Available Amenities
1. Electricity
Electricity for the entire airport and surroundings will be
provided by the Trinidad and Tobago Electricity Commission
(T&TEC).
2. Water Supply
It is expected that part of the daily domestic water requirement
for the entire facility will be provided through municipal mains
supply from the Water and Sewerage Authority (WASA). If the
supplier is unable to maintain the daily supply it is recommended
that 4 tube wells be inserted into the complex to provide the
domestic water requirement on need basis.
3. Waste Water Treatment
The estimated amount of waste water flow is approximately
2500m3/day from the entire facility. This effluent will be
discharged into the effluent and sewage treatment plants which will
be located in the vicinity of the airport. The plants will be
managed and operated by SWMCOL.
Effluent Treatment Plant
The effluent treatment plant shall have a capacity of
approximately 1500m3/day and the quality of the treated effluents
shall be of a quality suitable for re-use as flushing water in the
WCs.
Sewage Treatment Plant
The sewage treatment plant shall have a capacity of 1300m3/day
and the quality of the treated effluent shall be suitable for
re-use water in the cooling towers of the air conditioning systems
as well as for use in horticulture activities. It is also proposed
to use activated sludge process based o the principle of extended
aeration based on a Diffused Aeration System.
4. Telecommunications and Satellite Services.
Telecommunications will be provided by the Telecommunication
Services of Trinidad and Tobago. Satellite services will be
provided by VSAT and Satellite Technologies.
5. Fire Services
6. Police Services.
Conceptual Design Conceptual design in civil engineering refers
to a vague and creative phase at the beginning of the construction
process. In the later phases of a project, only a small part of the
building is under elaboration whereas in conceptual design the
entire building, its functionality and usage are all taken into
consideration. The purpose of a conceptual design is to determine
the most feasible alternative. At this stage the objective is to
study a number of possible schemes and select the most cost
effective one. To determine this, detailed calculations are
unnecessary however member sizes and reinforcement content must be
estimated in order to determine the relative amounts of materials
which will then determine the cost of the project.
The conceptual design of any project must consider the intended
functionality of the structure so that there is no ambiguity
concerning the function which the end product must serve. Based on
the given design brief, the design of the airport terminal and
control tower must fulfil the wishes of the client which are to
provide a unique, safe and feasible structure to accommodate the
growing economy and to improve transport links. The client also
wishes that the airport be seen as a reflection of the nation and
that they both display outstanding design qualities. Economy must
also be maintained since the airport proposal must set new
standards in cost effectiveness and quality.
For this conceptual design a number of alternatives were created
for each structure. This was done by a combination of research and
sketches producing a number of possible ideas. Each member of the
group produced an individual concept for the terminal as well as
the control tower. From this, sketches were produced combining a
number of ideas and possibilities. From the different ideas and
possibilities generated, each alternative was passed through a
design matrix and from this the most feasible option was chosen for
a terminal and control tower. The entire airport facility should
encompass:
i. Main terminal building
ii. Transport interchange facilities
iii. Runways
iv. Car parks
v. Control tower
vi. Water and waste management facilities
vii. Aircraft maintenance
viii. Future passenger terminal expansion
All of the above were taken into consideration for each
conceptual design.Preliminary design The preliminary design phase
is the phase in which high level design concepts are generated. The
objective of the preliminary design is to map out how the structure
will perform the functions specified in the requirements. The main
activities for the preliminary design phase are:
i. Create a high level design description
ii. Identify the major components of the structure
iii. Include reliability, maintenance and tests features that
are necessary to meet the performance and quality requirements
iv. Identify constraints on the structure that are a result of
high level design.
Method of Selection of Alternatives
To determine the most feasible alternative for the airport
terminal as well as the control tower a Design matrix was
configured. To develop this rational method for selection of the
final alternative, key influential factors were identified and
evaluated thoroughly to determine their impact on the final choice.
The main and most crucial factors which were selected for this
matrix were as follows:
i. Performance
ii. Costs
iii. Constructability
iv. Accessibility
v. Environmental impact
vi. Safety
vii. Aesthetics.
