SantoS's Communities Activities

Moving Load on Slab

SantoS — Fri, 23 May 2014 10:05:55 GMT

Dear All,

I want to check a structure due to Dead Load, Live Load and Moving Load.

SInce there are load on slab, so I create a dummy beam to cater this issue (let say for brickwall stands on slab).

Then the problem is with Moving Load. As we know that the Moving Load will be transfered to the nearest beam and the total load will be divided respectively by its distance to the nearest beam, so there some load that transfered to the dummy beam.

Do I need to remove the dummy beam? Or instead I should use dummy beam to indicate the moving load transfered to the slab?

I have checked that the moment profile of slab are different between with and without dummy beam.

Please your kindly advice.

Thank you.

Best Regards

Santos

different level of slab

SantoS — Sat, 28 Nov 2015 04:50:53 GMT

Hi Sir,

I want to ask about how to model if I have a different slab elevation that connect on the same beam.
Please check this cross section.
https://www.dropbox.com/s/27jpeg5903q6zjh/cross%20section.png 

Please your kindly advice.
Thank you.


Best Regards
Santo

How can I get bending moment results at Global axis?

Huseyin S. — Fri, 22 Jan 2016 08:07:23 GMT

Hello;

I described a foundation for my StaadPro model. And then I recognized that plates element's local axis are different. So I can't get safe values of one direction's bending moment.

So; Can I read that values on Global x-z-y axis or what do you recommend me?

Response Spectrum

SantoS — Wed, 09 Apr 2014 17:18:41 GMT

Dear All,

I have questions about Response Spectrum Analysis since I'm new to this dynamic load.

Q1. I want to analyze an existing building using Response Spectrum Analysis. The running process takes hours to analyze it. Could it be any mistake in my modelling so it needs hours to run? My building plan is about 60m x 100m and 4 floors.

Q2. I'm using Response Spectrum Sa vs Period then I use Custom to create the graph. I multiply the value of Sa with 9.81 (gravity acc) and Scale is 1. Direction will be in X and Z. Beside the X and Z direction I input the factor as I/R. I use SRSS combination method. Are those steps already correct? Please correct me if I'm wrong.

Q3. Before the Response Spectrum load case, there are IBC load case for both direction X and Z. After I run the program, there are 3 base shears from Response Spectrum which are SRSS, 10PCT and ABS. From what I learned in the video tutorial I found in Youtube, the program will tell us that Vb/VB need to use new factor to get the same base shear as static load case. Why I don't get the same information in the output? Is it because I use Custom response spectrum? If I need to determine the new factor by my self, which one is the base shear from Response Spectrum Analysis to be considered?

Q4. I use mode shape until 100 but I only get about 63% mass participation and also the first four mode result as ZERO SPECTRAL ACCELERATION due to the high periode. The periode is 271, 234, 79, 79, 7, ... Please your kindly advice.

Really appreciate your kindly help.

Thank you

Best Regards

Santos

Pdelta Analysis / Perform Analysis Command

SantoS — Mon, 02 Mar 2015 08:24:03 GMT

Hello everyone,

Q1: I want to know whether this format is already correct or not?

Q2: After we define the seismic definition, then we start to add Load Case of seismic first.. Does the PDELTA ANALYSIS command should be written in this load case? or PERFORM ANALYSIS ?

Q3: To obtain the result of all load cases acting concurrently, I use Repeat Load instead of Load Combination. Does it mean that even we don't use PDELTA ANALYSIS command, we'll get the same result since we already use Repeat Load?

Q5: The last command (before FINISH), it should be PDELTA ANALYSIS again or just PERFORM ANALYSIS ?

Please your kindly advice.

Thanks a lot.

Really appreciate your help.

********************************************************************

DEFINE IBC 2006 ACCIDENTAL

SS 0.1 S1 0.3 I 1 RX 8 RZ 8 SCLASS 3 TL 4 FA 1.005 FV 1.43
SELFWEIGHT 1
MEMBER WEIGHT
_ROOF UNI 5
FLOOR WEIGHT
_ROOFSLAB FLOAD 2.88
********************************************************************
LOAD 1 LOADTYPE Seismic TITLE EX
IBC LOAD X 1
PDELTA ANALYSIS
CHANGE

********************************************************************
LOAD 2 LOADTYPE Seismic TITLE EZ
IBC LOAD Z 1
PDELTA ANALYSIS
CHANGE
********************************************************************
LOAD 3 LOADTYPE Dead TITLE DEAD
SELFWEIGHT Y -1
FLOOR LOAD
_ROOFSLAB FLOAD -2.88 GY
MEMBER LOAD
_ROOF UNI GY -5
LOAD 4 LOADTYPE Live TITLE LIVE
FLOOR LOAD
_ROOFSLAB FLOAD -1 GY

*** Then to combine we use Repeat Load instead of Load Combination

PDELTA ANALYSIS
FINISH

Result of Seismic Load as per IBC2006

SantoS — Sun, 27 Apr 2014 18:09:43 GMT

Dear All,

Please your kindly help about this problem.

I create a modeling of a building where the main and primary beams are having 8m span. The secondary beams are at the midpoint of primary beams. It means each beam in my modeling is 4m length. Then I run the model where it included the seismic load as per IBC2006.

After that, I try to add midpoint for all beams. It means each section will be 0.25L now (2m length). So, by doing this I will get a better view about where is hogging or sagging. But after I run again, I got a different result from the first modeling.

The result from:

(first modeling)

************************************************************

* IBC 2006 SEISMIC LOAD ALONG X :

* CT = 0.030 Cu = 1.400

* TIME PERIODS :

* Ta = 0.767 T = 1.508 Tuser = 0.000

* TIME PERIOD USED (T) = 1.074

* Cs LIMITS : LOWER = 0.010 UPPER = 0.047

* LOAD FACTOR = 1.000

* DESIGN BASE SHEAR = 1.000 X 0.047 X 245173.19

* = 11539.58 KN

************************************************************

(second modeling)

************************************************************

* IBC 2006 SEISMIC LOAD ALONG X :

* CT = 0.030 Cu = 1.400

* TIME PERIODS :

* Ta = 0.767 T = ****** Tuser = 0.000

* TIME PERIOD USED (T) = 1.074

* Cs LIMITS : LOWER = 0.010 UPPER = 0.047

* LOAD FACTOR = 1.000

* DESIGN BASE SHEAR = 1.000 X 0.047 X 244673.84

* = 11516.08 KN

************************************************************

If we look at the T from second modeling is non-identified even the Cs is same.

The effective seismic weight is also a bit lower for the second modeling.

Can you help me what could the reason of these?

Which one is the correct modeling?

Since I concern to check the hogging and sagging where the section as 0.25L is really helpful, can I go with the second modeling?

Please your kindly advice.

Thanks a lot.

Regards

Santos

Seismic Load Based on IBC 2009 ASCE 7-10

SantoS — Wed, 19 Mar 2014 17:06:02 GMT

Dear All,

Does StaadPro provide the seismic load definition based on IBC 2009 and or ASCE 7-10?

I checked but I only found IBC 2006 (which refer to ASCE 7-05).

And the default is using Zip Code to determine the Ss and S1, is this Zip Code based on the US residential only?

And can we input manually Ss and S1?

By the way, what's differences between ASCE 7-05 and 7-10?

Thanks.