Dynamic Analysis of Concrete Structures Reinforced...
Transcript of Dynamic Analysis of Concrete Structures Reinforced...
ISSN No: 2309-4893 International Journal of Advanced Engineering and Global Technology I Vol-05, Issue-02, March 2017
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Dynamic Analysis of Concrete Structures Reinforced
with Basalt Fiber
M. M. Kamal M. A. Safan
Civil Engineering Department Civil Engineering Department
Menoufia University Menoufia University
Shebin El-Kom, Menoufia, Egypt Shebin El-Kom, Menoufia, Egypt
M. A. Hamada
Civil Engineering Department
Menoufia University, Shebin El-Kom, Menoufia, Egypt
Abstract- The basalt fiber plates reinforced with various types
of expanded steel meshes were developed with high strength,
crack resistance, high ductility and energy absorption proper-
ties which might be useful for dynamic applications. Five series
of plates were casted and tested under four different loading
conditions. The dynamic responses such as: frequency, mode
shape and damping factor were extensively investigated using
FFT analyzer. Experimental modal analysis was carried out
using B & K data acquisition type (3160-A-042) analyzer
equipped with B & K Pulse 17.1 software. The experimental
analysis and finite element technique were utilized to study the
effect of open steel mesh configuration, basalt fiber ratio and
boundary fixations on dynamic characteristics of concrete
structures. In addition, the investigated basalt fiber plates were
tested in the high frequency range (up to 140 kHz) through
ultrasonic attenuation technique. For this purpose, an
experimental setup was designed and constructed to measure
dynamic elastic modulus, phase velocity and damping
attenuation. The effect of mesh-layer de-bonding on the dynam-
ic characteristics (natural frequency and damping ratio) was
investigated. Damage was detected using vibration
measurements and identified by comparing signals in higher
frequency ranges before and after damage. Good agreement
between analytical and experimental modal analysis. This
results opens the way to carry out several scenarios to achieve
the best analysis of the dynamic performance of concrete
structures reinforced with basalt fibers.
Index Terms- Modal testing- Finite element- Concrete rein-
forced basalt fiber -Ultrasonic test -Frequency response func-
tion (FRF).
I. INTRODUCTION
Plain concrete has two major deficiencies; a low tensile
strength and low strain at fracture. The tensile strength of
concrete is very low because plain concrete normally con-
tains numerous micro cracks. It is the rapid propagation of
these micro cracks under applied stress that is responsible for
the low tensile strength of the material. These deficiencies
have led to considerable research aimed at developing new
approaches to modifying the brittle properties of concrete.
Current research has developed a new concept to increase
the concrete ductility and its energy absorption capacity,
as well as to improve overall durability. This new generation
technology utilizes fibers, which if regularly dispersed in
layers throughout the concrete matrix, provides better
distribution of both internal and external stresses by using a
three dimensional reinforcing network [1, 2, 3]. The primary
role of the fibers in hardened concrete is to modify the
cracking mechanism. By modifying the Cracking mecha-
nism, the macro-cracking becomes micro-cracking. The
cracks are smaller in width; thus, reducing the permeability
of concrete and the ultimate cracking strain of the concrete is
enhanced. The fibers are capable of carrying a load across
the crack. A major advantage of using fiber reinforced con-
crete (FRC) besides reducing permeability and increase
fatigue strength is that fiber addition improves the tough-
ness or residual load carrying ability after the first crack.
Additionally, a number of studies have shown that the im-
pact resistance of concrete can also improve dramatically
with the addition of fibers.
Basalt rock is a volcanic rock and can be divided into small
particles then formed into chopped basalt fiber strands,
continuous basalt filament wires and basalt mesh. Basalt
fiber has a higher working temperature and a good resistance
to chemical attack, impact load, and fire with less poisonous
fumes. Some of the potential applications of these basalt
composites are: plastic polymer reinforcement, soil
strengthening, bridges and highways, industrial floors, heat
and sound insulation for residential and industrial buildings,
bullet proof vests and retrofitting and rehabilitation of
structures. Up to now, several attempts have been carried out
to use basalt fiber as reinforcing material for concrete. Sim et
al. [4] used basalt fiber as a flexure strengthening material
for reinforced concrete beam members. From the results of
the bending tests, it can be seen that the basalt fiber strength-
ening obviously improved the yielding and the ultimate
strength of beam specimens. Dias et al. [5] studied the frac-
ture toughness of geo polymeric concrete with basalt fiber.