Performance
The performance criterion will be used to assess the variances
in the client and stakeholders demand satisfaction for each
alternative. It will qualitatively assess whether or not the
demands of the affected parties were abundantly satisfied. The
airport terminal must provide a reasonable financial return to the
stakeholders as well as provide efficient passenger services.
Future expansion of the terminal also falls under this category.
Some key factors which are to be used for the determination of
performance of the best terminal are:
i. Passenger flow
ii. Level of service for passengers
iii. Performance standards
iv. Walking distance
v. Traffic peaking characteristics
vi. Future growth
vii. Ease of way-finding
viii. Retail
Costs
This includes capital, operation and maintenance costs. For any
preliminary design the major objective is to determine the most
feasible alternative. This will be dependent on the cost of the
structure. The capital costs are the total costs which are needed
to implement the project and may be considered as the costs
incurred on the purchase of construction to be used in the
rendering of services.
Operation costs are the recurring expenses which are related to
the operation of the facility while maintenance costs result from
actually maintaining the facility. From this, the overall cost of
the entire structure for both terminal and control tower will be
determined for each alternative and based on this criterion, the
best one will be chosen.
Constructability
This may be defined as the optimum use of knowledge and
experience in designing, planning and field operations to achieve
the overall objectives of the project. Ares under consideration for
this are, simplicity, ease of construction, economy and statutory
restrictions. Careful attention must be paid to in this criterion
since economy plays a heavy role as well as ease and speed of
construction of the project. In order to determine the best
alternative based on this criterion, the costing of each structure
was determined as well a project schedule. The most feasible will
then be chosen.
Circulation or Accessibility
This refers to the ease with which passengers and vehicular
traffic can flow into, out of and within the facility. Each
alternative will be assessed based on:
i. Movement through the structure/ structures with the
differently capable in mind.
ii. Provision for vehicular traffic flow around the facility at
entrances and exits as well as flow into and out of the
facility.
iii. Zoning layout that provides ease of access between terminal
element and control tower.
iv. Provisions for aircraft and machinery mobility around and
about the concourse areas.
v. Provisions for movement and transport of cargo within the
facility.
vi. Proper and adequate parking facilities.
Environmental Impact
Environmental considerations such as effect on wildlife ecology,
ground water runoff, air pollution as well waste water management
systems all fall under this criterion. Ecological impacts may be a
result of poor construction practice and induced development by the
presence of the airport and hotels. Careful disposal of waste,
waste water handling and re-use must also be heavily considered so
that nearby existing water bearing zones will not become polluted.
For this design a waste water treatment facility is to be
implemented. An adequate water distribution system must also be
implemented for the entire facility.
Sites near bird habitats must also be avoided since there are
many previous accidents involving birds colliding with airplanes as
well as ingestion into jet engines.
Safety
For this criterion the layout of each structure is critical.
This means that the building must be designed to accommodate large
volumes of human traffic. The building must be carefully assessed
for earthquake resistant design, wind and hurricane design as well
as fire design. To determine this, careful analysis for earthquake
and wind loading must be done in detail in accordance with the
relevant codes and standards. Each component of the structure must
comply with the required standards for fire resistant design. The
type of glass sheeting and proper bracing must also be heavily
considered.
Aesthetics
This is the most subjective criterion considered for the
selection of the final alternative since it relies on the ability
to discriminate at a sensory level. Considerations will be given to
how each alternative meets the wishes of the client and how each
alternative blends with the environment. Since the client wishes
that the airport terminal and control tower be a representation of
the nation as well depict a Gateway to the sky, the model which
best suits this description will be considered.Selection
modelsCriteria consideration rating of alternatives
Based on the aforementioned selection criteria, several
selection models were developed and compared based on their
weaknesses and strengths. To determine the most feasible
alternative from all five alternatives, it was agreed that two
basic models will be used one of a qualitative and quantitative
measure. Holistic approach This model was used to rate the three
alternatives under each criterion using a consideration index. This
consideration index, rated each alternative based on their level of
consideration towards the criterion. The consideration index is as
follows:
i. High consideration (H) alternative reflects a high level of
considerationii. Moderate consideration (M) - reflects a moderate
level of consideration towards criterion.
iii. Low consideration (L) reflects a low level of consideration
towards criterion.
