Real Risk

for repair and retrofitting of overall building stock is possible. If this

assessment follows an initial round of rapid assessment, it can also

provide a more conclusive evaluation of structural safety. Unlike the

rapid assessment, the procedure for detailed assessment varies for

different kinds of construction and building types.

Engineering evaluation of buildings is required to determine the

structural adequacy and integrity or distress of a structure or selected

elements prior to undertaking retrofitting, strengthening or repair.

The decision to conduct an engineering evaluation is mostly the

responsibility of the building owner, due to the cost and time

involved in the process.

Structural elements to be considered for building damage

assessment

It must be recognized that different natural hazards have a differ-

ential impact on structures. Cyclones, with their high-speed winds,

impact lighter elements of a structure such as the roof (especially if

pitched), wall cladding and openings, while the heavy rains and

floods that often accompany cyclones affect the foundation.

Cyclones also often render the surrounding area unsafe by uproot-

ing power supply lines and trees.

In floods the level of physical vulnerability of a structure depends

on its capacity to withstand the prolonged inundation, and pressure

from water in case of flash flooding. Building damage assessments

following floods must integrate an assessment of components such

as the building’s foundation (or in case of some flood-prone areas the

stilts that prop the structure) and walls. Floods are also accompa-

nied by secondary hazards such as ground settlement.

In the event of earthquakes, every structural and non-structural

element needs to be examined carefully for damage. Damage to

vertical load-carrying elements such as columns and walls due to the

ground shaking is often the most dangerous, since this may cause

building collapse. Hence, particularly in the case of earthquakes,

columns need to be critically examined for vertical, diagonal and

cross cracks (wide or hairline width). In some cases, there may be

uneven settling of ground due to liquefaction, which can severely

impact the structure.

Policy and institutional considerations in damage assessment

While building damage assessment is undertaken after most major

disasters, not many countries have taken the necessary measures

for institutionalizing a scientific and consistent approach toward

building damage assessment in Asia. Gujarat state in India is one of

the few pioneers in having initiated the process of developing and

institutionalizing a methodology for damage and loss assessment.

Having the necessary human and material resources pre-

identified, trained and ready for deployment at any time is essen-

tial for an effective and efficient damage assessment system. Since

building damage assessment requires expertise in structural and

civil engineering, it is often useful to establish and maintain

contact with local engineering chapters or associations, which

can provide volunteers for undertaking such an exercise when

required.

As stated, one of the key functions of building damage assess-

ment is to point towards appropriate future policy with a view to risk

reduction. In many Asian countries, building codes are available,

but are either not mandatory or not complied with. Assessment

including engineering evaluation can ascertain the exact elements

of the construction that did not comply with building codes, conse-

quently causing structural failure and damage to the building. For

example, corner reinforcement of buildings in an earthquake-prone

region may be specified in the code, but might be frequently ignored,

resulting in cracking or collapse at the corners of buildings in an

earthquake.

Building codes tend to be exhaustive; therefore, such assessment

based on identification of typical failures would indicate precisely

which aspects of the code should be emphasized in future construc-

tion policy to avoid repetition of similar failures. Justification for the

enforcement of such policy could draw upon the findings of the

damage assessment. It could also form the basis for public aware-

ness, skills development and capacity building of professionals and

construction workers, and spontaneous compliance with codes,

leading to the mainstreaming of hitherto neglected aspects of the

building codes.

A similar scenario applies in the case of building regulations. Even

though, unlike building codes, these are mandatory, the vast major-

ity of owner-built constructions pay little heed to such regulations.

Enforcement is often lax and subverted by corrupt dealings between

building owners and authorities. A clear, scientifically-driven damage

assessment can be a powerful tool toward reversing this process by

demonstrating the adverse consequences of overlooking or avoiding

building regulations. Additionally, where adequate building regula-

tions have not been in place, the assessment would provide

directions for formulating relevant regulations based on the nature

of damages, and where applicable, be a basis for revising existing

regulations.

Similarly, existing land use plans are often not followed properly

– for example, an area demarcated for agricultural use might be

used for housing by building unauthorized settlements. When a

flood occurs in such an area, the property damage and economic

loss might be significant compared to what it would have been if this

was an agricultural area – benefits might even have been gained in

terms of crop irrigation. In such cases, damage assessment may

allow revision and reorganization, or the formulation of new land use

plans based on its findings and future risk reduction considerations.

At a more refined level, it may demonstrate the risk and possible

futility of settlement in areas earmarked hazardous through hazard-

zoning. Such hazard-zoning, not only on the macro-national level,

but also micro-zoning within cities, exists in some Asian countries.

However, people are often unaware of the risk of living in areas zoned

as hazardous until a disaster does strike. An opportune moment

then arises to build awareness for more selective settlement patterns

and policies, facilitated by and demonstrated through the findings

of a damage assessment.

[

] 114

Building damage assessment may be used to identify immediate damage

and measures to prevent this in the future

Photo: Mr. N.M.S.I Arambepola