The results showed that the strengthening and toughening
effects of basalt fiber were more efficient on geo polymeric
concrete than that on ordinary concrete. Li et al. [6] investi-
gated the impact mechanical properties of basalt fiber re-
inforced geo polymeric concrete, indicating that the addition
of basalt fiber can significantly improve deformation
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and energy absorption properties of geo polymeric concrete.
Dynamic tests [7] done with use of pre-tension Hopkinson
bar show that high performance fiber reinforced
concrete properties may be strongly affected by high tem-
perature. It is extremely important in many civil en-
gineering and military applications where structure re-
sistance against dynamic loadings may be lowered by fire.
Investigation of the dynamic behavior of concrete reinforced
with basalt fibers plates in the literature is rarely available.
However, limited studies were carried out on reinforced
concrete structures subjected to dynamic loads (e.g. bridge)
to characterize their dynamic behavior for the purpose of
fault diagnosis. Here are some examples: Salaw, W. [8],
conducted full-scale forced- vibration tests before and after
structural repairs on a multi span reinforced concrete
highway bridge. The tests were conducted to study any cor-
relation between repair works and changes in the dynamic
characteristics of the bridge. Comparison of the mode shapes
before and after repairs using modal analysis procedures
was found to give an indication of the repair. The bridge
response was measured using accelerometers and modal
parameters were extracted from the frequency response
function. The result of this study showed that damping ratio
could not be used as an indicator for damage.
Koh and Ray [9], used mode shapes and natural frequency
for modal updating method. The finite element model
updating process modifies parameters in the global stiffness
or mass matrix to reproduce the measured modal data. Thus,
local perturbation of parameters in the global stiffness or
mass matrix indicates damage location.
Richardson [10], focused on the determination of the
functional relationship between variations in the mass,
stiffness, damping and the variations in the model properties
of the structure. This function could be in a simple form in
case of small changes to detect, locate and quantify structur-
al faults by monitoring frequency and damping only. The
complete sensitivity function for mass stiffness and damp-
ing, also the validity of the stiffness sensitivity for small
changes were verified using a 3 DOF numerical example
[11].
In the present work, modal testing is performed using
accelerometers and data acquisition system to measure
structure dynamic response. Collected data are used through
some signal processing analysis to extract the dynamic
parameters. On the other hand, the theoretical models are
tuned fine models are used to form a data base for structure
dynamic behavior under different boundary conditions.
This research covers the application of two different
techniques, namely, mechanical excitation and ultrasonic to
characterize the dynamic behavior of the investigated
composite plates made from concrete reinforced with basalt
fibers. The scope of research covers the numerical simula-
tion and experimental verification.
II. MODAL ANALYSIS USING THE FINITE ELEMENT METHOD
A typical composite basalt fiber plates of dimensions
(150×150×20) mm with various boundary conditions,
C-F-F-F, C-S-F-F, C-C-F-F and C-C-C-C along the edges of
plate are modeled using the finite element method where C
clamped, S simply supported, F free as shown in Fig.1.
With the help of the mixture rule [12] the elastic modulus
of concrete plates reinforced with basalt fiber are com-
puted. The equivalent elastic modulus and density of basalt
fiber composite are computed also, different open mesh,
various volume fraction and boundary conditions are em-
ployed. A mesh of 20×20 elements, eight node brick ele-
ments are utilized in the analysis and as shown in Fig.
2.
The basalt fiber volume fraction can be classified as low
(0.1%-1%), moderate (1%-3%) and high (3%-12%) fiber
volume matrix [13], [14]. In the present study the volume
fraction level were determined as 1%, 3% and 12%
respectively.
Fig. 1 Geometry of specimen.
Fig. 2 Finite element model for specimen.
The stiffness matrix of the element can be then formulated as
[15]:
Where: t is the thickness of basalt fiber plate, [B] is strain
matrix and [D] is the elasticity matrix of basalt fiber plate,
which can be computed according to [15]. Consequently, the
mass matrix of element can be formulated [16] as
Where: ρ is the density of the equivalent composite plate
with various mesh type, [N] is the matrix of shape function
[17].
The eigen-frequency can be then evaluated from the solution
of the characteristic equation for the composite plate given
by:
| |
The eigen values and mode shapes are computed uses the
finite element method software package SOLIDWORKS
(Version 2015). Initially, the plates were modeled in order to
get a first estimation of the un-damped natural frequencies
and mode shapes utilizing finite element type SOLID Mesh.
