In running bond the vertical joints between the units are staggered (normal condition). In stack bond the vertical joints between the units line up. A wall laid up in running bond will be stronger because the units interlock better.
Kramer. Allowable stresses for CMU in the codes, I presume are for running bond. Is there "reduced" capacity if you use a stack bond? (assuming all other conditions being equal such as f'm, thickness, reinforcement etc)
Intuitively running bond is better than stack bond but I am just wondering if code makes the distinction for strength.
Stack bond walls are subject to additional requirements in U.S. codes. For example, the reinforcing ratio is higher for walls resisting seismic forces. Also, concentrated loads may not be distributed across the continuous joints.
Stack bond walls are most useful where a future doorway or opening may be installed; thus they generally occur only in non-load bearing walls. I can't think of a practical application for stack bond other than that.
maybe you can help with this too:
when designing a masonry retaining wall, is the proceedure for calculating the ultimate moments similar to that of a concrete wall - if not what are the distinctions? (ie. Mu = 0.156*b*d^2*fcu
where fcu = say 30 N/mm for concrete blocks
Is this correct?
Of course, the base will be reinforced concrete; masonry is being used for aesthetic purposes - the wall is 2m high and the blocks being used are 190x190x390mm. Horz and vert reinforcement will be required. gamma soil = 18kN/m^2, phi = 25 degrees, angle of retained soil = 14 degrees above horiz
