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HWY Engineering Service Pte Ltd, has been tasked by the Client, herein referred as H.W.T.G Development, to commissioned a new office development next to its existing stone building. Located in the city centre, this new building is to be connected to the existing building by an atrium with new basement carpark facilities in which the existing building is lacking.
HWY is called for the design proposal for the new building and atrium. The Client is looking for a high quality world class architecture, however, with a limited budget.
The clients are also concern with the environment factors and are keen to minimise waste of all forms during and after the construction of the project. Hence, careful thought of the materials used should be taken into consideration in which, the Client is also looking at the "Whole Life Costing" of the building.
2.0 ACCESS & ESCAPE
In order to determine the access and escape route during an emergency, the occupancy of the building have to be established.
2.1 Occupancy ratings
Based on the architectural plan that can be seen in Appendix 1, the occupancy ratings are as follows:
Occupancy load calculation for Atrium:
Area of floor per person (m2/Person)
No of persons
Cafeteria Preparation and Counter Area
Cafeteria Seating Area
Proposal: New Building
Occupancy load calculation for 1st Storey, 2nd Storey, 3rd Storey each:
Area of floor per person (m2/Person)
No of persons
Facilities Manager Office
Female Changing Room & WC
Male Changing Room & WC
Main Corridor & Lift Lobby
2.2 Evacuation and Escape Route
In the event of a fire outbreak, a building means of egress is the most important means of escape which is provided by 2 strategically located fire escape staircases.
The 2 fire escape staircases shall be fitted with a door with a fire resistance of at least half an hour, fitted with a self-closing device that runs automatically and doors which are made of single leaf door and shall be of the appropriate fire resistance as required by the code and regulation.
Direction of the opening of the exit door is according to the exit travel and the fire escape staircase shall lead to ground level outside of the building. Personnel shall not have to pass through other rooms to voyage to the fire exit. Hence, the access to the fire exit is by means of the main corridor. As per FSB Chapter 2.2.7 (pg42), the requirement for the clear width of the exit door of 0.85m wide shall be met and dead end within corridor shall not exceed the requirement of 15/20m. The only dead end located within the corridor is only at 6m which satisfied the regulation.
Appropriate signage outside and within the fire escape staircase shall be prominently placed to facilitate in directing occupants out of the building in case of an emergency. Signage shall also be strategically located and visible to occupants going up and down the fire escape staircase.
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Fire Escape Route
2.3 Fire Fighting Measures
Fire is a combustion process involving chemical reactions between 3 elements which are fuel, oxygen and heat. This reaction will take place when the three elements are in abundance.
2.3.1 Classes of Fire
Class A - Fires involving ordinary combustible materials such as wood, cloth, paper, rubber and many plastics
Class B - Fires involving flammable combustible liquids, greases and gases
Class C - Fires involving energies electrical equipment
Class D - Fires involving combustibles metals, such as magnesium, sodium and potassium.
Hence it is important to identify the classes of fire that could happen, so as to provide the appropriate firefighting equipment.
2.3.2 Fire Protection Facilities
Based on the stipulated Fire Fighting Regulation, the proposed facilities needed for the new building are as follows:
Smoke Detection Systems: Widely recognized to detect smoke and send warning to all relevant parties involved and to investigate.
Fire alarms / Break Glass system: A device that is designed to inform occupiers and employees in the building that an emergency exists. It includes audible alarms, which primary purpose is to give an early warning for warning and evacuation.
Fire Hose Reels: To provide a reasonably accessible and controlled supply of water to combat a potential fire risk strategically located
Fire Extinguishers: An active fire protection device used to extinguish the incipient fire. Most common type which will be used is the ABC dry chemical type. This type can be used for Class A, B and C types of fires and shall be strategically located
2.4 Accessibility for Disable Person
Design proposals for new buildings must take into consideration the accessibility of the disabled sand adequate planning and design to ensure proper emergency escape.
All new buildings should have one entrance for all people, which do not present a barrier for the disabled to use unaided. The subsequent pathway after the entrance shall be of at least 1200mm for at least a wheelchair user and a person to walk. The pathway should be free of protruding materials as these would further impair the sightless. (Building Construction Authority,2007)
Service counters should adopt a single lower height counter at a max height of 800mm. A kneehole space can also be designed to allow a wheelchair user to pull up to the counter. (Building Construction Authority,2007)
Sanitary provisions must be made available to the disabled at all floors, one for the male and female. The washroom must be adequately spacious where the opposite walls to be not less than 1750mm, to accommodate the wheelchair user. Washrooms have been designed and made available at every floor, as per required by the Accessibility Code. A water closet has been designed in every male and female washroom. In the event of an emergency, a call bell has to be provided in the washroom for the disabled. Help can be rendered to those in need. (Building Construction Authority,2007)
Access to the upper and basement of the building, is through the lift. The lift lobby has been designed to permit a wheelchair use to move clear of lift allowing another wheelchair use to pass. The lift is designed specifically to accommodate wheelchair users without any hindrance. Call buttons located at the lobby has to be free from obstruction. This is to prevent overreaching to the call button. The call button has to be at the height of 900mm to 1200mm. (Building Construction Authority,2007)
3.0 STRUCTURAL DESIGN
Structure as define in a building is the main form of system that holds the building in place to maintain its shape and position and resisting widely changing physical forces. (Iver Wahl,2007,p.3) The structure can take on many types of forms and shape and can be constructed using many kinds of materials.