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The material properties were then entered in the program,
and the constraint imposed to simulate a type of fixation.
The numerical results using finite element method
[F.E.M] were computed for different mesh types, various
volume fraction of basalt fiber (Vf) and boundary fixations
and are listed in Table II.
III. EXPERIMENTAL PROCEDURE
A. Materials Preparation
The experimental program was designed to investigate the
effect of reinforced steel mesh configurations and boundary
conditions on the dynamic behavior of concrete with basalt
fiber plates. Five different patterns of mesh reinforcements
were used. Different materials were used to produce the
plates (150×150×20) mm including: mortar, steel meshes,
silica fume, super-plasticizer, fly ash and basalt fibers. The
mix proportions are shown in Table I-b. Fig. 3. Shows the
configurations of steel mesh used in the present work, each
of which has a fixed dimension of 150mm×150mm. Table I-
a. declares the specifications of the used steel meshes ac-
cording to B.S. 405, 1997. The experimental details were
described elsewhere [18].
Table I-a. Expanded Steel Metal Specifications
Table I-b. Mix Proportions for Mortar.
Fig. 3 Configurations of steel meshes.
Table II. Values of the First Five Frequencies in Hz for Concrete with Basalt Fiber Plates under Four Different Boundary Conditions (Finite Element Experimental Results).
Percent open
area %
Overall thickness
mm))
Diamond size
(mm)
Wt
(Kg) Style
80 2 11 1.5 838
82 2.3 11 1.88 1037
72 3.8 22 2.4 1537
68 3.7 16 3.4 2038
Proportions
per Kg /1 m3
Type Materials
556
556 417
175
52 8
1%-3%-12%
Fine sand passing sieve #4
Coarse sand retained sieve #4 Ordinary cement type 1
Potable water
Silica fume SF Euco- Eypet CASTM C 494
Fiber 25 μm length
Sand
Gravel Cement
Water
Mineral admixtures Superplasticizer
Basalt fiber
Boundary Conditions
Plate Configuration EX. F.E EX. F.E EX. F.E EX. F.E
166.00 167.06 102.00 103.37 67.50 70.97 14.50 16.20
A 338.00 340.76 122.00 123.15 93.00 95.94 36.00 39.55
418.00 421.74 219.00 202.66 182.00 184.65 96.00 99.47
500.00 502.71 283.00 285.33 226.00 230.69 124.00 126.86
607.00 610.87 310.00 313.56 257.00 262.81 143.00 144.41
163.00 165.20 99.00 102.23 65.00 70.19 14.00 16.02
B 333.00 336.97 118.00 121.78 91.00 94.88 35.00 39.11
413.00 417.05 197.00 200.41 178.00 182.60 94.00 98.37
493.00 497.13 279.00 282.16 224.00 228.14 121.00 125.45
599.00 604.08 308.00 310.07 254.00 259.90 139.00 142.80
161.00 164.07 97.00 101.52 63.00 69.70 13.50 15.91
C 330.00 334.66 116.00 120.94 89.00 94.23 34.00 38.84
410.00 414.19 195.00 199.04 175.00 181.34 92.00 97.69
490.00 493.71 274.00 280.23 221.00 226.57 119.00 124.59
593.00 599.93 305.00 307.94 251.00 258.11 137.00 142.80
157.00 162.94 94.00 100.82 62.00 69.22 13.00 15.80
D 327.00 332.34 114.00 120.11 86.00 93.58 33.00 38.57
407.00 411.32 193.00 197.66 173.00 180.10 91.00 97.02
487.00 490.30 271.00 278.29 219.00 225.01 117.00 123.73
589.00 595.78 301.00 305.81 248.00 256.34 135.00 140.84
153.00 157.26 92.00 97.31 58.00 66.81 11.50 15.25
Plain 317.00 320.77 111.00 115.93 84.00 90.32 30.00 37.23
394.00 397.00 186.00 190.78 167.00 173.83 88.00 93.64
470.00 473.23 262.00 268.60 213.00 217.17 114.00 119.42
569.00 575.04 289.00 295.17 241.00 247.41 131.00 135.94
A B C
A D
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B. Frequency Response Function The experimental set up, used in the present work, was
described in details [19] where the specimen was
located in a test rig and excited by an impact hammer
"type 8202", which resembles an ordinary hammer but has a
force transducer type ʻ 8200 ʼ built into its tip to register
the force input. The hammer was used to excite the speci-
men at the free end position.
