Page 19 - Advanced Design Examples of Seismic Retrofit of Structures

10 Advanced Design Examples of Seismic Retrofit of Structures

particularly in complex coupled systems, all probabilities of risks are condi-
tional on some background knowledge, including suppositions that camouflage
unknown hazards. Given that a full knowledge of unexpected hazards and how
the cascading effects emerge in a complex coupled system cannot be gained,
risk management can fail when confronted with unexpected shocks. Resilience
represents an alternative design and management strategy. Resilience thinking
suggests adoption of design and management strategies for responding to
unknown and unexpected hazards through adaptation, flexibility, diversity,
and experimentation or innovation. Nowadays, designers and engineers
approach a structure as if it stands alone, without considering the interaction
with the community, which instead should be considered as an integrated part
of the design process. There is now a new fundamental way of looking at all
problems. The building is not considered alone, but as a group of buildings
using the “portfolio approach” which will allow regional loss analysis. This
concept is borrowed from the financial industry, where modern portfolio theory
(MPT) was developed in the 1950s through the early 1970s and was considered
an important advance in the mathematical modeling of finance. MPT is defined
as a theory of investment which attempts to minimize risk for a given level of
expected return, by carefully choosing the proportions of various assets. In the
last decade, earthquake engineers have given more attention to deformations
during their analysis, and life safety, while less attention has been given to
socio-economic parameters [9]. Nowadays, attention is shifting toward the
necessity to develop a damage-free structure using risk assessment tools which
should develop more robust structures against uncertainties. Shorter recovery
processes are possible at the building level if the structural damage is minimal;
otherwise it might take months to recover. One of the options in order to achieve
more resilient structures in face of an earthquake is, for example, providing
them with advanced technologies such as self-centering capabilities with min-
imum residual deformations, which will allow a faster recovery.

1.7 THE ORGANIZATION OF THE BOOK CHAPTERS

Focusing on the practical application considered for the current guideline, dif-
ferent chapters are designed to cover a variety of issues from design calculations
to the construction stages. The seismic upgrade of masonry existing building
through shotcrete and reinforcement is provided in Chapter 2.In Chapter 3, seis-
mic retrofit of an reinforced concrete (RC) building by adding shear walls is
investigated in detail. A relatively comprehensive discussion is dedicated to
the quantification of masonry infill behavior and its effect on the seismic per-
formance of a typical steel building in Chapter 4. The provision of concentric
bracing system as an efficient retrofit solution for an under-code steel structure
is presented in Chapter 5. Finally, seismic performance improvement tech-
niques for nonengineered buildings are encompassed in Chapter 6. In these
chapters, the aim is to provide readers with sufficient knowledge about the most