Preliminary study on the rapid assembly emergency shelter

Floods are the most common natural disaster that occurs in Malaysia, especially during the monsoon season. Emergency shelter is provided immediately to provide a safe and secure place for the victims to stay after a disaster. The typical emergency shelter provided by the government is an indoor emergency modular. However, the victims’ privacy and safety cannot be ensured, and feel uncomfortable. Hence, a better emergency shelter that is easy to assemble, dismantled, light, and strong should provide to the victims. The proposed conceptual design of a rapid assembly emergency shelter is a stackable shelter. The shelter can be stacked when the floor is separated from the shelter’s body and the beds are folded. This design allows many emergency shelters to be transported to the evacuation site in one trip. The material for the shelter’s body is natural fibre reinforced polymer composite. The natural fibre selected is jute, as the production of jute is high. The floor’s material is hollow composite wood decking, while the material for footings, bed, window, door and roof window is high-density polyethylene (HDPE). With the simple design of the shelter, the installation procedure also becomes very easy and can be installed by non-professional people.


Introduction
Natural disasters occur in every country. Although Malaysia is free from the typhoon and volcanic activities, Malaysia is still facing floods and haze. Over-exploitation of natural resources and unsustainable development are usually the leading causes of natural disasters. In Malaysia, floods are the primary disaster, especially during the monsoon season. Heavy rainfall, uncontrolled upstream development, lack of vegetation land and climate change will increase the seriousness of floods [1].
There are four phases of the disaster, which are mitigation, preparedness, response, and recovery. During the post-disaster, the response stage is crucial as response actions such as evacuation, rescuing, provide immediate assistance and emergency shelter, and prevent further damage are carried out immediately before, during and after a disaster happened. The response stage begins when the disaster occurs. Before the floods occur, a flood warning will be announced by the authorities to inform the maximum water level. Then, evacuation to a safer place is needed. Emergency measures before evacuation are carried out such as safeguarding valuable things and documents, switch off gas and electricity and so forth. After victims reach the emergency shelter, food, medicine, clothing are provided to the victims to maintain their lives and health [2].
There are three types of shelter for disaster relief which are emergency shelter, temporary shelter, and temporary housing. The victims would stay in the emergency shelter for a short period, and usually, the purpose is to seek protection. Then, temporary shelter is used for the short-term stay only. The period of stay should not be more than a few weeks. Next, temporary housing is a place where the victims can stay from six months until three years. The shelter is a prefabricated house. After finish rebuilding the house, victims can return to their permanent shelter. Victims can continue to live ordinary life [3].
This study will mainly focus on emergency shelters. An emergency shelter is a shelter that requires a roof and space for the victims to stay. Most of the emergency shelters are easily assembled, dismantled and light. Examples of emergency shelters are tents, public community buildings. Different types of rapid-assembly emergency shelters can cope with various conditions such as earthquakes, floods, hurricanes, and tornados.
An emergency shelter is different from a house. Shelters provide a safe and secure place for the victims to stay after a disaster happen. However, a home is a place to carry out household responsibilities and daily routine works. In short, an emergency shelter is an immediate shelter to provide protection, safety and temporary regular supplies to the victims [4].
A rapid-assembly emergency shelter is a type of shelter that can be set up in a short time when successfully transported to the site. In post-disaster, rapid-assembly emergency shelter is the only place that can protect the victims from the environment such as rain, wind, and sun. The preparation of emergency shelters needs to be fast to decrease the probability of loss of life. The most common type of rapid-assembly emergency shelter is a tent. A tent is easy to produce, assemble and the cost is cheap. In Sri Lanka, the most common type of emergency shelter is a tent. Sri Lanka manufactured many tents. Hence, tents are readily available and distribute to victims immediately. A tent is suitable for high terrain, but it cannot insulate the heat and cannot withstand extreme environments such as strong winds and draughts [5].
Moreover, the Turkish will provide tents to the victims. The tents are well-insulated and have bright colours which can reflect the heat and protect victims from the harsh environment. These tents are expensive and bulky. Therefore, it only manufactures in limited numbers and is not able to supply to other countries. Nevertheless, the fire issue is the main problem when using tents. Fire from heating stoves, kerosene lamps and smoke inhalation will easily be prone to fire [5].
When designing the rapid-assembly emergency shelter, few criteria need to be concerned such as the way to assemble a shelter, weatherproofing, ventilation, privacy, storage, and safety. Durability is essential to maintain the performance of the shelter from time to time. A high durability shelter can resist extreme conditions and tear or abrasion. The durability depends on the material used, structural integrity and maintenance [5]. In conclusion, the way to design a rapid-assembly emergency shelter and its usage are the critical basis. The most important criteria are the shelter needs to do quickly to provide a safe place for the victims. There are various types of emergency shelters available worldwide. Several researchers, such as [6][7][8][9][10][11][12][13][14][15], had designed various types of emergency shelters. The designed emergency shelters are used for different types of disasters. Table 1 shows the summary of emergency shelters.
The typical emergency shelter in Malaysia is an indoor emergency modular, and the shelters are placed at the school hall or community hall. This results in the victims' privacy and safety cannot be ensured and feel uncomfortable as they are too many people staying in the same place. Hence, the emergency shelter in Malaysia required more research and a better conceptual design is needed.

