Concrete Speical Moment Frame

[1asdfghjk]

Greetings,

I have been assigned the task of designing a single-story office building using reinforced concrete in accordance with ACI 318-14. This building is placed in seismic design category D with site class C. According to ACI and what other buildings are designed and built with, LFRS is a suitable special concrete moment frame. The decking system is a prefabricated hollow core slab that is placed on the frame. I would like to know when I design the frame, is my LFRS the whole frame or just the perimeter beam column? If this is the case, does the beam column detailing look for the non-LFRS? This is my first concrete design. Any expert opinion is appreciated.



Building geometry: 80ftx60ft
Building height: 13 feet
Size of columns according to architectural standards: 20"x20"
Size of beams according to architectural criteria: 20"x20"

Some background information:

J. Wind loads: initial wind speed, using a 3-second gust, 177 km/h (110 mph), exposure C, and
Importance factor of 1.0 determined from ANSI/ASCE 7-16.

D. Seismic design: spectral acceleration based on Ss = 1.12g; S1 = 0.53g, hazard category II, site class D,
Coefficient of importance (ie) = 1.0.
Seismic design category: D
Correction factor, R = 8.
The foundations are designed for an allowable bearing capacity of 72 kPa (1500 psf).
Subgrade modulus 40.7 MPa/m (150 lb/m2). in/in). Ka and kp are considered 0.33 and 3.0
Respectively.

 

[HTURKAK]

R is response modificatin coefficient. ( A measure of performance of the SFRS .Refer to FIGURE C12.1-1 Inelastic Force–Deformation Curve )

Refer to ASCE 7 -16 Clauses 12.2.2 and 12.2.3

12.2.2 Combinations of Framing Systems in Different Directions. Different seismic force-resisting systems are
permitted to be used to resist seismic forces along each of the two orthogonal axes of the structure. Where different systems are used, the respective R, Cd, and Ω0 coefficients shall apply to each system, including the structural system limitations contained in Table 12.2-1.
12.2.3 Combinations of Framing Systems in the Same Direction. Where different seismic force-resisting systems are
used in combination to resist seismic forces in the same direction, other than those combinations considered as dual systems, the most stringent applicable structural system limitations contained in Table 12.2-1 shall apply and the design shall comply with the requirements of this section.

You may consider to provide more details to get better responds.




Not to know is bad;
not to wish to know is worse.

NIGERIAN PROVERB

 

[OldDawgNewTricks]

I would like to know when I design the frame, is my LFRS the whole frame or just the perimeter beam column? If this is the case, does the beam column detailing look for the non-LFRS?

You could decide to designate some frames as not part of the seismic force-resisting system. But those frames will still need to undergo the same story drifts and associated deformations as the moment frames. So you will probably end up providing similar detailing as the moment frames anyway. Refer to ACI 318-14 Section 18.14.3 for more information.

 

[1asdfghjk]

Thank you all for the help!

OldDawgNewTrick- your response is very much appreciated. This is almost exactly what I wanted to do but needed confirmation. It makes sense to provide similar details elsewhere in the frame based on the response of the structure to the lateral loads.