Flexible vs Rigid buildings - ASCE 7
Flexible vs Rigid buildings - ASCE 7
(OP)
Greetings,
Per Chapter 6 of ASCE 7 "slender buildings or other structures are flexible if their natural frequency is less than 1 Hz".
In the commentary, it says when buildings have height greater than 4 times least horizontal dimension, then natural frequency should be investigated. It also says that Gust energy is smaller at frequencies aobove 1 Hz, and hence dynamic response may not be significant if frequency is greater than 1 Hz.
Suppose I have a building that is 100' tall and 50' x 50' in plan (h < 4 * horiz. dim). Assuming the calculated natural frequency is less than 1 Hz, does this mean that the building will have to be analyzed as a flexible building with modified Gust factors (6.5.8.2) and eccentricities per 6.5.12.3?
When you design buildings, how do you classify them as slender? using H < 4 * horiz. dim. or using the natural frequency.
I must tell you that 6.5.12.3 is a b*tch. Hope you can shed some light.
~Anantha
Per Chapter 6 of ASCE 7 "slender buildings or other structures are flexible if their natural frequency is less than 1 Hz".
In the commentary, it says when buildings have height greater than 4 times least horizontal dimension, then natural frequency should be investigated. It also says that Gust energy is smaller at frequencies aobove 1 Hz, and hence dynamic response may not be significant if frequency is greater than 1 Hz.
Suppose I have a building that is 100' tall and 50' x 50' in plan (h < 4 * horiz. dim). Assuming the calculated natural frequency is less than 1 Hz, does this mean that the building will have to be analyzed as a flexible building with modified Gust factors (6.5.8.2) and eccentricities per 6.5.12.3?
When you design buildings, how do you classify them as slender? using H < 4 * horiz. dim. or using the natural frequency.
I must tell you that 6.5.12.3 is a b*tch. Hope you can shed some light.
~Anantha






RE: Flexible vs Rigid buildings - ASCE 7
A structure with H < 4 * horizontal dimension can still have a natural frequency less than 1 Hz depending on the LFRS.
RE: Flexible vs Rigid buildings - ASCE 7
If fundamental frequency is less than 1 Hz, i.e, period greater than 1 second, do you calculate your eccentricities for a flexible building and apply them instead of 0.15 as in figure 6-9?
RE: Flexible vs Rigid buildings - ASCE 7