January 2015
The Hy-Pier Emtech Core Studio I
Giulio Gianni, Kuber Patel, Antoniya Stoitstova
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[Abstract] The project explores the possibility of framing quadrangular lycra membranes with hinged bamboo frames to obtain hyperbolic paraboloid as components to be aggregated for an urban intervention in Masthouse Terrace Pier, London. Three different aggregations with three different target environmental conditions to be produced within them are set out. Once the system parameters and the limitations and drivers for the aggregation of such components are identified, the different environmental conditions are obtained either via applying cuts and/ or doubling the membrane layer, or via the regional geometry of the aggregation. Proliferation of the aggregations is a step by step process where each stage of growth is re-evaluated against wind and shading performance and accessibility. Structural analysis of the aggregations is carried out only at the last stage of the proliferation and the creation of a feedback loop for the strucutral analysis to inform the growth of the aggregations is intended for future developments of the project. Other future developments include a more detailed design of the fixed and hinged joints within each component, as well as a detailed construct sequence. It is understood that the sequence in which these components are erected might indeed affect the possibilities for aggregation. Finally, the project has succeded in providing an alternative way to produce leightweight- and potentially foldable- membrane structures.
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[Table of Contents] [A] Abstract
4.3.2 Wind Test: on Aggregations 25
[C] Contents
4.4 Initial Shading Test
26
1 Introduction
6
5.1 Design 1 Proliferation
27
2.1 The Components
7
5.2 Design 2 Proliferation
28
2.2 Initial Component Design
8
5.3 Design 3 Proliferation
29
2.2.1 Empirical Tests (1)
10
5.4 3D Views
30
2.2.2 Emprical Tests (2)
12
5.5.1 Global Form Analysis (1)
32
2.3.1 Frame FE Analysis (1)
14
5.5.2 Global Form Analysis (2) 34
2.3.2 Frame FE Analysis (2)
16
5.6 Connections
36
2.4 Double Layer
18
6.1 Conclusion
38
3.1 Conditions Considered
20
6.2 Future Advances
39
3.2 The Site: Plan of intervention 21 4.1 Component Proliferation
22
4.2 Proliferation Process
23
4.3.1 Wind Test: Minimal
24
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1. Introduction
conventional membrane & hypar structures
01_Minimal surface: with external support frames
textile morphologies exhibition by Sean Alquist, Prof. Achim Menges, Bum Suk Ko- 2013
02_Membrane structures: with support masts & cables
Eagle Point amphiteatre (left) and Molesi Development is Samoa (right)
A lot of examples are available of membrane structures using minimal surfaces for obtaining light and long spanning roof or canopies. A common example of such practice is the wide use of ruled surfacesespecially hyperbolic paraboloids or “hypars” - where the membrane can be replaced by either a net of cables or an array of straight beams or rigid elements. However, with the endless possibilities that these structures give, they also come with several limitations. For example, being predominantly tensile structures, there is always the need for some “external” element such as compression struts/masts and
other cables to carry the reactions down to the ground. Some good examples are provided by the frames in the two top figures, and by the masts in the two bottom figures. The presence of such elements is a major issue when considering the possible aggregation of two similar structures/geometries together. For this reason the ways in which we are used to see hypar structures are either as individual self-standig elements, or and array of elements aggregated following a radial pattern. The most famous example of the latter is given by Los Maniantales (or “The flower”) by architect Felix Candela. Page
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2.1 The Component
component elements and system parameters
01_Hypar component elements Lycra membrane
bamboo frame hinged joint 02_Component parameters L0
n 0
1
L1 d 4
3
D
w t
Given the opportunities, and most importantly the limitations of the structures discussed in the previous section, a hypar component was developed. The component consists of a rigid bamboo frame (the choice of material will be explained in the next sections of the report) with two opposite angles with a rigid connection (or “fixed”) and two with a hinged connection that allows one degree of freedom. To this frame it is then attached a Lycra membrane (in this case the material was chosen for its easy availability on the market) by drilling holes in the frame and in the membrane and using a simple bolted or riveted connection. The
idea of framing the membrane itself not only means that the structure no longer needs other “external” elements, but also implies that new and unusual ways of aggregating hypars can be obtained. In fact, by letting two membranes share one side of the frame and by controlling the angle (tau in the legend) between them we can obtain numerous new aggregation types. Fianlly, the possibility of introducing cuts or openings for the hypar aggregations to interact with the environment is considered and studied in the following sections.
