Page 502 - Advanced Design Examples of Seismic Retrofit of Structures

Examples of Nonengineered Buildings Chapter 6 445

FIG. 6.44 Details for tying perpendicular masonry walls by DRES.

retrofitted specimens and led to satisfactory results. In addition, an example of
the details of similar concept which was implemented by the Organization for
Development, Renovation and Equipping Schools of Iran (DRES) are shown in
Fig. 6.44.
Also, cracks are more uniformly propagated and are narrower in part B-II
and C-II of this figure compared to part B-I and C-I, respectively, which proves
the effects of welded steel mesh in controlling the cracks from further widening.
The only vulnerable area in specimen SMRA-LW was at the both sides of the
opening. This area was partly unconfined by the existence of the opening and
hence it is harder to maintain its integrity. A solution which can be considered
for this specimen is folding back the steel mesh in such a way that the mesh
“embraces” the end of the piers in the vicinity of the opening [39] (Fig. 6.45).
A comparison of the results in part A-III of this figure with those in part A-I
indicates the ability of the retrofit method consisting of steel strips in further
propagation of damage throughout the wall’s surface and, in doing so, minimiz-
ing the severity of cracks. The major weakness of specimen SSRA-LW was
transforming the shear-dominated failure mode into toe-crushing. Nonetheless,
the maximum strength capacity of the retrofitted specimen was significantly
higher than that in the corresponding unretrofitted specimen, and considerable
ductility and energy dissipation was achieved before occurrence of this
failure mode.