Seismic retrofitting improves community resilience on
housing. Even it is smaller activities compare to the post-disaster reconstruction.
It is still workable even during Covid-19 pandemic on reducing earthquake risk
on densely populated houses. This writing is based on retrofitting program
implemented by Indonesian Red Cross and supported by the American Red Cross and Build Change, and
funded by USAID. The program takes place in Indonesia at a city and at a
sub-district which are located at earthquake prone area.
Many houses were poorly built in the earthquake prone area; therefore,
they are in vulnerable state. Homeowners might not realize that they are at
risk until earthquake with certain magnitude occurs. Their houses might
collapse or might have significant damage. Therefore, these houses need to be seismically
strengthened as a disaster risk reduction measure. In densely populated
community this initiative become more crucial since large-scale houses might collapse
if earthquake occur. Moreover, the debris might block their narrow evacuation
route. Even retrofitting is less expensive compared to the rebuilding cost, but
due to unavailability of funding more people reluctant to retrofit their
houses. During the program implementation, several initiatives have been taken to promote seismic retrofitting and strengthened with the community engagement initiatives. All of these are to create retrofitting demand at community level.
Seismic retrofitting and disaster risk reduction
Photo: Retrofitting with conventional method
Seismic retrofitting is to modify the existing structures to
make them more resistant to the seismic activity due to the earthquakes. After
the retrofitting, the structure could be damaged by the earthquake at certain
elements such as beams but must not catastrophically collapse. Retrofitted house
might prevent sudden failure which might cause its dwellers get injured. Seismic
retrofitting can be done either in recovery or in preparedness setting. But to
carry it out under homeowners’ initiative on preparedness setting is bit
difficult compare on post-disaster recovery. During recovery process the house
owners have the urgency to repair and retrofit their houses. On the other hand,
without disaster occurrence homeowners tend to put retrofitting below other
priorities.
There are similarities whether it is in recovery context and
preparedness setting. Retrofitting is intended not to demolish the house but
to strengthen it. It is the cost, to begin with. Cost-benefit assessment is used to
evaluate the effectiveness of various seismic retrofit strategies to address
concerns about earthquake safety and damage to older concrete frame buildings.
When houses evaluated on the basis of repair costs only, the maximum cost of
retrofit measures that offer a positive rate of return is 10% to 30% of the
building replacement value.[i]
Secondly, retrofit need skilled masons and under experienced technical person
supervision. It is because seismic retrofitting need’s structure evaluation to
check its vulnerability, design and then the construction work itself.
Since the cost is less than to construct from foundation to
the roof, retrofitting can be implemented in every economic situation. During
economic slowdown, retrofitting provides important contribution to the local
economy. The construction work will provide job for builders and workers from
other related sectors. Even it is a small-scale activity compared to the common
construction work, the construction process needs inputs from other industries
and production factors. This could generate considerable employment through
multiplier effects.[ii]
But its impact on the economy still depends on the volume of the retrofitting
work within the area. The bigger the demand it will bring more resources and
increase in economic activities. Moreover, the retrofitting cost might even
less than 30%, if the activities reach economies of scale.
Naturally construction works always need time to reach the
pace and amount of work of economies of scale. Surely kickstart always not easy
and simple. It needs preparation such as training for builders, construction
material provision, structure assessment and lastly homeowner confidence on
retrofitting. Therefore, to ensure the retrofitting program can be implemented
those for aspects should be prepared. In this writing, as it will be focused on
the community engagement.
Challenges on proper construction and retrofitting
In every country the Government issued Building Codes that
the people need to follow to ensure that they can have robust and earthquake
resistant structure. The code also available for structural elements such as
beam, column and foundation. The code also expected to be a guidance for design
and prerequisite to get building permit. But the challenge is on the
compliance. In the developing world, the compliance mostly only happens at
multi story buildings not at one or two story landed houses. The situation
even more challenging in the rural since the monitoring for compliance and
enforcement is quite rare. In most countries, house builders or masons do not
think that they are responsible for the vulnerability or collapse of the houses
they constructed[iii].
Photo: Brick gabble wall without concrete frame
In rural area construction practices are far different from
the code. The builders are confident about the safety of the houses which they
constructed although most of builders do not know the building codes[iv].
For instance, in a village in in Sukabumi, West Java, Indonesia the houses have
no columns. The builders laid the brick at the stretcher face not at their bed.
Besides of the ignorance of the codes, people done this because they want to
save money by putting less brick. Another example is how the homeowners and
builders construct brick gable wall. Since concrete structure is being
considered costly, the builders constructed it without concrete frame which
make their houses are quite vulnerable when the earthquake occur. The risks are
when the earthquake occurs, the brick gable wall might fall off. Surely it can
endanger the house owner since it is catastrophic.
Ignorance of the Building Codes is the first barrier to have
safe structure. The next barrier is the economic cost of retrofitting. Currently,
retrofitting is at the supply driven rather than demand driven as homeowners are heavily dependent on grant or financial
incentives. homeowners are unwilling to invest in their house as the house is
not a source of income for them and seismic safety is not a priority for them.[v]
If the people are willing put themselves at risks by putting no
column at the wall it will be difficult to persuade them to retrofit their
house. Some people put the retrofitting at lower priorities then other needs,
even though they received the information on earthquake risks. Earthquake is
not always occurred regularly like flooding which has seasonal occurrence. People easily forgotten. Even
if people have sufficient money, they want to enlarge the houses or just put
new paint in their houses.
