Effect of Different Temperatures on FRP Beam

This study investigates the effect of temperature changes on FRP reinforced concrete beams. The data obtained was used in ANSYS software to model the behaviour of the beams so as to establish how temperature changes affect various properties of the FRP reinforced concrete beams.

Effect of Different Temperatures on FRP Beam 1
EFFECT OF DIFFERENT TEMPERATURES ON FRP BEAM
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Effect of Different Temperatures on FRP Beam 2
Abstract
Construction industry is one of the leading markets for fiber reinforced polymers (FRP) all over
the world. FRP composites have numerous applications in industry because of the advantages
they offer over conventional construction materials. These advantages include the following:
high mechanical performance, lightness, design and manufacturing or production flexibility, high
specific stiffness and strength, low maintenance costs, ease of installation and controlled
anisotropy, among others. Unfortunately, FRP composites are prone to moisture and heat when
they are exposed to fluctuating environmental conditions. FRP composites’ response to heat is
one of the major issues dictating their acceptance and applicability in the construction industry.
The main concern is that the stability, functionality, safety and durability of FRP composites
structures may deteriorate if they are exposed to extreme temperatures. This paper involves
investigating the effect of temperature changes on FRP reinforced concrete beams. The study
was performed so as to show the lab experiment results obtained from two papers “Investigation
on influence of freeze/thaw on reinforced concrete beams with GFRP” by Waqas Khattak, and
“Effect of environmental temperature on FRP reinforced concrete beams” by Atikom
Ongphichetmetha. These results were obtained by preparing samples of FRP reinforced
concrete beams and loading them under different loads and varying temperature of between -20
°C and 50 °C. The data obtained was then used in ANSYS software to model the behaviour of
the beams so as to establish how temperature changes affect various properties of the FRP
reinforced concrete beams. The model was created by particular elements of ANSYS for
concrete, steel reinforcement bars, FRP reinforcement bars and steel plates. The beam model
was then subjected to different loads of 0KN, 2KN, 4KN, 6KN, 8KN and 10KN. Under each of
these loads, the beam model was tested under varying temperature by increasing temperature
from 20 °C to 50 °C (where it was held constant for 2 hours), dropping the temperature from 50
°C to -20 °C (where it was also held constant for 2 hours) and finally raising the temperature to
20 °C. The software simulated the behaviour of the model at these varying loading conditions
and temperatures.
The behaviour of steel and GFRP reinforced concrete beams, as shown by ANSYS simulation,
was similar but identical. This was as expected because the two types of materials have
different values of Young’s modulus and coefficient of expansion. Generally, the two beams had
a similar trend where deflection and train were proportional to load and temperature (an
increase in load or temperature resulted to a corresponding increase in deflection r strain, and
vice versa). Since the coefficient of expansion of steel is more than that of GFRP, former had
minimal reaction of strain than the later when subjected to the same loading conditions and

Effect of Different Temperatures on FRP Beam 3
temperature. Also, steel has a smaller Young’ modulus than GFRP thus the former had less
deflection than the later. Therefore the conclusion from this study is that temperature affects the
behaviour of steel reinforced ad GFRP reinforced concrete beams. Also, based on the
simulations obtained from this study, it can be concluded that since the values of strain in GFRP
reinforced concrete beam were smaller than those of steel reinforced concrete beam, GFRP is a
better reinforcement material than steel for use when constructing concrete structures in
extreme weather conditions, such as cold or hot climates.

Effect of Different Temperatures on FRP Beam 4
Table of Contents
Abstract.....................................................................................................................................................2
INTRODUCTION......................................................................................................................................5
History of composite materials.......................................................................................................6
Advantages of composite materials..............................................................................................6
Aim.........................................................................................................................................................8
Objectives.............................................................................................................................................8
LITERATURE REVIEW...........................................................................................................................9
Effect of high temperatures on concrete......................................................................................9
Effect of low temperature on concrete........................................................................................14
Effect of freeze and thaw on FRP reinforced concrete............................................................16
Research Hypothesis.......................................................................................................................19
METHODOLOGY...................................................................................................................................19
Creation of beams............................................................................................................................21
Details and creation of links used................................................................................................21
Creation of reinforced beam cages..............................................................................................22
Casting of concrete..........................................................................................................................26
Testing of Concrete Cubes.............................................................................................................30
Beam Results Hypothesis..............................................................................................................33
Testing of Beams..............................................................................................................................33
Testing system of beams................................................................................................................33
Testing process................................................................................................................................34
ANSYS software................................................................................................................................36
Experimental program.....................................................................................................................36
Finite element model input data....................................................................................................38
Boundary and loading conditions................................................................................................39
RESULTS ANALYSIS...........................................................................................................................40
Strain of steel reinforced beams at varied loads and temperature......................................40
Strain of GFRP reinforced beams at varied loads and temperature....................................40
Deflection of steel reinforced beams at varied loads and temperature..............................40
Deflection of GFRP reinforced beams at varied loads and temperature............................41
CONCLUSION........................................................................................................................................41
References.............................................................................................................................................43

