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SEISMIC LOADING IN STAADPRO

 
This forum is locked: you cannot post, reply to, or edit topics.This topic is locked: you cannot edit posts or make replies.    www.sefindia.org Forum Index -> Past Discussions Year 2003
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dharikrishna
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 5

PostPosted: Thu Nov 27, 2003 4:05 pm    Post subject: SEISMIC LOADING IN STAADPRO Reply with quote

HI FELLOW MEMBERS OF THE FORUM
HI I WISH TO KNOW IF ANY ONE SUGGESTS ME HOW TO  DEFINE THE SEISMIC LOADING
IN STAAD PRO
I HAVE ANALYSED A 5 STORIED SHEAR FRAMED STRUCTURE USING STAADPRO
I GOT THE ANALYSIS RESULT FROM STAAD PRO
I WANT TO ANALYSE THE SAME FRAME USING RESPONSE SPECTRUM METHOD USING
STAADPRO
BUT I M UNABLE TO DEFINE THE SEISMIC LOAD CASE , SO PLEASE IF ANY ONE COULD
SUGGEST ME IN THIS REGARD .. THEN I WILL BE GREAT FULL TO U
THANKING U ALL
FELLOW SEFI MEMBER

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bhumika
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 4

PostPosted: Mon Dec 01, 2003 5:24 am    Post subject: SEISMIC LOADING IN STAADPRO Reply with quote

Hello sir,

To apply "Response Spectrum" in STAAD Pro, the command line in text file of
staad is

SPECTRUM "MODAL COMBINATION" "DIRECTION" "FACTOR" "RESPONSE" DAMP ______
SCALE _______
T  RESPONSE ;

The above command line specifies that the modal responses can be combined
using either CQC method or SRSS method. The spectrum can be applied in
global X, Y or Z direction with some factor (usually 1.0). The "Response"
may be acceleration or displacement. Damping ratio is 0.05 (damping 5%) for
concrete structures. The scale factor is the quantity by which spectral
accelerations (and spectral displacements) must be multiplied by before they
are used in the calculations. The spectrum data is given as period vs.
acceleration.

Apply it after giving self-weight or dead load command.

For example,
As per IS 1893-2002 part 1, response spectrum ordinates in terms of T
(Natural period) and Acceleration for medium soil condition, structure
situated in zone 5 and for 5% damping is
0 0.54; 0.1 1.35
0.55 1.35; 1.0 0.73
1.5 0.49; 2.0 0.37
2.5 0.29; 3.0 0.24
3.5 0.21; 4.0 0.18

Command line for this spectrum is
LOAD 2 SEISMIC LOADING
SPECTRUM CQC X 1.0 ACC DAMP 0.05 SCALE 1.0
0 0.54; 0.1 1.35
0.55 1.35; 1.0 0.73
1.5 0.49; 2.0 0.37
2.5 0.29; 3.0 0.24
3.5 0.21; 4.0 0.18

In modeling mode

In "Commands" menu, go to loading,  primary load.
Define Load 2 as "seismic loading". Now load page will open. In that click
on spectrum and apply data as explained above.

Regards,
Bhumika





Quote:
----------------------------------------------------------
From: dharikrishna@hotmail.com
Subject: SEISMIC LOADING IN STAADPRO
Date: 27/11/03
Time: 21:35:42
----------------------------------------------------------
HI FELLOW MEMBERS OF THE FORUM
HI I WISH TO KNOW IF ANY ONE SUGGESTS ME HOW TO  DEFINE THE SEISMIC
LOADING
Quote:
IN STAAD PRO
I HAVE ANALYSED A 5 STORIED SHEAR FRAMED STRUCTURE USING STAADPRO
I GOT THE ANALYSIS RESULT FROM STAAD PRO
I WANT TO ANALYSE THE SAME FRAME USING RESPONSE SPECTRUM METHOD USING
STAADPRO
BUT I M UNABLE TO DEFINE THE SEISMIC LOAD CASE , SO PLEASE IF ANY ONE
COULD
Quote:
SUGGEST ME IN THIS REGARD .. THEN I WILL BE GREAT FULL TO U
THANKING U ALL
FELLOW SEFI MEMBER

_________________________________________________________________




----------------------------------------------------------







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vva at vsnl.com
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PostPosted: Wed Dec 03, 2003 12:18 pm    Post subject: SEISMIC LOADING IN STAADPRO Reply with quote

Dear Anand,
1. To simulate rigid diaphragm, you should use command
"SLAVE DIAPHRAGM ZX MASTER  (master joint number) JOINT (slave joints) "
You should not use master fx and fz command which will force the model to
have same displacements in x or z directions for all the floor joints.

2. Secondly, you will have different stiffness in x and z direction.
Accordingly, the base shear in x and z will be different. It generally
tallies with the hand calculations.

For more information you can refer to article in ISSE Journal Oct-Dec2001 on
this topic.


For STADD ENGINEERS Mumbai


Hemant Vadalkar
Consulting Engineer
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118, Veena Beena Shopping Centre, Opp. Bandra Station(W), Mumbai 400 050
INDIA
Tel. / Fax : 91-22-2643 0668 / 91-22-2641 0857
Email : info@staadpro.com        Website : www.staadpro.com

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mc.upadhyay1
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...


Joined: 26 Jan 2003
Posts: 134

PostPosted: Thu Dec 04, 2003 7:38 am    Post subject: SEISMIC LOADING IN STAADPRO Reply with quote

hello anand
STAAD does not calculate the time period as per
code formula (0.09*h/sqrt(d)) as you would be calculating.
although they say "define 1893 load".
So you have give the time period as calculated to get the
desired base shear.


Mukesh Upadhyay

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