Proceedings of the Institution of Civil Engineers
http://dx.doi.org/10.1680/stbu.13.00011
Paper 1300011
Received 11/02/2013 Accepted 04/04/2014
Keywords: buildings, structures & design/dynamics/wind loading &
aerodynamics
ICE Publishing: All rights reserved
Structures and Buildings
Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
Smart glass facade subjectedto wind loadingsFilipe Amarante dos Santos PhDProfessor of Civil Engineering, Centro de Investigacao em Estruturas eConstrucao – UNIC, Faculdade de Ciencias e Tecnologia, UniversidadeNova de Lisboa, Quinta da Torre, Caparica, Portugal
Pedro F. Goncalves MScGraduate Student, Centro de Investigacao em Estruturas e Construcao –UNIC, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa,Quinta da Torre, Caparica, Portugal
Corneliu Cismasiu PhDProfessor of Civil Engineering, Centro de Investigacao em Estruturas eConstrucao – UNIC, Faculdade de Ciencias e Tecnologia, UniversidadeNova de Lisboa, Quinta da Torre, Caparica, Portugal
Mauricio Gamboa-Marrufo DPhilProfessor of Civil Engineering, Facultad de Ingenierıa UniversidadAutonoma de Yucatan, Yucatan, Mexico
The design of a modern glass facade translates an architectural aspiration for transparency. Innovative technological
solutions have made it possible to materialise a transparent planar surface, exploring the load-bearing capabilities of
the glass itself. Facades also need to have back-up structures, which are designed to withstand seismic and wind
actions. This paper analyses the behaviour of a ‘smart’ glass facade, based on a bow-string truss solution, which is
able to continuously adapt its shape in order to compensate for the wind dynamic displacements, affecting the
structural appearance. The wave superposition method is used to generate samples of the wind distributions, using
sinusoidal functions. A proportional–integral–derivative control strategy enables a significant reduction of the
displacements shown by the facade during wind events. This design approach yields an optimised structural solution
in terms of weight, allowing the materialisation of a very light facade.
NotationA, B, C, D coefficients
B(s) feedback stress signal
b dimension in across-wind direction
C amplitude of the harmonic function
C(s) cable stress output signal
c damping coefficient (Ns/m)
cp,e pressure coefficient for the external surface
d dimension in along-wind direction
E(s) actuating error signal
Fw force in the able system due to detonator (N)
f frequency (Hz)
fL dimensionless frequency
Gc(s) controller transfer function controlled process
Gcp(s) transfer function
H(s) feedback-path transfer function
h height of facade
Kd derivative gain
Ki integral gain
Kn generalised nodal stiffnesses (N/m)
Kp proportional gain
Ku ultimate gain
k stiffness (N/m)
L turbulence scale
m mass (kg)
n natural frequency (Hz)
Pu ultimate period (s)
p load excitation (N)
qp wind dynamic pressure (Pa)
R(s) reference cable stress input
SL spectral density function
s complex variable
T control force (kN)
Td derivative time
Ti integral time
Tw force in the cable system due to wind (N)
t time
U(s) output signal of controller
u displacement (m)
v instantaneous wind speed (m/s)~vv turbulent fluctuations of wind speed (m/s)
vm mean wind speed (m/s)
we wind pressure on the external surface (Pa)
z height (m)
� damping ratio
r air density (kg/m3)
� time variable (s)
�k phase angle (rad)
øD damped frequency (rad/s)
øn natural frequency (rad/s)
1. IntroductionModern glass suspension techniques, exploiting the load-bearing
capabilities of glass, enable the elimination of structural elements
from the glass pane. The materialisation of a transparent planar
surface can only be truly achieved if the back-up structures, which
are designed to support the seismic and wind forces, are reduced
to their minimum expression. These structures can vary from
glass mullion systems, using glass fins, to steel trusses and cable-
stayed systems (tension structures). In either of these systems, a
1
close integration of glass and steel is of utmost importance in
order for the complete facade to meet high performance require-
ments (Dutton and Rice, 1996; Schittich et al., 1999).
Various forms of cable-stayed back-up system designs can be
used to support a glass facade. They can take the form of simple
steel trusses, with a secondary rigging system, yielding the most
rigid structural solutions, or bow-string trusses and cable tension
structures, with increased transparency (Nijsse, 2003; Vyzantia-
dou and Avdelas, 2004; Wurm, 2007). Cable trusses have the
disadvantage of generating high tensile loads in the boundary
structure, which needs to be stiffer. In all instances, the capabil-
ities and loading of the glass must be used as the basis of the
design for the back-up structural system.