[Legend] L-Length -angle inside square -angle of hypar -rotation between two components w-frame width t-frame thickness n-number of cuts d-diameter/angle of the cut D-edge conditon
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2.2 Initial component designs studying the possibility for different connections, inner frames & minimal cuts Component_01 \Edge connection \\300x300mm lycra
Component_02 \Vertex connection \\300x300mm lycra
Component_05 Edge connection 300x300mm lycra two aligned cuts
Component_06 \Edge connection \\300x300mm lycra \\\ dicrections
Connection
Minimal Cuts
The importance of “interrupting“ the continuous membrane surface is deemed to be huge in terms of enabling the component and the aggregations of components to “dialogue” with the environment either by modulating light or
by providing different response to both wind and rain. The way in whcih these apertures are achieved were the aim of the first investigations carried out on the component. Given the parameters outlined in the previous section, it Page 8
Component_03 \Edge connection \\300x300mm lycra \\\100x100 frame
Component_04 \Edge connection \\300x300mm lycra \\\R=50mm circ. frame
Inner Frames
Component_07 \Edge connection \\300x300mm lycra \\\linear array with varying angle
is immediately clear how a great range of variations can be obtained by simply exploring (i) the different connection type between the frame and the membrane, (ii) the possibility of introdcuing an inner frame withing the membrane
Component_08 \Edge connection \\300x300mm lycra \\\polar array with constant angle
and (iii) introducing different sizes and patterns of “minimal cuts�. The effect of such cuts are shown in the following pages.
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2.2.1 Empirical tests [1] On light: the effect of minimal cuts and tongue orientation on light modulation.
Component_07 [tongue: open; anchor points: 2] Direct sunlight when sun at zenith:
[tongue: closed; anchor points: 2] Direct sunlight when sun at zenith:
Component_07 and _08 were used to understand the effects that different arrays and sizes of minimal cuts can have on light modulation. It was understood that a major role in filtering the amount of direct sunlight that hits the interior is played by the direction of the
“tongues� in the minimal cuts. This, on the other hand, is controlled by the number and the position of the anchor points. Overall, it was understood that changing these simple parameters multiple different results can be obtained. It was also understood that apertures-
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Component_08 [tongue: open; anchor points: 2] Direct sunlight when sun at zenith:
[tongue: closed; anchor points: 1] Direct sunlight when sun at zenith:
such as minimal cuts- in the membrane could offer an excellent opportunity to regulate wind flow across the aggregation and possibly release surface pressure (see following sections). However, the greatest limitation of minimal cuts- or at least it has been seen as
a limitation for the designers- is the presence of the pulling cables. These would effectively act as “external elements� which our design tried to avoid in the first place.
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2.2.2 Empirical tests [2]
On membrane resistance: the effect of different connection types and frames on tensile strength.
Component_01 \Edge connection \\300x300mm lycra tensile strength:
30°
45°
60° [frame bending]
90° [frame bending]
Component_02 \Vertex connection \\300x300mm lycra tensile strength:
30°
45°
Once the membrane is connected to the frame and pre- stressed (in all of the above examples it is stretched by 30% more than the initial size in all directions) the component will be subjected to a tensile force (of the membrane) that will try to keep it closed. It was understood that by connecting the membrane to the frame in different ways (component_01 and _02) and by inserting a new smaller frame within the membrane
60° the membrane tensile’s strength would be altered. Understanding the behaviour of the membrane under different conditions was crucial not only to achieve overall equilibrium of the aggregation (where every component is pulling in the opposite way of the adjacent ones, contribuitng to global equilibrium), but also to determine the upper scalability of the component. From these empirical tests, in fact, it was understood
~90° that the frame undergoes a very high amount of bending due to the high tensile strength of the pre-stressed membrane. Although some tolerance (i.e. on deflection) is allowed, our aim was to keep the deflection under a controlled range. For this reason, FE tests were carried out on single components, The results of these tests shown in the following section.
