1. INTRODUCTION
Single-layer cable net supported glass curtain walls are
a new kind of structure with the advantages of
simplicity, lightness and transparency. They are widely
used in airport passenger terminals, exhibition centers,
gymnasia and hotel halls. Since the stiffness of the
single-layer cable net is much decided by the geometric
nonlinearity, the deflection of the structure is large, and
in practice the theoretical deflection is often found
to be greatly different to the practical one. One key
consequence of this phenomenon is that we always
neglect the effect of the glass panels. The problem we
are now facing is to decide the extent to which glass
panels influence the cable net and under what
circumstances we should take the effect of the glass
panels into consideration.
As a new kind of structure, the research mainly
concentrated on the mechanical behavior of the glass
panel. Saitoh et al. (2001) compared the deformation
and stresses of a glass panel with two kinds of
connecting joints. Jan et al. (2001) performed a static
experiment in order to determinate the load-carrying
capacity of an armored glass panel. Wang (2002)
summed up the factors which affect the load-carrying
capacity of a glass panel with the sunk type joint. From
the technological and morphological point of view,
Vyzantiadou (2004) put forward the requirements for
the fixed-point joints. However, there is little related
research on the problems posed by the writers. In order
to solve the above problems, the feasible ways through
which glass panels work in coordination with the cable
net are proposed. Relevant model experiments and
finite element simulations have been conducted to
verify them. In addition, the influence of factors, such as
cable pretension, severity of loading, cable diameter,
glass thickness and glass mesh size, on the coordination
work between the glass panels and the cable net have
been analyzed.
Advances in Structural Engineering Vol. 10 No. 2 2007 183
Working Mechanism of Single-layer Cable Net Supported Glass Curtain Walls
Ruo-qiang Feng1,2*, Yue Wu2 and Shi-zhao Shen2
1Shen Zhen Graduate School, Harbin institute of Technology, Shen Zhen 518055, China
2Space Structure Research Center, Harbin institute of Technology, Harbin 150090, China
(Received: 29 August 2005; Received revised form: 4 December 2006; Accepted: 21 December 2006) Abstract: In this paper experiments and numerical simulations were undertaken to
investigate the working mechanism of single-layer cable net supported glass curtain
walls. We brought out the feasible ways in which glass panels work in coordination
with the cable net, and verified by experiments. A parameter study was used to analyze
the influence of factors, such as cable pretension, severity of loading, cable diameter,
glass thickness and glass mesh size, on how glass panels worked in coordination with
the cable net. The results indicate that the bending stiffness of the glass panel has little
effect on the deflection of the structure, and the stiffness contribution of glass panels
to the structure is substantially decided by the glass face membrane action. This action
depends on the deflections of the glass panel and cable net.
Key words: point-supported glass curtain wall, cable structure, glass structure, work in coordination.
*Corresponding author. Email address: hitfeng@163.com; Fax and Tel: ?86-755-2603-5924.
Associate Editor. K.F. Chung
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184 Advances in Structural Engineering Vol. 10 No. 2 2007
2. WORKING MECHANISM OF GLASS
IN COORDINATION WITH CABLE
Single-layer cable net supported glass curtain wall
consists of three components: pretensioned cables,
connecting joints and glass panels. The four corners of a
glass panel are linked to cables at the joints, and the
open space between glass panels is filled with silicone to
form a weather-tight curtain wall. The load-transfer
path is: wind load??glass panels??connecting joints??
pretensioned cables??foundations or other supporting
structures.
The way that glass panels work in coordination with
cable net is closely related to the forms of joints that
connected glass panels together. Two types of joints, a
fixed-point joint and a clamped joint, are used in
practical engineering frequently, as shown in Figure 1
and Figure 2, respectively. The difference between the
two types of joints is in the way that they connect the
Figure 1. Fixed-point joint
Figure 2. Clamped joint
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Ruo-qiang Feng, Yue Wu and Shi-zhao Shen
Advances in Structural Engineering Vol. 10 No. 2 2007 185
glass panels. The fixed-point joint is connected with the
glass panel through the metal bolt drilled through the hole at the corner of the glass panel, while the glass
panel is clamped in the joint through the metal fasteners. The fixed-point joint is taken as an example to illustrate the working mechanism of the glass panels working in coordination with the cable net.