Each alternative was severely critiqued and from this,
Table...... below was produced giving a model which employs a
qualitative approach. The design alternative which gives the
highest consideration to criteria will be selected. CONSIDERATION
SELECTION MODEL - QUALITATIVE APPROACH
TERMINAL BUILDING
Concrete
Steel
Alternative 1
Alternative 2
Performance H
H
Environmental ImpactM
H
Costs (capital, operation and maintenance costs)M
H
ConstructabilityH
H
Circulation (movement around site)M
M
SafetyM
L
AestheticsH
H
TOWER
Concrete
Steel
Performance
Environmental Impact
Costs (capital, operation and maintenance costs)
Constructability
Circulation (movement around site)
Safety
Aesthetics
From the table above it can be seen that the holistic design
approach of alternative............ gave the most consideration to
the selection criteria making it the most suitable option.
Weakness of model and recommendations
More suitable for rapid evaluations and there is the possibility
of the same final result
Since little emphasis is placed in the detailing of each
criterion, the index can misrepresent the individual effects as
opposed to an overall effect.
Index allocation is based highly on emotions versus scientific
research.
Recommendations for improvement of model
Each of the selection criteria in the above table may be sub
divided into sub criteria so that they will be more specific to a
particular area of the main criteria. This would require less guess
work and more precise answers.
Total Weighting Approach
For this approach each criterion was marked based on the
importance to the provision of the terminal and control tower. Each
criterion was assigned a relative weighting factor which then
determined the weight of that particular criterion. This was done
for all the criteria for each alternative and the total weighted
score for each alternative was tallied. The ranking is as follows
and it should be noted that the criterion with the highest ranking
is of the greatest importance. One major weakness of this model is
that the ranking is still based on emotion rather than scientific
approaches.
Ranking Values
0 No relation
1 Totally incompatible
2 Very unsatisfactory
3 No satisfaction
4 Poor satisfaction
5 Moderate satisfaction
6 Average satisfaction
7 Good satisfaction
8 Excellent satisfaction
The ranking values were t hen distributed on the basis of the
main objective, that is, the economical development of a high
performance environmentally friendly airport facility. A weighting
factor of 0-4 stems unsatisfactory results whereas from 5-8 shows
ranges of high satisfaction. Table........... shows the
distribution of the weighting factors for each alternative
below.TOTAL WEIGHTING SELECTION MODEL - QUANTITATIVE APPROACH
TERMINAL BUILDING
DESIGN CRITERIAAlternative 1Alternative 2Ranking
Performance
Environmental Impact
Costs (capital, operation and maintenance costs)
Constructability
Circulation (movement around site)
Safety
Aesthetics
TOWER
DESIGN CRITERIAAlternative 1Alternative 2Ranking
Performance
Environmental Impact
Costs (capital, operation and maintenance costs)
Constructability
Circulation (movement around site)
Safety
Aesthetics
The total weighting for each alternative was calculated by
summing the products of the weighting and ranking for each
criterion for that particular alternative. Allocation of weighting
Terminal Performance Alternative..... showed the highest levels of
performance also taking into account room for future
performance.
Capital costsAlternative..... was allocated the highest
weighting value since it requires less capital to construct and
maintain. The building is of a simple design and very cost
effective.
ConstructabilityThe highest weighting was given to
alternative..... as this option was simple to design, economical
and with desirable speeds of construction.
Circulation or AccessibilityAlternative.... .. showed the
highest weighting for this criteria since the layout allows for
more accessibility and room for future expansion.