An adequate glass suspension system must be able to cope with
the weight of the glass elements as it braces the facade against
wind and seismic loads (Dutton and Rice, 1996). The glass
facade itself, while responding dynamically to the wind excita-
tion, must have sufficient strength to resist wind-induced forces
and adequate stiffness to satisfy serviceability criteria.
The purpose of this paper is to present a numerical study of a
‘smart’ glass facade based on a bow-string truss solution, as
shown in Figure 1, which is able to continuously adapt its shape
in order to compensate for the dynamic displacements induced by
the turbulent fluctuations of the wind. This is achieved by the
implementation of a proportional–integral–derivative (PID)
closed-loop control system, which allows the force in the cables
of the truss to be controlled. The response is studied for a
constant transversal wind load, perpendicular to the plane of the
glass, which is added to a random time-varying excitation
representative of the gust component.
2. Glass facade
2.1 Design of the glass facade
The glass facade is 8 m tall by 16 m wide and is integrated in a
building with an implantation area of 16 3 16 m2: The glass
panes, with dimensions 2000 3 2000 3 16 mm3, are suspended
from a main frame, which is not analysed in this study. Each
vertical alignment of suspended glass comprises four sheets,
connected to each other by point fixing systems (Bernard and
Daudeville, 2009). In the case of suspended facades, toughened
or tempered glass is most commonly used (Vyzantiadou and
Avdelas, 2004). These thermo-mechanical methods raise the
resistance threshold at which cracking of the glass occurs, by
creating a self-balanced stress condition within its cross-section
(Wurm, 2007). The resistance of the suspended glass facade to
wind is guaranteed by four bow-string trusses. These trusses are
built up of a vertical element and three horizontal brackets, which
act as deviators (circular hollow section with 76.1 3 3.0 mm),
and two pre-stressed stainless-steel cables with d ¼ 8.1 mm. One
of the main advantages of pre-stressing the cables is that, instead
of having one single cable resisting the wind load, there are two
cables in tension relative to each other. The bow-string trusses are
stabilised by three horizontal cable trusses, composed of pre-
stressed stainless-steel cables with a cross-section of d ¼ 8.1 mm.
The general configuration and the main dimensions of both the
glass facade and its supporting bow-string trusses are shown in
Figures 1 and 2.
The cables (2) of the two central trusses are active elements,
which are able to apply forces to the structure in a prescribed
manner (Housner et al., 1997). The control system is an active
control system with feedback, in which the applied forces are a
function of the tension in the cables, which are continuously
monitored. The control strategy for the facade is illustrated in
Figures 3 and 4. Figures 3(a) and 4(a) represent the initial state
of the facade, in which both cables have the same force,
T1 ¼ T2 ¼ Ti associated with the prescribed pre-stress. Figures
3(b) and 4(b) represent the facade subjected to the corresponding
wind loadings, which do not directly interact with the trusses. As
the trusses are within the building, the wind forces act on the
glass panes and are transmitted to the trusses through the point
fixings. According to Parts 1–4 of Eurocode 1, as the height of
the structure is low and the h/b , 1, where b is the dimension in
the across-wind direction and h is height of the facade, the wind
pressure profile is considered to be constant (BS EN 1991-1-4
(BSI, 2005a)). In Figure 3(b) the force in cable 1 decreases by
Tw, as the facade deforms due to the wind pressure loading. In
cable 2, the force increases by the same amount originating a
total force of T2 ¼ Ti + Tw: In the case of a wind suction loading,
the final forces in the cables are T1 ¼ Ti + Tw and T2 ¼ Ti � Tw, as
shown in Figure 4(b). In order to compensate for the wind-
induced deformations, the control system introduces an additional
load, Fw, in cable 1. In the case of a wind pressure load, this force
is positive and translates into an additional stress in cables 1 and
2, as seen in Figure (3(c). In the case of a wind suction load, Fw
is negative and translates into stress release in cables 1 and 2, as
seen in Figure 4(c). In either situation, one can observe that the
final force in cable 1, in order to compensate for the total wind-
induced displacements, amounts to Ti: For this reason, the control
variable of the control system is T1, and the correspondingFigure 1. General view of the proposed glass facade
2
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
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set-point is Ti: One can also see that the maximum force
fluctuation in the cables equals 2Tw and hence the initial force in
the cables, Ti, has to be larger than this value, in order for the
cables to remain tensioned.