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INTRODUCTION
Concrete is one of the oldest and widely used construction material. This is because of
various reasons, including simple methods of concrete production, high strength and durability
of concrete, design flexibility of concrete structures, etc. However, concrete as a construction
material has one major problem: it has low tensile strength. To overcome this problem,
reinforcement is added to the concrete to make it stronger. The new material formed then
becomes reinforced concrete, which is a composite material. The composite material contains
concrete (which has high compressive strength but low tensile strength) and reinforcement
(which has low compressive strength but high tensile strength). In other words, the concrete
complements the weakness of reinforcement whereas the reinforcement complements the
weakness of concrete. Therefore the reinforced concrete is a stronger material that is able to
resist both compressive and tensile loads applied on it. The most common concrete
reinforcement material is steel but numerous alternatives have been developed, such as glass
reinforcement, fiber reinforcement, plastic reinforcement, polymer reinforcement and several
composite reinforcements.
Composites are basically materials comprising of a combination of two or more materials
with different structural, physical, mechanical and chemical properties. FRP is a composite
material comprising of a matrix (polymer) and reinforcement (fibres). The fibers are stiffer and
stronger whereas the polymer is used as a binder to keep the reinforcement in place and also to
protect the reinforcement. The individual materials of a composite do not have the capacity to
perform the desired structural function but they do so when combined because one material
complements the weakness of the other material. For FRP reinforced concrete, the fibers
provide stiffness and strength to carry the largest percentage of the applied loads (Kakooei, et
al., 2012). On the other hand, the polymer binds the fibers, protects the fibers and transfers
most of the stresses developed in the concrete component.
The search for alternative building materials will never stop. Engineers, architects,
designers and developers are always looking for materials that have improved properties, such
as high strength, lightweight, sustainable, low-cost, environmentally friendly, durable, flexible
and resistant to extreme environmental conditions (Zaman, et al., 2013). These materials should
also perform the required function adequately and offer economic and environmental benefits.
Over the past decades, FRP has been found to be one of the best viable alternatives for
concrete structures (Bai, 2013); (Hawileh, 2011). As a result, use of FRP reinforced concrete

Effect of Different Temperatures on FRP Beam 6
continues to gain popularity all over the world (Uddin, 2013). However, the suitability of FRP
reinforced concrete must be scientifically proven. That is why it is necessary to conduct
research and perform experiments to demonstrate how and why FRP reinforcement is a better
material than typical reinforcements such as steel.
History of composite materials
Application of composite materials in the construction industry started many years ago.
One of the earliest applications of these materials was around 3400 B.C. by the ancient
Mesopotamians, when they created plywood by joining strips of wood at different angles
(Composites Lab, 2016).In 1500 B.C., ancient Mesopotamians and Egyptians created strong
and durable buildings by mixing straw and mud. Use of FRP started in 1935 when the first glass
fiber (fiberglass) was introduced by Owens Corning. The fiberglass was mixed with a plastic
polymer to create a very strong and lightweight structure (Johnson, 2017). Today, the
composites industry has greatly evolved and composite materials are used in almost all
construction projects. Composites research also attract large amount of grants from
governments, universities, manufacturers and specialized companies (Mar-Bal, Inc., 2018).
Advantages of composite materials
There are numerous advantages of composite materials. The main advantage is that they
combine the different abilities and strength of individual materials to provide rare mixture of
properties that are difficult to achieve separately by singular materials. The composite materials
can be customized so as to have particular properties that suit special requirements. Some of
the advantages of composite materials include:
High strength: composite materials are stronger than ordinary materials (they have
higher specific strength, compressive strength, tensile strength and shear strength. The strength
can be increased by changing the ratio of the reinforcement and fibers or changing the direction
in which the fibers are oriented. The composites are also anisotropic thus their properties can
be altered depending on number of fiber layers or how they are placed.
Lightweight: composites are very light because of their excellent strength-to-weight
ratios. The lightweight of composites makes theme easy to transport and install, can reduce
construction costs and assists in adherence to building standards and regulations.
Corrosion resistance: composites are more resistant to damage caused by harsh
chemicals and weather conditions. As a result, they do not corrode or rust easily. This makes
them appropriate for use in severe conditions such as those experiencing temperature

