BUILDING VULNERABILITY WEIGHTING ASSESSMENT

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25 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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BUILDING VULNERABILITY WEIGHTING ASSESSMENT


1.

Number of stories vs B
uilding
m
aterials = moderate

It is considered that the number of stories is moderately more influential than building
materials. A
f
ive (5 no.)

storey timber building is considered to be moderately less vulnerable
than a 1 storey concrete reinforced building. In this instance, a structure must already be
strong enough to carry the load of several stories. For the same reason, a single storey
buil
ding does not require such a strong (resistant) structure.

2.

Number of stories vs
H
ydrodynamics = strong

The number of stories is considered strongly more influential than the hydrodynamics of the
ground floor. A building with 5 or more stories and a totally

closed ground floor is thus
considered to have a structure strongly less vulnerable than a one storey, fully open plan
building. Even though post
-
tsunami field studies emphasise the importance of having an
open ground floor, the majority of buildings havi
ng only one storey suffered heavier

damage
than multi
-
storied ones
.

3.

Number of stories vs
M
oveable objects = strong

Whilst
this report is in agreement with the considerations of Dall’Osso and Dominey
-
Howes
(2009) that a multi
-
storeyed building will be less
vulnerable than that of a single
-
storey
building, and that it is not possible to predict where moveable objects and debris will be
dragged by any tsunami flow, it is recommended that in a worst
-
case scenario event, a
building situated behind a car park or
similar source area of moveable objects will be struck
by such objects. Therefore, whilst the number of stories is likely a more significant factor in
a buildings vulnerability, the influence of this compared to that of moveable objects is
considered to be

strong, rather than “very strong” as considered by Dall’Osso and Dominey
-
Howes (2009).

4.

Number of stories vs S
hape and orientation = very strong

This report is in agreement with that of Dall’Osso and Dominey
-
Howes (2009) in that the
direction of a tsunami
flow is not entirely predictable. However, the most likely general flow
direction, and therefore brunt of the flow is considered to be that of a perpendicular or near
perpendicular f
low to the coastline
. Therefore, the number of stories is considered to be

very
strongly more influential on
a building’s

vulnerability with respect to the building’s shape
and orientation. This is in contrast to Dall’Osso and Dominey
-
Howes’ consideration of
the
number of stories having an “extreme” influence on a building’s vul
nerability relative to its
shape and orientation.

5.

Number of stories vs Structural

condition = extreme

The number of stories is considered to be extremely more influential with resp
ect to a
building’s structural

condition. This report agrees with Dall’Osso
and Dominey
-
Howes’
consideration that a five storey building in poor condition would be less vulnerable than that
of a one storey building in excellent condition, because the former building could not be in
such bad condition, when the building is standing
, to be considered less resistant than the
structure of a well preserved one storey building. This links in to the consideration of the
number of storeys vs building materials, whereby a five storey structure, even in very poor
condition, is still structur
ally sound and capable of withstanding the loads of above ground
floors.

6.

Building materials vs
H
ydrodynamics = moderate

A building made of reinforced concrete but closed ground floor is considered to be less
vulnerable to that of an open plan timber struct
ure. Furthermore, Ghobarah et al. (2006)
identified that following the December 2004 tsunami, many reinforced concrete buildings
contained brick infill walls, which were broken where water depths exceeded 2m, although
the concrete structure resisted. Conve
rsely, wooden structures rarely resisted similar water
depths. (Reese et al., 2007).

7.

Building material vs M
oveable objects = moderate

Dall’Osso and Dominey
-
Howes

(2009)

consider the above relationship to be that of a
building’s materials being “strongly” m
ore influential in respect of moveable objects due to
the uncertainty of exactly where a flow will move such debris and objects. However, as
above, a worst case scenario would be to assume that a building in close proximity to objects
will be struck. For t
his reason, a building’s material is considered only to be moderate with
respect to the presence of moveable objects.

8.

Building material vs shape and orientation = strong

A reinforced concrete U
-
shaped building is considered
to be significantly more resista
nt to
that of a round timber structure with a more hydrodynamic shape.

9.

B
uilding material vs Structural

condition = extreme

A building’s material is considered extremely more influential in consideration of its
vulnerability. A reinforced concrete building
in very poor condition is considered extremely
less vulnerable compared to a wooden building in excellent condition.

10.

Hydrodynamics vs moveable objects = very weak

The ground floor characteristics are considered to be slightly more influential than the
pres
ence of moveable objects. It is considered that a building having at least 50% of its
ground floor open, located adjacent to a car park, is slightly less vulnerable than a building
having a totally closed ground floor, away from sources of moveable objects
.

11.

Hydrodynamics vs shape and orientation = moderate

Ground floor characteristics are considered to be moderately more influential than the shape
and orientation. A building with open ground floor but poor hydrodynamic shape is
considered to be moderately
less vulnerable than a building of high hydrodynamic shape, but
closed ground floor. As water is free to pass through the building, this is considered to be
more relevant than the shape of that building is with regards to drag forces.




12.

Hydrodynamics vs

Structural

conditions = very strong

Ground floor characteristics are considered to be very strongly more in
fluential than
structural

conditions. A building in very poor state but fully open plan ground floor is
therefore considered to be much more resista
nt than a closed ground floor of an excellently
conditioned building.

13.

Moveable objects vs shape and orientation = weak

The presence of moveable objects is considered to be slightly more important than the shape
and orientation. The number of buildings dama
ged by moveable objects in previous tsunami
are considered
to have caused more damage (
Ghobarah et al., 20
06; Dalrymple & Kriebel,
2005b)), even when hitting buildings with good shape and orientation.

14.

Moveable objects vs Structural

conditions = very strong

Moveable objects are considered to be very strongly more influential than structural
conditions. This means that a building in good condition parked adjacent to a car park would
be more vulnerable than a poorly conditioned building that is distanced from
moveable
objects.

15.

Shape

and orientation vs Structural

conditions = very strong

The shape and orientation of a building is considered to be very strongly more influent than
structural conditions. Therefore, a well preserved building with a poor hydrodynamic

shape
is considered to be more vulnerable than a rounded building in poor condition.

16.


Structural

conditions vs Lower factor = moderate

The lower factor is a fictitious factor, used to generate a weighted value greater than zero for
the structural
conditions factor. With respect to zero, the influence of structural conditions
has been considered moderate. This means that even if “sc” is the least important factor, it
will still give a contribution to the final vulnerability level.