The vibration response of the specimen to the excitation was
measured using piezoelectric accelerometer type (4506) its
weight 18 gram located at different positions away from the
nodes. Both the response of the specimens and the excitation
signal were measured and connected to a B&K data
acquisition type (3160-A-042) analyzer equipped with B&K
pulse 17.1 software used for the analysis and conditioning of
the signals. A PC equipped with the software is connected to
the multi-channel signal analyzer, which is used to collect,
analyze and display the signals, FRF is automatically
calculated and graphically presented through the software.
Modal parameters are extracted from the FRF for each
concrete reinforced with basalt fiber specimen. During mod-
al test, the specimens are fixed in a manner of cantilevered
beam as shown in Fig. 4.
The frequency response spectrum was recorded and printed.
A sample of frequency response function and phase angle for
concrete basalt fiber plate type (A) specimen in cantilever
fixation case is shown in Fig. 9.
The frequency and damping factor measurements for the
fundamental frequency and associated damping factor were
carried out for each specimen. The experimental results were
taken as an average of five measurements of each. The
damping factor (ξ) of a particular response was calculated
from the width of the response peak in the magnitude of the
(FRF) [20]. The experimental measurements of frequency
amplitude and damping factor are listed in Table IV.
C. Damage Identification Using Structural Dynamic Analy-
sis.
To study the effect of mesh-layer de-bonding on the vibra-
tion characteristics of basalt fiber reinforced with concrete
plates, the plates were provided with de-bonding lengths:
10,20,30,40,50&60 mm by inserting aluminum foils of
various sizes on the upper surface of the reinforcing mesh.
The fundamental frequency of cracked plate was recorded
and compared with those for non- cracked plate. The input
parameters were crack length and plate type. The crack
location was kept fixed at mid-line of the tested plate. the
experimental results of fundamental frequency and associat-
ed damping factor for cracked A-plate specimen under canti-
lever fixation as shown in Table V.
Table III. Values of Ultrasonic Measurements for Five Concrete with Basalt Fiber Plates.
Fig. 4 Schematic block diagram of the measuring circuit.
Table IV. Values of Fundamental Frequency (Hz), Amplitude (dB) and Damping Factor for Concrete with Basalt Fiber Plates Tested under Four Different Boundary Conditions* (Experimental Results)
Dynamic Elastic
Modulus (GPa)
Phase Velocity
(m/s) Attenuation
Factor
Code
Number
34.25 3420 0.00430 A
33.01 3375 0.00540 B
31 3350 0.00620 C
29.7 3300 0.00740 D
27.7 3250 0.00919 Plain
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D. Ultrasonic Measurements The magnetostractive pulse echo delay-line system [21] is
utilized to measure the attenuation factor ξ and phase veloci-
ty Cp investigations with slight modifications to allow the
resonance frequency spectra for the longitudinal modes of
these specimens to be obtained. In this modified system a
general burst of mechanical oscillation is possible to excite
the tested specimens along its main length at either the
specific natural frequency or at one of the harmonic
frequencies of the specimens. Fig. 5 shows the basic system
used for these measurements while the recorded signal echo
is schematically shown Fig. 6. The first part of the echo
including the cross-over is the direct return of the transmitted
signal, whilst the second part, the decrement, is the
exponential retransmission of the energy stored. The number
of oscillations to the cross over is a function of the line
(wire) cross-section and the properties of resonating materi-
al. The parameters shown in this figure are utilized to calcu-
late, absolutely, the attenuation factors according to
[22]:
(
)
Where, Am and An are respectively, the maximum amplitude
(voltage) of the mth
and nth
pulse echoes and also d is the
length of the wire and specimen. The percentage of error in
the attenuation measurement was ±2%. The longitudinal
resonant modes of vibration of each tested composite
specimen were excited by cementing it with the remote end
of the delay line (wire) of the system. The corresponding
resonance frequencies were detected by measuring periodic
time. For a specimen of length (d), periodic time (t), the
phase velocity Cp is related to this resonance frequency by
[23].
(5)
The most accurate dynamic Young's modulus (ED) usually
follows from determining ultrasonic phase velocity Cp as
using the general relationship [24].
(6)
Fig. 5 Schematic diagram of the magnetostractive delay-line system.
Fig. 6 Set-up of ultrasonic measuring system and the resultant echo.
