hani hossein

Comparison of Thickness of Frame Glass and the
Diameter of Hole of Junction Backrest to the
Structural Glass under Axial Compressive Loads
Hani Baghi, Seyyed Hossein Hosseini Lavasani
Abstract
Loads tolerance in-plane is basically a very important issue in terms of glass structures.
Glass structures are connected in two forms to each other and then to the substructure:
1. point Connection
2. Linear connections
Point Connection is common in this regard. Little research has been done on the glass
structures, so in this article, the effect of the thickness of the glass plane and also diameter
of the holes on the junction of the glass frames and backrest tension at the junction of the
frame is investigated. By observing the results it can be concluded with an increase in
thickness and diameter anchor holes in the junction of the glass frame, glass tension in the
frame decreases that increasing hole diameter more effectively to increase the thickness
of the glass frame to reduce tension in the frame.
Key words: Glass Structures, Pressure Loads inside the Plane, the Thickness of the Glass
Frame, Nonlinear Analysis
© 2015 BBT Pub. All rights reserved.
Introduction
Nowadays, due to advances in the glass industry and also rising demand for people to use the outside of the
building, the architects convinced to use of glass in architecture more. With regard to the role of glass in the
construction of buildings, there are different loads. These loads are imposed in addition to the vertical loads (e.g.
wind load) to glass components and bearings, are in the tensile or compressive loads. Examples of structural
blocks in Figure 1 are shown.
A
B
Figure 1- Examples of Glass Structure: B) the Glass House, Neuquén (America)
S) Farnsworth House, Plano (America)
Connecting Glass structure components to each other is done in two forms:
1. Connection point: on this type of connection glass frame are connected to each other by the anchor point (direct
connection) at the four corners of the glass frame.
2. Linear connection: In this type of connection, glass frame are connected to each other linearly through a doubleedged paste shortest.In the meantime, the connection point is more common. Inside page loads in this type of
support by fitting the screws are transferred to the frame glass. Pressure force of connections affected on the glass
hole because of the stress concentration.Overend [Overend 2002] investigated experimental and numerical
research on the connection point on the dubbing frame of the glass under load screen. His research and
experiments showed that when the coefficient of friction between the screw and the glass are reduced, the point of
maximum stress load is transferred into ° 90 of the. Linear material between the screw and the glass produce a
rigid connection, while the linear material PTFE produce a flexible connection. This difference has not relatively
large impact on the strength of connections, but linear of PTFE produce a hard point work is ahead of schedule.He
also conducted a test on linear anchor, with adhesive tape in order to better identify and compare it with the
anchor point. He has expressed his findings in a high load, linear anchor is inefficient ahead of point anchor. In
linear anchors, tend to deform near the moment of failure increases rapidly. The primary difficulty of adhesive is
much more in linear anchor than the point anchor. Length failure of the linear anchor is almost a third anchor
point. Blandini [Blandini 2005] examined numerical and analytical laboratory on some kind of glue (epoxy, acrylic,
polyurethane) and to study the behavior of tensile, shear and bending at different temperatures and different
loading and Yeoh numerical models is the most appropriate test results, which was used to simulate the glue
behavior. In standard temperature (+23°), glue shows up non-linear elastic behavior in the final temperature
H.Baghi, S.H.H.lavasani/ Teknologi Tanaman /Vol (12), Supp (2) 2015
245
(+80°) tested glue strength greatly reduced. In some cases, because of the high temperature adhesive behavior is
without loading. Final limit negative temperature (-20°) much lower resistance, which becomes brittle behavior.