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Component_03 \Edge connection \\300x300mm lycra \\\100x100mm frame
45°
60°
Component_04 \Edge connection \\300x300mm lycra \\\R=100mm circ. frame
~30°
45°
60°
tensile strength:
90° [frame bending] tensile strength:
90°
[frame bending]
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2.3.1 Frame FE Analysis On frame size and upper scalability Displacement:
Axial Stress:
400mm component
400mm component [mm]
[MPa]
148.9
0.027
0
0.001
1500mm component
1500mm component
[mm]
[MPa]
538.4
0.082
0
0.004
1800mm component
1800mm component
[mm]
[MPa]
732.5
0.099
0
0.005
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Axial Stress: [mm] 400mm component
1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0
1500mm component 1800mm component
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
[MPa] Displacement:
[mm] 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0
400mm component 1500mm component 1800mm component
100
200
300
400
The components used for physical experiments are with 400mm side of the quadrangular frame. In order to determine the upper scalability of the components, we tested digital models with 400mm, 1500mm and 1800mm side. We applied the same amount of pre-stress on the fabric (30% stretched) and same material properties and cross-section on the frame. After comparing the results we established that the ratio beam length – displacement changes inversely with the increase in length. In other words, the longer the beam, the smaller the displacement is and the larger the hinge angle
500
600
700
800
900
1000
[mm]
is. Therefore to achieve a particular angle with larger components we need to apply pre-stress with higher value, compared to the smaller components. The same principle applies for the frame axial stress. We did not test larger components. The upper scalability is not determined by the conducted structural analysis of a single component. The proposed site aggregations are with components with 1800mm side. This size was chosen for assembling and construction process reasons. Page
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2.3.2 Frame FE Analysis On section type and frame size
After choosing a component size, we tested a digital model with different values of pre-stress on the fabric. We established the relationship between amount of fabric tension and hinge angle. Smaller hinge angles can be achieved with higher values of pre-stress compared to larger hinge angles. When a global form is aggregated, the values from these tests are used for determining the exact value of pre-stress that is needed for achieving the hinge angle for every component.
max = 0.4 M 20° 30° 40° 50° 60° 70° 80° 90°
10°
10°
[MPa] 0.4
20° 30° 40° 50° 60° 70° 80° 90°
min = 0 MP
0
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Box section size: 100mm x 100mm
Hollow circular section diameter: 150mm \ thickness: 20mm [mm]
[mm]
300
Hollow box section size: 100mm x 100mm \ thickness: 20mm
0
[mm]
150
0
Strip size: 300mm x 50mm
[mm]
350
750
0
0
We applied to a digital model the amount of pre-stress needed for the smallest hinge angle in the proposed aggregations. After determining the node reactions in the beams when the component is open to a maximum by external force, we conducted several tests in order to establish the most suitable beam cross-section and size. According to the results, the beam with circular hollow cross-section deflects the least. This is why we chose bamboo for frame material. The circular cross-section has one more advantage – when an aggregation is assembled, it allows rotation between the components without doubling the frame. Beam cross-section and deflection [mm]
800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0
H = 300mm B = 50mm
R = 120mm
H = 100mm B = 100mm
H = 100mm B = 20mm
500
1000
1500
2000
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2.4 Double-layer
Digital form-finding & qualitative understang of state of stress in membranes.
01_edge connection
03_edge connection+5holes
[N] 80
640
02_vertex connection
04_vertex connection+4membranes [N]
0
400
In order to proceed more swiftly into testing the different types of membrane connections and geometries digital form-finding was carried out using the Grasshopper physical simulation plug-in Kangaroo. The meshes created using this technique can then be used to carry out any type of testing on such geometries in a digital environment. In the case of the double layers especially, the meshes were analysed for wind flow using a flow design software and for light qualities using a rendering tool. It was also understood that if the form finding was carried out in a very consistent manner, keeping the same number
of warp and weft springs, as well as the spring rest length (i.e. the membrane pre-tension) and spring stiffness (memebrane material quality), then the different results could have been qualitatively compared to understand not only the different state of stress inside the membrane, but also the different reaction at the supports. This sort of tool has several limitations in terms of accuracy and reliability of results, however, it was deemed to be acceptable when trying to give a qualitative and immediate understanding of the membrane’s behaviour. Further development of this tool could include tuning the
model parameters to the different membrane types in order to obtain results that can be interpreted quantitatively as well. Overall, the importance of carrying out such tests relies on the fact that in an aggregation every component is connected to each other, and the state of stress in one signle hypar will affect the performance and geometry of the whole system. A deeper understanding of this relationship is also part of the future advances of this project.
