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QUESTION: Dear Sir,

I have modeled a two story building frame in ETABS and for designing the Footings after running the analysis,exported the reactions to SAFE v12. But even for Dead and Live loads the reactions are getting in Rx and Ry whereas the loads are gravity(Fz).I checked the model and unable to understand this situation in ETABS where even for Dead and Live loads,it is giving

reactions in Horizontal Directions.One of my friend told me,this is due to pirated version of software,I don't understand this.Please,can you clarify.

Mohammed

ANSWER: Dear Mohammad

I guess you have defined Dead an Live load in etabs in X and Y direction. Check it first please and let me know.

Regards

BEH

---------- FOLLOW-UP ----------

QUESTION: Dear Sir,

Thanks for your response. I have double checked the model and the loads are in the gravity direction which is z-direction. If u wish i can attach the input file or send u the model.

The input is :

$ POINT ASSIGNS

POINTASSIGN "4" "BASE" RESTRAINT "UX UY UZ"

POINTASSIGN "5" "BASE" RESTRAINT "UX UY UZ"

POINTASSIGN "6" "BASE" RESTRAINT "UX UY UZ"

POINTASSIGN "7" "BASE" RESTRAINT "UX UY UZ"

$ POINT OBJECT LOADS

$ AREA OBJECT LOADS

AREALOAD "F1" "STORY2" TYPE "UNIFF" DIR "GRAV" LC "LIVE" FVAL 1

AREALOAD "F1" "STORY2" TYPE "UNIFF" DIR "GRAV" LC "SDL" FVAL 2.45

Here is the output:

ETABS v9.7.4 File:GUARDHOUSE Units:KN-m June 2, 2013 9:05 PAGE 1

S U P P O R T R E A C T I O N S

STORY POINT LOAD FX FY FZ MX MY MZ

BASE 4 DEAD 0.29 0.29 38.34 0.000 0.000 0.000

BASE 4 LIVE -0.02 -0.02 2.25 0.000 0.000 0.000

BASE 4 SDL -0.04 -0.04 5.51 0.000 0.000 0.000

BASE 4 WX -1.32 0.00 -3.95 0.000 0.000 0.000

BASE 4 WY 0.00 -1.32 -3.95 0.000 0.000 0.000

BASE 5 DEAD -0.29 0.29 38.34 0.000 0.000 0.000

BASE 5 LIVE 0.02 -0.02 2.25 0.000 0.000 0.000

BASE 5 SDL 0.04 -0.04 5.51 0.000 0.000 0.000

BASE 5 WX -1.32 0.00 3.95 0.000 0.000 0.000

BASE 5 WY 0.00 -1.32 -3.95 0.000 0.000 0.000

BASE 6 DEAD 0.29 -0.29 38.34 0.000 0.000 0.000

BASE 6 LIVE -0.02 0.02 2.25 0.000 0.000 0.000

BASE 6 SDL -0.04 0.04 5.51 0.000 0.000 0.000

BASE 6 WX -1.32 0.00 -3.95 0.000 0.000 0.000

BASE 6 WY 0.00 -1.32 3.95 0.000 0.000 0.000

BASE 7 DEAD -0.29 -0.29 38.34 0.000 0.000 0.000

BASE 7 LIVE 0.02 0.02 2.25 0.000 0.000 0.000

BASE 7 SDL 0.04 0.04 5.51 0.000 0.000 0.000

BASE 7 WX -1.32 0.00 3.95 0.000 0.000 0.000

BASE 7 WY 0.00 -1.32 3.95 0.000 0.000 0.000

Summation 0, 0, Base DEAD 0.00 0.00 153.36 76.239 114.579 0.588

Summation 0, 0, Base LIVE 0.00 0.00 9.00 4.523 6.773 -0.031

Summation 0, 0, Base SDL 0.00 0.00 22.05 11.082 16.594 -0.075

Summation 0, 0, Base WX -5.27 0.00 0.00 7.903 -13.831 2.635

Summation 0, 0, Base WY 0.00 -5.27 0.00 21.733 0.000 3.951

As u can see at point4 ,Fx is 0.29,Fy is 0.29.

This is confusing me,if u wish i can send u the model....It is a basic model of 3mx3m room with SDL of 2.45KN/m2 and LL of 1 KN/m2.

Thanks for ur help.

Mohammed

ANSWER: Dear Mohammad

I have here etabs 9.7.2 and safe 12.3.1. Please send me your models if you work with lower or same version of mine.

Regards

BEH

babak.e.hakimi@gmail.com

Dear Mohammad

I checked your model in etabs and safe. No problem exists in what I have revised. Then I guess your safe software may have some problems and need to be changed something.

Regards

BEH

---------- FOLLOW-UP ----------

QUESTION: Dear Sir,

Thanks for your response.

Hate to trouble you with silly questions but

why i am getting the reactions Fx and Fy for

Dead and Live loads with my model.As the loads

are gravity based,the reactions should also be

in z-direction.

Mohammed

Dear Mohammad

There are 2 sources of unexpected components:

1- Errors in software matrix computations. In non deterministic structures this kind of errors is more serious.

2- Any asymmetry in the structure shape . In your structure's case even one column or girder with different properties may be source of asymmetry.

3- Asymmetry in loadings when symmetry exists in the structure.

Please feel free to let me know about any troubles you would have with these concepts.

Regards

BEH

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