Page 24 - Advanced Design Examples of Seismic Retrofit of Structures

16 Advanced Design Examples of Seismic Retrofit of Structures

building site. Alternatively, if such a hazard is present, the hazard has been
mitigated by the design of the lateral-force-resisting system, including
foundations [2].
l The target is to offer a retrofit solution for several buildings of this type
under different circumstances. In order to take into account the effects of
different structural features on the vulnerability of the considered school
buildings, the items below are considered as variables and the vulnerability
assessment is performed for each case; accordingly, the retrofit solution for
each case is then proposed.
- Existence of tie columns: two cases are considered, unconfined unrein-
forced masonry (UM hereafter), and the corresponding confined unrein-
forced masonry building (CM henceforth).
- Diaphragm rigidity: two cases are considered; one case is the building
with a flexible diaphragm, and other is the corresponding building with
a rigid diaphragm.
- The effects of mortar shear strength, soil condition, and seismicity of the
region: all of these factors contribute directly to capacity of the building
and seismic demand.
l Considering that many school buildings of this kind have peripheral walls
which isolate the building from its adjacent buildings, it is assumed that the
effects of surrounding buildings on seismic performance of the school build-
ing are negligible (Fig. 2.4); otherwise, data will be collected to permit

FIG. 2.4 Isolation of the adjacent building from the considered URM school building. (Permission
from DRES.)