Page 448 - Advanced Design Examples of Seismic Retrofit of Structures
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394 Advanced Design Examples of Seismic Retrofit of Structures
FIG. 6.3 Comparison of different construction details and failure modes of two buildings, both of
which are categorized as adobe buildings. (A) Adobe building with very slender walls and very light
inclined roof after the 2009 Yunnan, China earthquake. (B) Adobe building with thick short walls
and very heavy arched roof after the 2003 Bam, Iran earthquake. ((A) Permission from EERI.
(B) Photo taken by Mohammad Yekrangnia.)
found in many parts of the world, minimal skill and experience required for
building adobe structures is required; and it is among the most energy-saving
building construction [5].
Compared to brick-masonry buildings, adobe buildings are generally
regarded as inferior in terms of seismic performance. However, thin-walled
masonry structures can easily fail due to gravitational effects shortly after
experiencing low to moderate seismic actions, whereas thick-walled adobe
buildings can exhibit significant structural ductility even though the building’s
construction material itself is brittle [6]. The main cause of severe damage and
collapse of adobe buildings is lack of integrity of different structural parts
including weak connection between perpendicular walls and also poor seismic
performance of wall-to-roof connection, both of which endanger the “box-like”
behavior of such buildings [4].
In this chapter, examples of various retrofitting methods and successful
national experiences on risk reduction of adobe buildings are presented.
6.2 RETROFIT APPROACHES
Structural stability is fundamental for the adequate performance of adobe build-
ings during major earthquakes and for designing appropriate retrofit measures.
The walls of adobe buildings will crack during moderate to large earthquakes
because massive adobe walls activate significant amounts of inertial forces, and
both adobe blocks and mud mortar are low-strength materials. After cracks have
developed, it is essential that the cracked elements of the structure remain sta-
ble, upright, and able to carry vertical loads.
Compared to the more traditional force-based approach, which aims at
increasing structural elements strength, the stability-based, retrofit design