Define Seismic Weight/Mass Model for Static Seismic & Dynamic Analysis || IS1893: 2016 || ASCE 7
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- čas přidán 9. 09. 2024
- Seismic analysis is very important for the stability and safety of any structure. If we design a structure in a moderate or high seismic prone area, seismic analysis results normally govern the reinforcement percentage or section size. And if we consider any high-rise structure, without a proper dynamic analysis, it is not possible to finalize the design or get approval. There are several factors which are significant for a static or dynamic analysis, seismic weight or mass model is one of those.
In this video, I will cover different methods available in STAAD to define seismic weight or mass model for static and dynamic analysis. Also, I will compare all these methods and let you know which one is the most suitable method of mass modelling for any concrete or steel structure. Finally I will cover how to avoid the common mistakes which can affect the seismic analysis.
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excellent... thank you for this video
great explanation sir. i had always doubt about this,now its clear.
Glad to hear that.
Very helpfull & informative.thank you sir
Thanks very much sir for detailed and tachnical explanation, sir please demonstrate the video on time history load along with time history load combination with other different load like DL, LL etc...., we are very eager for that.... Thank you sir....
Please make a detali video of practical staad design of G+4 or G+5 building ...
wait for your this content part -2 for that video.
It will be uploaded soon. Stay tuned for more updates.
Sir is there any Book for every topic explanation with an example related analysis and design in STAAD Pro,, please suggest
Hi sir,
Dead load of foundation not included in seismic weight calculation..If i give the value in local direction in plate elements,then it will not be consider in mass reference load..Am i right sir?
In your previous videos of IBC/ASCE only response spectrum load case is used for dynamic analysis, unlike in this video using both static & dynamic load case. As mentioned in this video timeline 22:50, problem arise in the absence of static load case. Kindly elucidate the correct method.
Yes, static seismic loads are required to compare the base shear (vb'/vb) values. Though the IBC/ASCE video is a discussion on response spectra load, still this comparison of base sher is already covered, check that video after 19min for more details.
@@surojit_ghosh thanks once again, how can I connect with you for the paid resources
You can reach me via my email (check about of my CZcams channel) or LinkedIn.
Can u plz demonstrate how to perform static and dynamic analysis along with the wind loads as per IS codes for high rise structure and how to scale the base shear in staad?
This topic will be covered soon. Stay tuned.
Sir
why RCDC v11.2 can not import mdb file created from Etab file. is there any solution. pl give a solution sir
How to use diaphragm in new mass model generation. Is it same like, SS5 Upto CE Update 8 ?, i.e mass reference load followed by floor diaphragm. Can we ignore property reduction & floor diaphragm, for both static & dynamic?. If yes then, how can we check story drift for both static and dynamic?
There is no change in the floor diaphragm command or sequence. Only change is - now mass model generation is automated which was previously a manual effort. IS1893 code suggests to use reduced property which can be considered in STAAD, not sure which code you are following. But if the code suggests to use reduced property, then it is better to use property reduction factor for analysis.
Sir .. if we making expansion joints model.. then how the diaphragm have to be applied for G+8 floor... do we want to consider static analysis of 35m height building .
You can define the diaphragm using range command. It is not suggested to use Static analysis for any building with height more than 15m (IS1893 recommendation). Better use Response Spectra method which produce more accurate results.
Thanks u sir..
Hi sir. Is it necessary to update load mass again Nd again once the primary load value got changed . ? Or it will update automatically
I feel still there are lot of confusiom in dynamic analysis done by staad
Hope any one can come with all solution
sir, what load combinations should we use for RSA method? in your video you haven't covered about the load combinations. Kindly comment on this, sir.
Load combination for RSA is covered in this video - czcams.com/video/S1KT5wzf-JM/video.html. Though the design code is different, same logic can be used for IS1893 code.
Sir, sir have said that if mass reference load is used then don't define seismic weight under seismic definition and mass model under dynamic load case then how can i apply response spectrum?
To perform dynamic analysis, you need to create two separate load cases, one for response spectra definition for X direction and another one for Z direction. Under those load cases, define response spectra definition with proper values. Mass modeling part you can skip, as it will be considered from mass reference load case.
@@surojit_ghoshthank you and one more thing, is it necessary to create two loaded cases as program takes only one load case. At the end of the analysis, a note is reflected saying only one load case will be taken in consideration
Dead load of slab load as floor load or modelling as a plate ? Which is recommended. ? Pls suggest sir.
It depends, there are several reasons to model a floor panel using FEM. In general for any small or medium structure with regular floor panel, you can skip modelling the slab using FEM and use RIGID DIAPHRAGM command to consider the in-plane slab stiffness and apply the dead load as floor load. If the floor panel is irregular, or if a detail analysis is required for slab design or if you want to design a PT slab, then it is better to model it using FEM.
This logic is more generic, there are several other factors and you need to keep in mind all those before modelling the floor panel. Whether the load is applied as floor load or plate pressure load, total load will remain same, but how to the load is transferred and how the slab will behave under that applied load, that needs to be considered first during modeling.
@@surojit_ghosh I have modelled both the case.
1. applied dead and live load of slab as floor load in YRANGE. 2. created a plate as slab and applied live load as pressure on plate. In results, the seismic weight differs for both the cases. Got confused sir. Pls suggest a solution. Thank you.