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Single layer
Support reactions [N] 320
0
Axial force in membrane (warp & weft)
Double Layer +
+
[N] 20
250+
Fibre density of membrane
Warp springs : 400
Weft springs: 400
Pre-stres of membrane
Fabric properties
Spring rest length: 0.7L
Spring length: 0.025m
1000 N/m
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3.1 Conditions Considered
Masthouse Terrace Pier’s environmental factors considered in design
Path Diagram 01 Sun Spherical Projection Location: 51.4, 0.0
N
E-51.487760,N-0.021727
40 1st Jul
1st June
60 80
270
90
1st Dec
1st Jan
180
Rose 02 Wind (Speed and N. of hours) N
270
90 10 km/h
Hours [h] 606+
20 km/h
30 km/h
424 242
40 km/h
<60
180
Site Map of precipitation 03 Probability at some point of the day (%)
The site being a pier is vulnerable to almost all environmental factors having no high buildings or objects to help cope with high wind, extended exposure to the sun and high/ low tides. Designing a spatial configuration should have a system performance based on its morphology along with the consideration of its access point as the major function of the peir is to embark and desembark from the ferry. However, the amount of sun exposure is less and quite suiteable for human comfort but the main issues where persistently high wind speeds and the dampness of the site due to frequent yet moderate rains over the year.
A light weight structure having a system made of fabric seemed suitable for such a context. The fabric shields from wind while also providing translucent light inside the spatial arrangement. The access points helped create the initial orientation, planning of spaces on site. Other consideration taken into account was the basic functions like waiting, passage, view to see the coming and going of ferry.
[chance]
light rain
70% 60%
moderate rain
[month]1
2
3
4
5
6
7
8
9
10
11
12
Access Points & 04 Site Flow Paths Ramp
s
e
id
hs
t ou
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3.2 The site: plan of intervention The different areas of intervention and cluster strategy
Shading
Wind Protection
Porosity
Clearance
Waiting Area 1 The space provides maximum covered area to cope with the function of seating and queing requirement before the arrival of the incoming ferry. It also holds the maximum amount of sheltered area connecting the two major access points.
Embark/Desemabark Points
The form of the gateways are designed keeping in mind the need to have visibility of the ferries with the right clearance. The aperture of embark/desembark points needs to be adequate inorder to reduce the incoming wind which has a negative surface pressure on the waiting area 1 creating more risk of collapse.
Wind Shields Wind shield is provided to withstand the incoming wind towards the semi-open waiting area. Different features have been introduced to maintain the comfort level in the saptial sonfiguration along with visibility.
Waiting Area 2 Waiting area 2 is the desembark point hence acting as a mobile space with medium shielding and sufficient visibility of the river. However, the wind velocity is exposed to a maximum on the form due to its location which forced us to develop different levels of support conditions. Page
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4.1 Component proliferation The system’s limitations and drivers for proliferation
System limitations hinge location
agg. angle
radial vs. linear
Proliferation drivers structural/ spatial min. width
max & min height
curved footprint
Environmental light qualities
Before carrying out the proliferation of the components to form the three different aggregations, an accurate distinction between the limitations and the drivers had to be done. Due to the unique geometry and setup of the component, the limitations mainly concern the geometrical or spatial constraints that apply to the aggregation of such hypar components. For example, the location of the hinged connection always has to meet in adjacent components, or the angle between two adjacent components
wind speed/ surface pressure
has to be greater than 180° for them to work or “pull” in opposite ways. The drivers were divided into two categories: structural/ spatial and environmental. Spatial drivers included achieving certain clearance for the passage of people, while a structural driver was to obtain as much as possible a curved footprint on the ground to maximise the aggregations resistance to lateral loads. Finally the two main environmental qualities that were tackled were the light (or shading) qualities, and the reduction of wind
speed inside the aggregation with subsequent reduciton of surface pressure on sensible components. Once these limitations and drivers were set out, one can proceed to form the aggregation using the process explained on the next page.
