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Knowledge map of week 1
Our team chose an approximate rectangular shape which we
thought can best fit the shape of the object given by tutor, has
the least space wasted and costs the least amount of materials
(MDF). Plus, as our base was the smallest among three groups, it
actually saved our time so that more time could be spent on wall
rising.
Studio 1 – Compression (hollow tower constructing)
When building the walls of the tower, we chose stretcher bond, which is most
frequently used in real building constructing because it has the longest load
path – with a longer pathway, the load is more separated (the shadow shows
the areas in which loads are separated) and therefore the structure becomes
more stable and can hold more load (ref: studio 1).
A technical problem showed up when we created the opening – in
order to make it wide enough to let the object get through, we
need to tie up at least three bricks horizontally with rubber band,
but it would become very unstable when more bricks are loaded
onto it because the three bricks are not strongly compressed
together and they would break up easily from the crevices
between them. Thus we did not build an enclosed structure but
left it semi-closed.
The final collapse happened when we tried to remove some of the
bricks from the middle part, which eventually caused a shift of the
gravity center and thus the whole body biased to one side and fell
down.
During the deconstruction
process, we found that the most
easily-removed bricks are either
on the open edges of the walls,
or at the turning corners where
the walls change direction. The
latter is because the plane walls
are the main support of the
whole structure and thus the
corner bricks are the weakest
parts which do not bear much
load as the plane walls do. The
marginal bricks are even easier
to remove because they are only
compressed at one end.
At first we were just making holes within the structure, but after an
accidental crush, the structure then became shuttle-shaped with a wide
body and a relatively narrow base. This is probably due to the strong
bending stress (ref: 2.14 Ching, ‘Beams’) created by the stretcher bond,
and also because the base is wide and firm enough to hold up the entire
structure.
Comparison with the other teams:
This team’s structure is not very high but must be the strongest among the three
groups. It has a base shape between circle and square, which behaves as a
two-way system (ref: 2.19 Ching, ‘Structural Units’) that spread the load equally
in four directions. Additionally, they thickened the base by adding several more
layers of bricks both vertically and horizontally, thus the load path is even longer
and the base is even stronger.
This team made a circular base for their tower, which uniformly
spreads the load in all directions to make the foundation stable.
It is also a large base which can bear more loads and thus
theoretically the tower can be built higher. However, the
grandness of the base also causes some problems, including a
waste of space and materials, and a much longer constructing
period, which actually limited the final height of their tower.
Their walls are also based on stretcher bond. And they created
an opening which we did not have. Yet they did not upload
many bricks onto the opening either, probably because they
met the similar problem as we did.
Their walls are also built in a
different way, laying bricks facing
two directions alternately, to
make it more efficient to build the
tower higher. However, as the
contact area between two brick
layers becomes smaller, the
stability of the whole structure is
also declined.
Knowledge map of week 2
This time the three groups coincidently chose the same
equilateral-triangle instead of square base, because triangle is
relatively rigid and stable. Also, among all polygons, triangle has the
least sides so it can help reduce material usage (ref: 2.17 Ching,
‘Frames & Walls’).
Studio 2 – Frame (balsa wood tower constructing)
Our team decided to build a triangular prism. To increase its stability,
in each storey, we joined every top vertex with the mid-points of its
corresponding side, so that three truss frames (ref: 2.16 Ching, ‘Truss’)
can be created within one single storey.
In this case, the load pressed on each vertex (except for the ones on the ground or at the top-end of the tower) can
be separated into four different pathways. In addition, we joined the three spatial sticks together to further
separate the load, and in the meantime, when one of the three sticks is overloading and tends to bend, the tension
provided by the other two can help prevent it from deforming.
To prevent the three vertical legs from
moving and strengthen the base, we
added a small piece to each base corner,
perpendicular to the bisector of that
angle, and then glue the four pieces all
together to create a strong joint.
Due to the lack of super glue, we had to try another two ways to join the sticks, using pins and tape
respectively.
Pin connection is not suitable in this case because the materials are thin balsa wood sticks, which are very
crisp and can be easily broken when drilling holes on them.
Super glue is the best choice as it can realize butt joint which is ideal for light materials like balsa wood (ref:
2.30 Ching, ‘Joints & Connections’).
Tape doesn’t fit this structure either because we were building a three-dimensional structure but tape can
only work well on a plane.
