www.sefindia.org

[chandramohan R.S]

DEAR SIR/MADAM,

KINDLY CLARIFY THE FOLLOWING.



1.PL. REF. TO CL 5.6.3. IN THIS IT IS STATED THAT " NATURAL VERTICAL  
VIBRATION FREQUENCY OF ANY FLOOR SYSTEM SHALL NOT EXCEED 3 HZ....." MY  
QUESTION IS HOW TO WORK OUT THE FRQUENCY OF FLOOR SYSTEM? WHETHER WE  
HAVE TO MODEL THE FLOORS, AND CARRY OUT TIME HISTORY ANALYSIS? IF SO  
WHAT SHOUD BE THE INPUT TIME HISTORY?


2.AGAIN CL.5.6.4 SAYS "UNDER GRAVITY LOADS PEAK VERTICAL  
ACCELERATION....." HOW TO WORK OUT THE ACCELERATION VALUES FOR EACH  
FLOOR UNDER GRAVITY LOADS?

3. 6.2.1 " FOR BUILDINGS... IN OUR COUNTRY WHETHER EXPERTS ARE  
AVAILABLE FOR CONDUCTING WIND TUNNEL  STUDIES?ARE THERE LABORATORIES  
AVAILABLE FOR BUILDINS? IF SO PL. GIVE DETAILS.


4. CL6.2.3 PERMISSIBLE PEAK ACCELERATION ARE SPECIFIED IN TABLE4. I  
UNDERSTAND THAT THESE VALUES CAN BE OBTAINED ONLY FROM WIND TUNNEL  
STUDIES. OR IS THERE ANY ANALYTICAL METHOD. PL. CLARIFY

5. TABLE 5. MINIMUM DESIGN BASE SHEAR COEFFICIENT: FOR DIFFERENT ZONES  
VALUES ARE SPECIFIED. IN IS1893:2016 SAME VALES ARE GIVEN IN TABLE7,  
BUT IN 1893 IT IS MENTIONED AS "PERCENTAGE", I SUPPOSE HERE ALSO IT IS  
THE SAME. IF SO IT IS "PERCENTAGE" OF WHAT? IS IT WEIGHT OF STRUCTURE  
INCLUDING DEAD+LIVE?


I REQUEST YOU TO CLARIFY THE ABOVE POINTS.

CHANDRAMOHAN.R.S

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Posted via Email

[abhio]

I believe this is an error in the Code. The 3 Hz limitation ought to be a lower bound, and not upper bound on the natural frequency of the floor.

As for your query, Er. Chandramohan, please refer to

https://www.steelconstruction.info/Floor_vibrations

and

http://nptel.ac.in/courses/105106113/2_industrial_building/3_industrial_floors.pdf

for ways to estimate the natural frequency of the floor.

Regards,

A S Oundhakar

[hemalmistry]

Many software have facility to perform vibration analysis (including footfall vibration). We can get natural vertical vibration frequency for particular floor or for required portion of floor. Acceleration can be worked out with some formulation using frequency and other parameter. However, according to ATC guidelines to check human sensitivity to floor vibration for particular use of floor, a particular combination of frequency and acceleration shall be checked as attached here.

IS:16700-2017 have specified limit for acceleration and frequency. However, even if frequency and /or acceleration if not within range/limit specified by IS:16700, a particular combination of frequency and acceleration may satisfy the vibration requirement of floor for particular use.

Regards
Hemal Mistry
Surat

[Manoharbs_eq]

Hi

Good questions


But answers are as follows 


For floor vibration study no need for input vibration only you need the load, section property and deflection. 


Currently CPRI institue perform wind tunnel test also IITs do. 


On Mar 13, 2018 10:31 AM, "chandramohan R.S" <forum@sefindia.org (forum@sefindia.org)> wrote:[quote]            DEAR SIR/MADAM,

KINDLY CLARIFY THE FOLLOWING.



1.PL. REF. TO CL 5.6.3. IN THIS IT IS STATED THAT " NATURAL VERTICAL
VIBRATION FREQUENCY OF ANY FLOOR SYSTEM SHALL NOT EXCEED 3 HZ....." MY
QUESTION IS HOW TO WORK OUT THE FRQUENCY OF FLOOR SYSTEM? WHETHER WE
HAVE TO MODEL THE FLOORS, AND CARRY OUT TIME HISTORY ANALYSIS? IF SO
WHAT SHOUD BE THE INPUT TIME HISTORY?