2.2 Dynamic characterisation of the glass facade
To evaluate the structural behaviour of the glass facade, a three-
dimensional finite-element (FE) model is implemented, in a
SAP2000 framework, including the glass elements of the facade
16·0
Front view
2·02·0
Side view
(1) (2)
1·15
8·0 8·01·4
2·8
Figure 2. Geometry and dimensions (in m) of the glass facade
and one bow-string truss
Ti Ti
W
T Ti w� T Ti w�
Tw
Ti
Tw
T Ti w2�
Fw
(a) (b) (c) (d)
Figure 3. Control strategy for a wind pressure load
Ti Ti
W( )�
T Ti w� T Ti w�
�Tw
Ti
�Tw
T Ti w2�
Fw
(a) (b) (c) (d)
Figure 4. Control strategy for a wind suction load
3
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
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and corresponding back-up structure. The FE model of the glass
facade enables the characterisation of the modal configurations
and frequencies. Figure 5 shows some of the first modal shapes of
the glass facade, as well as the corresponding vibration frequen-
cies. The first eight modes correspond to global modes of the
glass facade, with frequencies ranging from 4.53 Hz to 8.16 Hz.
Mode 9 is the first local mode, mainly involving the glass panes.
3. Wind modelWind is a dynamic and random phenomenon in both time and
space. Assuming that the wind speed only depends on the height
above the ground, the instantaneous wind speed v(z, t ), may be
described as a mean value v(z), at a given height, upon which
turbulent fluctuations are superimposed ~vv(z, t) (Holmes, 2007)
v(z, t) ¼ vm(z)þ ~vv(z, t)1:
Regarding the variable gust ~vv(z, t), it is usually assumed to be a
stationary Gaussian random process, having zero mean and a
specified spectral density, SL(z, n) (Pasca et al., 1998). According
to Parts 1–4 of Eurocode 1, the spectral density function may be
calculated as
SL(z, n) ¼ 6.8 f L(z, n)
[1þ 10.2 f L(z, n)]5=32:
where fL(z, n) is a dimensionless frequency, given by
f L(z, n) ¼ nL(z)
vm(z)3:
where L(z) is the turbulence scale and n is the natural frequency.
A sample of the wind speed can be generated using the wave
superposition method with sinusoidal functions. This method
assumes that the turbulent gust is caused by a superposition of
eddies simulated by harmonic summation. Once a power spectral
density function is given, the weighted amplitude wave super-
position method (WAWS) allows evaluation of the amplitude of
these harmonics (Kareem, 2008). The single process ~vv(z, t) can be
written as
~vv(z, t) ¼XN
K¼1
C(z, nk) cos (2�nkt þ �k)4:
with
C(z, nk) ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi2Sw(z, nk)˜n
p5:
where nk (k ¼ 1, 2, . . .) are the central frequencies of the
intervals n into which the frequency range of the power spectral
density function Sw of the process has been divided, and the
random phase angles �k have a uniform distribution between 0
and 2�.
Given the random nature of the generated samples of wind
turbulence, the glass facade is subjected to 20 different wind
series. Figure 6 shows the obtained power spectral density
function and one of the generated time histories of the wind
turbulence, superimposed over the calculated mean value of the
velocity. The mean value of the velocity is determined according
to Parts 1–4 of Eurocode 1, considering a basic value for the
reference mean wind of 30 m/s, a terrain roughness of 0.005 m
and a reference height of 10 m, yielding a value of 35.6 m/s. This
is approximately the characteristic wind velocity corresponding
to the 95% fractile of the statistical distribution of maximum
wind velocities in periods of 50 years (1000 years return period).