Details of the connection between the fixed-point joint and glass panels are shown in Figure 3. Based on the characteristics of the connection, two ways through which the glass panels work in coordination with the cable net are presented:
1As glass panels have bending stiffness, they are similar to statically indeterminate roof panels in the transfer of wind load on the glass panel and influencing the structural displacement of the cable net.
2When the glass panels are installed, there is a gap
between the joint and the edge of the hole at the corner of the glass panel in the plane, i.e. a clearance fit. Joints and holes are fabricated to machine accuracy, and the clearance fit between them is generally within 1 mm. When the glass panel deforms under wind load, the gap between the joint and the glass panel will be reduced or disappear. When the clearance fit disappears, the joint will touch the glass panel and there will be tension between the joint and the glass panel, as shown in Figure 4. Thus every glass panel is effectively joined together to form a complete glass face and has an effect on the stiffness of the cable net, as shown in Figure 5.
In addition, silicone is used to join every glass
panel together to a certain extent. Young’s modulus of silicone however is very small, and the influence of the silicon is much less than that of the glass panel. Furthermore, there is an ageing problem in silicone. The influence of silicone was therefore not considered in this study.
To sum up, the stiffness contribution of the glass panels to a cable net mainly consists of two ways, bending stiffness of the glass panel and membrane
action of the whole glass face. The focus of this paper is to study the influence of the above two effects of glass panels on the stiffness of a cable net through model experiment and numerical simulation.
Bore connection
(a) Connection between joints and glass (b) Details between glass bore and metal joint K
K
Flexible link
Metal bolt
Figure 3. Sketch of the connection between fixed-point joint and glass panel Tension between glass and joints
Cable
Figure 4. Glass panel deformation under wind load
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3. CABLE NET FACADE MODEL
EXPERIMENT WITH CLAMPED JOINTS
The connection details between clamped joint and the
glass panel are shown in Figure 6. Since the glass panel is clamped in the joint through the metal fasteners, there is no tension between the joints and the glass panel.
Therefore there is no membrane action but the bending stiffness of the glass panel to the clamped joint, which is the two ways of glass panels’ influence on the stiffness of cable net. We can observe the influence of the bending stiffness of the glass panel on the stiffness of a cable net through model experiment with clamped joints.
3.1. Experimental Model
There are two kinds of experiment model; cable net and cable net with glass, as shown in Figure 8 and Figure 9,
respectively. The size of the model is 2.95 m ??2.95 m
with the mesh size of glass of 0.375 m ??0.375 m.
The ratio of similitude to the real structure is 1:4, the
mesh of the cable net is 0.375 m ??7 (from top to
bottom),0.375 m ??7 (from left to right), the layout of
displacement measuring nodes,force sensors and axes of the cable net is shown in Figure 7. The diameter, the
Young’s modulus and breaking tension of the stainless steel cable are 4 mm, 1.03 ??105 MPa and 10 kN,
respectively. The thickness of armored glass is 4 mm,
and the steel frame is made of square tubes with the
length of 150 mm and 8 mm in thickness. Considering
the change of pretension of cable and the low stiffness of silicone, silicone is not applied in experiment.
3.2. Experimental Arrangements
and Procedures
1) Under the same conditions of load and pretension, the cable net model experiment was conducted
first, and then the cable net with glass model
experiment was conducted. By comparing the
deflections and cable forces between the two
models, the stiffness contribution of the glass
panel can be attained.
