PUSHOVER ANALYSIS

[seismosoft]

Hi Saso,
A couple of notes on materials, performance criteria ans strength degradation.
1) as you correctly pointed out the con_ma model has degradation inherently in its hysteretic rules and gives a residual strength at high strain levels
2) Steel materials on the other hand have a fracture/buckling strain parameter for strain, after which material is fractured and it gives a stress=0
3) The strength degradation of the performance criteria operates on the member level, reducing or eliminating the resistance of the member, if/when the criterion is reached. This degradation functions in parallel with the strength degradation of the materials (for instance to model the degradation of stength upon shear failure that cannot be modeled through the material hysteretic rules) and should be used with caution because often it leads to numerical instability

[seismosoft]

Regarding your other questions:

4-i am using infrmFBH ,as you know , the two integration section ( section a &b)that shown at stress & strain output is indication for two equal parts of element one at start and one at the end ?
These are two integration points at the two ends of the member. Please refer to the manual for details

5-in stress and strain output when i chosen for concrete , in the column of max stress is zero , what that mean?
It means that you have a zero tensile stength. Again, refer to the manual for details

6- the plastic hinge is didn't specified ,unless i defined in performance criteria a yield limit for reinforcement ?
It depends on the definition that you give to a plastic hinge and you can define it through the performance criteria

7- is there option for specifying the location of cracks on the element ?
Through strains from the performance criteria module. Again, refer to the manual for details

8- if the joint of RC for column-beam designed as non-seismic according to old codes ,should i use infrm FB to define that joint with different integration sections (with no stirrups )
The stress-strain conditions at the beam-column joints are very complicated to be simulated with linear FE elements (not only in SeismoStruct, but with any other similar program). Try to use hand-calculations to perform the relevant checks for the joints

9- the bent bars ,are the the seismostrut modeled it ?
No

[SASO]

Dear Seismosoft
Thank you for that valuable informations
But i have some questions
1 -if i use con_tl ( scott model) on what basis; i took the values of intial stiffness and post-peak stiffness
2- how can i define the yield strength of stirrups،because i notice that program took the yield strength of longitudinal bars same transverse. ?
Saso

[huffte]

Hi SASO. Regarding item 2, I think you may be able to mimic the effect of a different yield stress for transverse confinement (stirrups or hoops) by specifying a faux size and spacing of the transverse bars. Specify (Av x fy / s) such that the value matches your actual conditions. For example, suppose your stirrups have actual fy = 40 ksi and that your steel in SeismoStruct has fy = 60 ksi. Further suppose that the stirrups are #5 spaced at 6 inches. Then to get the correct confining pressure calculated, you would specify the number 5 stirrups with a faux spacing of (60/40) x 6 = 9 inches. (60/9 = 40/6). As I say, I believe this gets the correct confining pressure, but the confinement effectiveness factor would vary somewhat due to the larger spacing.

Another option is to hand calculate the confinement factor and enter it manually. Best of luck, SASO.