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prash1730 SEFI Member
Joined: 02 Jul 2008 Posts: 5
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Posted: Thu Aug 15, 2019 6:33 am Post subject: ZERO SPECTRAL ACCELERATION ENTERED FOR MODE 1 |
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Dear All,
I am performing CQC method of response spectrum analysis and getting the warning as below.
**WARNING- ZERO SPECTRAL ACCELERATION ENTERED FOR MODE 1
Request you to let me know the possible issues.
The structure is a space frame with roof truss is released for moments at ends as it is prestressed beam.
CQC response spectrum is defined as below.
The base shear values are NULL as indicated in the below extract.
Request your advise on how to go resolve the same as we are in the midst of a crucial deliverable.
LOAD 16 LOADTYPE Seismic TITLE EQX - SEISMIC
REFERENCE LOAD
R1 1.0 R2 1.0 R3 1.0 R4 0.8 R5 0.8 R6 0.2
SPECTRUM CQC X 0 ACC DAMP 0.05 LIN
0 3.59281; 0.05 3.75612; 0.075 3.83778; 0.093 3.89657; 0.15 4.08274;
0.5 4.08274; 0.527 3.87357; 0.55 3.71159; 0.6 3.40229; 0.8 2.55171; 0.9 2.26819;
1 2.04137; 1.2 1.70114; 1.6 1.27586; 2 1.02069; 2.5 0.653239; 2.75 0.539867;
3 0.453638; 3.25 0.386532; 3.5 0.333285; 3.75 0.290328; 4 0.27468;
LOAD 17 LOADTYPE Seismic TITLE EQY- SEISMIC
SPECTRUM CQC Y 0 ACC DAMP 0.05 LIN
0 2.31; 0.01 2.373; 0.025 2.467; 0.05 2.625; 0.05 2.625; 0.15 2.625;
0.25 1.575; 0.4 0.984; 0.5 0.787; 0.6 0.656; 0.75 0.525; 0.9 0.437; 1 0.394;
1.5 0.175;
LOAD 18 LOADTYPE Seismic TITLE EQZ- SEISMIC
SPECTRUM CQC Z 0 ACC DAMP 0.05 LIN
***************Load combinations************************************
***************************SET-A************************************
0 3.59281; 0.05 3.75612; 0.075 3.83778; 0.093 3.89657; 0.15 4.08274;
0.5 4.08274; 0.527 3.87357; 0.55 3.71159; 0.6 3.40229; 0.8 2.55171; 0.9 2.26819;
1 2.04137; 1.2 1.70114; 1.6 1.27586; 2 1.02069; 2.5 0.653239; 2.75 0.539867;
3 0.453638; 3.25 0.386532; 3.5 0.333285; 3.75 0.290328; 4 0.27468;
========================================================================
==RESULTS==
MODE ACCELERATION-G DAMPING
---- -------------- -------
1 0.00000 0.05000
**WARNING- ZERO SPECTRAL ACCELERATION ENTERED FOR MODE 1
2 0.01099 0.05000
3 0.02077 0.05000
4 0.02926 0.05000
5 0.06170 0.05000
6 0.06530 0.05000
MODAL BASE ACTIONS FORCES IN KN LENGTH IN METE
-----------------------------------------------------------
MOMENTS ARE ABOUT THE ORIGIN
MODE PERIOD FX FY FZ MX MY MZ
1 2.053 0.00 0.00 0.00 0.00 0.00 0.00
2 1.653 0.00 0.00 0.00 0.00 0.00 0.00
3 1.435 0.00 0.00 0.00 0.00 0.00 0.00
4 1.244 0.00 0.00 0.00 0.00 0.00 0.00
5 0.658 0.00 0.00 0.00 0.00 0.00 0.00
6 0.618 0.00 0.00 0.00 0.00 0.00 0.00
STAAD SPACE -- PAGE NO. 196
MASS PARTICIPATION FACTORS IN PERCENT BASE SHEAR IN KN
-------------------------------------- ------------------
MODE X Y Z SUMM-X SUMM-Y SUMM-Z X Y Z
1 0.00 0.00 89.49 0.000 0.000 89.493 0.00 0.00 0.00
2 3.70 0.00 0.01 3.705 0.000 89.503 0.00 0.00 0.00
3 14.94 0.00 0.02 18.644 0.000 89.519 0.00 0.00 0.00
4 75.29 0.00 0.00 93.937 0.000 89.520 0.00 0.00 0.00
5 0.00 0.17 9.49 93.940 0.169 99.006 0.00 0.00 0.00
6 4.22 0.00 0.00 98.164 0.170 99.006 0.00 0.00 0.00
---------------------------
TOTAL SRSS SHEAR 0.00 0.00 0.00
TOTAL 10PCT SHEAR 0.00 0.00 0.00
TOTAL ABS SHEAR 0.00 0.00 0.00 |
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rojanmathewtsy General Sponsor
Joined: 21 Apr 2013 Posts: 29
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Posted: Fri Aug 16, 2019 5:11 am Post subject: Re: ZERO SPECTRAL ACCELERATION ENTERED FOR MODE 1 |
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prash1730 wrote: | Dear All,
I am performing CQC method of response spectrum analysis and getting the warning as below.