Once the wind instantaneous speed is determined, it is possible to
compute the wind dynamic pressure accordingly
qp(z, t) ¼ 1
2rv2(z, t)6:
where r is the air density, which is usually taken as 1.25 kg/m3: The
wind pressure on the outside surface of the glass facade we(z, t ) is
obtained in the following way
we(z, t) ¼ qp(z, t)cp,e7:
where cp,e is the pressure coefficient for external surfaces, which
is a function of the building geometry, including aspect ratios
such as h/b and d/b, where d is the dimension in the along-wind
direction, roof pitch and wind direction. The pressure coefficients
presented in Parts 1–4 of Eurocode 1 generally produce con-
servative design load distributions, representing approximate
worst-case pressure distributions. For this study, it appears
sufficient to define simultaneous pressure coefficient distributions,
as an approximation, for calculating the extreme displacements in
the main trusses (Kasperski, 1996). The pressure coefficients for
external surfaces are identified in Figure 7, for the considered
wind directions. A positive wind load stands for pressure,
whereas a negative wind load indicates suction on the surface.
4. Dynamic response of the glass facade towind excitation
In order to investigate the efficiency of active control in reducing
the glass facade displacements induced by a random gust, gener-
ated according to the weighted amplitude wave superposition
(WAWS) method and Eurocode prescriptions, a numerical time-
stepping method for the integration of the equation of motion is
used. The stiffness of the system is determined using 11 degrees
4
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
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(a) (b)
(c) (d)
(e) (f)
Figure 5. Modal shapes and frequencies of the complete facade:
(a) mode 1 ( f ¼ 4.53 Hz); (b) mode 2 ( f ¼ 6.05 Hz); (c) mode 3
( f ¼ 6.22 Hz); (d) mode 4 ( f ¼ 7.15 Hz); (e) mode 6
( f ¼ 7.64 Hz); (f) mode 9 ( f ¼ 8.35 Hz)
5
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
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of freedom (DOF), represented in Figure 8, which are associated
with the horizontal displacements in the centre of the glass panes
and in the nodes of the truss. In this way, the additional
aerodynamic self-induced loads due to the vibration of the glass
panes are also accounted for in the simulations. As the system is
linear, an exact solution for the equation of motion is obtained,
interpolating the excitation over each time interval (Chopra,
2001). The excitation function, p(t ), results from the combined
action of the wind load, W(t ), and the tension in the cables, T(t ),
for each degree of freedom. The wind load acts on the DOF
associated with the glass panes, which are DOF 4 through 8 and
the tension load acts on the DOF associated with the nodes of the
truss, which are DOF 1 through 3. The calculation of the
excitation function is illustrated in Figure 8.
For the time interval ti < t < tiþ1, the excitation function is
given by
p(�) ¼ W (�)þT (�)¼ pi þ˜pi
˜ti
�8:
where
˜pi ¼ piþ1 � pi9:
For the general case of a damped system, the equation of motion
is given by
m€uþ c _uþ ku ¼ pi þ˜pi
˜ti
�10:
The structural response in terms of displacements, u, is given by
u(�)¼ uie��øn�
�ffiffiffiffiffiffiffiffiffiffiffiffi1��2
p sinøD�þcosøD
!
þ _uie��øn� 1
øD
sinøD�
� �
þ pi
Kn
1�e��øn� cosøD�þ�ffiffiffiffiffiffiffiffiffiffiffiffi
1��2p sinøt
D
!" #
þ ˜pi
Kn
�
˜ti
� 2�
øn˜ti
þe��øn� 2�2�1
øD˜ti
sinøD�
"
þ 2�
øn˜ti
cosøD�
��11:
0
0·05
0·10
0·15
0·20
0·25
0·001 0·01 0·1 1 10 100 1000
Sf
LL
()
fL
(a)
34·0
34·5
35·0
35·5
36·0
36·5
37·0
37·5
38·0
0 100 200 300 400 500 600
v: m
/s
t: s(b)
Figure 6. Characterisation of the wind action: (a) power spectral
density function; (b) wind velocity–time history
�0·8(a)
�0·4(b) (c) (d)
�0·8 �1·2
W W W W
�1·2 �0·8
Figure 7. Characterisation of cp,e for different wind directions
6
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
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The corresponding velocities yield
_u(�) ¼� uie��øn� ønffiffiffiffiffiffiffiffiffiffiffiffiffi
1� �2p sinøD�� �
þ _uie��øn� cosøD��
�ffiffiffiffiffiffiffiffiffiffiffiffiffi1� �2
p sinøD�
!
