Which seismic base shear V is larger?
Which seismic base shear V is larger?
(OP)
One is a steel eccentrically braced frames, non-moment-resisting, connections at columns away from links, the other is special steel concentrically braced frames, if they have same effective seismic weight, which one will have larger seismic base shear?






RE: Which seismic base shear V is larger?
RE: Which seismic base shear V is larger?
RE: Which seismic base shear V is larger?
It looks like the "R" value for the first Building Frame System is 8 and the value for the second system is 6. Since Cs=(Sds)(I)/R that means that the second system (special steel concentrically braced frame) will have the higher Base Shear.
RE: Which seismic base shear V is larger?
The response modification factor is a function of global ductility of the seismic system selected and the inherent overstrength.
RE: Which seismic base shear V is larger?
RE: Which seismic base shear V is larger?
RE: Which seismic base shear V is larger?
The definition of an Irregular Structure is any structure that is determined to meet one or more irregularity types in Tables 12.3-1 and 12.3-2.
RE: Which seismic base shear V is larger?
Thank you very much for your information. It does helped me a lot and solved my puzzle. But can you please give me some visual example of eccentrically braced frame and still be considered as regularity structure, because I still have hard time to imagine how can "eccentrically" braced be considered as "not irregularity".
RE: Which seismic base shear V is larger?
You can have a building consisting of eccentrically braced frames (previous codes did not make a distiction whether beam connection at columns away from the link is moment connected or not) laid out such that none of the listed horizontal irregularities exist. This means that your frames are distributed relatively equal on each side of the center of mass, no offsets exist and building is more or less square to rectangular in plan view.
I won't ge into much detail about vertical irregularities but you can control that by making sure mass at each level is lower than the ones below, stiffness and strength of a particular level is lower than the one below, and all the frame bays are full height.
The term "eccentrically" in Eccentrically Braced Frame refers to the eccentricities in the detailing and not in the context of eccentricities for checking the torsion of the overall floor.
RE: Which seismic base shear V is larger?
Now I understand "eccentrically braced" is talking about an individual member (column or beam), while irregularity is talking about the whole building. This solved my puzzle completely. Thanks for your help.