Page 105 - Advanced Design Examples of Seismic Retrofit of Structures

Example of a Two-Story Unreinforced Masonry Building Chapter 2 97

This steel mesh was applied externally at critical locations of adobe walls
such as at corners and free ends. This was then covered with a layer of mortar.
A large earthquake (M w 8.0) occurred in Pisco, Peru on August 15, 2007 result-
ing in 519 deaths, the collapse of over 70,000 houses, and the serious damage of
>33,000 houses. However, five houses in Ica that had been reinforced in 1998
survived the earthquake without suffering any damage.
A comparison of various retrofit methods for URM buildings is presented in
Table 2.13.

2.8.4 Shotcrete
In this part, performance improvement of the considered building by shotcreting
method is evaluated. In the absence of the available design codes for determi-
nation of the capacity and acceptance criteria of shotcreted masonry walls, the

TABLE 2.13 Comparison of Various Retrofit Methods for URM Buildings [22]

Retrofit
Method Pros Cons
Ferrocement l Low cost l Space reduction
l Low technology l Architectural impact
l Limited added mass l Requires architectural
finishing
l Limited efficiency
l Limited improvement in
energy dissipation
Reinforced l Low technology l Space reduction
plaster l Limited added mass l Architectural impact
l Required architectural
finishing
Shotcrete l High improvement in l Space reduction
ultimate strength l Heavy mass
l Very significant l Violation of performance
improvement in energy level
dissipation l Disturbance occupancy
l Architectural impact
l Requires architectural
finishing
Injection l No added mass l Epoxy create zones with
l No effect on building varying stiffness and strength
function l High cost of epoxy
l No space reduction l No significant increment in
l No architectural impact l ultimate strength using
cement-based grout
Continued