Another challenge on retrofitting is unavailability skilled
builders and proper construction material which need to be used in retrofitting.
This can be easily understood since retrofitting is not common in the area
therefore it is difficult to find builders which have retrofitting skills. Also,
if most of the houses in the area were built without following the Building Code,
then it is difficult to find construction material as directed in the code, for
instance on using steel deformed rebar. Steel deformed rebar is prerequisite for earthquake
resistance reinforced concrete structure. In those area, the demand for deformed
rebar is less than the smooth rebar, hence the deformed rebar become expensive.
Creating the demand for retrofitting
Provision of skilled builders and retrofitting material is directly
proportional to the demand for retrofitting. The more people want to retrofit their
houses the more builders come and work in the area. New builders will be introduced
to the retrofitting technique by the skilled builders, as they will work as an
intern. More construction material will be available due to the needs of ongoing
retrofitting work. Then how to increase the retrofitting demand?
Photo: Retrofitted house using Ferrocement technique which developed by Dr. Teddy Boen
The recent development, many retrofit strategies are
feasible and several traditional and innovative options are available to
engineers[vi].
There are research and studies on retrofitting which can be implemented on
using available material and with affordable price. For instance, ferrocement[vii]
technique which developed by Dr. Teddy Boen, can be implemented with simple
technique and at an affordable cost. And depends on the needs, homeowners also
have the option on choosing conventional method by adding seismic resistance attribute
to particular structural element.
Other than the engineering approaches is the encouragement with
social language using the positive messages, i.e. homeowners are crucial to be convinced
that the investment in safer housing will eventually prove to be worthwhile.[viii]
On the other hand from the negative messages, it is also important to increase
disaster imagination of the people to understand the importance of seismic
retrofit of weaker houses that is the main cause of casualty and to create some
social systems by which homeowners are encouraged to retrofit their own weaker
houses by themselves.[ix]
These initiatives should carried out by trained community volunteers.[x]
Other initiatives to create demand is through connecting the
people with the banking institution. Some of banks have financial loan for house
renovation but they do not have loan for retrofitting. The bank has been approached
and currently is calculating the potential market and benefit of the loan
program.
Currently Indonesian Red Cross is developing strategic level
collaboration with the Public Works and Housing, to re-shape the government
program. It is expected that the current house renovation program which funded
by government can be changed to house retrofitting. More retrofitted houses
also mean more training opportunity for the builders.
Photo: Training of community volunteers to equipped them on their role as Retrofitting Agents. Another campaign done by the trained community volunteers who are
using the retrofitted houses as retrofitting showcase. People invited to visit
the houses, discuss with the homeowners and trained community volunteers. This
campaign was launched to create bandwagon effect in the community. The Community Volunteers acted as Retrofitting Agent visited homeowners door-to-door sending the messages of retrofitting.
Still, more effort needs to be made. Supply chain is one
important area need to be developed. The need of affordable construction and
retrofitting material such as deformed bar, wire mesh, Polypropylene (PP) bands
or fiber-reinforced paint should be available in local shop. At the end it will
reduce the cost.
Collaboration with other humanitarian organization program,
such as livelihood and others, need to be developed. Improved quality
of living of the society will increase homeowners’ capacities and then at the
end they may retrofit their houses.
All of these should be seen as approaches which can strengthen
the community effort, since the retrofitting awareness should be a bottom-up
initiatives. Homeowners who eventually aware on earthquake risk reduction should be able to connect with available retrofitting resources. Then at the end the retrofitting
can be implemented and initiated by the community.
Arwin Soelaksono
[i] Liel,
Abbie & Deierlein, Gregory. (2013). Cost-Benefit Evaluation of Seismic
Risk Mitigation Alternatives for Older Concrete Frame Buildings. Earthquake
Spectra. 29. 1391-1411. 10.1193/030911EQS040M.
[ii] Wibowo,
M. Agung. The Contribution of The Construction Industry to the Economy of
Indonesia: A Systemic Approach (2009)
[iii] Okazaki,
K and T. Saito. Seismic Risk
Perception Concerning Non-engineered Houses (2012)
[vi] Zerbin,
Matteo . et. al. Sustainable retrofit design of RC frames evaluated for
different seismic demand (2015)
[viii]
Okazaki, Kenji et. al. Study on willingness of the residents in seismic
retrofitting of the house - comparison among Indonesia, Nepal, Pakistan,
Turkey, The Philippines, Fiji, and Japan
[ix] Sathiparan,
Navaratnarajah. Mesh type seismic retrofitting for masonry structures:
critical issues and possible strategies. European Journal of Environmental and
Civil Engineering. Volume 19, 2015
[x] In Indonesian Red Cross (PMI) program, supported by the American Red Cross and Build Change and funded by the USAID, the trained community volunteers (known as Community Based Action Team) acted
as Retrofitting Agents. They have been trained how to spot vulnerabilities,
provide retrofitting option and solution including calculating retrofitting
budget. On their role the Retrofitting Agents are equipped by Retrofitting
field guide the help them during house visits and encourage their neighbors to
retrofit their houses.