2.AGAIN CL.5.6.4 SAYS "UNDER GRAVITY LOADS PEAK VERTICAL
ACCELERATION....." HOW TO WORK OUT THE ACCELERATION VALUES FOR EACH
FLOOR UNDER GRAVITY LOADS?

3. 6.2.1 " FOR BUILDINGS... IN OUR COUNTRY WHETHER EXPERTS ARE
AVAILABLE FOR CONDUCTING WIND TUNNEL STUDIES?ARE THERE LABORATORIES
AVAILABLE FOR BUILDINS? IF SO PL. GIVE DETAILS.


4. CL6.2.3 PERMISSIBLE PEAK ACCELERATION ARE SPECIFIED IN TABLE4. I
UNDERSTAND THAT THESE VALUES CAN BE OBTAINED ONLY FROM WIND TUNNEL
STUDIES. OR IS THERE ANY ANALYTICAL METHOD. PL. CLARIFY

5. TABLE 5. MINIMUM DESIGN BASE SHEAR COEFFICIENT: FOR DIFFERENT ZONES
VALUES ARE SPECIFIED. IN IS1893:2016 SAME VALES ARE GIVEN IN TABLE7,
BUT IN 1893 IT IS MENTIONED AS "PERCENTAGE", I SUPPOSE HERE ALSO IT IS
THE SAME. IF SO IT IS "PERCENTAGE" OF WHAT? IS IT WEIGHT OF STRUCTURE
INCLUDING DEAD+LIVE?


I REQUEST YOU TO CLARIFY THE ABOVE POINTS.

CHANDRAMOHAN.R.S

Posted via Email

[dndhastak]

For Wind tunnel testing




https://www.iitk.ac.in/nwtf/index.php?option=com_content&view=article&id=5&Itemid=124r your # 3 wind tunnel testing

• t

On Tue, Mar 13, 2018 at 12:00 PM, chandramohan R.S <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote]            DEAR SIR/MADAM,

KINDLY CLARIFY THE FOLLOWING.



1.PL. REF. TO CL 5.6.3. IN THIS IT IS STATED THAT " NATURAL VERTICAL
VIBRATION FREQUENCY OF ANY FLOOR SYSTEM SHALL NOT EXCEED 3 HZ....." MY
QUESTION IS HOW TO WORK OUT THE FRQUENCY OF FLOOR SYSTEM? WHETHER WE
HAVE TO MODEL THE FLOORS, AND CARRY OUT TIME HISTORY ANALYSIS? IF SO
WHAT SHOUD BE THE INPUT TIME HISTORY?


2.AGAIN CL.5.6.4 SAYS "UNDER GRAVITY LOADS PEAK VERTICAL
ACCELERATION....." HOW TO WORK OUT THE ACCELERATION VALUES FOR EACH
FLOOR UNDER GRAVITY LOADS?

3. 6.2.1 " FOR BUILDINGS... IN OUR COUNTRY WHETHER EXPERTS ARE
AVAILABLE FOR CONDUCTING WIND TUNNEL STUDIES?ARE THERE LABORATORIES
AVAILABLE FOR BUILDINS? IF SO PL. GIVE DETAILS.


4. CL6.2.3 PERMISSIBLE PEAK ACCELERATION ARE SPECIFIED IN TABLE4. I
UNDERSTAND THAT THESE VALUES CAN BE OBTAINED ONLY FROM WIND TUNNEL
STUDIES. OR IS THERE ANY ANALYTICAL METHOD. PL. CLARIFY

5. TABLE 5. MINIMUM DESIGN BASE SHEAR COEFFICIENT: FOR DIFFERENT ZONES
VALUES ARE SPECIFIED. IN IS1893:2016 SAME VALES ARE GIVEN IN TABLE7,
BUT IN 1893 IT IS MENTIONED AS "PERCENTAGE", I SUPPOSE HERE ALSO IT IS
THE SAME. IF SO IT IS "PERCENTAGE" OF WHAT? IS IT WEIGHT OF STRUCTURE
INCLUDING DEAD+LIVE?


I REQUEST YOU TO CLARIFY THE ABOVE POINTS.

CHANDRAMOHAN.R.S

Posted via Email