Environmental Impact
Alternative ....... was elected with the highest weighting since
this showed the smallest scale of development for the area. Safety
For this criterion, alternative.......... was chosen. By looking at
the architectural drawings we see that this alternative provides
safer surroundings and measures than alternative......
Aesthetics
Both alternatives show contrast however they both enhance the
existing environment therefore they were both given the same
weighting. From the analysis of the above results it shows that
alternative..... is the most suitable option for this preliminary
design. The total weighting for this option was ...... which is not
to far from the alternative ........ Alternative ...... provides
better performance for stakeholders and also leaves adequate room
for future expansion. When capital costs are compared for both
structures it was seen that alternative....... was the most cost
effective option. Therefore it can be said that from the above
results alternative....... is the most feasible alternative for the
clients.
The same process described above for choosing the most feasible
option for the terminal was carried out for the control tower until
it was determined that alternative........ was the most suitable
alternative for the client.Structural Analysis of the Reinforced
Concrete Control Tower Initial sizing of structural members and
other materialsThe initial sizing of the beams and columns was done
in accordance to the Preliminary Design Guide of Structural Members
by Richard Clarke. A detailed analysis of the total loads will be
done in the detailed design section. For this preliminary design
section, the load cases considered for this stage of design were as
follows:
Dead Loads
Live Loads
Earthquake Loads
Wind Loads
Earthquake Loading ConditionsThe base shear is calculated as 10%
of the total weight of the structure. For earthquake analysis
checks will be performed in the lateral and vertical sections of
the building in plan view. Point loading at each level will be
distributed by looking at the relative surface area ratios
throughout the entire building since the building is not evenly
distributed or symmetrical. The figure below shows the distribution
of earthquake forces on the control tower.
From the earth analysis the period of the structure was 0.75
Hertz
The total earthquake loading was calculated to be 2057.86
KN.
Figure...... showing distribution of earthquake forces on
control tower.In the detailed design this analysis will be done
using plane frame analysis. The loading conditions considered are
as follows:
1.2D + 0.5L+1.0E
1.4D + 1.6 L
The required longitudinal and transverse steel will be
calculated in the detailed design stage.Wind Loading Conditions
Wind loading on the control tower plays a critical part since
the tower was designed as a high rise structure. Wind loading on
tall buildings needs to be considered in the early design stages so
that the size and form of the structure can be optimised to
capitalise on the possibilities of reducing the wind loads.
At a height of 52 metres high, wind velocities provide lateral
forces throughout the entire length of the building. In Trinidad
the wind speed generated for design purposes is that of 45m/s. This
is critical to the building since this can cause the tower to sway
immensely which can be detrimental to the structural integrity of
the tower. A regular rigid frame has its deflections produced by
bending of columns and bending of the beams. Dynamic wind loading
can cause over-turning if the restoring moment cannot counteract
these forces. Figure..... below shows how wind loading is
distributed throughout the control tower. The wind loads were
calculated for each floor height of the building but the diagram
below shows a general distribution of the forces. The wind loads
were calculated to produce a total wind load of 2171.0 KN.
Figure....... showing the distribution of wind loads on the
structure.Load Path Analysis
Type of frame system
For the preliminary design of the control tower, the type of
frame system chosen was critical. Since the airport is being
designed for a location in Trinidad and Tobago, the type of system
chosen had to be capable of resisting earthquakes. Since most
structures are designed to resist the vertical forces of gravity,
little additional strength is needed to account for the vertical
aspect of seismic forces. However since seismic forces also impart
horizontal forces, a successful structural design must account for
this additional horizontal force. Although buildings are already
designed to resist wind forces, seismic forces are typically
greater than wind forces therefore buildings require greater
strength components to resist seismic forces. These components form
system called an earthquake resistant structural system.An
earthquake resistant structural system is a structural system with
properties and behaviour that area favourable towards the objective
of adequately resisting earthquake forces (Clarke, Earthquake
Resistant Design n.d.)The main desiarable quality of such a
structural system is ductility. The other desirable properties
which promote high ductility and overall favorable responses are:i.