Table V. Natural Frequencies and Damping Factor for the Cracked A-Plate
under Cantilever Fixation
Damping Ratio N. Frequency (Hz) Crack Length (mm)
0.10 92 Intact
0.18 88 10
0.28 83 20
0.36 70 30
0.42 53 40
0.51 39 50
Boundary Conditions
166 102 67.5 14.5 Frequency
A 26 31 32 38 Amplitude
0.016 0.05 0.07 0.10 Dam. Factor
163 99 65 14 Frequency
B 30 33 36 42 Amplitude
0.03 0.07 0.09 0.15 Dam. Factor
161 97 63 13.5 Frequency
C 34 36 39 46 Amplitude
0.05 0.12 0.14 0.18 Dam. Factor
157 94 62 13 Frequency
D 38 41 43 48 Amplitude
0.07 0.14 0.17 0.22 Dam. Factor
153 92 58 11.5 Frequency
Plain 20 22 28 26 Amplitude
0.006 0.014 0.015 0.03 Dam. Factor
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IV. RESULTS AND DISCUSSION
The resonant frequencies, mode shapes and damping factors
of square concrete plates reinforced with basalt fibers have
been measured and analyzed for different mesh configura-
tion and boundary fixations. The measured and computed
values of the frequencies are given in Table II. Comparisons
between the experimental and numerical results of the fre-
quencies indicate good agreements. Table IV. shows the
variation of fundamental frequencies, amplitude and damp-
ing factor of different mesh configuration at the same plate
thickness. It can be seen that the damping factor for different
of plate A is relatively low compared with the other. The
is due to the minimum dissipated energy at this mesh rein-
forcement. Also, it can be noticed that the damping factor of
plain plate is relatively low compared with the other due
to the small stiffness value for this case of bulk material.
In the concrete structure reinforced with basalt fiber plate,
the resonance frequencies of the specimens have recorded
and analyzed for different volume fraction of basalt fiber and
boundary fixation. The measured and computed are
given in Table II. As expected the frequencies of specimens
plain are lower than those of other specimens an specimen
(A) have the higher one. The magnitude of natural frequen-
cies of specimen (A) are greater than those in the plain spec-
imen. The changing of fiber volume fraction from (A) spec-
imen and dummy in the plain specimen decreases the natural
frequencies approximately by 1.26% for the different bound-
ary fixation.
In general, the damping factor in composite materials is
relatively high relative to bulk materials. It is difficult to
control the value by variation of the mass and stiffness. From
Fig.11, it can be noticed that minimum values of the damp-
ing factor occur in the case of clamped [CCCC] plates with
different types of mesh configuration. In all boundary
conditions, it is observed that the damping factor is high for
mesh type [D] compared with other reinforced type. This
explained by the fact that mesh reinforcements are expected
to decrease the plate stiffness and result in maximum energy
dissipation. In view of the state of fixation. It is observed
that the effect of the degree of constraints is dominant on
values of natural frequency and damping factor compared
with the variation of the open mesh type as shown in Fig.10
and Fig.11.
Fig. 8. shows mode shape for the first five mode shapes for
specimen (A) for cantilever boundary conditions.
Determination of the natural frequencies and mode shapes of
a vibrating structure is an important aspect from the stand
point of view of the structure dynamic behavior. The natural
frequency gives information about resonance avoidance for
certain loading conditions. Mode shape, on the other hand,
gives indication about the vibration level at each position of
the structure. One of the most important parameters from
designer's point of view is the location of nodes and anti-
nodes. The nodes are the position in which the vibration van-
ishes, while the antinodes are the positions at which maxi-
mum vibration level occurs. In Table. V, the natural frequencies and damping ratios for
the cracked A-plate under cantilever fixation are set out
based on the dynamic measurements. A group of natural
frequencies can be recognized that represent the dynamic
characteristics of the no cracked plate; that the natural fre-
quencies in this group decrease proportionally until a critical
de-bonding extend ( 20 mm) is reached. The damping
ratio in this group shows an increase, while the natural fre-
quency decreases. Beyond this critical de-bonding extent,
another group of frequencies decrease which represents
the dynamic characteristics of the damaged plate.
The damping ratios in this group increase noticeably beyond
the critical de-bonding extent.
Fig. 7-a Effect of various concrete basalt fiber specimens on attenuation
factor.
Fig. 7-b Effect of various concrete basalt fiber specimens on dynamic
elastic modulus
Fig. 7-c Effect of various concrete basalt fiber specimens on phase velocity.
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Fig.8 The first five mode shapes for specimen (A) for cantilever boundary
condition.
Fig. 9 A sample of frequency response function and phase angle for
concrete basalt fiber plate (A-type C-F-F-F).
