Page 512 - Advanced Design Examples of Seismic Retrofit of Structures

Examples of Nonengineered Buildings Chapter 6 455

vulnerability of the retrofitted adobe building is comparable with higher-quality
steel and reinforced concrete (RC) building noted by class number (2), (3), (4).
Descriptions about seismic intensities, MMI against which the vulnerability
functions of buildings are plotted in part B of this figure, are found in Table 6.9.

TABLE 6.9 The Modified Mercalli Intensity Scale [41]
Level Description
I Not felt except by a very few under favorable circumstances
II Felt only by a few persons at rest, especially on the upper floors of buildings.
Suspended objects may swing
III Felt quite noticeably indoors, especially on upper floors of office buildings,
but not necessarily recognized as an earthquake. Standing cars may rock
slightly. Vibration similar to that of a passing truck
IV If during the day, felt indoors by many, outdoors by few. If at night, few
awakened. Dishes, windows, and doors rattle, walls creak. A sensation such
as a heavy truck striking the building. Standing cars rock noticeably
V Felt by nearly everyone, many awakened. Some dishes and windows broken,
some plaster cracked, unstable objects overturned. Disturbance to trees,
poles, and other tall objects. Pendulum clocks may stop
VI Felt by all; many people run outdoors. Fallen plaster, minor chimney damage.
Movement of moderately heavy furniture
VII Everyone runs outdoors. Damage negligible in buildings of good design and
construction; slight to moderate in well-built ordinary structures;
considerable in poorly built or badly designed structures. Some chimneys
broken. Noticed by persons driving cars
VIII Damage light in specially designed structures; considerable in ordinary
substantial buildings. Panel walls thrown out of frame structures. Chimneys,
factory stacks, monuments, walls, and columns fall. Heavy furniture
overturned and damaged. Changes in well water. Sand and mud ejected in
small amounts. Persons driving in cars are disturbed
IX Damage considerable in specially designed structures; well-designed frame
structures thrown out of plumb; great damage in substantial buildings, which
suffer partial collapse. Buildings shifted off foundations, ground noticeably
cracked, underground pipes broken
X Some well-built wooden structures destroyed, most masonry structures
destroyed, foundations ruined, ground badly cracked. Rails bent.
Considerable land-slides from steep slopes and river banks. Water splashed
over banks. Shifted sand and mud
XI Few, if any, masonry structures remain standing. Bridges destroyed. Broad
fissures in ground. Under-ground pipes out of service. Earth slumps and land
slips in soft ground. Rails bent greatly
XII Total damage. Waves are seen on ground surface. Lines of sight and level are
distorted. Objects thrown into the air