The membrance froce of
glass face
Figure 5. The membrane force in glass face
Armored
glass
Front
press platen
A
A–A
A
Rubber
blanket Stainless cable
Fastener
Retainer plate
Stainless cable
Figure 6. Sketch of the connection between clamped joint and glass panel ASE 10-2-06 (5-397) 22/3/07 8:29 am Page 186
Ruo-qiang Feng, Yue Wu and Shi-zhao Shen
Advances in Structural Engineering Vol. 10 No. 2 2007 187
2) In order to investigate how the stiffness
contribution of the glass panels relates to the
deflection of the structure, three different
cable pretensions, 2.5 kN, 1.875 kN, 1.25 kN
were adopted. The stainless steel cable was
overdrawn to eliminate the inelastic deformation
before the experiment.
3) For the convenience of the experiment, the
actual vertical structure in practice was tested
horizontally, and gravity load was thus used
to simulate wind load. Wind load was
wk ??1100 N/m2, and five classes of loading were
employed. When the cable net model experiment
was conducted, load was applied to the cable net
by adding sandbags in the nacelles tied to the
cable net nodes, as shown in Figure 8. When the
cable net with glass model experiment was
conduced, uniformly distributed load was applied
to the surface of the glass panel with sandbags, as shown in Figure 9.
3.3. Analysis of Experimental Results
The stiffness contribution of glass panels to the cable net is defined by Eqn 1.
Cg ??1?Ug/U (1)
Where Ug, U are the deflections of the cable net with glass and cable net alone, respectively.
The distribution of the glass stiffness contribution in the three cases is shown in Figure 10, Figure 11 and Figure 12, respectively. It can be seen that the stiffness contribution at the corners and sides is greater than that in the middle of cable net, and they are all below
4.5%; In the cable net with glass model, the largest deflections in the three cases are 1/44,1/39,1/34 of the cable net span, and the stiffness contribution is all less than 1%. The comparison of the largest cable forces are shown in Figure 13, Figure 14 and Figure 15,
respectively. It can be seen that the largest cable forces in both models are almost same, the difference is less than 2%.
In these experiments, the thickness of glass was
4 mm, representing a real structure thickness of 16 mm when the size of glass is 1.5 ??1.5 m. This means that the bending stiffness of our experimental glass is greater than would apply in a real full size case; at the same
time the deflections of the structure in the three cases are large, i.e. 1/44,1/39,1/34 of the span of the structure, and Sensor
36 30 24 18 12 6
35 29 23 17 11 5
34 28 22 16 10 4
33 27 21 15 9 3
32 26 20 14 8 2
31
375 375 375 375 375 375 375
375 375 375 375 375 375 375
2781
2781
25 19 13 7 1
Figure 7. Layout of measuring system
Figure 8. Cable net model
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188 Advances in Structural Engineering Vol. 10 No. 2 2007
since the deflections of the nodes which connected the glass panel and cable net are very different from each other, it can be seen that therefore the bending stiffness of the glass panels would have been
fully developed. Even in that case, the stiffness
contribution is very small, and especially for the nodes with bigger deflections, it can be neglected. Thus we can deduce that the bending stiffness of glass panels has little effect on the overall structural behaviors and can be neglected when structural deflection is calculated.
4. CABLE NET FACADE MODEL
EXPERIMENT WITH FIXED-POINT JOINTS
Based on the above experimental result, that the bending stiffness of glass panels makes little stiffness contribution to the cable net, only the membrane action of the whole glass face could influence the stiffness of the cable net in the model with fixed-point joints.
