this is assumed. I came up with the following arrangements, 1. If the vertical leg is against the sheathing, is it...

Hey guys, I am working on a project with Intermediate Moment frames as the Main lateral force resisting system. Is there any prequalified moment connection that connects to the column web? I did not see any details in AISC Seismic Design Manual. Is this allowed?

This was exactly what went through my head when reading the paper. The connection has to undergo permanent deformation before it is even ready to take in the wind moment. The method relies on knowing the real ductility of the connection which can be very difficult and far fetched when doing it...

Thanks KootK and everyone for your responses. EngineerEIT: I will check out those seminars. I had started watching the AISC webinar on these connections but need to finish it. bhiggins: This paper references the British standards. I have read about this drift amplification factor in the paper...

Thanks for all your answers guys! I got access to a journal paper by Louis Geschwindner- "Flexible Moment Connections for unbraced frames subject to lateral Forces". I will be going through it over the weekend. We have a senior engineer in the office who has used flexible moment connections...

I have HSS columns and the Envelope moment (including gravity and wind) is much higher than the HSS wall can take. I can't have diaphragm plate because it interrupts the sheathing on the exterior and the Arch would not be happy about it. Any thoughts in this scenario?

Exactly, I was trying to search in the 14th edition of AISC if they allow to do "Type 2 with Wind" design (from 9th edition) but couldn't find it. Has anyone on this forum designed flexible moment connections before? What approach did you take? Thanks for all your answers.

When designing a steel moment frame, if the beam is designed to support the full gravity load as a simply supported beam and the connection is designed for moment due to wind only (instead of envelope combinations including Dead and Live), how does this affect the drift? Do we have to check the...

Thanks. But since this opening is inside the critical perimeter, should b0 in the punching shear equation be reduced??