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4.2 Proliferation process Tools and techniques adopted for proliferation
Global aggregation geometry
hours of shading analysis
New Global geometry
Ladybug
Rhino Rhino
Flow analysis
Double layer form
Kangaroo FlowDesing
Local and regional structural analysis
(missing)
key: Strand7+ Karamba
Once the “rules” (i.e. the limitations and dirvers) by which the aggregations can be formed, the process by which this is done can be expalined. Since it was not possible to create an algorithm for such proliferation (although we intend to do so for future developments of the project), the way in which the components were aggregated is very similar to a conventional “design loop”. Such loops consisted in the typical “design, test, evaluate” paradigm where the process is never truly completed (i.e. there is no
“final design”) but it is terminated when results are deemed to be satisfactory. This way, initial aggregation of 5 to 8 components were first designed, then their performance for shading and wind control was tested, informed by the level of performance more components were added to the aggregation, repeating this loop, until it was deemed to have reached and accepatable size. Although it was intended to, structural analysis did not feed into the design process informing the growth of the
aggregation
double-layer
aggregation as it was carried out only as a final step. For this reason, it is intended in future to include such test and evaluation even in the earlier stages of the growth. To this process we must add the formfinding and qualitative evaluation carried out with a physics engine to simulate the performance of double-layers. These were in fact inserted in areas of the aggregations identified during the growth project (see the next section). Page
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4.3.1 Initial Wind Test on minimal cuts Introducing porosity and edge conditions at local scale
Edge Support
Edge support _01 18 16 14 12 10 8 6 4 2 0
none
1 center
2 narrow
2wide
4 center/wide
1 center
2 narrow
2wide
4 center/wide
Edge support_02 18 16 14 12 10 8 6 4 2 0
none
As the entire system works in equillibrium understanding the edge support condition becomes very important. The balance between surface pressure and wind velocity with the least drag coefficient was the main focus of this exercise. We observed that support having point achorage with respect to linear edge support shows a decrese on parameters considered given the right angle of the hypar [See edge support 1,2,3]. The support conditions where compared with placement, size and number of cuts on the fabric. The addition of more cuts came with an idea of increasing the surfaceâ&#x20AC;&#x2122;s porosity and response
to different enviornmental conditions. Higher amount of holes equally cut disepates wind and keeps the pressure to a minimum. See figure [A] and [B]. The angle of the tongue allows for wind flow to be directed controlling the wind inside the spatial configuration. Comparing different angles of the tongue give a conclusion that when the air flow towards ground radically reduces wind velocity making the best solution for wind damping & surface pressure release.
Tongue direction/angle Edge support _03 18 16 14 12 10 8 6 4 2 0
none
[upwards]
1 center
2 narrow
2wide
[downwards]
4 center/wide
Minimal Cuts
Wind Velocity[m/s]
figure [A]
[Hole location] 10
[1 Centre]
0
Surface Pressure [Pa]
7
[2 Centre]
10
[2 Wide]
10
[4 Centre]
8
0
0
0
0
20
20
20
20
20
-20
-20
-20
-20
figure [B]
-20
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4.3.2 Initial Wind Test on aggreagation Design response based on the most dominating aspect on site 20
-20
A1
Wind Velocity[m/s]
[Pa]Surface Pressure
Based on the anchor points several different aggregations where studied and analysed with increase in number of components. The aggregation demonstrated a unique response to wind velocity, surface presure and the drag coefficient.
20
20
0
B1 24
The study gave results showing how the system profile facing windward significantly changes with change in shape and aggregation density. -20
A2 10
Further analysis helped us control the wind flow on the local components and the orientation effects on its adjacent components with the global scale.
0
B2 11
Concave surface helps create less surface pressure and lower wind velocity inside the spatial arrangement. See B1,B2 & B3. -10
A3
Convex surface was observed having similar properties but at a much lesser pressure and minimum velocity of wind. See B4, A3.
19
-19
0
B3 11
Void in between aggregation having open gateway parallel to the windward side also had a significant decrease in pressure. Circular void has best results creating a vortex inside strucuture with reduced wind velocity. See A3, A4 and B5.