4.1. Experimental Model
The size of the model is that of the single-layer cable net glass curtain in Harbin International Exhibition Center, Figure 9. Cable net with glass panels model
0 0.04 0.017 0.007 0.009 0.021 0.045 0
0 0.021 0.017 0.013 0.012 0.01 0.02 0
0 0.001 0.011 0.012 0.01 0.013 0.007 0
0 0.009 0.013 0.011 0.012 0.012 0.009 0
0 0.019 0.019 0.014 0.011 0.015 0.021 0
0 0.043 0.02 0.007 0.011 0.02 0.041 0
0 0 0
0 0
Figure 10. Distribution of glass contribution in case 1
0 0.044
0.018 0.005 0.007 0.018 0.042 0.011 0.008 0.014 0.012 0.007 0.01 0.007 0.011 0.008 0.023 0.014 0.009 0.006 0.015 0.009 0.011 0.013 0.006 0.014 0.008 0.015 0.015 0.006 0.012 0.04 0.016 0.007 0.007 0.017 0.038 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
0 0
Figure 11. Distribution of glass contribution in case 2
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Ruo-qiang Feng, Yue Wu and Shi-zhao Shen
Advances in Structural Engineering Vol. 10 No. 2 2007 189
with a ratio of similitude is 1:1. The cable net mesh is 2.6 m ??2.8 m ??2.8 m ??3.2 m (from top to bottom),
2.7 m ??2.5 m ??2.7 m (from left to right), as shown in Figure 16. The diameter, the Young’s modulus and the breaking tension of the stainless steel cables are 22 mm,
1.31 ??105 MPa and 304.8 kN, respectively. The thickness of mid-hollow armored glass is 10 mm ??12 mm ??
12 mm ??34 mm, and the steel frame is made of two I-sections, the pipe is 152 mm in diameter and 6 mm in thickness. The layout of displacement measuring
nodes, force transducer and cable net axes are shown in Figure 17.
0 0.039
0.011
0.009
0.007
0.015
0.03
0.015
0.007
0.005
0.007
0.006
0.014
0.009
0.009
0.006
0.008
0.009
0.006
0.008
0.009
0.008
0.005
0.008
0.007
0.01
0.006
0.004
0.006
0.006
0.013
0.035
0.017
0.007
0.007
0.011
0.033
0 0
0 0
0 0
0 0
0 0
0 0 0
0 0
Figure 12. Distribution of glass contribution in case 3 0 20 40 60 80 100 120 140 160 180
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
Cable force(N)
Panel load (N)
Cable net?glass
Cable net
Figure 13. Comparison of the largest cable force in case 1 0 20 40 60 80 100 120 140 160 180 200
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
Cable force (N)
Panel load (N)
Glass?cable net
Cable net
Figure 14. Comparison of the largest cable force in case 2 0 20 40 60 80 100 120 140 160 180
1800
2000
2200
2400
2600
2800
3000
3200
3400
3600
3800
4000
Cable force (N)
Panel load (N)
Glass?cable net
Cable net
Figure 15. Comparison of the largest cable force in case 3
Experimental arrangements and procedures were the
same as in the previous experiments. Two cases of
different cable pretension were tested: pretension of
70 kN and 60 kN in long cable and shot cable in case 1;
80 kN and 70 kN in case 2.
4.2. Analysis of Experimental Results
The deflections of the cable net with glass and the cable net alone are listed in Table 1 and Table 2, and the
largest deflections of cable net with glass in both cases are reduced to 85% of those of the cable net alone. Thus the glass panels can improve the stiffness of the cable net. At the same time the cable forces in the net in two models change little, as shown in Table 3 and Table 4.
Because the variation of cable force, while depending
on the increment of structural deflection, is less than that ASE 10-2-06 (5-397) 22/3/07 8:30 am Page 189
Working Mechanism of Single-layer Cable Net Supported Glass Curtain Walls 190 Advances in Structural Engineering Vol. 10 No. 2 2007
as a glass stiffness contribution to the cable net.
Consequently the variation of cable force is not listed in the following section.
5. NUMERICAL SIMULATION
OF THE EXPERIMENTAL MODEL
The numerical simulations of the experimental model
with fixed-point joints were undertaken by ANSYS,
a widely used commercial FE package. The cable was
modeled with cable element LINK10, the steel beam
was modeled with beam element BEAM4, and the steel
joint was modeled with beam element BEAM188. The
key to the numerical simulations is the connection
between the glass panel and the fixed-point joint, which needs to meet the following demands: 1the connection
between the glass panel and the fixed-point joint is
hinged, and the deflections vertical to the glass face of them are everywhere the same; 2the gap between the
joint and the glass panel in the plane of the glass face is a clearance fit (below 1 mm). When the structure
deforms under wind load, the clearance fit is reduced,
and then it disappears, so the membrane force can be transferred between panels. Therefore the methods used 1in this study are: the freedoms vertical to the glass face between the glass panel and the joint are coupled; 2the spring element “COMBIN39” is used to simulate the clearance fit between the glass panel and the joint, and the stiffness of the springs changes with its elongation. When the elongation of the spring is less than 1 mm, the stiffness of the spring is very small, and the tension of the springs is nearly zero; when the elongation of the spring is greater than 1 mm, the spring turns to be a rigid body connecting the glass panel and fixed-point joint together, the membrane fore between them can thus be transferred.
