Vertical Structure Irregularties
Vertical Structure Irregularties
(OP)
Hi all
I have structure located in Seismic zone 2A, the main lateral load resisting system is core wall, the main problem I have is that some RC walls are added starting from the 4 the floor up to last floor (12 floor), This will result in weak story irregularity according to UBC and IBC, can I assume that this walls will not be part of the lateral load resisting system and the all the load will transfer to my core wall and ignore this weak story effect?
I have structure located in Seismic zone 2A, the main lateral load resisting system is core wall, the main problem I have is that some RC walls are added starting from the 4 the floor up to last floor (12 floor), This will result in weak story irregularity according to UBC and IBC, can I assume that this walls will not be part of the lateral load resisting system and the all the load will transfer to my core wall and ignore this weak story effect?






RE: Vertical Structure Irregularties
Why do you need these walls? If the core is good enough up to 4th floor then it will be good enough above that.
That said, if deflection is an issue then maybe an out rigger system may be feasible to engage the outer lines of columns.
csd
RE: Vertical Structure Irregularties
walls are need for construction issue and vertical load , the core can handle the lateral load safely. can i ignore this walls in lateral load analysis?
RE: Vertical Structure Irregularties
RE: Vertical Structure Irregularties
But I have not designed anything over 8 stories, so this is not really my forte.
csd
RE: Vertical Structure Irregularties
StructuarlEIT,
How can I separate the wall from the diaphragm?
Construction section shall be as follows
1-walls will be casted first with its top level equal to the level of slab soffit
2-Reinforcement will be placed for the slab and negative slab Rft will pass over the wall.
3- Slab will be casted with the reaming part of the wall (the slab wall connection will act as diaphragm)
RE: Vertical Structure Irregularties
RE: Vertical Structure Irregularties
csd
RE: Vertical Structure Irregularties
what you mean by blade column?
RE: Vertical Structure Irregularties
Mike McCann
McCann Engineering
RE: Vertical Structure Irregularties
RE: Vertical Structure Irregularties
RE: Vertical Structure Irregularties
According to IBC2003 Table 1616.5.1.2 Item 5
Discontinuity in Capacity—Weak Story
A weak story is one in which the story lateral strength is less than 80 percent of that in the story above.
The story strength is the total strength of seismic-resisting elements sharing the story shear for the
direction under consideration.
in case i will apply to this type of vertical irreg. the design will be completly changed, so iw ould like to ignore this extra wear from shearingin the shear force for lateral loads, but for sevriceablty limits and gravity loadings this walls shall be considered
RE: Vertical Structure Irregularties
RE: Vertical Structure Irregularties
Several of these would be much more flexible than one long wall and may meet the 80% criteria.
csd
RE: Vertical Structure Irregularties
I would run both scenarios though if you decide to leave the wall in place, as loads can shift with different layouts. Also, ifleft in place, the center of rigidity will be affected, possibly inducing some unanticipated torsional forces.
Mike McCann
McCann Engineering