Regularity Little change in stiffness, mass and strength from floor
to floor
ii. Continuous load path- The absence of gaps between members so
that the force is effectively transferred from each member to
successive members on its way to the foundation
iii. Short load path- Small offsets in beams, columns and
wallsiv. Multiple Load paths the presence of several routes which
the force can travel through to the foundation means that if any
one member becomes overstressed other members can be relied upon to
absorb its energy.
v. Strong connections- to ensure that the load path is not
broken by excessive deformations or rupture.When all these factors
are maximised, the sequence and formation of hinges are such that
their energy absorption in the system is maximised. With the above
mentioned, the safest and most reliable structural system to be
considered was that of a Moment Resisting Frame. Framed Tube
Structure
Framed tube structures are a special type of a moment resisting
frame. They are constructed with very wide columns closely spaced
and relatively deep beams. Framed tubes have narrowly spaced
exterior columns combined with beams to form rigid structures to
resist lateral loads. This type of framing is usually located on
the perimeter of the structure. Due to the added strength of the
wide columns and deep beams, this type of system introduces more
stiffness. The stiffness is used to overcome the potential problems
caused by the horizontal sway which occurs during an earthquake.
The framed tube method is frequently used in very tall buildings
where swaying can be detrimental to the structural integrity of the
building. The first noted example of a framed tube structure is the
Dewitt Chestnut Apartments, Chicago Illinois constructed in 1964 as
shown in Figure.... below.
Figure ..... showing Dewitt Chestnut Apartments in Chicago
constructed using a tube frame structure.The 43 story reinforced
concrete tower was designed by Dr. Fazlur Khan at Skidmore Owings
and Merrill (SOM). Due to its high relative strength and stiffness
the tubular form immediately became a standard in high rise design
(D. F. Khan 2006)
For the design of the control tower, the shaft comprises of an
inner and outer shaft. The outer shaft which models a framed tube
structure has a square base with a total of eight wide columns each
600 x 600 mm in dimension as shown in the figure... below.
Figure .................showing arrangement of columns on outer
shaft.
The columns are equally and closely spaced which helps to
generate the required stiffness. The inner shaft comprises of a
rectangular elevator shaft with columns placed at each corner each
column having dimensions of 300 x 300 mm. This shaft acts as a
symmetrical shear core due to the arrangement of the columns. On
the outer shaft there are deep beams of dimensions 600 x 800 mm
spanning between columns whereas in the inner shaft secondary beams
are used to join inner to the outer shaft for each floor. This beam
and column arrangement can be seen in figure....... which shows how
this framed system caters for stiffness in the control tower.Roof
StructureThe type of roof chosen for the control tower is that of a
domed structure. This was chosen since it will mimic an arched
system which is structurally sound as well it adds to the
aesthetics of the structure. The dome spans 12 metres in diameter
and has a rise of 2 metres. The type of dome chosen is that of a
Ferro-cement dome. Ferro-cement is a composite of steel and
cementitious material. The large size steel reinforcing bars are
replaced with wire meshes, while the coarse aggregate is removed
completely from the cementitious matrix. The resultant composite
called Ferro-cement lends itself to casting in thin sections. The
properties of Ferro-cement such as strength, water tightness light
weight, durability, fire resistance and environmental stability are
hard to match. (T.P. Singh, High Performance Ferrocement Dome). The
dome shell will be designed to be 1 inch thick with 24 nos.
longitudinal stiffener ribs in the form of truss frames projecting
inwards. An example of this can be seen in Figure..... below which
shows the arrangement of the reinforcement being used in the
construction of the dome.
Figure..... showing reinforcement detail (Temple in Doraha,
India)Six layers of GI wire meshes will be wrapped on the armature.
The truss will consist of 2-8 mm bars connected with zig zag
lattice bars. The trusses will be curved to follow the shape of the
dome. The trusses will be erected on a ring beam of size 300x400mm
which will be welded on to dowels left in the beam. At the top the
trusses will be arranged and held in place by a pipe ring which
will be imbedded in the concrete. The trusses once erected will be
wrapped around be hoop steel 6mm diameter MS bars at every 3
inches.
