Page 85 - Advanced Design Examples of Seismic Retrofit of Structures

Example of a Two-Story Unreinforced Masonry Building Chapter 2 77

The values of V bjs1 of the walls in the example building walls are presented
in Appendix Table A-C-2-10. As an example, the bed-joint sliding capacity of
Wall#1 on the first row of this table is determined as:

10,883
0:75 0:75 2:5+
3255 2
v me ¼ ¼ 2:61kgcm
1:5
V bjs1 1 ¼ 2:61 3255 ¼ 8493kg
And accordingly:
V bjs2 1 ¼ 0:5 10883 ¼ 5441kg

2.7.5.2 Force-Controlled
Lower-bound in-plane strength of URM walls shall be the lesser of toe-crushing
strength, diagonal tension strength, or vertical compressive strength in “Lower-
Bound In-Plane Toe-Crushing Strength of URM Walls and Piers”, “Lower-
Bound In-Plane Diagonal Tension Strength of URM Walls and Piers”, and
“Lower-Bound In-Plane Vertical Compressive Strength of URM Walls and
Piers” sections, respectively.

Lower-Bound In-Plane Toe-Crushing Strength of URM Walls and Piers
Based on ACE41-13 [2], the lower-bound in-plane toe-crushing strength, Q CL ,
of URM walls or pier components for toe-crushing failure mode shall be calcu-
lated in accordance with Eq. (2.35):
L f a

Q CL ¼ V tc ¼ αP D +0:5P W Þ 1 (2.35)
ð
h eff 0:7f m 0
where:
h eff , L, and α ¼the same as given for Eq. (2.31);
f a ¼axial compression stress caused by gravity loads specified in Eq. (2.28);
f m ¼lower-bound masonry compressive strength;
0
P D ¼superimposed dead load at the top of the wall or pier under
consideration;
P W ¼self-weight of the wall pier; and
V tc ¼lower-bound shear strength based on toe crushing for a wall or pier.
Similar to the rocking failure mode, Code 360 [10] does not include the
effects of wall’s or pier’s self-weight into account for determination of
lower-bound in-plane toe-crushing strength of masonry walls.
The values of V tc of the walls in the example building walls are presented in
Appendix Table A-C-2-10. As an example, the toe-crushing capacity of Wall#1
on the first row of this table is determined as: