Low Technology Anti-Seismic System Application in Post Disaster Housing Reconstruction Project Hafiz AMIRROL (25209022) Department of Architecture Institut Teknologi Bandung, Indonesia Abstract In the last decade, the world has witnessed a multitude of earthquakes ranging from the great tsunami of 2004 to the recent earthquake in Chile. These series of unfortunate events had caused millions to lose their homes, and even worst, thousands were killed and injured. Most of these cases were caused by collapsed building structures that failed to resist the magnitude of the earthquakes. Since the recent series of earthquakes took place in developing countries that cannot afford expensive, high technology anti-seismic building system, this paper will discuss the many possibilities to have safe houses that can resist the force of the earthquake by the implementation of low-technology anti-seismic system to their structural components and other parts of the house. The concept of cheap, buildable and fast construction system for reconstruction and rebuilding projects is most crucial in order to response the contextual demand of the areas involved. The paper will also address the challenges and opportunities for improved building concepts and system that may contribute to the response and recovery efforts in enhancing safer house construction for post disaster housing reconstruction project. It is hoped that the paper could excite the dissemination and exchange of expertise, experience and information among the allied built environment professions. Keywords: low technology anti-seismic system; disaster area; core house; rebuilding and reconstruction

Introduction

Most earthquakes are causally related to compressional or tensional stresses built

up at the margins of the huge moving lithospheric plates that make up the earth's

surface. The immediate cause of most shallow earthquakes is the sudden release of

stress along a fault, or fracture in the earth's crust, resulting in movement of the

opposing blocks of rock passing one another. These movements cause vibrations to

pass through and around the earth in waveform, just as ripples are generated when

a pebble is dropped into water. Volcanic eruptions, rock falls, landslides, and

explosions can also cause a quake, but most of these are only of local extent.

Shock waves from a powerful earthquake can trigger smaller earthquakes in a

distant location hundreds of miles away if the geologic conditions are favorable.

Earthquakes are among the most common and widespread of potential problems

that architects and builders must plan for. Earthquakes can cause many different

types of damage, and all must be taken into consideration. The most common type

of damage normally happened during the event of earthquake is surface rupture

(Hadi, 2006). An earthquake occurs when the earth at a fault line shifts in reaction

to deep underground pressures that build up as the tectonic plates grind up against

each other. When the pressure is released through an earthquake, the land on one

or both sides of the fault line moves a little or a lot. Building damages caused by

surface rupture and earth movements will be the main topic of interest to be

discussed in this paper.

Problem Statement: Earthquake-related Damages in Household Buildings

This paper will discuss in particular the problems facing poorly built houses that

were hit and damaged by earthquake. These earthquake-related damages in

household building were mostly caused by:

1. Badly built structures and housing components (i.e. foundations, columns,

beams, roof, wall, openings, etc.)

2. Lack of basic strengthening components for house structure (i.e. lintels,

stiffener, bracings, etc.)

3. Poor construction practices

4. Community’s lack of understanding on the importance of safe building and

good construction practice.

The main problem with rebuilding and reconstruction projects after a disaster lay

first in the scale of the destruction of buildings and infrastructures and, to a lesser

extent, in the poverty of those who lived with them. Taking the 2004 Indian Ocean

Tsunami, in the three worst hit countries – Indonesia, India and Sri Lanka, the

majority of people who suffered lived on the margins, on the edge both of the sea

and of society. Houses were often fragile and so the violence of the waves

rendered extraordinary numbers of people homeless. In Aceh, for instance, no

houses at all were left standing, over many acres of land, and large amounts of land

were permanently lost (Figure 1). Along the coasts of Southern India and Sri

Lanka, virtually all homes were destroyed in a belt stretching up to half kilometers

inland, for hundreds of miles. In Aceh alone, almost 700,000 people have been

made homeless. In addition to these shelter problems, clean water, sanitation and

hygiene issues are at the poorest level, thus contributing to the spread of diseases

(Kuntoro, 2005). With most of medical facilities such as community clinics and

hospitals were seriously affected, these problems have worsen the living standards

of the disaster victims.