Yet tape can be very useful for two-dimensional joining, especially
when joining three sticks together to make a right angle, because it
actually creates a triangular shape at the corner to make it a rigid
frame. The following shows how to make the best use of tape joint
(based on experiments in studio 2):
Turn over Repeat
Comparison with the other teams (1):
This team made a complex structure with four
different bracing patterns to reinforce the tower,
namely K-brace, cross bracing, Knee bracing and the
simplest one-member brace (ref: 2.22 Ching, ‘Lateral
Stability’). All of them are based on triangular frames
to spread out loads and make them rigid.
They cut the materials into very thin pieces, which
actually lightened the dead loads provided by the
self-weight of the structure (ref: 2.08 Ching, ‘Loads on
Buildings’). The final structure is bamboo-shoot-shaped, with the
storeys becoming narrower as the tower grows up.
Unlike prism ones, this structure has bevel sides in some
storeys. Because those bevels have the same length,
they need to have very similar inclination angles to make
the top plane even. Obviously this requirement is hard
to achieve manually, and that’s why their tower biased
to one side for several times. However, since the
materials are very light, the slight shift of the gravity
center didn’t matter a lot. Thus their tower finally grew
very high and reached the ceiling.
This team’s structure is a combination of a few separate triangular
prisms, and each of them is a completed frame without any shared
side with others. This means those sections can be built separately
at the same time and thus the constructing process can be much
more efficient.
Comparison with the other teams (2):
Similarly, they also chose a K-brace-like
frame to strengthen the tower walls. But
they made a difference by inserting a
right-trapezoid-shaped frame to each side
plane, which meant there were three
triangular frames within one side plane and
this structure should be the most stable one
among the three groups (ref: 2.22 Ching,
‘Lateral Stability’).
The challenge is to make
sure the base and top of
two adjacent storeys have
the common mid-point or
center of gravity, so that the
whole structure can stay
steady with a gravity center
right in the middle as it
grows up.
Knowledge map of week 3
This building is a typical concrete
structure, which is qualified as rigid and
non-combustible construction. The
reinforced concrete columns are laid out
along a regular grid, because the
structure is nearly square and thus
two-way system of beam-and-slab
forming would be the most effective and
economic one. (ref: 2.19 Ching,
‘Structural Units’)
Similarly, the concrete columns supporting this
underground car park are also laid out regularly in grids.
Particularly, as the car park requires massive span for
cars to move and park, all concrete columns are
thickened at the top to make a funnel shape. Those
thickened parts act as a transition between the top plate
and the columns, transferring loads from top to ground
in a more smooth way. (ref: 2.20 Ching, ‘Structural
Spans’)
The photo in the bottom right corner shows the
resealing paint on the top plate. Due to
potential deformation of concrete elements, it
is common to see tiny gaps between concrete
slabs which would allow moisture to get in.
This structure is a steel trapezoid-shaped ladder. Nearly all of the
structure’s weight is bear by the side wall and the two supporting beams in
the bottom. Thus the two hanged beams at the top are not actually
load-bearing but for visual purpose only.
The main structure is formed with ‘C’ beams
and the supporting elements are wide-flange
‘I’ beams. Those steel beam types are
supposed to be light-weight and
material-efficient, and also show good quality
in resisting bending forces and shearing
forces. (ref: 4.16 Ching, ‘Steel Beams’)
This is a membrane structure,
using thin, flexible surface to carry
loads through the development of
tensile stresses.
Each membrane edge is connected
to a pole using steel cables,
transferring loads to the ground.
(ref: 2.29 Ching, ‘ Membrane
Structures’)
In the middle of the membrane there is a waterhole,
through which rainwater can be transmitted
downwards to the ground.
The steel cables here are actually loose and are not
providing much tensile stress, because the
self-weight of the structure is already providing the
downward force for equilibrium. Yet those steel
cables are still useful in fixing the gravity center and
preventing the structure from being unstable under
lateral forces.
This structure is a decorating steel beam, with truss
frames inside. It is a simple beam supported only at
both ends, as it is a light-weight structure and only
needs to bear its self-weight.
This indoor swimming pool
is a simple structure built
with steel rigid frames and
two concrete walls on both
sides.
The steel rigid frames are
left exposed. The two side
walls are shearing walls,
bracing the whole structure
and protecting it from lateral
forces like wind.
