Page 493 - Advanced Design Examples of Seismic Retrofit of Structures

436 Advanced Design Examples of Seismic Retrofit of Structures

details shown in Fig. 6.32 was transferring the cracks from the more dangerous
upper parts of the wall to the lower parts in which initiation and propagation
of cracks due to considerable shear capacity of the walls can be minimized.
The only problem that may arise is the necessity of cutting through the shear
key in areas where two mesh sheets overlap, in order to fit the steel box shown
in Fig. 6.34E in one of the mesh cells.
The steps for strengthening of adobe walls by steel strips are presented in
Fig. 6.35. The necessary step in this retrofit procedure is initially to drill the
positions of the connection rods with smaller drill. Then, after assembling
the strips on the wall, these holes are widened by a larger drill which goes into
the adobe wall. Similar to the steel mesh method, retrofitting adobe walls by
steel strips does not require any form of mortar. Also, none of these strips is
attached to the foundation of the wall. The main difficulty regarding implemen-
tation of this method is mapping the connection precise position on the over-
lapping areas of the strips; otherwise, the connection rod cannot pass through
the eccentric holes on the two overlapping strips.
The retrofitting steps by chicken wire with light steel strips are shown in
Fig. 6.36. The main steps are tying several layers of chicken wire if necessary,

(A) (B)

(C) (D)
FIG. 6.35 Retrofitting steps by steel strips. (A) Mapping the strips on wall. (B) Initial drilling
of the strips. (C) Final drilling of the strips. (D) Completed retrofit scheme. (Photos taken by
Mohammad Yekrangnia.)