Glue DP490 only under conditions shows acceptable behavior, but it is very little information about the thermo
mechanical behavior. Maniatis [Maniatis 2006] examined the bearing capacity of screw connections on the glass
frame under the burden of inside page based on the mechanism of communication theory and research Hertz and
important results about the connection between the screw and the hole in the glass plates is reached. Researches
analytical, numerical and laboratory have been directed to focus on parameters. This research has shown that
different linear material has little effect on the distribution of power around the hole. Reduce the gap between
screw and the hole, increases the force on the surface of the hole until the maximum tensile force of change. Daniel
Mocibob [Daniel Moci Bob] in 2009 conducted some researches and has its results in these terms: load bearing in
glass structures is important is related with a screen and transfer their loads during a connection point. Due to the
fact that In introduction inside page loads, structural stability and mechanical damage to axial tensile loads have
been studied in great abundance, but for axial compressive loads, especially when that does not happen twisting
component has not been studied.In his own research into the issue of the distribution of power, stability and
mechanical failures of small glass has been subjected to compressive forces. He uses laboratory samples and also
benefited from numerical examples. He concluded that the distribution of power and crack of the mechanical
failure occurs on the tension for tension and compression force.He believes that the main source of tension cracks
is significantly less than the compressive axial force. Glass frame damage caused by compressive axial force during
a complex power level is not a simple power distribution in the design of glass to be used in a practical manner.
In this article example of the connection point that has been tested by researchers in the laboratory, examined and
then the numerical modeling and finally the effect of increasing the thickness and increase the diameter of the
holes in the anchor to the frame glass junction is examined.
Research Laboratory
Danijel Mocibob and Jan Belis in 2009 carried out experimental and numerical studies on the behavior of many
glass structures under compressive loads by fulcrum point. In this paper, a research laboratory on the frame of the
glass with fulcrum point under compressive loads were presented and discussed.
Sample
They cover three types of glass with different thicknesses 6 and 8 mm studied in the laboratory. These laboratory
samples with dimensions of 200 x 500 mm composed of two glass that has two holes (∅42mm) one on top of the
other at the bottom of the sample and also connections have formed fulcrum point.Material Hilti HIT HY 50, the
hole in the glass, between glass and metal, is injected. Force F into the glass case in the center of symmetry created
systems and linear force is applied to the glass frame. The connection between the screw and the glass is rigid.
M20 screw connection point of a metal, a metal pipe and a metal cylinder and the rigid connection between glass
and metal. Between metal and glass cylindrical linear material (POM) is placed. The sample is tested under
compressive load Fc. (Figure 2)
A
B
C
Figure 2. Glass frame components under compressive load inside page
(A) Front view (b) side view, (c) details of connection
Methods
The samples shown in Figure 2 show, under a compressive axial load and also axial tensile located. Glass frame
displacement during testing and also distribution around the hole and also middle of the span, respectively, by the
variable differential transformer (LVDT) and also pressure to be measured.
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Test Results
Measuring machine, the force F and the displacement of the sample length δL (including glass frame longitudinal
displacement and also deformation injection) is measured. In Table 1 and Table 2 failure in the Ffailure and also
ultimate longitudinal displacement δL,failure for tensile load and also compressive load is shown.
Table 1- sample under tensional load Ft
Sample
1*6-1
1*6-2
1*6-3
2*6-1
2*6-2
2*6-3
2*8-1
2*8-2
2*8-3
Ffailure
[KN]
19:12
18.92
19:48
33.68
30.44
23:52
48.88
46.04
51.12
δL,failure
[KN]
6.97
5.70
7.55
2.54
2.25
2.33
2.34
2.64
2.51
Table 2- sample under compression load Fc
Sample
1*6-1
1*6-2
1*6-3
2*6-1
2*6-2
2*6-3
2*8-1
2*8-2
2*8-3
Ffailure
[KN]
14:34
15:08
12:05
24.56
20:04
32.80
38.92
39.48
49.80
δL,failure
[KN]
3.96
7.78
1.75
3.58
2.92
2.33
1.58
2.23
2.78
In Table above-order frame of the first number of layers of glass, the second number the glass thickness of the
glass frame and the third one sample is tested; For example, the order of 2*8-1, the first glass frame with two
layers of glass with a thickness of 8 mm.Chart 1 Show Fc compressive force to deform longitudinally and chart δL
4-2 and deformation of the longitudinal Ft tensile force δL for Glass frame with different thicknesses (only a test
curve is drawn, for example.)