It can be seen in Table 5 and Table 6 that the
theoretical and experimental results show little difference, and the error is within 5%. The Numerical simulations do reflect experimental behavior of glass panels acting
coordinately with the cable net, and the techniques used in the numerical simulations are correct.
6. PARAMETRIC ANLYSIS OF CABLE NET
WITH GLASS PANELS
In order to further investigate the mechanism of glass panels working coordinately with a cable net, a parametric study of a cable net with glass panels of size 15 ??15 m was made by the FE method, considering changing the factors of cable pretension, class of loading, cable diameter, glass thickness and glass mesh.
In designing a structure, what we care most about is the largest deflection, therefore the stiffness contribution of the largest deflection is the most important. For the f152?6
f152?6
f22
3200 2800
11400
2800 2600
2700 2500
I36a
2700
7900
Figure 16. Experimental model
A2 B2 C2 B1 C1
2700
3200 2800 2800 2600
2500
A1
A B C D
A3 B3 C3 A4 B4 C4 A5 B5 C5 2700
Force
transducer
Dial gauge
2
1
1 2
3
4
5
c
4
5
3
b
a a
b
c
Figure 17. Arrangement of surveying points
of structural deflection, glass panels have more effect on
the deflection of the cable net but less effect on the cable
force. Therefore the influence of the glass panels when
working integrally with the cable net mainly influences
the deflections of the cable net, and it can be regarded
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Advances in Structural Engineering Vol. 10 No. 2 2007 191
Table 1. Comparison of nodal deflections between cable nets with/without glass panels in case one Class of loading Node B2 B3 B4 C2 C3 C4
1 wk UG (mm) 108 131 109 107 131 110
U (mm) 121 154 134 121 154 134
UG/U (%) 89.3 85.1 81 88.4 85.1 82
Table 2. Comparison of nodal deflections between cable nets with/without glass panels in case two Class of loading Node B2 B3 B4 C2 C3 C4
1 wk UG (mm) 107 140 117 112 140 123
U (mm) 128 165.8 138 132 165.8 145
UG/U (%) 83.5 84 84.7 84 84.8 84.8
Notes: U and UG are the deflections of cable net and cable net with glass, and nodes are shown in Figure 17. Table 3. Comparison of cable forces between cable nets with/without glass panels in case one Class of loading Cable number 1 2 3 4 5
1 wk TG (kN) 88.52 89.11 92.23 100.24 97.72
T (kN) 91.73 91.49 94.69 104.2 100.12
TG/T (%) 96.5 97.4 97.4 96.2 97.6
Table 4. Comparison of cable forces between cable nets with/without glass panels in case two Class of loading Cable number 1 2 3 4 5
1 wk TG (kN) 77.39 78.11 83.67 91.92 90.28
T (kN) 83.3 84.51 86.73 98.12 93.93
TG/T (%) 0.929 0.924 0.965 0.937 0.961
Notes: T and TG are measured cable forces in cable net and cable net with glass, and cable number is shown in Figure 17.
Table 5. Comparison of nodal deflections between experimental and theoretical results in case one Class of loading Node B2 B3 B4 C2 C3 C4
1 wk UL (mm) 103 127 111 103 127 111
UG (mm) 108 131 109 107 131 110
UL/UG (%) 95.4 97 101.8 96.3 97 100.9
Table 6. Comparison of nodal deflections between experimental and theoretical results in case two Class of loading Node B2 B3 B4 C2 C3 C4
1 wk UL (mm) 108 138 122 108 138 122
UG (mm) 107 140 117 112 138 123
UL/UG (%) 101 98.6 104 96.4 100 99.2
Notes: UG and UL are the experimental and theoretical results, and nodes are shown in Figure 17.
