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* Corresponding author: zaidir@eng.unand.ac.id
Repair and retrofitting of buildings post earthquake
Zaidir1,*
1Civil Engineering Department, Engineering Faculty, Andalas University, 25163, Padang, Indonesia
Abstract. This paper discusses the damage types, repair methods and retrofitting of buildings post an
earthquake. Data were taken by conducting surveys and assessment of buildings directly, both engineered
and non-engineered buildings affected by the West Sumatra earthquake in 2009. Some causes of damage,
among them is the detailing of reinforcement that do not follow the existing standard, soft-story effect,
foundation failure, low material quality and does not meet the requirements, design and implementation of
the construction do not follow the rules and technical provisions of the building earthquake resistant.
Improvement and buildings retrofitting can be done after the buildings damage types or its
components/parts and the quality of the building materials used were known. The structural analysis was
done in order to know the cause of the building elements damaged and if the results of analysis with the
latest regulations earthquake load, the building structures is able to withstand the earthquake loads and a
repair is not required, but if not, the retrofitting is required.
1 Introduction
Earthquake disasters could cause many buildings to be
damaged and may also collapsed. After the earthquake,
many of the damaged buildings are to be destroyed
based on the advice of experts, consultants or
stakeholders, while actually the buildings could still be
repaired and be retrofit so that the buildings can be
reused (Ismail et al, 2011, 2014). To destroy the
damaged buildings after an earthquake is an easy
decision, but not supported by adequate data. Until now,
Indonesia has not had a standard in damage assessment,
repair and retrofit the damaged building post earthquake.
The main advantages of repairs and retrofit the damaged
buildings after earthquake will be save time and money
(Ismail et al, 2011, 2014).
In general, civil engineering buildings could be
grouped into non-engineered building and engineered
building. Non engineered building is a simple building
such as a community house that is no structural
calculations while engineered building is a building that
is designed and done structure calculations by
consultants or structural experts (Boen, 2010). At West
Sumatra earthquake of 2009, a ten years ago, many
buildings were damaged, both non engineered building
and engineered building.
Damages caused an earthquake could be divided as
non-structural damages and structural damage. The
damages of non-structural is a damage that occurs in
non-structural parts of buildings such as wall plaster
cracks, brick walls cracked or broken, ceiling damaged
etc. While a structural damage is the damage that occurs
at elements of building structures, such as cracks in the
column, plates or beams, the crack of concrete covers of
beams/columns or rupture at the parts column head or
bottom (Boen, 2010)
Retrofitting of the post-earthquake building include
repairs and restoration or strengthening a damaged
buildings. Repair work is to restore the building
architecture, such as; repair and retrofit of wall cracks,
re-plaster, repair of power cables, water pipes, gas pipes,
sewer, doors, windows or replace the window/door glass,
etc. Restoration work is to improve the structural
element strengths and restore to the original strength,
such as; perform injection of cement grout or
epoxy/polyurethane material at small cracks that occur
on the wall, beam or column, increase the amount of
reinforcement on the beam or column that has a large
crack and then do injection of cement grout, adding and
repairing the reinforcement then cast/grout back.
The strengthening is in order to make buildings
stronger than the its original strengths, such as; eliminate
the sources of weakness or that can lead to the
concentration of stress in certain parts, among others: the
location of columns/walls that are not symmetrical, the
difference in the rigidity between the building floor,
excessive openings, added the capacity of buildings to
lateral forces, by adding shear walls, bracing, adding and
enlarging column dimensions, increasing the building's
ductility by repairing, use additional reinforcement
(shear, bending, axial or torque stress) on the necessary
parts, making the building in one unity to tying all the
elements structure to each other (Arya, 2013).
This paper discussed the cause of damages,
retrofitting methods and strengthening carried out on
number of buildings damaged after the West Sumatra
2009 earthquake.
E3S Web of Conferences 156, 05023 (2020)
4th ICEEDM 2019
https://doi.org/10.1051/e3sconf/202015605023
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative
Commons Attribution License 4.0
(http://creativecommons.org/licenses/by/4.0/).
2 Methodology
Data in this paper were taken directly after the
earthquake by the buildings assessment team of Andalas
University by conducting surveys and assessment on a
number of buildings affected by the earthquake in the
city of Padang.
Assessment were done to engineered building and
non-engineered building. The collected data includes the
type of damage of each building element, the quality of
the building material (concrete and steel reinforcement),
the configuration of buildings, buildings foundation and
the cause of damages. Repair and retrofitting of damaged
buildings carried out on structural elements as well as on
non-structural elements in some public buildings such as
schools and hotels.
3 Results and Discussion
3.1 Damage causes and types
From the survey and assessment that has been done in a
number of buildings damaged in the city of Padang, is
obtained some causes of damage or collapse that
occurred in engineered building are :
a. Reinforcement detailing does not follow the standard
include on the beam-column joints. Fig 1 and Fig 2
show the detailing do not meet the standards.
Fig. 1. Bad reinforcement detailing of beam-column joint
Fig 2. Reinforcement detailing do not meet a standards
b. Soft-story effects followed by the collapse of the
beam-column joint as shown in the following Fig 3.
Fig 3. Soft-story effect on buildings
d. Foundation failure, especially in the soil-structure
interaction, such as the liquifaction shown in Fig 4.
Fig 4. Foundation failure due to liquifaction effect.
d. The poor quality of materials and do not meet the
requirements, both strength and its quality, as shown
in Fig 5.
E3S Web of Conferences 156, 05023 (2020)
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Fig 5. Building collapsed due to material quality do not meet
the standards
e. Planning and implementation of construction do not
follow the rules and technical provisions of the
standard of building earthquake resistant.
