Page 115 - Advanced Design Examples of Seismic Retrofit of Structures

Example of a Two-Story Unreinforced Masonry Building Chapter 2 107

f meq ¼equivalent compressive strength of the composite section of the
shotcreted wall.
The equivalent compressive strength of the composite section f meq can be
determined by assuming compatible strains at shotcreted layer and masonry
wall based on Eq. (2.48):

0 0
f t m + f t c
m
c
f meq ¼ (2.48)
t m + t c
where:
f m ¼compressive strength of masonry prism;
0
f c ¼compressive strength of concrete in the shotcrete layer;
0
t m ¼thickness of masonry wall; and
t c ¼thickness of the shotcrete layer.
Shear (Diagonal Tension) The proposed relation for determination of the
capacity of shotcreted masonry walls with shear failure mode is according to
Eq. (2.49) [50]. All terms of this equation except for V c are included in the rela-
tion for determination of reinforced masonry capacity in ASCE 41-13 [2]. Also:
(2.49)
V d ¼ V m + V c + V s + V p

M p ffiffiffiffiffi
V m ¼ 0:083α 4 1:75 f 0 (2.50)
A g
m
Vd e
p ffiffiffiffi
V c ¼ 0:2 f t c d e (2.51)
0
c
H
V s ¼ 0:5f y A v (2.52)
S
V p ¼ 0:25P u (2.53)
where:
V d ¼expected shear capacity of shotcreted masonry wall;
V m ¼contribution of masonry wall in the shear strength of the wall;
V c ¼contribution of shotcrete layer in the shear strength of the wall;
V s ¼contribution of shear reinforcement in the shear strength of the wall;
V p ¼contribution of vertical loads in the shear strength of the wall;
M ¼flexural moment in the section;
V ¼shear force in the section;
d e ¼effective length of the wall equal to 0.8 of the total wall’s length;
A g ¼wall’s cross-sectional area;
f m ¼compressive strength of masonry prism;
0
f c ¼compressive strength of concrete in shotcrete layer;
0
t c ¼the thickness of shotcrete layer;