Published at : 29 Apr 2018
Volume : IJtech
Vol 9, No 3 (2018)
DOI : https://doi.org/10.14716/ijtech.v9i3.463
Cindy Novaria Nada Karina | Department of Civil and Environmental Engineering, Faculty of Engineering, ehime University |
Ali Awaludin | - Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada - |
Bambang Suhendro | Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada |
Pang-jo Chun | Department of Civil and Environmental Engineering, Faculty of Engineering, Ehime University |
This study aims to analyze the collapse mechanism
of an Ammu Hawutraditional Indonesian house, which has palm wood (Borassus flabellifer) as its main material, by
using Wallstat program and extended
distinct element method. Wallstat is a collapse analysis program used to
determine a building’s damage status and
likelihood of collapseduring an earthquake. A total of 10 models were generated for numerical
simulation. Among them, 1 represented the original
structure, 4 were bracing reinforced models, and 5 were shear-wall reinforced
models. These models were observed under the conditions of the ElCentro (1940) and Kobe (1995) earthquakes. Results showed that the models reinforced with diagonal bracings used at the first story of the Ammu Hawu
house were significantly more effective in collapse prevention than the shear wall reinforcement at the second story.
Ammu Hawu traditional house; Bracings; Extended distinct element method; Shear walls; Wallstat program
Kinasih et al. (2014) found that
2,081 earthquakes occurred in Indonesia’s Lesser Sunda Islands (LSI) or Nusa
Tenggara region at coordinates 9°S and 120°E
during the 1900 to 2014 period. Among
these earthquakes, 1,709 had a 4–4.9 magnitude, 336 had a 5–5.9 magnitude, and
36 had a 6–8 magnitude. An earthquake visualization of the LSI region is
presented in Figure 1.
In general, factors that influence the failure of
traditional Indonesian houses due to earthquakes include the following: proximity to the epicenter,
local geological formation, high population density, and imperfect construction
(Idham, 2010). Traditional timber houses were not developed with structural
engineering considerations, but they can withstand earthquakes without damage
to their structural components; one example was the OmoHadatraditional house in
North Sumatra province, which survived the 7.7-magnitude Nias earthquake (USGS,
2009). These facts show that traditional houses that use timber materials as
their main structural components are able to satisfy earthquake-resistant
requirements (Awaludin, 2010 & Awaludin, 2012).
Although many timber structures have survived earthquakes, some of them have collapsed probably due to the failure of connections. As lateral movement effects during earthquakes are resisted by the stiffness of connections, the structure would collapse if these connections are not strong enough (Triyadi & Harapan, 2009). Moreover, earthquakes areunpredictable and unpreventable natural phenomena.
At the first stage, previous related works were reviewed to understand the
general structural behavior of traditional timber houses. The literature review
was followed by identifying the Ammu Hawu house as the research object in terms
of its geometry, history of collapse behavior under earthquakes, and overall
structural components. From this step, the position of the vertical shear wall and additional
timber shear walls can be determined by
using Cashew program, version 1.0. Then, 3D models of the house were generated
using Wallstat program, version 1.09. All
elements, including frames,
walls, and weight of the overall structure, were
simulated in the Wallstat program. After the 3D models
were developed, partial experimental
Based on the
output data from Wallstat, model 0 completely collapsed at 18 s,
as shown in Figure8. As illustrated in Figure9, the
deformation of point A drastically moved along the time duration. The base
shear force and internal force reached their maximum point at a period between
9 and 12 s, which is close to the collapse time of
the entire structure. The results showed that maximum internal and base shear
forces occurred at the same time when the structure was
about to collapse completely.
In this study, 10
models, including an original model and models with braces and shear walls,
were analyzed under the El
Centro (1940) and Kobe (1995) earthquake conditions. The analysis considered the
effects of the earthquakes on collapse time, base shear force values, internal
force values, and cross-section controls. Table 7
shows the collapse time of each model under
the two earthquakes. The results indicate that, in terms of collapse time, the collapse mechanism of the models reinforced with braces
provide a better outcome than that of the models reinforced by vertical shear
walls.
In
this study, 10 structural models numbered from 0 to 9 were generated in the
Wallstat program. Model 0 showed the original structure without any
reinforcement. Models 1 to 5 were equipped with vertical shear walls, and
models 6 to 9 had diagonal bracings. Each reinforced model had a different
bracing or shear wall configuration. These models were observed under the
conditions of the El Centro (1940) and Kobe (1995) earthquakes. The results
were then analyzed considering the earthquake effects on collapse time, base
shear-force values, internal force values, and cross-section controls. The
results indicated that generally, the models with bracing reinforcement
exhibited better results than those with vertical shear walls. Thus, these
research findings can be used as a reference to provide ideas in strengthening
traditional heritage houses so that they can withstand future earthquakes.
The authors would like to
thank I Ketut Suwantara research team PTPT of Denpasar for supporting this
research project by providing required data and partial experimental results on
the Ammu Hawu house in NTT province.
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