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sakumar79...

Joined: 18 Apr 2008Posts: 518

Posted: Fri Jun 21, 2013 4:41 pm Post subject:

Dear Er. Rajan, First of all, I want to point out one thing that is often misunderstood. In the definition of seismicconditions, the value of ST=1 corresponds to RC Frame WITHOUT INFILL WALLS. This is not specifiedclearly by STAAD but if you use ST=1, it will end up using the formula corresponding to RC framewithout infill walls only. In India, generally we have 9" walls, at least on the outer sides. Hence, weneed to either specify ST=3 or we have to calculate and enter the time periods manually in place ofST value.

Secondly, the methodology posted by you for Seismic Load definition is the original methodprovided by STAAD which is a bit tedious. The Joint load is very time consuming (especially if you haveto go about with multiple revisions during planning) and the member weight method is a bit easier,but there is a chance for inconsistencies between Dead and Live load definitions and their adoption inmember weight command, especially if you are working through multiple revisions.

For some time now, there is a much simpler method to define seismic load through the use ofReference Loads. I am pretty sure I have posted about this earlier, but I will do this again to avoidsearching around again....

First, create Reference Loads ­ One (R1) for Dead Loads, One (R2) for Live Loads less than 3kN/sqm, One (R3) for Live Loads more than 3 kN/sqm, and one (R4) for Live loads on terrace. In this,you specify the loads....

Then, during seismic load definition, you can specify the seismic weight to be calculated with thereference loads instead of joint weight or member weight with factor 1 for R1, .25 for R2 and .5 forR3 (R4 will be omitted as per code).

Then, we can define the primary load cases for DL and LL from the reference loads.

By this, we end up defining the loads only once, thus creating a more definite consistency in thedefinition of dead/live loads and seismic weight calculation, which will not be affected if we makemultiple revisions during planning/design.

Yours sincerely Arunkumar

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es_jayakumarGeneral Sponsor

Joined: 24 Nov 2011

Posted: Sat Jun 22, 2013 12:40 am Post subject:

Dear Er Arunkumar,

Can you please post detailed steps in this connection?

Regards, E S Jayakumar

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Posts: 641

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rajancivildesign...

Joined: 26 Jan 2011Posts: 455

Posted: Sat Jun 22, 2013 2:17 am Post subject: SEISMIC ANALYSIS

Thank you very much for indicating the correction in the seismic procedure. I also know about theReference Load command. Can you upload any example of this type of command. V.M.RAJAN.

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rajancivildesign...

Joined: 26 Jan 2011Posts: 455

Posted: Tue Jun 25, 2013 1:49 pm Post subject: Reference Load command in Seismic Analysis

Dear Arun kumar, Can you please upload any staad example using Reference Load command. Very long back I haveseen one similar example in this forum. If you remember or come across, pl. post the reference in theform. V.M.RAJAN

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sakumar79...

Joined: 18 Apr 2008Posts: 518

Posted: Wed Jun 26, 2013 5:03 pm Post subject:

Dear Sir, For your and other sefians' convenience, I am attaching a simple example staad model made tohighlight usage of reference loads in defining earthquake loads. I will post details about assumptions ifany clarifications are required.

Yours sincerely

Arunkumar

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Sample1.zip Description:

Download Filename: Sample1.zip Filesize: 3.45 KB Downloaded: 437 Time(s)

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es_jayakumarGeneral Sponsor

Joined: 24 Nov 2011Posts: 641

Posted: Thu Jun 27, 2013 1:27 am Post subject:

Sir,

Some error message is seen while analysing. Can you please post the stepwise procedure on thecreation of seismic load cases ?

Regards, E S Jayakumar

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sakumar79...

Joined: 18 Apr 2008Posts: 518

Posted: Thu Jun 27, 2013 8:29 am Post subject:

Dear Sir, Procedure for defining seismic load is explained by me a few posts above this... Please inform whaterror messages you are getting ­ I am only getting some warnings (To use CHANGE command in caseof Tension/Compression only members, and to note that Dimensions at Base level are used incalculation of Time Period) that are not important. Hope you are using latest version of STAAD...

Yours sincerely Arunkumar

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thirumalaichettiarSilver Sponsor

Joined: 26 Jan 2003Posts: 3396

Posted: Thu Jul 04, 2013 11:02 am Post subject: Pile Cap Design

A note and guiding notes for Plie cap modelling and design using STAADPRO is attached for those wholove STAADPRO.

May be useful.

T.RangaRajan

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Download Filename: Pile cap.pdf Filesize: 21.89 KB Downloaded: 241 Time(s)

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Rajesh123General Sponsor

Joined: 30 Apr 2013Posts: 36

Posted: Thu Jul 18, 2013 5:46 am Post subject: Re: Reference Load command in Seismic Analysis

rajancivildesign wrote:

Dear Arun kumar,

V.M.RAJAN

Dear Sir,

Please send me Staad manual and tutorial to my mail ID ­ ramkumark@live.in

Regards

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SudhakaranGeneral Sponsor

Joined: 16 Jul 2013Posts: 207

Posted: Wed Jul 24, 2013 8:35 am Post subject: Re: SEISMIC ANALYSIS PROCEDURES USING STAADPRO

Dear Rajan sir,

How the analysis of space frame as per "Cl:22.4.1 of IS 456 Arrungement of ImposedLoad" carried? 4b) Consideration may be limited to combinations Of: 1)Design dead load on all spans with full design imposed load on two adjacent spans;and 2)Design dead load on all spans with full design imposed load on alternate spans.

When design imposed load does not exceed three­fourths of the design dead load, the load arrangement may be design dead load and design imposed load on all the spans.

rajancivildesign wrote:

Dear SAFIANS, I herewith attached seismic procedures to be followed in STAAD PRO for the benefit ofyoungsters. Any comments/correction in the procedure is welcomed. V.M.RAJAN.

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