Frequency Response H1(Responce,Force) - Input1 (M agnit ude)
Working : Input : Input : FFT A nalyzer
5 10 20 50 100 200 500 1k 2k 5k 10k
10m
30m
100m
300m
1
3
10
30
[Hz]
[(m/s² )/N] Frequency Response H1(Responce,Force) - Input1 (M agnit ude)
Working : Input : Input : FFT A nalyzer
5 10 20 50 100 200 500 1k 2k 5k 10k
10m
30m
100m
300m
1
3
10
30
[Hz]
[(m/s² )/N]
Frequency Response H1(Responce,Force) - Input (P hase)
Working : Input : Input : FFT A nalyzer
5 10 20 50 100 200 500 1k 2k 5k 10k
30m
100m
300m
1
3
10
30
100
[Hz]
[Degree] Frequency Response H1(Responce,Force) - Input (P hase)
Working : Input : Input : FFT A nalyzer
5 10 20 50 100 200 500 1k 2k 5k 10k
30m
100m
300m
1
3
10
30
100
[Hz]
[Degree]
(C-F-F-F)
(C-S-F-F)
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Fig.10 Frequency response surface of volume fraction and young modulus
for five specimens concrete basalt fiber under four different boundary
conditions.
Fig.11 Damping response surface of volume fraction and young modulus
for five specimens concrete basalt fiber under four different boundary
conditions.
The measuring results of ultrasonic parameters are recorded
and listed in Table III. Where, ρc is the denoted mass densi-
ty.
The ultrasonic phase velocity propagation in the specimen
Cp, the dynamic elastic modules ED and attenuated
damping factor for the first two echoes are given in
Table III. It is clear that specimen with plate A
has higher Cp and Ed values compared with the other
specimens. This is because the basalt fibers are oriented in
the
same direction of wave propagation path.
So the attenuation of the ultrasonic phase velocity was
kept minimum. On the contrast damping values were
(C-C-F-F)
(C-C-C-C)
(F-F-F-C)
(C-C-C-C)
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lower for this type of orientation duo to the relative ease
of energy transmission.
It is observed that the obtained results for ED and Cp are
found to be symmetrical. In every basalt fibers specimen a
maximum on the curve of ED is corresponding to a
minimum in attenuation factor as shown in Fig. 7-a, and
Fig.7-b.
In addition, the basalt fibers which at plate A with the
direction of excitation are found to give the highest Cp to
the concrete composite as shown in Fig. 7-c, simply because
the fibers are aligned in the direction of the elastic sound
waves and consequently are able to transmit their energy.
Their propagation is limited with the resultant increase in
dissipated energy and so attenuation factor ζ.
V. CONCLUSION
The dynamic analysis of concrete plates reinforced with
basalt fiber and various steel mesh was configurations
investigated experimentally and numerically under different
boundary conditions. The experimental techniques were
employed, namely, hammering excitation for law frequency
ranges and ultrasonic attenuation for high frequency ranges
(up to 140 kHz). The following conclusions were arrived at:
1. The dynamic characteristics of basalt fiber plates differ
considering depending on mesh and configuration boundary
conditions. There for basalt fiber structures may be tailored
for specified modal parameters and nodes positions to satisfy
certain operations conditions.
2. The numerical results from finite element method indicate
good agreement with those obtained from modal analysis.
However, it is recommended to use finer mesh for the
numerical finite element method considering more nodes of
vibration.
3. The mutual influences of basalt fiber volume, open mesh
area, boundary conditions and vibration mode are significant
on the damping capacity.
4. The positions of the nodes and antinodes are shifted for
basalt fiber plates compared with the plain ones.
5. In the high frequency range (ultrasonic data), the rein-
forced plates have higher stiffness and damping compared
with the un-reinforced plates. In this regard, steel mesh con-
figuration (volume fraction of fibers, open mesh area, wire
diameter, …) have their specific contributions to keep both
stiffness and damping at high levels. However, further ex-
perimentations one required to quantify the specific weight
of those parameters on ultrasonic data.
6. Use of basalt fibers resulted in an increase of the modulus
of rupture of the concrete. However, the increase in the
flexural strength was more pronounced for concrete mix
containing fly ash, admixtures, and with low water-cement
ratio.
Finally, this study is useful for the designer in order to select
the basalt fiber volume fraction, open mesh area, boundary
conditions, to shift the natural frequencies as desired or to
control the dynamic nature.
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