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fluctuations, toxic chemicals, salt water, etc. This high resistance t corrosion reduces whole-life
costs of composite materials (Hollaway, 2009).
Design flexibility: composites allow greater design flexibility because they can take
almost any type of shape and form. These materials can be customized to fit unique design
specifications depending on the application. The composites are the reason there are many
exceptional building designs today because the materials can be used to create innovative
geometries with exciting surface appearance and precise properties.
Durability: composites also have minimal maintenance requirements and they last
longer. Their long lifespan is attributed to high resistance to fatigue, resistance to weather
conditions and reduced maintenance.
Environmentally friendly: composite materials have less impacts on the environment
than other materials. The composites are made so as to minimize the negative impacts they
have on the environment (Chatzimichali & Potter, 2015). They are also made from eco-friendly
materials such as bio-based polymers and recycled plastics. Composites can minimize harmful
gas emissions, production of construction waste and depletion of natural resources (Sun, et al.,
2015).
Composite materials have also made significant contributions towards the exciting
architectural structures seen today. These materials have made it possible for architects and
engineers to design and build fascinating and breathtaking structures that are aesthetically
pleasing, durable, low cost and environmentally friendly, not only in the construction industry but
also in other industries, such as aviation, manufacturing, automobile, etc. (Beck, et al., 2011).
The composite materials are also playing a major role in solving the global challenge of climate
change because they have made it possible to combine materials with low greenhouse gas
emissions and whole-life costs. As a result, any research that is associated with promoting
application of composite materials is worthwhile and should be supported as it will not only be
beneficial to the current generation but also to the future generations.
On the other hand, disadvantages of composites, including FRP materials, include: lack
of design standards and guidance, low ductility, high initial cost of the material, negative attitude
by ignorant people, variation in properties of finished product and uncertain properties at high
temperatures.

Effect of Different Temperatures on FRP Beam 8
FRP materials have all the above mentioned advantages and disadvantages. But
despite the numerous potential benefits of FRP reinforced concrete, this material has one major
challenge, just like any other construction material. The major challenge of FRP reinforced
concrete is that the composite is susceptible to moisture and heat when exposed to fluctuating
environmental conditions. When this composite material is used in countries that have severe
weather conditions, like Russia, it is structural soundness is likely to deteriorate. Therefore it is
very important to examine the effect of temperature on FRP reinforced concrete so as to
establish the temperature rage within which this material is not affected or to identify measures
that can be put in place to improve the structural soundness of FRP reinforced concrete
structures built in countries or areas with extreme environmental conditions.
Aim
The aim of this study is to model the behaviour of FRP reinforced beam under seasonal
temperature ranging from -20 °C to +50 °C using the results obtained from lab experiments
conducted in two aforementioned past papers.
Objectives
The project objectives include the following:
 To carry out literature review so as to establish findings of similar work conducted by
different researchers in the past.
 To model the experimental lab results obtained in the two papers using ANSYS
software.
 To compare results obtained in this study (using NNSYS software) and the results
obtained from lab experiment data in the case studies.
The project created a model that demonstrates the behaviour of FRP reinforced concrete
beam under different temperatures. Findings from this project are useful for professionals in
construction industry, such as architects, designers, engineers and developers, in
understanding how temperature affects the behavior of FPR reinforced concrete. This is
important in determining maximum design loads of FRP reinforced concrete structures and
identifying appropriate strategies that can be put in place to protect these structures from
extreme temperatures. Using this model, it will be easier to evaluate and understand the
behaviour of FRP reinforced concrete components at different loads and temperatures.
As stated before, the model in this project was created using results obtained from two past
studies: “Investigation on influence of freeze/thaw on reinforced concrete beams with GFRP” by

Effect of Different Temperatures on FRP Beam 9
Waqas Khattak, and “Effect of environmental temperature on FRP reinforced concrete beams”
by Atikom Ongphichetmetha. These papers are similar because they all involved investigating
the effect that environmental temperature changes have on FRP reinforced concrete beams.
The researchers used a similar methodology that involved preparing steel and FRP reinforced
beams in the lab and subjecting them to different loads at different temperatures, ranging from -
20 °C to 50 °C. They then used the data collected from the lab experiments to draw graphs in
Excel showing different relationships between applied load, temperature and behaviour of the
FRP reinforced beams. All these conditions and procedures were the ones used in this project.
The only difference is that in this project, the data obtained from the lab experiments was used
in ANSYS software to create a model demonstrating the behaviour of FRP reinforced concrete
beam at different applied loads and temperature.
LITERATURE REVIEW
The literature review was done by collecting and reviewing information from different
previous works that discussed the topic of effect of temperature variation on properties of
reinforced concrete. The information was sourced from journal papers, books, articles, reports,
design standards and manuals, conference proceedings, websites, etc. Some of the scientific
search engines that were used included: google scholar, science direct, research gate, national
academy of science, etc. The papers reviewed were those discussing mechanical, structural
and physical properties of concrete and the effect of changing temperature on reinforced
concrete, particularly steel and FRP reinforced concrete. The main objective of literature review
was to find out what other researchers discovered about the topic of effect of temperature on
the properties and behavior of FRP reinforced concrete, and establish any trend associated with
this topic.
Strength and other properties of concrete can be affected by a wide range of factors,
including: mix proportions of concrete ingredients, method of preparing, placing/pouring,
compacting or curing concrete, external factors such as temperature, etc. (Cecconello &
Tutikian, 2012). This paper is about the effect of temperature (low and high) on FRP reinforced
concrete hence the scope of literature review is limited to this topic only.
Effect of high temperatures on concrete
Concrete is a composite material consisting of aggregates (coarse and fine aggregates),
cement and admixtures (optional). The cement paste bonds together all the other ingredients of
cement through hydration process. The proportions of these ingredients determines how well
they bind together and the final properties of the concrete. When concrete is exposed to high