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192 Advances in Structural Engineering Vol. 10 No. 2 2007
convenience of comparison we only list the stiffness
contribution of the largest deflection Cgmax. The
membrane force in the whole glass face is the resultant
membrane force of all the glass panels, as shown in
Figure 5. At the same time the ratio Pgc of the membrane
force of the whole glass face to the resultant cable forces
is used to indicate the magnitude of the membrane force
in the whole glass face, and is called the membrane
force ratio.
6.1. Influence of Glass Thickness
Figure 19 shows that the glass stiffness contribution
decreases with the increase in glass thickness. However,
when the glass thickness is greater than 14 mm, the
glass stiffness contribution become constant. That
contradictions the idea that thicker glass would provide
a greater stiffness contribution, but it is in accordance
with the change of the membrane force in the whole glass face. Table 7 shows that the membrane force changes significantly between glass thickness of 8 mm and 14 mm. When the glass thickness is greater than 14 mm, the membrane force changes little.
The above phenomenon can be explained as follows:
There is a clearance fit between the fixed-point joint and the glass bore at the corners of the glass panel. When the glass panel deforms under wind load, the distance between ends of the glass panel is shortened, and the clearance fit disappears, the joint mechanism contacts the glass panel and there is tension between them, thus the membrane force is transmitted to the cable net. If the glass is thinner, the deflection of the glass panel
becomes larger, the clearance fit disappears earlier, the membrane force works earlier and the glass stiffness contribution to the cable net is larger. This also explains why the glass stiffness contribution decreases as the glass thickness increases. It needs to be pointed out that when the glass thickness increases to a certain value, the bending stiffness of the glass panel becomes very large and the deflection of the glass is small under wind load, therefore the membrane force deceases gradually and turns to be constant. In general, we can deduce that as the two ways in which glass panels work in coordination with a cable net, under the symmetrical static wind load, the membrane force in the whole glass face plays the dominant role, and the bending stiffness of the glass panel has little effect. In order to verify the above
deduction, we studied the influence of clearance fit on the glass stiffness contribution.
In most cases, the clearance fit is between 0.5 mm and 1 mm, and the clearance fit in the finite element model was 1 mm. Figure 20 shows that the glass stiffness contribution has a close relationship with the size of a clearance fit in glass bore. When the clearance is 3 mm, the connection between the glass and fixed-point joint is loose, little tension is transferred, and the membrane force is nearly zero. The glass stiffness contribution is only 0.95%, so the bending stiffness of the glass panel does a little influence to the deflection of the cable net. Thus verified is the above deduction that the membrane force plays the dominant role and the bending stiffness of the glass panel can be neglected.
This is in consistence with the above experimental results in 3.3.
6.2. Influence of Cable Pretension
Figure 21 shows that the membrane force ratio and glass stiffness contribution decrease with the cable pretension. This is because if the cable pretension is lower, the
deflection will be bigger, the clearance disappears earlier, and the membrane force works earlier. Thus the glass Figure 18. The analytical model of cable net with glass
8 10 12 14 16 18
10.50
11.25
12.00
12.75
13.50
14.25
10.3% 10.31% 10.33%
10.8%
11.3%
12%
13.7%
Glass stiffness contribution /%
Glass thickness/mm
Figure 19. Influence of glass thickness on glass contribution ASE 10-2-06 (5-397) 22/3/07 8:30 am Page 192
Ruo-qiang Feng, Yue Wu and Shi-zhao Shen
Advances in Structural Engineering Vol. 10 No. 2 2007 193
stiffness contribution to cable net is larger. This
shows that the glass stiffness contribution holds a close relationship to the deflection of the cable net.
6.3. Influence of Severity of Loading
Figure 22 and Figure 23 show that the glass stiffness contribution and membrane force ratio increase with load. The larger the load, the larger the deflection. Hence the relationship between glass stiffness contribution and load can be represented by that between glass stiffness contribution and deflection.
