Page 154 - Advanced Design Examples of Seismic Retrofit of Structures

146 Advanced Design Examples of Seismic Retrofit of Structures

– An elevator is missed.
– Requirement of adding a passage bridge between the two building parts
which results in the necessity of stairs due to difference between the
elevations of the stories in the two building parts.
– Missing an area enclosed between axis F in the southern part and the
elevator wall of the northern part.
– Requirement of demolishing the walls in the South-East corner of the
northern building part and reconstruction by proper materials.
– The details of the floor between the two buildings is rather complex.
– The required time for this strategy is longer than that of the strategy in
Section 3.4.1.
– The required budget for this strategy is larger than that of the strategy in
Section 3.4.1.
– The total cost of retrofitting according to this strategy is estimated to be
$385,000. A general schematic view of the first retrofit strategy is shown
in Fig. 3.18.

3.4.3 Isolation the Two Building Parts From Each Other
and Decreasing Stiffness of Each Part

l The main strategies are as follows:
– Providing the freedom for each building part to experience the necessary
displacements.
– Decreasing stiffness of each building part to ensure a more optimum dis-
tribution of stiffness and to reduce the seismic demands in the existing
shear walls and columns.
l The drawbacks are as follows:
– Considerable demolition.
– Requirement for adding a system of columns and beams to tolerate the
gravitational loads.
– An elevator is missed.
– The majority of columns need to be retrofitted because the increase in
their seismic demands.
– The existing RC shear walls need to be retrofitted for flexural and shear
actions.
– Requirement of adding a passage bridge between the two building parts,
which results in the necessity of stairs due to the difference between the
elevations of the stories in the two building parts.
– Requirement of demolishing the walls in the South-East corner of the
northern building part and reconstruction by proper materials.
– The details of the floor between the two buildings are rather complex.
In this method, the columns ends should be retrofitted. As a result, the costs for
the “enhanced” performance objective are considerably higher than those in the