Effect of Different Temperatures on FRP Beam 10
temperatures, it undergoes numerous changes that alter its mechanical and physical properties.
This change is as a result of a change in moisture content, which affects the bond between
aggregates and cement paste. Therefore the bond between cement paste and aggregates gets
significantly affected if the concrete is exposed to high temperature variations i.e. large thermal
expansion variance (Klein & Nellis, 2012). By definition, thermal expansion refers to the ability of
a material to change its physical properties and shape when it is exposed to different
temperatures. Temperature change affects the surface condition of aggregates and the
interaction between physical and chemical interface, which in turn affects the bonding quality of
the concrete. Therefore high temperature weakens the interfacial bond between cement paste
and aggregates (Salau, et al., 2015).
The behaviour of concrete at high temperatures is affected by several conditions,
including: moisture content, the highest temperature attained, rate of temperature increase, type
of aggregate, loading and time (Ma, et al., 2015). When concrete is being cured, the duration of
curing depends on several factors such as desired strength of concrete, mix proportions, and
exposure conditions. When temperature changes abruptly, thermal shock can cause cracking
and spalling of concrete, while aggregate expansion can cause concrete distress. All these
factors also affect the hydration process of concrete. The condition of cement paste is affected
by the temperature in which the concrete is exposed to and thus affect the final strength of
concrete. When this temperature increases to the extreme over a long period of time, the
strength of concrete will also be adversely affected. Generally, the strength of concrete
decreases with rising temperature.
In a study conducted by Alex (2015) to determine the suitability of different types of FRP
reinforcements accepted for use in Germany, it was found that FRP reinforcements performs
well within a certain range of temperature, that is, temperature variance is a major factor
affecting performance and behavior of FRP reinforcement. One of the findings of the study was
that one of the disadvantages of FRP reinforced concrete is that it is suitable for use in
conditions with a maximum temperature of 40 °C (Alex, 2015). The research concluded that it is
important to define the characteristics and scope of FRP reinforcement so that it is not used in
conditions where its physical, mechanical and structural properties will deteriorate considerably.
This is important as it will help the user determine whether the FRP reinforcement is suitable for
use in the intended environmental conditions or not. This information can also be useful when
developing design standards and guidelines of RFP reinforced concrete (Teng, et al., 2008).

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Canbaz (2016) conducted a study to establish the effect of elevated temperature on
concrete made using waste ceramic aggregates. His findings showed that the strength of
concrete made from conventional aggregates reduces largely when the concrete is exposed to
high temperature than concrete made from alternative coarse and fine aggregates, such as
crushed ceramics (Canbaz, 2016). Canbaz further showed that the loss of concrete strength
was very high at greater temperatures of above 400 °C. However, the losses were low for
concrete made using crushed ceramics, which is a type of a FRP. In a study conducted by Li
(2012), findings showed that properties of concrete changed critically at a temperature of 400 °C
(Li, et al., 2012). A similar study showed that ductility of concrete increased after 750 °C as a
result of reducing strain values and absorption of specific energy. The two studies concluded
that mechanical properties of concrete at high temperatures showed a positive correlation
between dynamic compressive strength and strain rate.
Hager (2013) research on the effect of elevated temperature on the behavior of concrete
involved investigation of different physical and mechanical properties of concrete at high
temperatures. The researcher examined thermal strains, colour change, compressive strength,
stress-strain relationship and modulus of elasticity, and how they are affected by increasing
temperature. He found that temperature increase causes changes in aggregates and cement
paste, and the interaction between these two ingredients (Hager, 2013). The findings further
revealed mechanical and physical properties of concrete changes differently depending on
temperature level. Compressive strength of concrete declined by 20-30% at a temperature from
20 °C to 120 °C. This decrease can be attributed to three main causes: creation of hygral
gradient in the heated concrete, formation of additional stresses and a decrease in cohesive
forces between concrete ingredients. When water inside the concrete expands due to high
temperature, the distance between layers of concrete ingredients also increases thus
weakening Van der Waals forces and causing a decrease in compressive strength. Also, high
temperature causes water in concrete to evaporate thus increasing internal stresses due to high
internal pore pressure. However, the researcher also noted that compressive strength of
concrete increased slightly between temperature of 120 °C and 250 °C. But at high
temperature, compressive strength of concrete continued to decrease significantly.
In another study conducted by Drzymala et al. (2017), concrete loses its significant
properties at high temperature (Drzymala, et al., 2017). The researchers tested three different
high-performance concrete samples: polypropylene fibre reinforced concrete, air-entrained
concrete and reference concrete. The results showed that initial tensile strength was highest