**WARNING- ZERO SPECTRAL ACCELERATION ENTERED FOR MODE 1
Request you to let me know the possible issues.
The structure is a space frame with roof truss is released for moments at ends as it is prestressed beam.
CQC response spectrum is defined as below.
The base shear values are NULL as indicated in the below extract.
Request your advise on how to go resolve the same as we are in the midst of a crucial deliverable.
LOAD 16 LOADTYPE Seismic TITLE EQX - SEISMIC
REFERENCE LOAD
R1 1.0 R2 1.0 R3 1.0 R4 0.8 R5 0.8 R6 0.2
SPECTRUM CQC X 0 ACC DAMP 0.05 LIN
0 3.59281; 0.05 3.75612; 0.075 3.83778; 0.093 3.89657; 0.15 4.08274;
0.5 4.08274; 0.527 3.87357; 0.55 3.71159; 0.6 3.40229; 0.8 2.55171; 0.9 2.26819;
1 2.04137; 1.2 1.70114; 1.6 1.27586; 2 1.02069; 2.5 0.653239; 2.75 0.539867;
3 0.453638; 3.25 0.386532; 3.5 0.333285; 3.75 0.290328; 4 0.27468;
LOAD 17 LOADTYPE Seismic TITLE EQY- SEISMIC
SPECTRUM CQC Y 0 ACC DAMP 0.05 LIN
0 2.31; 0.01 2.373; 0.025 2.467; 0.05 2.625; 0.05 2.625; 0.15 2.625;
0.25 1.575; 0.4 0.984; 0.5 0.787; 0.6 0.656; 0.75 0.525; 0.9 0.437; 1 0.394;
1.5 0.175;
LOAD 18 LOADTYPE Seismic TITLE EQZ- SEISMIC
SPECTRUM CQC Z 0 ACC DAMP 0.05 LIN
***************Load combinations************************************
***************************SET-A************************************
0 3.59281; 0.05 3.75612; 0.075 3.83778; 0.093 3.89657; 0.15 4.08274;
0.5 4.08274; 0.527 3.87357; 0.55 3.71159; 0.6 3.40229; 0.8 2.55171; 0.9 2.26819;
1 2.04137; 1.2 1.70114; 1.6 1.27586; 2 1.02069; 2.5 0.653239; 2.75 0.539867;
3 0.453638; 3.25 0.386532; 3.5 0.333285; 3.75 0.290328; 4 0.27468;
========================================================================
==RESULTS==
MODE ACCELERATION-G DAMPING
---- -------------- -------
1 0.00000 0.05000
**WARNING- ZERO SPECTRAL ACCELERATION ENTERED FOR MODE 1
2 0.01099 0.05000
3 0.02077 0.05000
4 0.02926 0.05000
5 0.06170 0.05000
6 0.06530 0.05000
MODAL BASE ACTIONS FORCES IN KN LENGTH IN METE
-----------------------------------------------------------
MOMENTS ARE ABOUT THE ORIGIN
MODE PERIOD FX FY FZ MX MY MZ
1 2.053 0.00 0.00 0.00 0.00 0.00 0.00
2 1.653 0.00 0.00 0.00 0.00 0.00 0.00
3 1.435 0.00 0.00 0.00 0.00 0.00 0.00
4 1.244 0.00 0.00 0.00 0.00 0.00 0.00
5 0.658 0.00 0.00 0.00 0.00 0.00 0.00
6 0.618 0.00 0.00 0.00 0.00 0.00 0.00
STAAD SPACE -- PAGE NO. 196
MASS PARTICIPATION FACTORS IN PERCENT BASE SHEAR IN KN
-------------------------------------- ------------------
MODE X Y Z SUMM-X SUMM-Y SUMM-Z X Y Z
1 0.00 0.00 89.49 0.000 0.000 89.493 0.00 0.00 0.00
2 3.70 0.00 0.01 3.705 0.000 89.503 0.00 0.00 0.00
3 14.94 0.00 0.02 18.644 0.000 89.519 0.00 0.00 0.00
4 75.29 0.00 0.00 93.937 0.000 89.520 0.00 0.00 0.00
5 0.00 0.17 9.49 93.940 0.169 99.006 0.00 0.00 0.00
6 4.22 0.00 0.00 98.164 0.170 99.006 0.00 0.00 0.00
---------------------------
TOTAL SRSS SHEAR 0.00 0.00 0.00
TOTAL 10PCT SHEAR 0.00 0.00 0.00
TOTAL ABS SHEAR 0.00 0.00 0.00 |
From the command file above, what I can guess is that you have defined the Response Spectrum Wrongly.
I assume that you have defined the spectrum using custom option.
SPECTRUM CQC X 0 ACC DAMP 0.05 LIN, this line means that you have not entered any value for X direction component, so your defined spectrucm become null or zero value. You have to enter the value Z*I/(2*R) in that field based on the eq zone and other parameters as per code.
Rojan Mathew
mathew.rojan@gmail.com |
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venkatasalamkl SEFI Member
Joined: 27 Oct 2017 Posts: 13
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