Figure 1. Diagram of compressive force by deformation of the glass frame in the laboratory
Chart 2. Chart tensile force according to deformation of glass frame in the laboratory
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Verification sample
In this frame of the glass that was tested in the laboratory using ABAQUS finite element software model and then
compare its results with experimental results.
Numerical Modeling
In this section, numerical model glass frame loaded along the screw into the hole, which was discussed in the
previous section using the finite element software to model it. Numerical modeling consists of the following stags:
Construction of the constituent elements, material properties, mesh the model, fulcrum of the sample
Sample loading and sample analysis methods
Results deformation and stress distribution
Validation examples: Comparison of numerical results with experimental samples
Making a Model
Due to the symmetry of the prototype, can be used to save computing time and also memory, only half the samples
in finite element modeling. (Figure 3) All geometry and also material properties, such as the number of laboratory
samples is considered.
Figure 3. Example of numerical modeling
For numerical meshing example of the manually mesh is used. Approaching into the hole, for a finer mesh is more
accurate results.Since half of the sample is given a numerical model, the boundary conditions at the bottom of the
model based on the symmetry axis is considered which prevents displacement in the y-direction is vertical and
two horizontal displacement in the x and z happens. If the boundary conditions at the end of the screw to prevent
screw displacement in x and z direction and thus screw can be displaced in the y-direction.
Table 2 shows the properties of the materials used to build the model. (Material low, modulus of elasticity E,
Poisson's ratio ν and material yield point fy)
Table 2. Material properties for modeling connection point
ν [-]
Material
Glass panel
Material low
linear
E [N/mm2]
70000
0.23
fy [N/mm2]
-
Mortar
linear
2780
0.30
-
PVB interlayer
linear
1.5
0.49
-
Pin
bilinear
210000
0.3
235
Bolt
bilinear
197000
0.3
900
Results
In this section we review the results of modeling and compared with experimental results.
Figure 2 is shown a longitudinal compressive force Fc to change δL for glass frame modeling as well as the
deformation of longitudinal compressive force Fc and medium δL obtained from laboratory experiments.
Figure 2. Comparison Chart compressive force according to deformation, for numerical modeling sample with
laboratory samples
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Due to the amount of compressive force Fc to change the length δL obtained from experimental results and also the
values of compressive force Fc to change the length δL, obtained by numerical examples modeled and compared
these values can be seen with glass frame 6 * 1 about 1% and about 10% longitudinal deformation in the amount
of compressive force defeat, glass frames 6 x 2 about 6% in longitudinal deformation and about 7% in the amount
of compressive force defeat and glass frame 8 x 2 about 14% of longitudinal deformation and failure disagree
about 9 percent in the amount of compressive force.Figure 3 is shown δL longitudinal tensile force Ft to
deformation the glass frame modeling as well as the tensile force Ft and longitudinal deformation δL, the average
obtained from laboratory experiments.
Figure 3. Comparison of tensile force according to deformation graph, for numerical modeling sample with
laboratory samples
Given the amount of tensile force Ft to change the length δL obtained from experimental results and also the values
of tensile force Ft to change the length δL obtained from numerical modeling samples and compared these values
are observed, glass frames 6 x 1 7% longitudinal deformation and about 3 percent in the amount of tensile force
defeat, glass frame 6 * 2 about 12% longitudinal deformation about 11% of in tensile force of failure and glass
frame 8 2 About 6% in longitudinal deformation and differ about 4% in the amount of power failure.
By comparing the graphs compressive force Fc to change the length δL and also charts the tensile force Ft to change
the length δL, for sample experimental and numerical modeling examples, it can be concluded that the numerical
model is valid and reasonable and realistic results.
Static load applied to the sample
According to the results of the last valid sample, in this section, KN20 compressive load to the frame of the glass
modeled with different thickness and also different holes diameters acts and then compare our results.
