Page 490 - Advanced Design Examples of Seismic Retrofit of Structures

Examples of Nonengineered Buildings Chapter 6 433

(A) (B)
FIG. 6.31 Out-of-plane collapse of nonload-bearing walls in barrel adobe roofs. (A) After 2003
Bam earthquake. (B) After 2005 Zarand earthquake. (Photos taken by Mohammad Yekrangnia.)

between bed joints only. In order to study different possible failure modes, walls
with various opening configuration are considered. One group of the specimens
is solid walls; the other group has a large central window and the other has a
door and a small side window. The dimensions of the openings were selected
based on the data from the previously performed field study of numerous adobe
buildings throughout Iran by the SUT team.
As shown in Fig. 6.32, three methods of retrofit for the specimens were con-
sidered, as follows:
(i) The first method included installing welded steel mesh connected to the
wall by through-wall connections at appropriate locations. The steel mesh
had a 5cm cell and consisted of 4mm elements. The mesh was not
attached to the foundation and it was extended up to 25cm lower than
the base of the windows.
(ii) The second method included using steel strips with the connection details
similar to that in the first method. The patterns of these strips, which
included horizontal, vertical, and diagonal elements, were based on the
observed crack pattern of the corresponding unretrofitted specimens.
The width of all the strips was 10cm and the thicknesses of the horizontal
and vertical strips and diagonal stripes were 1 and 2mm, respectively.
(iii) In the third method, chicken wire was used together with 0.5mm thick-
ness, 50mm wide steel stripes. Compared with the second method, the
diagonal stripes were removed and the connection of the stripes which
confined the chicken wire to the wall was made by nails without the need
for drilling, hence its implementation was considerably simpler and
faster.

It is noteworthy that in all the implemented retrofit methods, both surfaces of the
walls were retrofitted. As the results of the shaking table tests in the next section
prove, there is no need to cover both faces of the adobe walls in practice. Cov-
ering both faces of the walls in the static cyclic tests was done in order to