The Ferro-cement dome shell will have 6 layers of GI wire meshes
with 3 on each side. Voids in the shell will be filled with PVC
grouting nipples. This type of structure was chosen due to its
light weight which will in turn reduce the earthquake damage
potential to the building. Examples of this particular type of
structure can be seen in the temples in Doraha, India built by the
Gurudwara Brahm Bunga Trust as well as off shore structures which
use the improved Ferro-cement techniques developed by Martin Iorns.
Reinforced Concrete BeamsAssume a ductile frame and a beam span of
6 metres
For non-cantilever, d = span/26 + 300 mm (span in mm)
= 6000/26 + 300 = 530 mmUse 600 mm depth beamsFor spans 6000mm
< span < 9000mm width (b) of beam = 350 mmFrom the above, use
600 x 800 mm beams in the preliminary design stage.In the detailed
design the calculation checks will include beam slenderness,
span/effective depth, reinforcement and depth of cover using the
BS8110:Part 1:1997.
Reinforced Column Design
Square columns will be used for the preliminary analysis. All
columns are braced columns.On each of the 13 floors of the outer
shaft 600 x600 mm square columns will be placed each 2.1 metres
apart on each side.
On each floor the inner shaft 300 x 300 mm square columns will
be placed at each corner of the rectangular shaft.
On the first floor of the cab, 8 square columns of size 400 x
400mm will be used along the perimeter of the slab.
On the second floor of the cab, 8 slanted columns projecting
outwards of size 400 x 400 mm will be arranged on the perimeter of
the slab. Typical reinforcement is calculated as 4% of the gross
cross sectional area of the column. In the detailed design full
reinforcement detail will be calculated and verified using the
BS8110:Part 1:1997 Structural Use of Concrete: Part 2 Code of
Practice for Design and Construction.Floor SystemThe type of floor
system chosen is that of a typical two-way solid slab design with
beams running underneath forming a grid like pattern. This type of
floor system is simple with a typical solid concrete slab of 6
inches thickness and diameter of 9 metres. This was also chosen
since this floor system makes use of cantilever beams. In the
detailed design the slab will be designed taking into account
bending strength and deflection with references to the BS8110:Part
1:1997.Reinforced Concrete Block Walls
These block walls are non-load bearing walls since the beams and
columns which make up the frame of the structure transfer the loads
from the roof to the foundation. However they will be reinforced so
as to add to the general stiffness of the shaft in the control
tower. The walls will also serve the purpose of shelter. The blocks
will be interlocked however the technique of groove pointing will
be employed as a finish.The size of blocks for external and
internal walls are 6 inch hollow concrete blocks.
Concrete infill and vertical reinforcement will also be
used.
Internal Concrete Stair Case For each floor the stair case will
rise 3 metres in height per floor. Each step will have a rise of
0.2 metres and a run of 0.3 metres. The landing top and bottom will
be of dimensions 1.5 x 1.5 m. The landing will be of thickness 4
inches. The stair will join the walls of the inner shaft and tie to
the walls of the outer shaft forming a wrap throughout the shaft of
the control tower. Foundation From the borehole data provided, the
type of soil being considered is that of a silty medium to dense
sand. This means that we are designing for a shallow foundation.
The advantages of using a shallow foundation type are:
Affordable cost
Simple construction procedure
Materials are mostly concrete and reinforcement
The disadvantages of using a shallow foundation type are;
Settlement
Foundation subjected to pull out, torsion and moments.
Irregular ground surface.
The type of foundation chosen is critical since the foundation
will act as an anchor to prevent the control tower from over
turning. The type of foundation considered for the control tower is
that of a pad foundation for the dense silty sand provided. A
typical pad foundation is seen in Figure.... below.
Figure .......... showing a typical reinforced pad footing.