Figure 1: Destroyed houses due to earthquake

In lieu of human losses in recent earthquakes and tsunamis, not much research and

development were conducted on seismic resistance of low-cost masonry and timber

buildings. Extensive amount of earthquake related research and development has

been carried out in research centers and universities of the developed and

developing countries but mainly deal with expensive modern buildings (Goodman

and Tabujara, 1979). It is the interest of this paper to share the author’s experience

in initiating, developing, implementing and completing a humble humanitarian

housing reconstruction project that responded to the 2004 Indian Ocean Tsunami

in Aceh, Indonesia. It will particularly discuss the subject on the importance and

techniques in constructing safe houses within a cheap and low- technology, simple

anti-seismic system. The case study will be the construction of 300 units of Core

Houses (Figure 2), constructed at Desa Weu Raya, Lhoknga, Aceh. The author was

the design and project architect, and worked under the banner of MERCY

Malaysia, a Malaysian-based non-profit organization that helps globally in the

name of humanitarian.

Figure 2: Core House design proposal

Anti Seismic Technology in Housing Construction

Due to economic and contextual constraints in post-tsunami Aceh, only masonry

and timber houses are the best choice for MERCY Malaysia to construct for the

internally displaced person (IDPs). This type of construction cannot be replaced

quickly and easily with modern earthquake resistant construction systems due to

the large dependence on low technology construction system, availability of

materials, and the ability of local workforce. Instead of relying on technological

approach for rapid and efficient construction, we decided to build simple houses

with conventional techniques of construction (Figure 3). This decision was driven

by the fact that the local community was becoming more associated to the project

and is seeing a potential of employment from the project (Amirrol and Samah,

2006). Communities were slowly being absorbed to contribute to the project by

understanding their capabilities to work. By assimilating the community into the

project, problems relating to understanding the purpose of the new design, which

are quite alien for them were successfully stripped away.

Collaborations between architects, engineers, contractors, experts, humanitarian

workers and local communities have resulted in an idea of tolerance that reduces

the risk of construction failure during earthquakes. Without overestimating the

omnipotence of new construction method and technology, architects should remain

committed to utilizing the progressive potentials of surrounding resources.

Shortages of materials, machineries, skilled workers and budget have driven the

architect to undertake creative solution. Architects are inherently charged with the

mission of creating works that contributes in the enhancement of the quality of life

of victims. In our process of reconstructing the new houses for the survivors of the

earthquake, we believe that technology must be manageable by locals for their

benefit. The use of technology and techniques should always be constructive to

civilization.

Figure 3: Structural and construction system

Discussion

Unreinforced masonry and timber structures generally have a brittle lateral-load-

resisting system. These types of buildings have a very poor seismic performance

(Razani, 1979). Total or partial collapse of these structures has been one of the

main causes of the loss of life during past earthquakes. Some of the important

causes of the failure of the walls and the subsequent collapse of roofs of this type

of structure are as follows:

1. The durability and the poor strength of materials (earth/clay) used in the

construction of adobe buildings.

2. The inferior quality of the mortar used in the construction of brick, concrete

block or masonry buildings, and the poor quality of the bricks and concrete

blocks.

3. Lack of sufficiently strong connection between the various elements of the

structure, such as between walls, partitions and roof. In addition, the

brittleness and low strength of the individual elements especially the walls.

Often, these structures do not behave as a rigid frame. Under moderate shaking,

various elements become disconnected from each other and gradually causing

the failure of the whole system.

4. The collapse of the unreinforced load-bearing walls, partitions and spandrels

over the openings due to the effects of shear-compression and shear-tension.

The failure modes by these effects are very brittle and highly strength

degrading. Therefore, under intense tremor, the wall elements crack and

subsequently disintegrate the load-bearing walls and partitions destroying the

lateral strength and rigidity of the structure and also the vertical-load carrying

capacity of the walls resulting in the collapse of roofs and supporting

structures.

5. Disintegration of the heavy, brittle, non-monolithic and non-rigid timbered

roofs or roofs made of unbraced trusses.

In reference to the proposed earthquake protection criteria for the Core Houses,

the primary goal is to prevent structural collapse during major earthquakes. From

our research and experiments through earthquake simulations, a structure become

less susceptible to collapse under strong earthquake if:

1. The roof and floor of the building remain monolithic with sufficient in-plane

rigidity during and after earthquakes.