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fibre in reinforced concrete at 20 °C. This proves the fact that fibre reinforcement improves
tensile strength of concrete. After heating the concrete at a temperature of 300 °C, average
tensile strength of air-entrained and fibre reinforced concrete decreased by 7% whereas in
reference concrete it reduced by 5%, but fibre reinforced concrete still had the greatest tensile
strength. The researchers further showed that when the concrete samples were heated beyond
450 °C, fibre reinforced concrete lost the highest percentage (24%) of tensile strength than the
other two concrete samples. When heated beyond 600 °C, fibre reinforced concrete had the
least tensile strength because of the pyrolysis process of polypropylene fibres, which damages
the material’s internal structure.
One of the mechanical properties that can be used to predict concrete’s structural
performance at high temperatures is stress-strain relationship. According to Hooks’ law, stress
and strain are directly proportional, but for real materials, this law only holds at low strain rates
because strain-strain properties are affected by several factors (Goncalves, et al., 2011); (Yeh,
2016). Figure 1 below shows a typical stress-strain curve of typical concrete. Initially, the
ultimate load increases linearly up to 40% then becomes non-linear as a result of higher strain
levels with lower stress increments. This behaviour is caused by extra micro-cracks created at
the interface between cement paste and aggregates. High temperature affects stress-strain
relationship of concrete. Several other researchers have conducted studies to investigate effect
of high temperatures on concrete and found similar results (Huo, et al., 2013); (Kodur, 2014);
(Tai, et al., 2011).
Figure 1: Stress-strain curve of typical concrete (Weiss, (n.d.))

Effect of Different Temperatures on FRP Beam 13
An increase in temperature causes substantial decrease in modulus of elasticity and
dynamic strength. This is demonstrated by the curves in Figure 2 below, where peak stress is
smaller but strain rises at peak stress when the concrete is exposed to higher temperatures.
According to Nadeem et al. (2013), this is as a result of pressure gradients from capillary effects
and liquid flow and adsorbed water content gradient (Nadeem, et al., 2013). In another study
carried out to establish factors affecting stress-strain curve of HSC concrete at high
temperatures, it was found that aggregate type and steel fibre have minimal effect on Young’s
modulus of HSC concrete at high temperatures. Also, plain HSC concrete showed brittle
properties when temperature was below 600 °C and ductile properties when temperature was
above 600 °C (Cheng, et al., 2014). Similar findings were discovered by other related studies
(Chowdhury, 2014); (Shang & Yi, 2013).
Stress-strain curves for high strength concrete at elevated temperatures
Figure 2: Stress-strain relationship of concrete at high temperatures (Stojkovic, et al., 2017)
In a study by Akca & Zihnioglue (2013) to determine how elevated temperatures affect
high performance concrete (HPC), the researchers added air entrenching admixture (AEA) and
polypropylene (PP) fibres to create improve fire performance of the concrete and create
interconnected reservoirs within the concrete. The researchers found that increasing
temperature resulted to a decrease in concrete mass (at 900 °C, concrete had lost 11.6% of its
mass). Results also showed that AEA helped in reducing the decrease in concrete’s residual
strength but this was irregular after temperature reached 300 °C. PP fibres and AEA also helped
in reducing the risk of concrete spalling (Akca & Zihnioglu, 2013).
In Rana (2018) research on how performance of fly ash reinforced concrete is affected
with increasing temperature, it was seen that an increase in fire temperature resulted to a

