Determine distribution or mezzanine shear force to vertical resisting elements
Mezzanine shear forces in the transverse direction are distributed to the interior CMU shear walls (B1-B2
& H1-H2) and the exterior walls (A1-A2 & I1-I2) based on their relative rigidities. For longitudinal forces,
it is assumed that each braced frame bay receives of the force due to symmetry.
Wall Rigidity Calculations
Mechanical Properties of Masonry
1500.psi
f' m
(10.34 MPa)
Assume masonry strength of 1500 psi with
Type S mortar.
6
1.6.10 .psi
Em
( 11032MPa )
Elastic Modulus of CMU (ACI
530-95 Table 5.5.2.3)
5
0.4.E m
E v = 6.4 10 psi
Ev
( 4413 Mpa )
Shearing Modulus of CMU (ACI
530-95 Sec. 5.5.2.3 b)
4.7.in (117 mm)
est
Equivalent solid thickness 8" CMU grouted
at every 40" o/c
1.kip
P
( 4.45 N)
Shear load to determine pier stiffness
Masonry Stiffness Functions:
est .d
A( d )
Area of wall segment
1. . 3
I( d )
est d
Use uncracked section (Assuming that wall
12
piers will not crack, per FEMA 273 Sec.
7.4.4.1)
3
( 1.2.P.h )
P.h
∆ c( h ,d )
Deflection of a cantilevered pier
A( d ) .E v
3.E m.I( d )
3
( 1.2.P.h )
P.h
∆ f( h ,d )
Deflection of a fixed-fixed pier
A( d ) .E v
12.E m.I( d )
1
R f( h ,d )
Rigidity of fixed pier
∆ f( h ,d )
H1-18
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