MiguelPenaWSE
Structural
Good afternoon.
I am working on a one story steel moment resisting frame in Ontario, Canada.
I am currently modeling and analyzing the structure in Sframe.
I am trying to understand why my hand calcs are not comparable with the FEA from Sframe. It's a simple structure with no irregularities.
Please see below;
Equivalent static force procedure yields a base shear of 92 kN.
The period of the structure based on 1.5Tcode is 0.46 seconds. (1.5*3.1s = 0.46s)
The calcualted seismic weight of the structure is 1,785 kN.
Class C soil, Normal importance, Rd of 1.5, Ro 1.3.
Sframe is showing a period of 1.12s (97.7% mass X) and 0.96s (89.7% mass Y).
Seismic force in X-dir is 104 kN and Y-dir is 102 kN.
These results are when I fully fix the columns at the base.
We are hoping to pin the base of the columns but if I model it as a pinned base, the periods and base shears increase. I find this odd since the higher the period, smaller the force - Response Spectra analysis.
We are calling out a 38mm steel deck (without concrete). This should behave as a flexible diaphragm hence I have modeled it as a "General Diaphragm" per Sframe options.
According to their help menu, "General Diaphragms" have all joints constrained in the XY plane.
I am just hoping for some guidance. I don't really know how to force Sframe to analyze the structure with a user defined period of 0.46s. This is the maximum period I am allowed to use per Code recommendations.
Also, for those who are experts on Sframe, if you could share a few tips, that would be great. This is clearly my first model and there is not much info out there, specially for flexible diaphragms.
I am working on a one story steel moment resisting frame in Ontario, Canada.
I am currently modeling and analyzing the structure in Sframe.
I am trying to understand why my hand calcs are not comparable with the FEA from Sframe. It's a simple structure with no irregularities.
Please see below;
Equivalent static force procedure yields a base shear of 92 kN.
The period of the structure based on 1.5Tcode is 0.46 seconds. (1.5*3.1s = 0.46s)
The calcualted seismic weight of the structure is 1,785 kN.
Class C soil, Normal importance, Rd of 1.5, Ro 1.3.
Sframe is showing a period of 1.12s (97.7% mass X) and 0.96s (89.7% mass Y).
Seismic force in X-dir is 104 kN and Y-dir is 102 kN.
These results are when I fully fix the columns at the base.
We are hoping to pin the base of the columns but if I model it as a pinned base, the periods and base shears increase. I find this odd since the higher the period, smaller the force - Response Spectra analysis.
We are calling out a 38mm steel deck (without concrete). This should behave as a flexible diaphragm hence I have modeled it as a "General Diaphragm" per Sframe options.
According to their help menu, "General Diaphragms" have all joints constrained in the XY plane.
I am just hoping for some guidance. I don't really know how to force Sframe to analyze the structure with a user defined period of 0.46s. This is the maximum period I am allowed to use per Code recommendations.
Also, for those who are experts on Sframe, if you could share a few tips, that would be great. This is clearly my first model and there is not much info out there, specially for flexible diaphragms.