Effect of Different Temperatures on FRP Beam 14
decrease in compressive strength of the concrete (Anon., 2018). The temperature increase
weakens the bonding strength between concrete ingredients thus reducing compressive
strength of the concrete. An increase in fly ash content reduced compressive strength of
concrete. Similar results were found in other studies by different researchers (Mundle, 2014);
(Shang & Lu, 2014);(Su, et al., 2014).
Li et al. (2017) carried out a study to establish the effect of elevated temperature on
mechanical properties of FRP reinforced concrete. They exposed the concrete to temperatures
of 80 °C, 160 °C and 240 °C for a period of one-and-a-half hours, and measured flexural
strength, tensile strength and interface bonding properties of the concrete (C30 and C50). The
findings revealed that bonding strength, strain and ultimate tensile strength of the FRP
reinforced concrete declined with increasing temperature and time. The loss rates of high
strength concrete were also higher than those of low concrete strength. The researchers
concluded that elevated temperatures degrade mechanical properties of FRP reinforced
concrete (Li, et al., 2017). Similar results were found in a research done by Ozkal et al. (2018).
In this study, 300 °C and 600 °C were found to be critical temperatures where mechanical
properties of FRP reinforced concrete changed considerably (Ozkal, et al., 2018). Degradation
of bond strength in the concrete was almost linear with increase in temperature. Nevertheless,
serious deterioration of concrete strength started at 600 °C. These results were supported by
Wang et al. (2009) research, which showed that failure strength of FRP reinforcement at high
temperature reduced at an almost linear rate to zero when temperature reached about 500 °C.
They also found that elastic modulus of the FRP reinforced concrete remained almost the up to
300-400 °C, after which it dropped sharply with increasing temperature (Wang, et al., 2009).
Effect of low temperature on concrete
Several studies have been conducted to determine the effect of low temperatures on
concrete. Most of these studies have found that compressive strength of concrete increases
almost linearly with decreasing temperature (Cai, et al., 2011). This change is as a result of
changing moisture content ratio that alters properties of concrete mix. Therefore the higher the
moisture content at decreasing temperature, the higher the compressive strength and elastic
modulus of concrete. The stress-strain relationship of concrete is also affected by low
temperature making it non-linear thus not following Hook’s law. The non-linearity is due to the
distribution of micro-cracks within the transition zone between mortar matrix and coarse
aggregates. The elastic modulus of concrete increases substantially when temperature drops

Effect of Different Temperatures on FRP Beam 15
from 30 °C to -60 °C and this is because of improved cement paste matrix and strengthened
transition zone for the matrix and aggregates.
In a study carried out by Khaliq et al. (2015) to examine material properties of calcium
aluminate cement concrete (CACC), the researchers found that high compressive and tensile
strength of concrete were recorded at lower temperature than at high temperatures. In this
study, the researchers prepared five samples of concrete using calcium cement concrete and
five other samples of normal strength concrete (NSC). They then placed the samples in a
furnace at temperatures of 0 °C, 23 °C, 200 °C, 400 °C, 600 °C and 800 °C, and then removed
and placed them in a thermal jacket where they performed compression test. This study also
proved that elastic modulus of concrete is higher when the concrete is exposed to lower
temperatures (Khaliq & Khan, 2015). Just like most other research papers, the study by Khaliq
et al. (2015), the study did not test the concrete at temperatures below 0 °C. This is a potential
research gap that future researchers should look into. Most of the studies investigating concrete
properties below the temperature of 0 °C refer to it as testing the effects of freeze/thaw cycle on
concrete.
Pigeon & Cantin (1998) postulates that temperature decrease causes the concrete to
contract. From a microscopic point of view, this results to a decrease in equilibrium distance
between atoms as a result of a decline in kinetic energy caused by lower thermal tension
resulting to an increased rate of attraction or boding between cement paste and aggregates.
This increased attraction continues until when temperature reaches -273 °C where no more
thermal tension exists. Therefore the increase in proximity of the atoms causes the increase in
compressive strength and brittleness of the concrete (Pigeon & Cantin, 1998).
Other studies investigating the effect of low temperature on properties of concrete have
found that a reduction in temperature causes a corresponding increase in flexural strength of
concrete. One study found that flexural strength of NSC at -60 °C was 1.6 times greater than the
same concrete at a temperature of 30 °C. Water porosity is also an important factor that affects
permeability of hardened concrete and therefore should be taken into account when performing
tests on concrete. The water that penetrates through the concrete after laying the concrete
structure affects the behaviour of boundary transition zone between the cement paste and
aggregate matrix, and later micro cracks that may form in the concrete. Thus water influx should
be controlled by taking into account the porosity of concrete during experimental tests of
concrete because when concrete is exposed to low temperatures, ice can be created and affect
several mechanical properties of the concrete.

Effect of Different Temperatures on FRP Beam 16
Effect of freeze and thaw on FRP reinforced concrete
Use of fibre reinforced polymers (FRP) to improve strength of concrete has continued to
gain popularity in the construction industry over the past years. FRP, also known as fibre
reinforced plastics, is a composite material that comprises of fibres and polymer matrix. This
material is rapidly replacing steel that has been used for many years for making reinforced
concrete (Lau, 2013). The various types of FRP include: glass fibre, carbon, ultra-high
molecular weight polyethylene, aramid, polypropylene, basalt, nylon and polyester (The
Constructor, 2018). The FRP have a variety of applications in industries such as construction,
automotive, marine and aerospace, among others (Craftech Industries, 2018). Some of the
advantages of FRP are: it can provide maximum stiffness of concrete, ability to absorb impact
energies, high endurance to fatigue, ability to strengthen concrete properties, reduces potential
of corrosion in concrete structures, it simplifies or limits joints and fasteners that are usually
structural weak points in concrete structures, low cost, flexibility, low weight-to-strength ratio,
etc. (Kitane & Aref, 2013). In FRP, the fibres take the biggest volume fraction of the
reinforcement and they subsequently take the largest percentage of the applied load. The fibres
provide strength and stiffness whereas the adjacent plastic matrix protects the fibres and
transfers stress between them. The FRP have very high tensile and yield strength that steel, as
shown in Figure 3 below
Figure 3: Comparison of tensile strength of FRP and steel (Prince, 2017)
Generally, FRP reinforced concrete is the concrete that has been reinforced with FRP
and the reinforcement can come in different types and shapes (Nayak, et al., 2017). The
location of these fibres also has an effect on final strength of concrete (Abdel-Kader & Fouda,