6.4. Influence of Cable Diameter
Figure 24 shows that the relationship between the glass stiffness contribution and the cable diameter is
approximately linear, and the glass stiffness contribution decreases between 12% and 18% with increase of cable diameter. At the same time, the membrane force ratio is proportional to cable diameter and decreases with cable
diameter. The smaller the cable diameter, the larger the
deflection, similarly, the relationship between glass
stiffness contribution and cable diameters can also be
represented by that between glass stiffness contribution
and the deflection of the cable net.
Table 7. Influence of glass thickness on glass stiffness contribution and membrane force Glass thickness (mm) 8 10 11 12 14 16 18
Glass stiffness contribution (%) 13.7 12 11.3 10.8 10.3 10.31 10.41
The membrane force (kN) 159.3 128.1 113.1 98.5 83.5 74.5 72
The largest cable force (kN) 103.2 103.4 103.4 103.4 103.4 103.4 103.2
0.5 1.0 1.5 2.0 2.5 3.0
10
20
30
40
50
60
10
20
30
40
50
Membrane force ratio change along with clearance fit 60
Glass contribution change along with clearance fit
Membrane force ratio /%
Glass stiffness contribution /%
Clearance fit/mm
Figure 20. Influence of glass clearance on glass contribution and
membrane force
20 40 60 80 100 120
10
20
30
40
50
60
70
80
10
20
30
40
50
60
70
80
Membrane force ratio change along with pretension
Glass contribution change along with pretension
Membrane force ratio /%
Glass stiffness contribution /%
Cable pretension/kN
Figure 21. Influence of cable pretension on glass contribution and membrane force
0.25 0.50 0.75 1.00
4
8
12
16
20
24
Glass stiffness contribution /%
Class of loading
Cable pretension
20 kN
40 kN
60 kN
80 kN
100 kN
120 kN
Figure 22. Influence of class of loading on glass contribution
6.5. Influence of Glass Mesh
The glass mesh should not be too big or too small, and in a range of between 1.2 m and 2.4 m in common.
With increase of size of glass mesh, the membrane force and glass stiffness contribution increase linearly,
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because: when the glass mesh is larger, the deflection of glass and the reduction of the distance between ends of the glass are greater, so the membrane force would work earlier; the number of cables is fewer, so the deflection of the cable net is larger. This is illustrated in Figure 25.
6.6. Discussion
Through analysis of the influence on glass stiffness
contribution, of glass thickness, cable pretension,
severity of loading, cable diameter and glass mesh, it is obvious that the glass stiffness contribution is mainly due to the two factors, the deflections of the glass panel and the cable net. As long as the strength and deflection specifications are met, the thinner glass is preferred, since the deflection, the membrane force and glass
stiffness contribution is greater. When the glass
thickness is determined, the glass stiffness contribution is decided by the deflection of the cable net. Therefore the glass stiffness contribution relative to the deflection of cable is listed with all parameters in Figure 26 and Figure 27.