This tongue-like three-storie
structure is an extended part of
the main building.
To hold the overhanging part, the
whole structure needs to be long
enough and have a reasonably
long part being placed on the
base, so that the gravity center
can stay within the main building.
The bracing structures underneath
the extended part are mainly cross
bracings, using trusses to increase
rigidity.
Knowledge map of week 4
Construction workshop – Beam spanning structure
The materials we got were three solid timber beams and a thin, hard
plywood board.
The beam structure made by our team is a continuous beam sitting on
a series of solid supports, with the plywood board pinned on one side.
(ref: 2.15 Ching, ‘Beam Spans’)
Compared with simple beams, continuous beams are
supposed to have greater rigidity and smaller moments,
and thus can bear more pressure. We place more studs in
the middle to bear more pressing force. The plywood
board on one side also helps spread the loads.
Nails are pinned in two directions to make the studs tight
within the wood frame, increasing the rigidity of the
structure. (ref: 2.15 Ching, ‘Beam Spans’)
The structure bends under the pressure in the middle. Its
deflection is not satisfying, around 15mm, because the
continuous beam structure is weaker in bending moment.
The tendency of the studs’ rotation
results from bending stress – tension
in the bottom and compression on
the top. When the pin joints can no
longer hold the bending stress, the
studs would fall off. (ref: 2.14 Ching,
‘Beams’)
The natural knots and the points
where nails are pinned in are the
weakest points, which would break
more easily.
Thus instead of slowly transforming in shape before the collapse, this structure almost stays straight all the time
until it suddenly breaks. Yet due to its rigidity, the maximum load goes up to 168kg. (ref: 2.14 Ching, ‘Beams’)
The first crack happens in the plywood board because it is thinnest and holds the least load in the whole
structure.
Compared with other teams (1):
This team’s structure is formed by two thin
plywood boards with a series of short wood
studs in between. Yet some studs in the middle
are not well fixed to the plywood and thus
most of them fall off later, which means they
do not bear much load in this case. Their main
function then changes into linking the two
plywood boards at both ends.
Thanks to the accidental loss of some studs in the middle, the plywood boards become very
flexible and can be rotated easily. Thus it can have an incredibly strong bending moment and
high deflecting level – the maximum deflection goes to over 100mm! (ref: 2.14 Ching, ‘Beams’)
Yet due to the great flexibility, this structure easily reaches its maximum deflection and then
cracks. Therefore it shows very poor quality in load bearing – only 45 kg maximum.
Compared with other teams (2):
This team’s beam structure is an open-web timber joist, using
trusses to reinforce the structure. (ref: 4.20-4.21 Ching,
‘Open-web Joist Framing’)
A thin plywood board is added on one side of the structure,
but in fact it does not bear any load in the beginning because
it is only attached to the bottom timber panel. Yet when the
top plywood board is bended under pressure, this side board
becomes useful as it is flexible enough to be twisted, which
actually helps buffer the compressive force. An obvious twist can be seen in both top and side boards.
Similar to the previous team, this is because thin plywood
boards show good quality in flexibility and bending moment.
The following graph shows how the members at the two
ends, which are supposed to be zero-force members and
carry no direct load, can actually create a moment to resist
the bending moment and help maintain the shape of the
whole structure.
This structure combines the rigid framing of truss and the
flexibility of plywood boards. Thus it shows good
load-bearing quality and medium deflection– maximum
320kg and 65mm respectively.
Knowledge map of week 5
Our team’s structure is
two-storie, with a kitchen
on the first floor and a
public restroom on the
second.
The overall structure is
simple and direct, but
there is a slope on one
side of the roof.
The rooms in our structure are framed by
stud walls.
In those stud walls, each section is braced
with a nogging in the middle, and every
adjacent noggings are slightly different in
height, so that a better quality in bearing
shearing forces can be achieved.
Compared with other teams
This team’s structure is
one of the top parts of
the roof. It is a
complex, geometric
structure with lots of
trusses and cross
bracing to create a
rigid triangular roof
frame.
This team’s structure is the part located just
beneath the one of the previous team. It is a
single-skin open-web joist, braced with trusses
and cross bracings.
Knowledge map of week 6
Site 1: Box Hill North
In site 1, prefabricated roof trusses have been placed. Later a
series of tile joists will also be added to make a tile roof.