Effect of Different Temperatures on FRP Beam 17
2017). For many years, steel has been used as a major reinforcement in concrete structures.
However, increasing steel prices, its associated carbon emissions and vulnerability to extreme
environmental conditions have driven engineers, designers, scientists and researchers to look
for viable alternatives to steel. FRP is one of these alternatives and it is gradually being
accepted by stakeholders in the construction industry due to its benefits mentioned above (Lee,
et al., 2013). The composite has been proved to have higher flexural strength than steel
(Richardson & Heather, 2013). However, there has been minimal studies on the behaviour of
FRP under harsh weather conditions, such as hot and cold climates. This paper focuses on
reviewing the effect of freeze and thaw on FRP reinforced concrete.
One of the major factors that contribute to deterioration of concrete structures in cold
climates is thaw and freeze (El-Zefzafy, et al., 2013); (Hanjari, et al., 2011). According to Shang
& Yi (2013), freeze/thaw cycles occur when temperature changes abruptly. The freeze/thaw
cycles can cause two types of deterioration in concrete: surface scaling or internal crack growth
(Shang & Yi, 2013). At low temperatures, freezing water increases and since it cannot be
accommodated within concrete pores, it ends up penetrating into the concrete. As a result,
tensile stresses get created and micro and macro cracks get formed resulting to frost damage
(Li, et al., 2017). The change of stress-strain relationship of concrete also causes occurrence of
tension and compression deformation resulting to changes in bond strength and elastic modulus
of the concrete.
One of the most significant papers about the effect of freezing and thawing cycles on
tension properties of concrete was prepared by Marzouk and Jiang in 1994. The researchers
tested NSC and HSC under freeze and thaw conditions up to 700 cycles with 100-cycles
increments. The researchers found that durability of HSC increased after 700 cycles but
thereafter, the flexural strength and compressive strength of concrete reduced by 15%. The
mass of HSC concrete also reduced by 1% after 700 cycles. After 700 cycles, the modulus of
elasticity of NSC and HSC had deteriorated by 39% and 66% respectively (Marzouk & Jiang,
1995).
Chen & Qiao (2015) conducted a study to test fracture energy and dynamic modulus of
elasticity using different numbers of freeze/thaw cycles with an aim of determining the effect of
freezing and thawing on concrete. Results obtained from the study showed that there is a
negative correlation between dynamic modulus of elasticity and the number of freeze/thaw
cycles (Chen & Qiao, 2015). A similar study was conducted by Ji, Song & Liu (2008) where they
sought to establish the effect of freeze/thaw cycles on mechanical properties, particularly bond

Effect of Different Temperatures on FRP Beam 18
strength, of steel reinforced concrete. After subjecting the test samples on freeze/thaw cycles,
the researchers obtained bond stress-slip curves. The findings from this study showed that
freezing and thawing deteriorated bond strength between steel reinforcement bars and concrete
(Ji, et al., 2008). This information is very useful for designing durable reinforced concreted
structures in cold climates.
Another study by Shang et al. (2014) showed that freezing-and thawing reduces
compressive strength, tensile strength and cleavage strength of ordinary air entrained (OAE)
concrete. In this study, researchers subjected concrete specimens to tension and compression
tests. They concluded that during freezing, water froze into ice resulting to volume expansion
that induced cracks in concrete. The repeated freeze/thaw cycles also caused thermal stress to
develop thus inducing cracks in concrete. In their conclusion, the researchers stated that
durability of concrete in freeze/thaw conditions can be improved significantly by adding FRP in
concrete. In their case, they recommended addition of air-entraining agent in concrete (Shang,
et al., 2014). Bisby & Green (2002) also conducted a study and found that the damage on FRP
reinforced concrete due to freezing and thawing is less compared to the damage on ordinary
concrete (Briby & Green, 2008).
Khanfour & Refai (2017) carried out a study to establish how basalt-fiber reinforced
polymer (BFRP) concrete is affected by freeze-thaw cycles. They created 12 BFRP concrete
beams each with a span of 1800 mm and subjected them to freeze-thaw cycles. When the
specimens were exposed to low temperature of up to -20°C, their bond strength decreased by
10%. Nevertheless, freeze-thaw conditioning had minimal effect on ductility of BFRP concrete
beams (Khanfour & Refai, 2017). This further shows that use of FRP is a reliable strategy of
reducing freeze-thaw effect on concrete structures in extreme weather conditions.
An experimental study was carried out by Yun & Wu (2011) to determine the behaviour
of externally-bonded fibre reinforced polymer (EB-FRP) joints when they are exposed to freeze-
thaw cycles. Shear tests were performed on 26 samples by considering parameters such as
class/grade of concrete, exposure condition and no. of freeze-thaw cycle. The results obtained
from the tests showed that bond stiffness, bond strength, maximum slip and interfacial fracture
energy of the EB-FRP joints declined with increasing no. of freeze-thaw cycles. Additionally, the
researchers found that effective bond length and depth of cracking increased with increasing
number of freeze-thaw cycles (Yun & Wu, 2011). It was concluded from this study that freeze-
thaw cycling caused damage of concrete that deteriorated the bond strength of joints.