þ pi
Kn
e��øn�ønffiffiffiffiffiffiffiffiffiffiffiffiffi1� �2
p sinøD�� �
þ ˜pi
Kn˜ti
3 1� e��øn� �ffiffiffiffiffiffiffiffiffiffiffiffiffi1� �2
p sinøD�þ cosøD�
!" #12:
These equations can be rewritten as recurrence formulas, after
substituting Equation 9
uiþ1 ¼ Aui þ B _ui þ Cpi þ Dpiþ113:
_uiþ1 ¼ A9ui þ B9 _ui þ C9pi þ D9piþ114:
The resulting coefficients A, B, . . ., D9, depend on the system
parameters øn, k and �, and on the time interval ˜t � ti (Chopra,
2001). Given that the recurrence formulas are derived from the
exact solution of the equation of motion, the only restriction in
terms of ˜t is that it enables a close approximation of the
excitation function. The total response of the dynamic system is
obtained by the superposition of the modal responses.
4.1 Implementation of the PID controller
The control strategy for the active glass facade is based on a PID
controller, combining the proportional, integral and derivative
control actions. The controller transfer function Gc(s) compre-
hends three terms, each one associated with the corresponding
control action, yielding
Gc(s) ¼ Kp 1þ 1
T isþ T ds
� �15:
where Kp is the proportional gain, Ti ¼ Kp/Ki is the integral time
and Td ¼ Kd/Kp is the derivative time. Being a closed-loop control
system, the cable stress output signal C(s) is fed back to the
summing point, where it is compared with the reference cable
stress input R(s), yielding the actuating error signal E(s). The
output signal of the controller is U(s), and the feedback-path
transfer function, H(s), corresponds to a force sensor, which
measures the output variable in order to make it comparable with
the reference input signal, resulting in the feedback stress signal,
B(s). Figure 9 shows the block diagram of the stress control
system of the cables. The controlled process is defined by the
transfer function Gcp(s). The transfer function Gcp(s) evaluates
the dynamic response of the system for the current excitation
load, which comprises the wind load effects as well as the tension
input in the cables. As in many control systems, the input
4 8
59
2
6
103
7
11
W4 W8
W5W9
W10
W6
W7
W11
T
T1
T2
T3
T
1
Figure 8. Characterisation of the excitation load
7
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excitation is of unpredictable nature and cannot be expressed
deterministically by a mathematical expression (Ogata, 1997).
This constitutes a practical difficulty during the design and testing
of a control system, since it is not feasible to implement a system
that performs adequately for every input signal. In order to
achieve an acceptable performance, the constants Kp, Ti and Td, in
Equation 15 have to be adequately adjusted. To improve the
performance of the controller, a tuning algorithm based on the
Ziegler–Nichols stability boundary rule is implemented. In this
tuning method, the Ki and Kd gains are first set to zero and the Kp
gain is increased until it reaches the ultimate gain, Ku, at which
the output of the loop starts to oscillate. The corresponding
period of oscillation, Pu is called the ultimate period. The
ultimate gain Ku and the corresponding oscillation period Pu are
used to set the gains as Kp ¼ 0.6Ku, Ti ¼ 0.5Pu and Td ¼ 0.12Pu,
in order to obtain a quarter decay ratio, yielding a good
compromise between quick response and adequate stability
margins (Franklin et al., 1994).
For the proposed prototype the ultimate gain yields an approx-
imate value of Ku ¼ 4.00 and the ultimate period Pu ¼ 0.05 s.
Hence, the gains of the PID controller are finally set to Kp ¼ 2.4,
Ti ¼ 0.025 and Td ¼ 0.006.
5. Results of the numerical simulationThe evaluation of the performance of the system is done using
the 78%-fractile value of the extreme displacement (u2) asso-
ciated with the 20 time series (ISO 4354 (ISO, 2007)), as well as
the corresponding control force in the active cable. For the
positive wind pressure case, the displacement yields 39.88 mm,
for the uncontrolled system, and 2.7 mm, for the controlled
system. In the case of negative pressures, the displacement yields
60.0 mm, for the uncontrolled system, and 3.88 mm, for the
controlled system. This represents a reduction of the displace-
ments of about 94%. The control force yields 17 kN and 26 kN,
for the positive and negative wind pressures, respectively. The
histograms of the structural response, in terms of horizontal
displacements and cable forces, associated with one of the
artificially generated wind series, can be seen in Figures 10 and
11, respectively.