On non-engineered buildings a lot of damage occurred
on buildings without reinforcement (unreinforced
masonry, URM). Some types of damage that occur in
general are as follows: a. Crack on the wall in the
corners of the openings, b. Diagonal crack on the wall, c.
Separation occurs on the walls, d. Wall bricks collapsed,
e. Beam-column joint failure, f. Building collapsed.
Fig 6, 7 and 8 show some types of collapse that occur in
non-engineered buildings.
Fig 6. Brick walls collapsed
Fig 7. Wall separation of URM
Fig 8. Some brick walls are collapsed
In general, the main cause of damage that occurred,
especially in the engineered building due to the West
Sumatera 2009 earthquake could be concluded as
follows:
a. Understanding and awareness of construction actors
(owners, contractors and consultants) regarding the
provisions of regulations/building standards of
resistance/safe earthquake are still low.
b. Implementation of regulations/standard earthquake of
low construction actors.
c. Supervision of the construction of the stakeholders,
especially for public buildings is still lacking.
d. Tendency is less concerned with structural needs
(safety) and more concerned with the needs of
aesthetic (architectural).
e. Especially for non-engineered buildings that are
severely damaged is a building that has no
reinforcement on its structural elements (unreinforced
masonry building, URM).
3.2 Post-earthquake building retrofitting and
repair methods
The steps of repair and retrofitting work in a damaged
building after the earthquake could be done as follows:
1. Conducting field survey to determine the type of
buildings damaged or components/parts of buildings
and the quality of the building materials used.
2. For engineered buildings carried out structure analysis
based on the latest earthquake standard in order to
know the cause of a damaged building elements,
whether due to shear force, compression, tensile,
bending, torque or other causes.
3. Once the type of damage can be determined, repair
and restoration of the components separately can be
done.
4. If the results of the analysis with the earthquake load
in accordance with the latest regulations, building
structures are able to withstand the earthquake loads
then the retrofitting is not required, but if not, then it
is necessary to repaired and do retrofitting.
3.2.1 Repair and retrofitting of elements structure
Some types of retrofitting work of structural and non-
structural elements conducted are as follows:
E3S Web of Conferences 156, 05023 (2020)
4th ICEEDM 2019
https://doi.org/10.1051/e3sconf/202015605023
3
Fig. 1 shows the repair process of column damaged at
the bottom. The damaged column at the bottom (1. a).
Installation of the temporary support (1.b), then done
concrete chipping (1.c) addition of longitudinal and
shear reinforcement (1.d). Then installation of form
work and concrete casting (1. e), and the final result on
(1. f)
(a) Damaged column (b) Temporary support
installation
(c) Concrete chipping
(d) Addition longitudinal and
shear reinforcement
(e) Installation of form work
and concrete casting
(f) After repaired and
retrofitting
(a) Damaged column at the
top, lack of reinforcement
(b)
Addition of longitudinal
and shear reinforcement
(c) Form work installation
and concrete casting
(d) After repair and
retrofitting
Fig. 10. Repair and retrofitting process of damaged column at the top.
Fig. 9. Repair and retrofitting process of damaged column at the bottom.
E3S Web of Conferences 156, 05023 (2020)
4th ICEEDM 2019
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The repair process and the retrofitting of the damaged
columns at the top were shown in Fig. 2. The damaged
column at the top with lack longitudinal and shear
reinforcement (2.a), addition of shear and longitudinal
reinforcement (2.b). installation of the form work and
concrete casting (2.c), and the final result as in (2. d).
Fig. 3 shows a repair process of the damaged beam as
follows. Repair and retrofitting were done by adding a
shear reinforcement on the beam, and done the concrete
grouting.
Fig. 11. Repair and retrofitting process of damaged beams
Non-engineered building repairs and retrofitting were
shown in Fig 9 below. The building without
reinforcement (Unreinforced Masonry, URM) was added
with the reinforcement of the tie beams, columns and
link beams. The brick wall were retrofitted with the wire
mesh.
Fig. 12. Repair and retrofitting of non-engineered building by
adding the reinforcement of tie beams, columns and link-beam
3.2.2 Repairs and retrofitting of non element
structures
Repairs and retrofitting in a non-engineered buildings
are shown as in Fig. 4 below. The wall that will be
strengthened was chipped in diagonally direction (4a),
then install the wire mesh material and do plaster back
(4b). For the new brick wall retrofitting can be done with
the installation the wire mesh diagonally (4c) or install
the wire mesh on the entire wall (4d), then do the plaster
work.
(a) plaster chipped (b) wire mesh installation
of brick wall
(c) wire mesh installation (d) wiremesh installation
diagonally on the entire brick wall
Fig. 13. Repairs and retrofitting process of brick
wall with wire mesh materials.
4. Conclusions
From the evaluation and discussion, it could be
concluded as follows:
1. Repair and retrofitting can be used to restore and
strengthen damaged buildings due to an earthquake.
2. Before the retrofitting, firstly do a numerical
simulation in order to know the capacity of the
building to an earthquake load based to the latest
standards.
3. The type of retrofitting performed to the structural
elements depends on the damage level of structure
itself.
4. The main advantages of the repair and retrofitting of
buildings damaged due to an earthquake could save a
cost and work implementation time compare to the
new building.
The author thanked the University of Andalas's civil
engineering department which has been support financially so
that this article can be published
E3S Web of Conferences 156, 05023 (2020)
4th ICEEDM 2019
https://doi.org/10.1051/e3sconf/202015605023
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