CMU Height Guidlines for Exterior Walls Bearing at Grade
CMU Height Guidlines for Exterior Walls Bearing at Grade
(OP)
Are there practical or code based height restrictions on exterior CMU walls which are tied laterally at each floor but gravity loaded to the foundation?
Obviously I need to account for floor deflections and thermal movements.
Code or design guide references would be helpful.
Thank you,
Greg
Obviously I need to account for floor deflections and thermal movements.
Code or design guide references would be helpful.
Thank you,
Greg






RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
thread507-310458: wall height
Dik
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
-Greg
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
Dik
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
Dik
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
Construction Maximum l/t or h/t
Bearing Walls
Solid units or fully grouted 20
All other 18
Nonbearing walls
Exterior 18
Interior 36
t is the nominal thickness of wall.
The code defines wall carrying vertical loads greater than 200 pounds/ft in addition to its own weight as loadbearing.
Many times the thickness of the exterior nonbearing cmu wall used as a back-up is governed by deflection requirements of the finish / cladding /veneer attached to the wall.
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
Dik
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
The question is about if relieving the CMU is necessary. For example with brick veneer we limit the maximum unrelieved height.
I.E. Can the wall be built 25, 50, 100 feet tall off the foundation wall without relief?
Thanks,
Greg
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
dik - Ref ACI 318-05: Commentary R10.8 - Design dimensions for compression members - With the 1971 code, minimum sizes for compression members were eliminated......... Commentary R10.11.5 - For slender compression members, an upper limit of 100 is imposed on the slenderness ratio if designed by the moment magnified method. No similar limit is imposed if design is carried out according to section 10.10.1 - forces obtained using second order analysis considering nonlinearity.
ACI allows concrete walls to be designed either using provisions of Chapter 10 or Chapter 14. Thicknesses of walls designed using provisions of Chapter 14 shall not be less than 1/25 the supported height or length, nor less than 4". For slender walls provisions of Chapter 10 would apply.
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
Dik
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
The relieving for brick veneer is a practical/detail situation since brick has a long term expansion, while concrete and concrete masonry have a long term shrinkage/creep and steel is just normally creep due to the magnitude of the permanent loads. It is because compatibility of materials to allow openings (doors, windows) to match the exterior.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
Mike McCann
MMC Engineering
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade
LonnieP
RE: CMU Height Guidlines for Exterior Walls Bearing at Grade