Rahulkld

Hi @Rahulkld,
That is expected. Since your bottom and top chords have high axial load near support, the first 2 diagonals are always critical. You can use heavier sections for the first two diagonals and lighter elsewhere.
Thanks.
 

Finally I got it. It's only available for ACI codes.

Sir how to activate the feature for alert of exceedance of D/C ratio

Base located at the ground in that case.

 
 
Location of Base for Seismic Design.pdf

Base located at the ground in that case.

 
 
Location of Base for Seismic Design.pdf

Above referred site is related to Concrete Masonry. Following site may be helpful in connection with Clay Brick masonry:-
http://www.gobrick.com/
Moreover, you may find several other sources through internet search.
Regards.

Thank you sir. This forum is by far one of the best forum I'm in.

*SEFP Consistent Design*
*UBC Seismic Drift Limits*
*Doc No: 10-00-CD-0003*
*Date: June 04, 2013*
 
The goal of this tutorial is to demonstrate how to evaluate building drifts and story drifts using UBC 97 guidelines. The philosophy behind Story Drift Limits is “Deflection Control”; In UBC 97, deflection control is specified in terms of the story drift as a limit on the lateral displacement of one level relative to the level below. The story drift is determined from the maximum inelastic response, ΔM.
 
Let’s start by defining the design-level response displacements. The elastic deflections due to strength-level design seismic forces are called design-level response displacements. These are denoted by ΔS, where the subscript ‘s’ stands for strength design. Design level response displacements are what you get out of your software, when you run analysis. Please note that structural analysis softwares may provide these values in different formats; say a percentage of height or a direct output.
 
Well, to calculate your story drifts, first you need to find maximum inelastic response displacements from your design-level response displacements. The maximum inelastic response displacement is defined as:
ΔM = 0.7RΔS
Where, R is the structural system coefficient, the subscript ‘m’ in ΔM signifies that we are calculating a maximum value for the deflection due to seismic response that includes inelastic behavior.
 
Seismic drift values are much larger than wind values. UBC uses maximum inelastic response displacements rather than the design level displacements to verify the performance of the building. Seismic drift limits are 2% & 2.5% of the story height for long and short -period buildings. For a floor to floor height of 12 feet the max., allowable inelastic drift value would be 2% of 12 feet= 0.02*12*12 in=2.88 in. For wind for a 12 story height, drift would be L/400=12*12/400 =0.36 inches, A comparison of both wind and seismic drift limits shows that earthquake inelastic displacements are quiet large compared to wind displacements. That is why proper detailing is emphasized in seismic design.
 
When calculating ΔS for seismic, make sure:
You have included accidental torsion in your analysis. Use strength design load combinations: 1.2D + 1.0E + 0.5L & 0.9D + 1.0E. You are using cracked section properties for reinforced concrete buildings. Typical values are Icr walls= 0.5EcIg, Beams = 0.5EcI g & for Columns 0.5 - 0.7 EcIg. Use a reliability/ redundancy factor= 1 to calculate seismic forces. Whenever the dynamic analysis procedure of §1631 is used, story drift should be determined as the modal combination of the story drift for each mode. Determination of story drift from the difference of the combined mode displacements may produce erroneous results because maximum displacement at a given level may not occur simultaneously with those of the level above or below. Differences in the combined mode displacements can be less than the combined mode story drift.  
Example:
A four-story special moment-resisting frame (SMRF) building has the following design level response displacements.(See attached Image)

R= 7.0,
I= 1
Time period= 0.6 sec
(See the attached image for Story Information)
 
 
Calculate:
Maximum Inelastic response displacements. Story drift in story 3 due to ΔM. Check story 3 for story drift limit. Maximum Inelastic response displacements ΔM = 0.7RΔS
ΔM = (0.7) (7) ΔS = (4.9) ΔS
(See the attached image for Maximum Inelastic response displacements)

 
Story drift in story 3 due to ΔM Story 3 is located between Levels 2 and 3. Thus
ΔM drift = 5.39 - 3.43 = 1.96 in.
 
Check story 3 for story drift limit. For structures with a fundamental period less than 0.7 seconds, §1630.10.2 requires that the ΔM story drift not exceed 0.025 times the story height. For story 3:
Story drift using ΔM = 1.96 in.
Story drift limit = 0.025 *(12*12) in = 3.6 in. > 1.96 in. Therefore, Okay.

Thanks. I forgot to state that I was using RISA3D but its good to know options available in ETABS.
You can also use the formula for maximum inelastic response displacement to separate the buildings. Check this 
Thanks.

You can use ETABS 2015 or higher and use 'Tower' option to separate both buildings in the same model.

Thank you sir. This forum is by far one of the best forum I'm in.

The following site has good masonry design resources:
http://ccmpa.ca/
Thanks.
 

It is a very good question. I was in a similar situation recently but I separated my models. Wonder how do softwares consider that..
 

Hello everyone, I tried modelling two buildings which are close to each other in ETABS. When i tried to see time period at different modes. Etabs animated one building only for a particular mode. How does Etabs deal with such models? How can I see the animation of both building at once???

Seismic performance or resistance of a structure having a 'torsional irregularity' will, in general, be less than a structure WITHOUT such irregularity. Therefore, the design codes have put limits and restrictions on the types of seismic-force-resistance-systems as well as the configurations that can be used for such structures.
Actual performance level, however, will vary depending upon whether the torsional irregularity is less or more than the 'Extreme Torsional Irregularity' as given in applicable design or loading code.
Torsional Irregularity may be reduced in certain cases, e.g., by changing the building configuration.
Following links may help you understand torsional & extreme torsional irregularities as well as their effects on structures:-
1. Effects of torsional irregularity to structures during earthquakes
2. Extreme Torsional Irregularity
Regards.

CSI SAFE also has a Detailer. You may export ETABS results to SAFE and using the commands available under its 'Detailing' menu option, it will prepare structural drawings for you. You may give it a try to see whether it fulfills your requirements or not.
Regards.

Thank you very much sir. Thanks for your time and effort. 

You are welcome. Simplest way to learn something new to model is to take an example out of the book, do the model and compare the results. If your results are same as that of the book example, you have done a good job.
Here are some tips:
1) Top and bottom members need to be modelled and designed as continuous members.
2) Make sure your unbraced lengths are correct.
3) Manually resolve wind and snow loads on trusses. In that way, you will minimize any chances of error in load application.
4) Manually check at least dead weight reactions and member forces. If they match, you can trust your model.
Hope that helps.
Thanks.
 

Hi Rahul,
There are a number of ways to do it. I have suggested one in the attached pdf.
Thanks.
Steel Truss Concrete Column Connection.pdf

this book also useful NED research paper
https://www.academia.edu/8983144/A_Practical_Guide_to_Nonlinear_Static_Analysis_of_Reinforced_Concrete_Buildings_with_Masonry_Infill_Walls