2. The vertical load-carrying system of the structure can survive the earthquake

without its function impaired.

3. The lateral load-resisting system of that structure during the main earthquake

and succeeding after shocks can retain enough residual capacity to resist safely

the lateral forces due to lateral instability, wind load and future earthquake

lateral loads.

Figure 4: Roof bracing for rigidity

An alternative means in preventing the collapse of the roof and other structure of

houses is to use the techniques, which MERCY Malaysia developed in

collaboration with other experts. The construction technique incorporates a simple

braced skeleton system within the house design that can prevent structure failure

and collapse during an earthquake. The function of this skeleton is to tie together

various parts of the building. The main design components of this system are:

1. A horizontal in-plane umbrella-shaped bracing system (Figure 4) to tie together

the roof beams so that a monolithic roof with sufficient rigidity is obtained.

2. An auxiliary system of timber or reinforced concrete columns embedded within

the masonry walls so that in case of destruction of the walls, the ductile

columns can support the vertical loading.

3. These columns are braced together laterally by means of a vertical system of

diagonal bracing in such a way that the lateral instability and subsequent

collapse of the structure during earthquake is prevented.

Although possessing unique structural characteristics for better seismic resistance

behavior, the whole process of construction methods adopted conventional

building techniques which the community and local builders are familiar with

(Amirrol and Zubir, 2007). Collaboration with local engineers and experts, such as

from local universities also helped, not only for the contextualized design of the

project but to socialize the community with an ongoing educative program

Figure 5: Shake table demonstration

Conclusion

The development of anti-seismic construction methods and techniques does not

only stop after the technical parts are resolved. Educative explanations need to be

channeled down to the local community for them to absorb the new technology

with confidence. These can be carried out with workshops, simulations,

presentations and continuous discussion with communities and authorities (Figure

5). During these stages, we progressively learn to understand the contextual

elements of the area (soil, climate, resources availability, etc.). It is also as

important to understand the construction techniques practiced by local builders in

Aceh in order for us to introduce them with alternative and better techniques. As

architecture is absorbed into the knowledge industry, and the role of the architect

has shifted from building to organizing social relations, MERCY Malaysia feels

that in any future interventions of the public realms, a better inter-relation between

the architects and the end users must be established in order to generate successful

aid programs.

Figure 6: Construction strategies and technical details

In building houses for a community that live with risks, all plans that have been

developed need to be properly studied, discussed, and put on test (Figure 6). From

our experience of designing, constructing and completing these Core Houses (Figure

7), it is proven possible to have cheap, efficient and decent houses that can resist

earthquake forces and prevent it from being damaged or destroyed. Through the

process of developing the idea of having a low- technology anti seismic system for

houses to be reconstructed after the event of disaster, we learnt that by

understanding the readily available resources (materials and construction workers),

it is the best practice to further apply these ideas when they are needed in the

future. However, the tested idea must be well documented and further improvise,

and to be spread to a wider audience of humanitarian workers, experts in the built

environment, and the civil society.

Figure 7: The completed Core House References

Hadi, M. (2006) Case Study of Indonesia on Research and Development (Research Center for Human Settlements, Research and Development Agency, Ministry of Public Works, Jakarta) Kuntoro, M. (2005) BRR NAD-Nias: One Year After the Tsunami, BRR First Year Report (BRR NAD-Nias, Jakarta) Goodman, L.J. & Tabujara, E.G. (1979) Low-Cost Housing Technology: an East-West Perspective (Pergamon Press, New York) Amirrol, H. & Samah, N.A. (2006) Civil Society Role in Disaster, Disaster Risk Reduction – Learning from the Tsunami Experience Training Workshop (MERCY Malaysia, Kuala Lumpur) Razani, R. (1979) Criteria for Seismic Design of Low Cost Housing (Pergamon Press, New York) Amirrol, H. & Zubir, S.S. (2007) MERCY Malaysia’s Experience in Recent Response and Rebuilding of Disaster Areas (WIT Press, Southampton)