0
A4
B4 12
9
Arch form provides the most efficient streamline profile with least effects against velocity and pressure. See B4, A5. -12
A5
0
B5
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4.4 Initial Shading Test
Understanding the basic results of shading at regional scale 3B
3D
4B
Summer Solstice
shading :
shading :
shading :
Winter Solstice
4C
shading :
5A
shading :
5B
shading :
Summer Solstice
shading :
shading :
shading :
Winter Solstice
shading :
The aggregation at regional scale with cluster having components from 4 to 5 were tested for shading during all the year. The experiment cannot be considered precise as the system is composed of bamboo frame and lycra fabric giving more translucent light than the ones we considered having a solid plane. However, it does give a qualitative
shading :
shading :
understanding of the shadow patterns and how with different cuts, double membrane and component proliferation imporves the shading performance of the system. The surface profile exposed to the incident sun can be manipulated by the amount of shading required.
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5.1 Design 1 Proliferation Aggregation 1 proliferation logic & evaluation
Proliferation of each aggregation was a back and forth process evolving at every stage based on drivers mentioned above. The adopted algorithm implied that at every stage the performance of the cluster in terms of wind velocity, surface pressure, light quality and view aperture should be adequate. The idea of double membrane was
introduced to add more strength to the system at a local level to components that are experiencing high surface pressure. The evolution of the wind shield started with linear proliferation with convex funnels holding the high winds. The hinge angles of each local component ranges from 45° to 60°. Interlocking of two components had more or less no rotation as change
in linearity regulated change in the negative wind response. Components with double membrane experienced the maximum surface pressure.
Stage_01 9 components
Surface Pressure
Pa
Wind Velocity 15
-23
m/s 10
0
Stage_02 12 components
Surface Pressure
Pa
Wind Velocity 10
-10
m/s 10
0
Stage_03 12 components 3 double-layers
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5.3 Design 2 Proliferation The system logic used to proliferate the deign
Stage_01 8 components
An arch gate towards the embark point with wider aperture, however the structural performance was reduced by the wide span.
Views + Accessibility (at 1.8m height) Hours of sunlight
Velocity/Surface Pressure
Hrs
Pa
50
13
0
-45
Stage_02 12 components
Hrs
=Access/views =Blocked
The queing zone had less anchor points and is supported on the neighbouring aggregations. Hence, the rotation between the angle is controlled by stage 01 proliferation. Visibility was made directional. However, there was no change in the sun exposure. Pa
50
18
0
-38
Stage_03 12 components 3 double-layers
Hrs
Final evolution rectifies the previous issue in addition to accomodate the waiting area 1 and also connecting the access point to the site. Geometry formed on the canopy between components was always hexagons allowing more feasibility on the design parameters. Pa
50
19
0
-20
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5.4 Design 3 Proliferation The system logic used to proliferate the deign
Stage_01 5 components
The arch gateway contrarily to what previous tests suggested, could not be kept parallel to the wind direction as we also intended to provide views towards the desembark points.
Views + Accessibility (at 1.8m height) Hours of sunlight
Velocity/Surface pressure
Hrs 50
0
Pa 20
-47
=Access/views =Blocked
Stage_02 8 components
Pa 17
Hrs 50
0
-40
Stage_03 13 components 3 double-layers
Hrs 50
0
The arch gateway is now fully exposed to prevailing winds. However, because of the narrow area on which it stands, the aggregation required further support.
We introduce supports as there was lesser availability of ground area onto the ramp after acheiveing a certain height so as to obtain allowbale clearance. Having support greatly reduced the pressure and velocity also solving the issue of having clear visibility line. Pa 21
-20
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5.5 3D views
Views from inside and overall view of the pier from outside
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5.6.1 Global form analysis Digital self-weight tests of the aggregations
[mm] 20
0
After proceeding with several component based structural tests and establishing the exact size, cross-section and material of the frame, an overall structural analysis of the global form was needed. We tested on self-weight load all proposed aggregations. Although the displacement values in all cases are low and donâ&#x20AC;&#x2122;t affect the stability of the structure, we are concerned by
[mm] 50
0
the fact that the proposed frame size is calculated based on the highest possible pre-stress values. As a further development of the system, an optimisation of the beam cross-sections needs to be conducted.
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[mm] 5
0
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5.6.2 Global form analysis Membrane and frame structural analysis As one of the componentâ&#x20AC;&#x2122;s elements is a hinged angle, such angle could be controlled not only by amount of fabric pre-stress, but also purely geometrically by connecting one component to another. An aggregation could be assembled with components with the same value of fabric tension and variable one. In order
to understand what the effect of the two different solutions have on the structure, we tested digitally on wind load the same aggregation in two cases â&#x20AC;&#x201C; with constant pre-stress (highest possible) and variable pre-stress. The displacement and stress values in the digital model with constant pre-stress are higher compared to the one with variable pre-stress. This is a
result of the decreased strength of the pre-stressed fabric when a force is applied perpendicular to the surface. Therefore, a different amount of tension should be applied on the separate components of an aggregation and the size of the beams should be optimised for these values.