6. DiscussionWith reference to part 1-1 of Eurocode 3 (BSI, 2005b), the
horizontal deflections affecting the appearance of a structure are
limited to h/300, in which h is the storey height. The mean
maximum horizontal displacement in the system without control
amounts to h/133. This value does not comply with the design
prescriptions regarding maximum admissible deflections in build-
ings. The control system is able to reduce this displacement to
h/2105, guaranteeing the fulfilment of this serviceability limit
state. Observing Figures 10 and 11 it can be seen that the
displacements shown by the facade, when subjected to a wind
loading, can be expressed as the superposition of a mean
displacement, associated with the mean value of the wind
loading, and the additional oscillations due to turbulence. The
mean displacement is positive, in the case of wind pressure
loadings, or negative, in the case of wind suction loadings. The
effect of the proposed control system in the overall behaviour of
the facade is two-fold; that is, it greatly reduces the displacement
amplitude of the facade due to wind turbulence as it shifts the
system back to its original position, by eliminating the mean
displacement component of the response. This is achieved by a
control force of 26 kN, corresponding to a maximum travel of
0.020 m at the end of the active cable. This type of performance
can be easily achieved by a small electromechanical linear
actuator, yielding a rated speed of 1.0 m/s, which is the maxi-
mum speed needed to comply with the proposed control solution.
R s( )
(Ref.stress)
B s( ) (Stressfeedback)
E s( )
(Error)��
(Stress PID controller)
K K s K sp i d/� � Gcp( )s
H s( )
(Force-sensor)
C s( )U( )s
Figure 9. Block diagram of the stress control system
�0·05
�0·04
�0·03
�0·02
�0·01
0
0·01
0 100 200 300 400 500 600
μ 2: m
t: s(a)
ControlledFree
�0·005
0
0·005
0·010
0·015
0·020
0·025
0·030
0·035
0·040
0 100 200 300 400 500 600
μ 2: m
t: s(b)
ControlledFree
Figure 10. Time history of the horizontal displacements, during
wind events (u2): (a) negative wind pressures; (b) positive wind
pressures
8
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
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The proposed active glass facade enables a significant reduction
of the mean maximum displacement of about 94%, for both
positive and negative wind pressures. This is a very clear
indicator of the good performance shown by the system. It has to
be stressed that the proposed cable control system is designed
mainly to satisfy serviceability criteria regarding deflections. This
means that the structural resistance and overall stability of the
facade is not impaired by the deactivation of the control system.
All the design prescriptions of Part 1-1 of Eurocode 3 (BS EN
1993-1-1 (BSI, 2005b)) are verified, regardless of the control
system status.
The approval of innovative systems in structural engineering
results from a combination of performance enhancement set
against construction costs and long-term effects (Soong and
Spencer, 2002). In order to obtain the same level of displace-
ments shown by the active glass facade, the steel structure would
require ten times more material.
7. ConclusionThe essence of a suspended glass facade is transparency. The
inventive capacity of engineers has enabled the development of
sophisticated technological solutions, which are able to fulfil this
architectural aspiration. With the wider implementation of active
control in civil engineering applications, the integration of these
systems in suspended glass facades opens new possibilities both
in terms of lightness and structural performances.
This paper presents a new proposal for an active facade, aiming
to provide a realistic evaluation of its dynamic performance
during wind events. It is shown that the active system is
extremely effective in reducing the horizontal wind displace-
ments of the facade, allowing structural solutions to be obtained
that are more slender, while also complying with the mandatory
design prescriptions regarding ultimate and serviceability limit
states.
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Parts 1–4: General actions. Wind actions. BSI, London, UK.
BSI (2005b) BS EN 1993-1-1: Eurocode 3: Design of steel
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�14·0
�13·5
�13·0
�12·5
�12·0
�11·5
�11·0
�10·5
�10·0
0 100 200 300 400 500 600
T: k
N
t: s(a)
6·0
6·5
7·0
7·5
8·0
8·5
9·0
9·5
10·0
0 100 200 300 400 500 600
T: k
N
t: s(b)
Figure 11. Time history of control force in the active cable, during
wind events (u2): (a) negative wind pressures; (b) positive wind
pressures
9
Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
Offprint provided courtesy of www.icevirtuallibrary.comAuthor copy for personal use, not for distribution
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Structures and Buildings Smart glass facade subjected to windloadingsSantos, Goncalves, Cismasiu andGamboa-Marrufo
Offprint provided courtesy of www.icevirtuallibrary.comAuthor copy for personal use, not for distribution