As mentioned by Derek O. & Roger.G,2002,pg.28-34, there are 4 basic kind of structure form which are:
Continuous Structure - Continuous supporting walls which transfer the combined loads and forces mainly by direct compression
Frame Structure - Framework of timber, steel, reinforced concrete consisting of a regular horizontal beams and vertical columns
Panel Structure - Load-bearing panel which carry load without the use of columns and beams
Membrane Structure - Non-structural membranes forming walls and roof supported by tension and or compression members
Derek O. & Roger.G,2002,pg.2 defines the requirements of a building as:
Typically, there are many types of materials used for construction of buildings. Some of these examples are ice, wood, clay, concrete, steel, stone, straws.
However, to construction a building of 3 storeys high and a basement carpark, the choices of materials are being narrowed down to reinforced concrete and or steel. These 2 materials choices are considered due to its properties for enabling to construct a building of our nature. An analysis of the 2 materials is given below:
3.1 Reinforced Concrete
Concrete is a mixture of water, sand, Portland cement and aggregates which combines to form a material that is good in compressive strength but low in tensile strength and ductility. With inclusion of steel reinforcement into the composite materials, reinforced concrete is achieved in which it is both good in compression and tensile capacity. Thus, the construction of strong and high building is possible and straightforward.
And due to its liquid state before the concrete is cured, the ability to mould the concrete into various shapes and sizes is effortless with the uses of suitable formworks.
Concrete also performs well in resisting fire as it has a non-combustible material and has a slow heat transfer rate. However, prolong heat and extreme temperature can cause concrete to become brittle and crack.
3.2 Steel Structures
Steel is an alloy of iron and carbon which gives it his high tensile strength, ductility and hardness properties. Steel used in the construction sectors are in the form of an I-beam, steel plates, hollow sections, C-channels and angle bars. By using these structural steel members, building can be form and constructed to very strong and high buildings.
However, steel loses its properties when heated to sufficient temperature and thus, loses its abilities to support its intended load. In order to enhance its fire resistance properties, normally steel structural members are encased in concrete or fire retardants.
Steel, unlike concrete which requires sufficient time to gain its strength, can be used to construct a building in a relatively shorter period of time as compared to using concrete. However, due to this property, the costs of using steels are generally higher than of concrete.
3.3 Environmental Consideration
Steel are traditional, consider to be more environmental friendly as compare to concrete due to its ability to be recycle, (Steel can be re-melted and again forge into useable product).
However, "Green concrete" has emerged in the modern world as technology advances. "Green concrete" are made by using waste products generated by other industries and in the midst of using the waste products, water can also be saved in the manufacturing of concrete as the process suggest. (Holcim, 2012)
The new building shall comprising of a frame structure consist of column, beams and slab in a 2 way span system using reinforced concrete has been chosen for the project. As the main form of the building is in a square grid system, the 2 way span system is best to utilized to full potential load bearing capacity of the frame structure.
Heavy loads can be support using the 2 way columns, beams and slab span system and the span between each column can be maximize. And by using reinforced concrete, the frame structures are capable of heavy loads and enhance stability.
This structure system is easy to construct and is cost-effective in providing one of the best solution in medium span and heavy load construction. This is system is also very commonly use in the industry and hence, resources, technology and pricing is very competitive which is beneficial to the client.
"Green concrete" shall be used for the construction and due to its identical layout of the structural frame, temporary materials like formworks are reusable in which reduce waste by product from the construction works.
With the use of concrete, durability of the building can be ensured and maintenance of the building shall be relatively easy. Fire protection, sound control and thermal comfort of the occupants in the building are also easily satisfy due to the nature of the material itself. Not only that this suggests that satisfaction of the occupants can be ensure, the whole life costing of the building shall be kept at its minimum.
The same concept is applied to the atrium with the exception of the roof which shall be constructed using a steel frame system supporting a glass roof.
The primary concept of having a glass roof at the atrium is for the influx of natural light. As most occupants shall not be in the atrium as night falls, illumination of atrium during the night shall be kept at minimum. It is during the lunch hour in which most of the occupants shall be at that location in which natural lighting can illuminate the area; hence, energy savings can be potential from this design.
As Derek O. & Roger.G,2002,pg.4 suggest, this is the performance requirements of a building.
Source: Derek O. & Roger.G,2002,pg.5