Constant pre-stress
Displacement [mm] 60.6
Stress
0
[MPa] 0.03
-0.12
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Variable pre-stress [MPa] 0.17
Displacement
0.10
[mm] 53.1
Stress
0
[MPa] 0.02
-0.11
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5.7 Connections
Single and double-membrane to beam, hinge and fixed connections Single-layer mambrane / frame connection
Double-layer mambrane / frame connection upper membrane offset distance metal rod
membrane
lower membrane
beam
Fixed connection
metal / 3D printed connection socket
150+mm M12 Bolts
Hinged connection
metal hinge 100mm M12 Bolts rotation angle angle between two components
The membrane is being attached to the bamboo beams by 150mm bolts in the case of a single-membrane and metal rods are being used for the components with double-membrane with varying length depending on the distance between separate membrane layers. For hinged connection we propose a metal hinge, which allows one degree of rotational freedom. For fixed beam connection we propose a 3D printed joint, as the angle between two beams of a component and the angle between separate components is variable in an overall aggregation and a universal joint cannot be used. 3D printing technology offers relatively fast and mass manufacturing of unique elements. Page
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Physical model in the EmTech studio
6.1 Conclusion
Where has the project failed and succeded
Rendered aerial view of the entire pier as seen from the river
Throughout the different aspects of the design carried out in this project there are several areas of success and failure that must be pointed out. The project has failed in providing a detailed description of the connection between elements (or at least has provided only an approximate solution to the problem). Hence it has also failed in providing a complete set of specifications that would allow the design to be built. Indeed, as it will be explained in the next sections,as of today, the work done necessary
to erect the aggregations is far from sufficient. However, from this project many different interesting points for further development have been brought out and several new skills have been acquired. First of all, the possibility of having a foldable leightweight structure that could be erected on site within minutes indeed triggers our imagination. In order to work on such a feature it is also understood that the dynamics and the sequence of erection must be studied and detailed carefully as they will inevitably affect the
way in which this structure might proliferate. Finally, the project has also given us the opportunity to develop new skills, especially regarding form finding techniques using digital tools and structural analysis of complex membrane components.
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6.2 Future Advances
How can the project be developed further
Rendered view of the northwest corner of the pier.
Throughout the report, there are several areas that have been highlighted for future development. Although the project has opened some interesting opportunities for the design and construction of such unique leightweight structures, the amount of detailing work done necessary to erect them is far from sufficient. For this reason we believe that the first area of interest for future development should be the detailed design of both the fixed and the hinged nodes, with great care given to the nodes where multiple
beams (more than two) connect. Conventional ball-joints have been suggested for fixed cases, however, it is unclear what could be the best solution for hinged joints. Together with the detailed design of such joints we also believe that a FE anlaysis should be developed in order to understand the forces that run through them. Furthermore, we have not been able to create a global model where the membrane pre-stress is a force experienced by the frame. This can be done by analysing the relationship between
the angle of aperture of the frame and the forces experienced on it, then, such forces can be simulated by applying external loads on every beam. Due to time constraints, it was not possible to do so. Finally, although we do not deem it to be necessary, it is also intended to develop a digital algorithm for the proliferation of the components in order to obtain new aggregations.
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Architectural Association School of Architecture Graduate School Programmes COVERSHEET FOR SUBMISSION 2014-2015
PROGRAMME: Emergent technologies & Design TERM: 1
STUDENT NAME(S): Giulio Gianni, Kuber Patel, Antoniya Stoitsova SUBMISSION TITLE: Core Studio I Documentation
COURSE TITLE: Emtech Core Studio I COURSE TUTOR: Evan Greenberg SUBMISSION DATE: 14.01.2015 DECLARATION: “I certify that this piece of work is entirely my/our own and that any quotation or paraphrases from the published or unpublished work of others is duly acknowledged.” Signature of Student(s):
(Antoniya Stoitsova)
(Giulio Gianni)
(Kuber Patel)
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