Compressive load applied to glass with a glass frame 6 mm
At this stage in finite element software, glass pane glass with a diameter of 32 mm, 42 mm and 62 mm can be
modeled. Glass specifications and boundary conditions quite similar to laboratory sample intended; glass injection
frame and fulcrum inner radius between 15 mm and 10 mm diameter pin is intended and the M20 screw is used,
the distance between the centers of the hole to the edge of glass frame is 100 mm. (Figure 4)
Figure 4. Glass frame 6 x 1 100 mm from the center of the hole to edge
Figure 5 shows the stress distribution around the hole for glass frame 6 x 1 with diameters hole of 32, 42 and 62
mm also under compressive load.
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A
B
C
Figure 5. Distribution of stress around the glass frame 6 * 1; (A) 32 mm diameter holes (B) holes diameter 42 mm;
(C) 62 mm diameter hole
Figure 4 shows the stress distribution around the hole in glass frame.
80
D=64
mm
σc [N/mm2]
60
40
20
0
-180
-135
-90
-45
0
45
-20
angle , α[°]
90
135
180
Graph 4. The graph of stress distribution around the hole in glass frame 6 x 1 100 mm from the edge
Graph 5. Shows the distribution of time to frame glass.
80
σc [N/mm2]
60
D=32
mm
40
20
0
-20
0
0.2
0.4
0.6
0.8
1
1.2
Time [Min]
Graph 5. The stress distribution according to the glass frame 6 x 1 100 mm from the edge
Compressive load applied to glass pane with two glass plates 6 mm
At this stage in finite element software, glass frame with two layers of glass between 1.52 mm and 6 mm and a
holes center distance of 100 mm from the edge of the frame with a diameter of 32 mm, 42 mm and 62 mm can be
modeled. Glass specifications and boundary conditions quite similar to laboratory sample intended; glass injection
frame and fulcrum inner radius between 15 mm and 10 mm diameter pins and screws M20 has been considered.
(Figure 6)
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Figure 6. Glass frame 6 x 2 with 100 mm center holes to edge
Figure 7 show stress distribution around the holes for glass frame 6 x 2 holes with diameters of 32, 42 and 62 mm
under compressive load.
A
B
C
Figure 7. stress distribution around the glass frame 6 * 2; (A) 32 mm diameter holes (B) 42 mm diameter holes (C)
62 mm diameter holes
Graph 6 shows the stress distribution around the holes glass frame.
40
D=32
mm
σc [N/mm2]
30
20
10
0
-180
-135
-90
-45
0
45
-10
angle , α[°]
90
135
180
Diagram 6. Graph stress distribution around the holes glass frame 6 * 2 at a distance of 100 mm from the edge
Graph 7 shows distributed according to time for glass frame.
40
D=32
mm
σc [N/mm2]
30
20
10
0
0
-10
0.2
0.4
0.6
0.8
1
1.2
Time [Min]
Graph 7. Stress distribution according to the glass frame 6 * 2 at a distance of 100 mm from the edge
3.3 compressive load applied to glass pane with two glass plates 8 mm
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At this stage in finite element software, glass frame with two layers of glass between 1.52 mm and 8 mm and a
holes center distance of 100 mm from the edge of the frame with a diameter of 32 mm, 42 mm and 62 mm can be
modeled. Glass specifications and boundary conditions quite similar to laboratory sample intended; glass injection
frame and fulcrum inner radius between 15 mm and 10 mm diameter pins and screws M20 has been considered.
(Figure 8)
Figure 8. Glass frame 8 x 2 with 100 mm center holes to edge
Figure 9 shows the stress distribution around the holes for cover glass 8 x 2 holes with diameters of 32, 42 and 62
mm also under compressive load.
A
B
C
Figure 9. stress distribution frame around the glass, 8 * 2; (A) 32 mm diameter holes (B) 42 mm diameter holes
(C) 62 mm diameter holes
Graph 8 shows the stress distribution around the holes glass frame.
30
D=32
mm
25
σc [N/mm2]
20
15
10
5
0
-180
-135
-90
-45
45
-5 0
angle , α[°]
90
135
180
Graph 8. The Graph of stress distribution around the holes glass frame 8 * 2 100 mm from the edge
Graph 9 shows the distribution of time to frame the glass.