The foundation uses ‘waffle pod footing’. The pods are hollow
and are about to be filled with grout to create concrete
footing columns.
Around the bottom of the building, there is a temporary slope
to transfer rainwater away from the foundation. Additionally,
a permanent guttering system is also set around the building.
As a part of service system, some unfinished PVC sewage
pipes can also be seen.
The main bracings in this building are ply bracing, cross
bracing and hoop bracing.
- Ply bracing is made of thick ply wood, but still not strong
enough for load bearing, thus always used as wall
connections.
- Cross bracing uses truss function to make a rigid form.
- Hoop bracing is similar to cross bracing, but is adjustable
in tension.
Site 2: Footscray
In site 2, the building is a townhouse and is attached to it
neighbours. Thus fire-check walls and insulation foil (blue
board) is used for safety issue.
Also for fire purpose, many materials have fire rating signs on
them, showing the fire resistance level of the material.
Stud-framing walls are widely used in this building.
Fosil joists can be seen in this site, using keyed strutting
instead of other joints.
5 stages for constructing:
- Slab stage
- Framing stage
- Fixing stage
- Lock up stage
- Occupying stage
Knowledge map of week 7
Knowledge map of week 8
Knowledge map of week 9 & 10
General built form & materials
The main material of this building is structural reinforced concrete, with a few steel framing
and glass cladding. Recycled concrete is used, which creates less carbon footprint, but takes
more time.
The building is curve-shaped, not only for aesthetic purposes, but to create more space
between itself and the surrounding buildings (shadowed area in the top right diagram).
In response to the curved shape of the
building, all individual bedrooms are
slightly different in shape and direction
Besides, the interior view along the
corridor also changes according to the
curved shape, which creates a visual
effect of ‘endlessness’.
Interior construction
The side walls of the
entrance hall are
formed with steel
framing, and are
ready to be filled
with glass to make a
good view of the
surroundings
The bottoms of the main windows are double framed, not only to hide the wiring and concrete
beams, but also to achieve better finishes with a thicker bottom.
There is also flushing in the window frames to prevent water from moving in. (ref: 7.18 Ching,
‘Flushing’)
The hollow spaces in the floor are left for
air-conditioning piping and probably
electricity wiring as well
Some height differences can be seen on the floor.
Those gaps are prepared for the ongoing timber
frames to fit in.
Interior construction
Two shearing walls are already built up in
cross directions on the third floor. They are
constructed to bear lateral shearing forces
like wind or earthquake
Light-weight steel frames are widely
used for interior framing
Between every two bedrooms,
double studs are used for both fire
resistance and noise separation.
Service system
The two photos on right hand side show the heating
and ventilation system in the bedrooms:
- Black pipes for the heater
- Rectangular metal tubes for air freshening
The two photos above show the service systems in public spaces. Electricity systems, gas system, heating
systems, water supply and sewage systems are mostly set up in site:
- White pipes for water supply and sewage disposal
- Red wires for electricity
- Black and red metal tubes for gas or heating
Functions & Finishes
For both public and private spaces,
concrete celling is to be exposed.
Therefore, neat cutting and clean
finishing are needed for aesthetic
purpose.
Those rectangular frames are for bathrooms – using timber to create the shape, in which liquid
concrete is to be poured and tiles are to be set up to make a base for water collection.
The roof is built of concrete and is prepared for another floor to be
added. From the photo above, the lift, columns and stairs are all set up
and are ready to go.
Flushing – preventing moisture form moving in
Insulation – waterproof and heat separation.
Gap between surface and insulation – for further insulation
Wall ties – tying the surface walls and the internal walls
Weepholes – for water to get out of the building
Vapour barriers – for moisture proofing
Steel strip and plastic/glass – forming a lighting tube.
Some layers of brick work are set
a few centimeters in from the
surface, probably for aesthetic
purpose.
The walls are formed with a
combination of soldier course
and stretcher course.
Weepholes provide an exit for
the moisture to get out. Downpipes transfer the
collected rainwater to the
ground.
The white stripe is a lighting
tube.
The gutter system for this building is eaves gutter. It
is exposed at the edge of the roof but is well
integrated in the roof structure.
Another gutter type is box gutter. It is hidden
within the walls and so has a better finish and is
more commonly used. But there is one main thing
to be considered: rainwater may directly come into
the house when there is a crevice in box gutters.