Picture taken from An Overview of Footings and Foundations A pad
foundation normally supports a number of column loads in both
horizontal directions. The minimum size of the pad is given by the
practical requirement of being able to excavate by hand to the
required depth and level off the bottom and to lay brickwork or fix
steel for the columns. For this design the pad is continuous with
beam foundation. The continuous beam foundation may be required to
bridge over weak pockets in the soil or to prevent excessive
differential settlement between adjacent columns.
The advantages of these foundations are, ease of excavation, any
formwork required can be fabricated and assembled in longer lengths
and there is more continuity and ease of access for concreting the
foundation.For the preliminary design of the pad foundation with
continuous beams, it must be sufficiently large so that it can
prevent any over-turning moments generated from the cantilever
structure. This overturning moment was calculated using wind and
earthquake loads and the total weight of the structure as well as
the foundation size to produce a Factor of Safety. From the wind
and earthquake analysis the base shear generated was more than the
total wind loads.
Therefore the Mrot or acting moments due to earthquakes =
43189.2 KNMres (restoring moment due to weight of structure) =
81999.6 KN
Factor of Safety against over-turning = 43189.2 / 81999.6
= 1.9 > 1.5Since this is greater than 1.5 the Design for
over-turning is Safe. The length of the foundation must be larger
than the top most floor of the control tower. Each column in the
external shaft will rest on a pad foundation. The internal columns
will also each rest on a pad in the centre of the external shaft.
On each side of the external shaft an extra metres of pad
foundations will be added on. Each pad is inter connected with
ground beams with the beams connecting to the centre of each
footing. This foundation arrangement for the control tower can be
seen in Figure...... below.
Figure........ showing layout of pad and continuous beam
foundation.Dimensions of pad footing:Dead load of tower = 13223.0
KN
Assume a weight of footing = 130.0 KN
Total dead Load = 13353.0 KN
Live Load = 443.5 KN
Design Axial Load (N) = 13353.0 + 443.5
= 13796.5 KN
Load per column on outer shaft = 13796.5 /8
= 1724.56 KN
Bearing capacity of soil = 2 x N x 10N is the SPT value, average
SPT value at depth of 1, 2 and 3m = 17 blowsPlan Area of pad
footing = 1724.56 / 340 = 5.0m 2Length of footing = 2.25mHence
provide a 2.25 m square base.
Depth of footing assumed to be 600 mm thick = 0.6 m
Size of Reinforced Beam connecting to footing = 1500 x 600 mm In
order to compensate for over-turning extra footings will be added
on to reach a total length of 12m.
The footing will be 1 metre deep to the column footing. Concrete
blocks will be placed along the continuous beams or backfill can be
used followed by hard core, then sand blinding. Over this layer of
sand blinding, polythene will be placed, then a layer of BRC. Over
this the ground floor slab will be placed.
From the calculations done, it was observed that the footings
will be closely spaced and for this preliminary design it will be
more economical to use a raft foundation of size 12 x 12 m.
Figure ...... showing section of footing and fillFinishes The
cab of the control tower will be fitted with double glazed
laminated glass. This type of glass is structurally sound since it
is a composite high performance product which combines the material
properties of the glass with the unique properties of PVB such as
adhesion to glass, elasticity and impact resistance. When broken it
will still remain integral due to the plastic between the glass,
remaining safe even when broken. The thickness of the glass is
6.4mm thick which is widely used giving a Class B performance to BS
6206:1981.The ceilings of the cab will be fitted with acoustic
ceiling tiles for aesthetic purposes. The floors will be tiled and
walls painted. The exterior walls will be groove pointed as well as
painted. Double doors will be used at the base of the shaft as well
as throughout the shaft windows will be placed to allow for natural
lighting. Finally around the first floor of the cab, a metal
balcony will be placed so as to provide ease of access to glass
panels in the VCR when they need to be cleaned.Structural materials
used in the Control Tower Reinforced concreteConcrete is strong in
compression but very weak in tension therefore to compensate for
this weakness tensile reinforcement will be applied to all concrete
sections. For this material selection it is important to note the
ease of construction and costs play a critical role since it is
less expensive than structural steel.
