Steps for designing and analysis structure 2

Krsl · Feb 11, 2024

Hi all experienced engineers! I have a basic question for you. I am a recently graduated structural engineering student who has just started a job. I have given a structural analysis and design task. I have to design a warehouse in high seismic zone which has shear walls and moment frames to resist lateral load. The joist girders are K series and structure will have HSS columns. So, this my thinking of how should I proceed. Please provide suggestions if there is better way to do it. Here are the steps that I am thinking.

1) Find the loads by hand calc/spreadsheet.
2) Determine the member sizes based on preliminary hand calculations (i.e. from 1).
3) Model the structure in analysis software (which will be SAP in my case) and let the software do the design and analysis. Here is one confusion I have. I am thinking of modeling the joist's complex geometry based on the manufacturer (let's say Vulcraft for now). Do you guys also do the same?
4) Check if any structural members are failing or not?
5) Finalize the members if everything looks okay and don't forget to check drift limits.

rb1957 · Feb 11, 2024

1) Are you alone there ? is there no one in your company who can mentor you ? your supervisor ?? a colleague ?? It seems to me a big ask for a recent grad.

I think you're over stating 2) ... can you accurately size all the members ? I think this is more "size by experience/typical design".

3) sure, model joists as beam elements (I guess that is the recommendation). The option is to model as "caps and web", which would allow better modelling of pinned joints.
I see joints as a very more detail to design, and to model. I don't know SAP (and don't like what I do know) but maybe you can release bending freedoms at joints to get a pinned behaviour ?

I'd expand 1) to include defining the applied loads (and which part of the code they come from).

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

BulbTheBuilder · Feb 12, 2024

rb1957 (Aerospace said:
Are you alone there ? is there no one n your company who can mentor you ? your supervisor ?? a colleague ?? It seems to me a big ask for a recent grad

I hope not, but from experience, you can be such a situation ....well, enough about myself.

@OP-
1)This is not an easy task especially for a high seismic zone. You can use ASCE hazard tool to find your seismic parameters

ASCE Hazard Tool

Quickly retrieve site structural design parameters specified by ASCE 7-10, ASCE 7-16, and ASCE 7-20, including wind, seismic, snow, ice, rain, flood, tsunami, and tornado.

ascehazardtool.org

To find the seismic loads reference:

https://ascelibrary.org/doi/book/10.1061/9780784415504

You don't necessarily have to buy it but if you'll be working in a high seismic zone then it will come handy. Preferably you can google and find any PDF on ELF loads. That will help as well

2)How big is your warehouse? You have shear walls and moment frames...
Sizing joist, reference Vulcraft they have good material ->

https://vulcraft.com/

Sizing column, AISC. You can use the table 4 or 6 [AISC 15th edition] to pick column sizes
Sizing beam, AISC. You can use table 3.

driftLimiter · Feb 12, 2024

Dont forget, we need to design and detail all the connecting elements, steel-steel connections, Roof ledgers etc.

Also we have significant out of plane seismic forces locally at the walls that need to be addressed.

Additionally the diaphragm design for this type of building is not straight forward, the diaphragm must be designed and detailed to resist the wall out of plane anchorage forces (subdiaphragms).

Lateral systems and seismic detailing is pretty intense, and the software's are notoriously bad at dealing with these requirements.

And foundations, no one has mentioned it, but design of foundations is equally important to all of the above.

Dont make the mistake of thinking if you put enough effort into a SAP model you will get all the answers out. You will not.

This is a fantastic guide for the roof structure. Link

For the walls I can recommend SEAOC seismic design guides. These have pretty comprehensive tilt up examples.

best of luck

dold · Feb 13, 2024

@drift

That Verco link is great.

Here's one of my favorite warehouse diaphragm documents. Probably a bit much for OP but you might find it fascinating: [URL unfurl="true"]https://www.fema.gov/sites/default/files/documents/fema-p-1026.pdf[/url]

BulbTheBuilder · Feb 13, 2024

Great reference, dold! I love it

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Steps for designing and analysis structure 2

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