The deflections of the cable net are shown in
Figure 26. It can be seen that under wind load wk, the glass stiffness contribution is decided by the deflection of the cable net. Figure 27 shows that under different cable pretensions, only when the deflection reaches
Working Mechanism of Single-layer Cable Net Supported Glass Curtain Walls 194 Advances in Structural Engineering Vol. 10 No. 2 2007
14 15 16 17 18 19 20
12
16
20
24
28
32
12
16
20
24
28
32
Membrane force ratio change along with cable diameter
Glass contribution change along with cable diameter
Membrane force ratio /%
Glass stiffness contribution /%
Cable diameter/mm
Figure 24. Influence of cable diameter on glass contribution and membrane force
1.4 1.6 1.8 2.0 2.2 2.4 2.6
10
20
30
40
50
60
70
10
20
30
40
50
60
70
Membrane force ratio /%
Glass stiffness contribution /%
Glass mesh/m
Membrane force ratio change along with glass mesh %
Glass contribution change along with glass mesh %
Figure 25. Influence of glass mesh on glass contribution and membrane force
260 280 300 320 340 360 380 400 420 440 460
4
8
12
16
20
24
28
32
Glass stiffness contribution /%
Deflection of cable net /mm
Deflection under different cable pretension
Deflection under different glass mesh
Deflection under different cable diameter
Figure 26. Influence of deflection on glass contribution under different conditions
0.25 0.50 0.75 1.00
10
20
30
40
50
60
70
80
Membrane force ratio /%
Class of loading
Cable pretension
20 kN
40 kN
60 kN
80 kN
100 kN
120 kN
Figure 23. Influence of class of loading on membrane force
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Ruo-qiang Feng, Yue Wu and Shi-zhao Shen
Advances in Structural Engineering Vol. 10 No. 2 2007 195
a certain level is the glass stiffness contribution
significant, when the level of the deflection is 1/70 of the span of cable net. When the deflection of the cable net is above this level, the glass stiffness contribution increases in an approximately linear manner.
7. CONCLUSION
(1) The bending stiffness of the glass panel itself has little effect on the glass stiffness contribution to
the coordinate work with the cable net and can
be neglected.
(2) The glass stiffness contribution depends on
the membrane action of the whole glass face,
and extent of the membrane action depends on
the deflection of the glass panel and cable net.
(3) The deflection of the glass panel is determined by glass thickness and mesh size. When glass
thickness is thin and glass mesh is large, the glass stiffness contribution is significant.
(4) The deflection of the cable net is influenced by cable diameter and pretension. When cable
diameter and pretension are small, the deflection
and glass stiffness contribution are large.
The conclusions in this paper are drawn for the
symmetrical cable net subject to a static uniformly distributed wind load. Thus the deflection of the cable net is distributed uniformly and the curvature is small. Consequently the bending stiffness of the glass panels has little effect on the largest deflection of the cable net. However, a fluctuating wind load is always asymmetrical,
and the effect of the bending stiffness of the glass panel may be more complicated. This needs further investigation.
ACKNOWLEGMENTS
This research is financially supported by the National Natural Science Foundation of China under the grant number 50478028.
REFERENCES
Feng, R.Q. (2002). Study on Cable Structure of Point Supported Glazing and Design Software Development, Master Thesis,
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Jan, B. and Rudolf, A. (2001). “Glass and steel structure”,
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Saitoh, M., Okada, A. and Imamura, R. (2001). “Study on glass
supporting system pinched at corner structural characteristics and structural design method”, Proceedings of International
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Spatial Structures, Nagoya Japan, September.
Shen, S.Z., Xu, C.B. and Zhao, C. (1997). Design of Cable Structures, China Architecture & Building Press, Beijing, China (in Chinese). Vyzantiadou, M.A. and Avdelas, A.V. (2004). “Point fixed glazing systems: technological and morphological aspects”, Journal of Constructional Steel Research. Vol. 60, No. 6, pp. 1227–1240.
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Wang, Y.Q., Shi, Y.J., Yang, W. and Ma, Y. (2003). “Calculating analysis and experimental study of loading-carrying properties of sunk-typed point-supported monolayer glass plate”, Journal of building structure (in Chinese), Vol. 24, No. 6, pp. 72–78.
Wu, Y., Guo, H., Chen, X.L. and Shen, S.Z. (2002). “Study on windinduced vibration of a large-span dot point glazing supporting
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APPENDIX: NOTATION
Cg : glass stiffness contribution to cable net
Ug : deflection of cable net with glass panels
U : deflection of cable net
Cgmax : glass stiffness contribution of the largest
deflection
Pgc : ratio of membrane force of the glass face to the resultant cable forces
50 100 150 200 250 300 350 400 450
?2
2
4
6
8
10
12
14
16
18
20
22
Glass stiffness contribution /%
Deflection under different cable pretension and load /mm Cable pretension
20 kN
40 kN
60 kN
80 kN
100 kN
Figure 27. Influence of deflection on glass contribution under different pretensions and load
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