Some key advantages of reinforced concrete are:
High compressive strength
Economical material for below grade structures
Low maintenance required
Good fire and water resistance
Inexpensive labour requiring less skilled workers for placing
and mixing of concrete
Disadvantages of reinforced concrete
Lower strength to volume ratio than steel
Composite material complexities
Lower strength per unit weight compared to steel
Bulky structural member requiring lager foundations
High Tensile Steel High tensile steel will be used as
reinforcement for each concrete section of the structure. Sizes
range from 16-20 diameter bars as well as 10mm diameter bars for
stirrups. The steel provides tensile reinforcement so as to prevent
cracking and defections.Masonry Concrete versus clay blocks
Concrete blocks have higher compressive strength than clay
blocks
Concrete blocks have lower water absorption rates than clay
blocks
Clay blocks react more with a humid environment, that is, they
tend to swell.Ferro-cement
This a thin composite made with a cement based mortar matrix
reinforced with closely spaced layers of relatively smaller
diameter mesh (Antoine E. Naaman 2000). The basic parameters which
characterise ferrocement are the specific sruface area of
reinforcement, the volume fraction of the reinforcement, the
surface cover of the mortar over the reinforcement and the
relatively high quality of the mortar. Ferrocement behaves like
reinforced concrete in its load bearing characterisitcs, with the
essential difference being that crack development is retarded by
the dispersion of the reinforcement in fine form throughout the
mortar. Advantages of ferrocement:
Low weight compared to RCC Cheaper in construction
Less thermal conductivity as compared to RCC
Long lifetime in comparison to steel structures
Ease of construction
Disadvantages
Labour intensive
References Websites
1. 9th International Symposium on Ferrocement, Bali 2009-01
http://ferro9.unila.ac.id./latest/about-ferrocement.html
(Accessed 10, 01, 2009)
2. Raft Foundation Solutions
www.raftsolutions.co.za(Accessed 15,01,2009)
3. Earthquake Resistant Design
http://www.Richardpclarke.tripod.com(Accessed 10,01,2009)
4. Advantages and disadvantages of moment resisting frames
http://www.scholar.google.com/scholar?q=advantages+disadvantages+of+momnet+resisting+frames(Accessed
19,01,2009)
BOOKS
5. Reinforced Concrete Designers Handbook , Tenth Edition
Charles E Reynolds and James C Steedman - Chapter 20, Design of
Beams and Slabs.6. Design of Structural Elements Concrete,
steelwork, masonry and timber design to British Standards and
Eurocodes Chanakya Arya Page 76, design of pad footing.
7. Structural Design -Extracts from British Standards for
Students of Structural design- 5th Edition BSI.
Proposal for Alternative 1: Reinforced Concrete Control
TowerDesign Philosophy for Control TowerThe design of the control
tower takes into account two primary considerations which are
elegance and structural stability. The control tower in any airport
should be able to carry out its functions while at the same time be
attractive. In this conceptual design the tower was created from a
number of different ideas all bearing in mind simplicity and
dynamic performance. The tower was designed to be able to withstand
earthquake and wind loading as well the foundation was designed to
prevent overturning of the tall structure. With dynamic performance
taken care of, the group was left to make the tower aesthetically
pleasing. The domed shape roof of the structure provides beauty as
well as an air of elegance to the high rise building.
The cab was designed with a total 3600 view port fitted with
glass facades which amplifies the appearance of the cab. The shaft
of the tower being structurally stable will be painted and groove
pointed with glass windows present on each side of the shaft per
floor. This gives the tower a sophisticated finish as well as it
lends to natural lighting of the shaft. The design keeps true to
the wishes of the client since it is distinctive, highly sculpted
as well as it represents an iconic landmark. W3
W2
W1
W4
W0
Footing 2.25 x 2.25m 3m
Continuous beam 1500 x600mm
backfill
Hardcore
Sand blinding
Polythene
BRC
4 inch thick Floor Slab
SOIL