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30
σc [N/mm2]
25
D=32
mm
20
15
10
5
0
-5 0
0.2
0.4
0.6
Time [Min]
0.8
1
1.2
Graph 9. Stress distribution according to time frame glass 8 x 2 with 100 mm from the edge
According to figures 4, 6 and 8 can be concluded that by increasing the diameter of the hole in the cover glass,
reduced stress. Graphs can also be deduced by observing the maximum stress on the frame blocks in the lowest
junction fulcrum to the frame glass happen; glass frame with a hole with a diameter of 32 mm, this stress is
reduced at low speed so that the tension in the upper half of the entrance holes at the highest point (° 180 ±)
becomes zero.But in the frame of the glass with a hole with a diameter of 42 mm at a speed higher than the
maximum stress glass frame with 32 mm hole diameter is reduced, as for the tension in the middle of the upper
half holes (±135°) to zero and in frame of the glass with a hole with a diameter of 62 mm, stress high speed has
been reduced to zero if the tension in the upper half holes.As in Figures 5, 7 and 9 can be seen, over time,
increased tension in the glass frame, with the difference that by increasing the diameter of the holes, the rate of
increase in stress is reduced, as for the tension in glass with a diameter of 62 mm frame with a gentler slope than
the stress in the glass case with a diameter of 32 mm to reach its maximum level.Stress also can be seen in the
frame of the glass with a hole diameter 62 mm longer than the frame to glass with a diameter of 32 mm holes is
zero, because of injection layer is thicker than that of self-restraint stress transfer to the glass frame.As can be
seen in Figure 10, by increasing the thickness of the glass frame, maximum stress are reduced and by comparing
this rate of decline than the decrease of maximum stress on the frame of the glass with different hole diameter, can
be concluded that the effect of increasing diameter to reduce the maximum stress in glass frames to increase the
thickness of the glass frame is much higher.
80
σc [N/mm2]
1*6
60
2*6
40
20
0
20
30
40 D [mm] 50
60
70
Graph 10. Stress distribution according to the diameter of the hole in the frame of the glass with different
thickness and common connections
Conclusions
In this section the results of the behavior of glass frames with different layers, different thickness and different
holes diameter is expressed.
1. According to the figures provided in Section 3 can be concluded that by increasing the diameter of the hole in the cover glass,
reduced stress on glass frame. Also, the maximum stress on the frame blocks in the lowest junction fulcrum to the frame glass
happen; glass frame with a hole with a diameter of 32 mm, this Stress is reduced at low speed so that stress in the upper half of
the entrance holes at the highest point (±180°) becomes zero, but in the frame of the glass with a hole with a diameter of 42 mm
at a speed higher than the maximum stress glass frame with 32 mm hole diameter is reduced, as for the tension in the middle of
the upper half holes (±135°) to zero and in the frame of the glass with a hole with a diameter of 62 mm, the stress of high speed
has been reduced to zero if the stress in the upper half holes.
2. It can also be concluded that, over time, increased stress in the glass frame, with the difference that by increasing the diameter
of the holes, quickly tensions can be eased, as for the tension in glass with a diameter of 62 mm frame with a gentler slope than
the stress in the glass case with a diameter of 32 mm to reach its maximum level. Stress also can be seen in the frame of the glass
with a hole diameter 62 mm longer than the frame to glass with a diameter of 32 mm holes is zero, Because of injection layer is
thicker than that of self-restraint stress transfer to the glass frame.
3. With compare reduce tension and reduce stress by increasing the thickness of the holes diameter can be concluded, effect of
increasing diameter to reduce the maximum stress in glass frames to increase the thickness of the glass frame is much higher.
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253
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Hani Baghi, Master of Science Student, Department of Engineering, Roudehen Branch, Islamic Azad University,
Roudehen, Iran
Email:[email protected]
Seyyed Hossein Hosseini Lavasani, Assistant Professor, Department of Civil Engineering, Faculty of Engineering,
Kharazmi University, Tehran, Iran