Tension only member and Response Spectrum Analysis
Tension only member and Response Spectrum Analysis
(OP)
Since Response Spectrum Analysis is a linear analysis, it is unable to account for the tension only Braces in a braced bay.
What is the best way the model tension only braces while performing RSA?
I am trying to model my braces with a 0.5 stiffness modifier, so that the brace bay would act as if it was a tension only brace bay in RSA. Is the method generally valid? or would I get completely erroneous results?
Another thing that I notice is that RSA only show Maximum axial forces in elements. This is leading me to think that RSA theory doesn't distinguish between positive and negative force? Is there any way of finding compression forces?
Any advice would be much appreciated!
What is the best way the model tension only braces while performing RSA?
I am trying to model my braces with a 0.5 stiffness modifier, so that the brace bay would act as if it was a tension only brace bay in RSA. Is the method generally valid? or would I get completely erroneous results?
Another thing that I notice is that RSA only show Maximum axial forces in elements. This is leading me to think that RSA theory doesn't distinguish between positive and negative force? Is there any way of finding compression forces?
Any advice would be much appreciated!





RE: Tension only member and Response Spectrum Analysis
It is not possible to run an RSA analysis with tension only or compression only elements. So, if you have an X brace type configuration (or any configuration where there is an equal / symmetric arrangement of braces) then it makes sense to use a 0.5 multiplier on the axial stiffness of the brace. That should work pretty well.
When you get your analysis results the axial forces in the braces are equally likely to be tension or compression.... you don't know. So, in an X brace configuration you would add them together. The total sum is the maximum axial force in the tension brace. That works great if your assumption is that the movent of the structure is almost entirely lateral.
Note: I'm not a SAP guy at all (I actually work for a SAP competitor). But, I can't imagine that this basic concept would be different between programs.
RE: Tension only member and Response Spectrum Analysis
RE: Tension only member and Response Spectrum Analysis
Regards.
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...
RE: Tension only member and Response Spectrum Analysis
RE: Tension only member and Response Spectrum Analysis
RE: Tension only member and Response Spectrum Analysis
Which one is easier: A multiplication by 2 or a Non-Linear Time History Analysis?
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...
RE: Tension only member and Response Spectrum Analysis
I was not advocating use of N/L analysis; it was just a reminder. Also, use of 0.5 factor will affect not only the bracing members, but also the force in the members connected to the braces.
RE: Tension only member and Response Spectrum Analysis
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...
RE: Tension only member and Response Spectrum Analysis
To design the column and its base on the other side of the bracing, you can make a second model with mirrored diagonals.
RE: Tension only member and Response Spectrum Analysis
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...
RE: Tension only member and Response Spectrum Analysis
RE: Tension only member and Response Spectrum Analysis
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...