Conceptual design of the shelter
According to the United Nations High Commissioner for Refugees claimed that a good shelter should provide a healthy environment and ensure the safety and privacy of the victims. Moreover, the shelter should provide emotional security and psychological comfort to the victims. Hence, a few basic requirements of the emergency shelter should be achieved to produce a suitable emergency shelter. Firstly, the minimum total area of the shelter is 3.5 m 2 exclude cooking facilities, and the minimum height is 2 m. The shelters' elements must be strong enough to protect the victims. Besides, the materials for building the shelters should be as culturally and familiar as possible so that the victims can feel comfortable. The emergency shelter should be easy to assemble by non-professional people. Lastly, necessities such as blankets and mats must be provided [16]. In short, the emergency shelter should adapt to climate conditions and be durable. Furthermore, the design should be as simple as possible so that the refuges can assemble the emergency shelter faster and stay in a comfortable situation.
The proposed conceptual design of a rapid assembly emergency shelter is a stackable shelter that the shelters can stack on each other during transportation. The shelters are easy to transport and can be transported in a considerable amount to the affected area. The most advantage of the stackable shelter is the shelter can assemble within five minutes, providing a safe and comfortable place for the victims rapidly.
The conceptual design of the shelter in this study is made up of four wall panels, one roof, one door, two windows, one air vent, a transparent roof window and a solar cell as shown in Fig. 1

Body of the shelter
The dimension of the shelter's body is 3 m in length × 2 m in width as shown in Fig. 1. To connect the shelter's body with the floor, holes with 10 mm diameter are provided. The shelter body, such as wall panels and roof panels, should be strong enough to resist the wind impacts and rainfall impacts as Malaysia mostly suffering from the monsoon season. Hence, the suggested material is a natural fibre reinforced polymer composite (NFPC). The chosen natural fibre is jute as jute's production is high, and it can increase the tensile strength, bending strength, impact strength and provide low density for NFPC. Fibres are divided into two categories, which are natural fibre and synthetic fibre. The fibre chosen for wall and roof panels is natural fibre. Examples of natural fibres are jute, oil palm, sisal and flax. Although synthetic fibre has good mechanical properties such as high strength, durability, and moisture resistance, it is not environmental-friendly and cannot be biodegradable. Natural fibres are low density, have good thermal properties, have low abrasion resistance, and most importantly, can be recycled [17].
NFPC is a composite material that the polymer matrix is embedded with the natural fibres. It is light in weight, low cost has good mechanical properties such as high tensile modulus and flexural modulus, high stiffness and is biodegradable. The physical and mechanical properties of NFPC can be enhanced through a chemical treatment. For example, when polylactic acid (PLA) is added to jute fibres, the tensile strength is improved by 75.8%. Moreover, to enhance the fire resistance of NFPC, magnesium hydroxide can be applied at the surface of the shelter and provide better thermal stability. The fire coating will expand upon heating and form a charred surface, protecting the internal components [18].
However, NFPC is weak in water-resistant. When there is water absorption, the bonding between fibre and polymer will become weak. Eventually, the strength will decrease and might cause deflection on the nearby structures. Hence, a coupling agent, maleic anhydride polyethene can reduce water absorption by NFPC [18]. Thus, maleic anhydride polyethene will be added to the NFPC of the shelter's body to increase water resistance and reduce moisture attacks.

Roof
The roof is made up of the same material as the shelter's body, a natural fibre reinforced polymer composite. It inclines 3º to prevent the rainwater accumulate on the rooftop.
According to Fig.1(d), there is a window to allow sunlight to penetrate the shelter. Thus, it can bright out the internal of the shelter during the daytime. The window is made of transparent high-density polyethylene (HDPE). HDPE has a high melting point. It will remain rigid when the melting point is not yet reached. HDPE also has a high resistance to corrosion, mould, and rotting. Hence, it is suitable to be used in outdoor conditions with high moisture. Furthermore, it has a low density with high strength. Thus, it can withstand a strong wind impact when there is heavy rain. Lastly, it is easy to recycle and reduce plastic waste; eventually, sustainability is achieved.

