Two-way slab as moment frame
Two-way slab as moment frame
(OP)
Hello,
Reviewing an existing concrete building for lateral loads and noticed that the building has shear walls in one direction only. The slabs are similar to waffle slabs but differ in that the ribs are not continued to the next column line as seen in the attached. Was this system, i.e. the slab/columns, consider a moment frame? In my sketch I drew a section at the top and on the plan the slab at the bottom columns is the same as indicated ablove. Thanks for the input.
Reviewing an existing concrete building for lateral loads and noticed that the building has shear walls in one direction only. The slabs are similar to waffle slabs but differ in that the ribs are not continued to the next column line as seen in the attached. Was this system, i.e. the slab/columns, consider a moment frame? In my sketch I drew a section at the top and on the plan the slab at the bottom columns is the same as indicated ablove. Thanks for the input.






RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
This reminds me of way back when I used ADOSS, That program allowed you to add lateral moments into your design strip.
RE: Two-way slab as moment frame
Only university does that kind of researh !
I can assure you that a two-slab equivalent frame is not a standard SFRS ! You need beams and column system clearly defined. 10" slab arent beams ! Did the engineer add shear reinforcement in the "Beams", does the joint capacity checked ?
** Of course, this only apply to region where seismic design is required !
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
MainMan10 is correct that the concern is with the punching shear which is sometimes significantly affected by the addition of the moment.
RE: Two-way slab as moment frame
The slab that makes a drop panel is 30" thick. probably you're talking about thin flat plates.
RE: Two-way slab as moment frame
I am trying to fit this system into what the code calls a moment resting frame to calculate the time period and then the seismic loads. Then -and based on that- check the system's adequacy.
Can I call this system a moment resisting frame?
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame
Be sure that at your joint, your beam are weaker that your column !
RE: Two-way slab as moment frame
This is a 2 way rib slab which is not a normally accepted two way system system according to most codes. The designer would need to do a full grillage analysis to determine design actions rather than assuming a flat slab action as is assumed for a waffle slab.
RE: Two-way slab as moment frame
RE: Two-way slab as moment frame