Flooring system
The dimension of the slab is 3 m in length × 2 m in width × 0.03 m in thickness. The holes with 10 mm diameter are provided, as shown in Fig. 2(a) so that the shelter's body is connected tightly to the slab. The chosen bolt to attach the shelter and the floor is a hexagon bolt with 10mm diameter and 60mm length. The chosen nut is Grade 12 with 10mm to lock the bolt tightly, while the washer is Grade 316 with 10mm.
Furthermore, according to Fig. 2(b), there will be reinforcement at the bottom of the slab to resist the floor's deflection. The slab is supported by a steel frame which is composed of long beams and short beams. There are four holes to insert the footings so that the shelter will not directly contact the ground. For the steel frame, the chosen cold-formed steel (CFS) Grade 350 square hollow steel section used is 60 mm in height × 60 mm in width × 4 mm in thickness. The most critical member, which is in 3 m length beam, using 80 mm in height × 80 mm in width × 4 mm in thickness CFS square hollow section. The size of the bracing used is 150 mm in height × 25 mm in width.
Moreover, the steel frames are bolted together with the three-sided angle corners to support the beams further, as shown in Fig. 2(c). On the other hand, the steel beams in the middle part are connected to the steel frame using an endplate, as shown in Fig. 2(d). The dimension proposed for the endplate with Grade 275 is 100 mm in length × 50 mm in height × 10 mm in thickness.
Hollow composite wood decking is a suitable material for the flooring system. Composite wood is a combination of natural wood fibres and synthetic materials such as recycled plastic. However, hollow composite wood decking does not have strong waterresistant when exposed to heavy moisture. The board can be surrounded by full caping with a waterproof material layer to overcome this problem. It can help to protect the core and form a non-slip surface. Unfortunately, capping will not bond to the core of the board and cause water intrusion; hence, the co-extruded caping is extruded with the boards when it leaves the mould to ensure the decking is waterproof for a long time. The core and the capping will form as a single unit also. Furthermore, there will be no screw on the board to ensure adequate moisture resistance. Hidden fasteners should be used to create a smooth surface [19].

Interior of the emergency shelter
There are four beds and one air vent provided in the shelter, as shown in Fig. 3(a). The dimension of the upper bed is 0.60 m in width × 1.75 m in length × 0.05 m in thickness, while the bottom bed is 0.50 m in width × 1.75 m in length × 0.05 m in thickness. Each bed is supported by two foldable arms that are connected to support the beds. The beds can be folded up into a vertical position to align with the support arms so that the shelter has enough place to allow another shelter to stack on it. Furthermore, the air vent is provided to allow good ventilation so that the victims will feel comfortable with the temperature inside the shelter. According to Fig. 3(b), both the upper beds and bottom beds are being supported. Two steel studs support the bottom bed, while the upper beds are supported by the steel ladder so that people can climb onto the bed and prevent the bed from bending. Both the supports and ladders can be folded to save more places when the shelters are stacked on each other.

Footing
A footing is a vital component for a shelter as it can make sure the shelter is above the ground and prevent the water flow into the shelter. As shown in Fig. 4(a), the dimension of the footing is 0.6 m in length × 0.5 m in width × 0.4 m in height. The footings will be inserted into the holes under the slab, as shown in Fig. 4(b). The holes have a diameter of 400 mm and deep 20 mm.
The footing proposes to be made of high-density polyethylene (HDPE). HDPE has a high strength which can replace heavier materials such as steel and concrete. Furthermore, the footings are in a hollow structure so that when there is rain, the water can flow into the footings to provide ballast and keep the shelter stand firmly on the ground.

Shelter installation procedure
When the shelter reaches the evacuation site, it is needed to be built in a short time. Hence, a simple and easy way to assemble the shelter is necessary so that the victims can have a safer place to stay. The first step is to take out the shelter from the stacked shelters. It can be done either by manpower or by using a mobile crane if the stacked shelters are too high. Then, insert the footings into the holes of the floor to ease the work. If the footings install at the last step, it will become a difficult task. After that, the shelter is attached to the floor using bolts, washers, and nuts to form a complete shelter. When attaching the shelter's body to the floor, the holes of the shelter's body and the floor must match correctly so that the shelter's body and floor are joined tightly. After the installation is completed, the users can go into the shelter and flatten the foldable bed. The steel and ladder must be unfolded and During installation and after installation of the shelter, few precautions need to take: 1. During assembling, the nuts must screw the bolts tightly so that the shelter's body will not separate from the floor. 2. During rain, it is encouraged to install the footing so that water will not flow into the shelter, provide ballast, and let the shelter stand firmly on the ground.

Conclusion
In summary, the proposed conceptual design of a rapid assembly emergency shelter is designed as a stackable shelter. This shelter is made up of a shelter's body, roof, floor, four footings, door, window, roof window and four beds. The materials chosen for each element are based on sustainability, durability, and weight. The material for the shelter's body is a natural fibre reinforced polymer composite. The natural fibre selected is jute, as the production of jute is high. The floor's material is hollow composite wood decking, while the material for the rest elements is high-density polyethylene (HDPE). All of the materials fulfilled the requirements, which are sustainable, durable and lightweight. The shelter's floor can be separated from the shelter's body, and the beds are foldable so that there is enough space for stacking another shelter. This can help transport many shelters to the evacuation site and protect the victims immediately. With the simple design of the shelter, the installation procedures have become very simple also. The floor is joined with the shelter's body by using bolts, nuts, and washers. It can be installed by nonprofessional people.