Effect of Different Temperatures on FRP Beam 19
A study was conducted by Kong et al. (2015) to investigate the performance of FRP-
confined concrete when it is subjected to 300 freezing and thawing cycles under sustained load.
The results showed that glass fibre polymer reinforced concrete lost 6% of its strength when
under freeze-thaw condition whereas carbon fibre polymer reinforced concrete collapsed even
before the freeze-thaw cycles were completed. The results also indicated that strength of both
glass fibre polymer reinforced concrete and carbon fibre polymer reinforced concrete reduced
by 3% when subjected to continuous load and freeze-thaw cycles. The specimens also
exhibited higher resistance than those that were under freeze-thaw cycles only. The reason for
this was loading confinement that could not allow longitudinal movement (Kong, et al., 2015).
Many studies have shown that freezing-thawing has adverse effects on concrete
structures in severe environments, such as cold or hot climates. As a result, it is important to
develop and implement freezing-thawing resistance strategies. One of the widely used
strategies to protect concrete structures against freezing-thawing effects is use of FRP
reinforced concrete. In a study conducted by Green et al. (2003), the researchers strengthened
27 concrete beams using FRP, subjected them to 200 freeze-thaw cycles then conducted failure
tests. The test results showed that the damage to FRP-strengthened beams after subjecting
them to freeze-thaw cycles was insignificant (Green, et al., 2003).
In general, freeze/thaw cycles have significant effects on ordinary concrete but the effect
on FRP reinforced concrete is minimal (Omran & El-Hacha, 2016). Several studies have
demonstrated that the durability of concrete structures in areas that experience freezing and
thawing can be improved by reinforcing the concrete using FRP reinforcement instead of steel
reinforcement (Sen & Reddy, 2013).
Research Hypothesis
The hypothesis of this study is that thermal expansion or temperature changes have a
significant effect on properties of FRP reinforced concrete and the systems built using it.
METHODOLOGY
As stated before, this paper used results obtained from two case studies, one by and the
other by to create a model showing the behaviour of FRP reinforced concrete systems at
different temperatures (between -20 °C and 50 °C). The methodology of the two studies was the
same, as discussed below
The experiment was carried out in Kingston University concrete laboratory. The author of
this report prepared 4 beams with class C30 reinforced concrete and several concrete cubes.

Effect of Different Temperatures on FRP Beam 20
The dimensions of the beams was 1500x125x175mm while each cube measured 150x150mm.
Two of the beams were reinforced with glass fibre reinforced polymer whereas the other two
beams were reinforced with mild steel. The diameter of both the glass fibre reinforcement and
mild steel reinforcement bars was 10 mm. The beams had an identical span of 1200 mm with
the side measuring 100x125mm. After casting the beams and cubes, they were cured for 28
days then tested for strain and deflection behaviour under a controlled temperature environment
(environment chamber) that simulated an extreme environment that the components were likely
to be exposed (thermal cycling). Initially, the temperature of testing machine was raised from
room temperature to 50 °C. Ideally, it was left between 19 °C to 20 °C for five hours then
lowered to -20 °C where it was left for another five hours. Finally, it was left at room temperature
for another five hours. During testing, applied loads ranging from 0 KN to 10 KN, with
increments of 2 KN, were applied to the beams. The first cycle, which lasted for approximately
24 hours, did not have any load applied on the beams (0 KN). The temperature profile of
environmental chamber where the beams were tested is as shown in Figure 4 below
Figure 4: Temperature profile of environmental chamber (Author, 2018)
A summary of the program of the project work is as shown in Table 1 below
Table 1: Summary of program of work
Activity Date
Constructing beam reinforcements July 20, 2018
Installing strain gauges on beam reinforcements July 27, 2018
Constructing reinforced concrete beams August 1, 2018
Curing of reinforced concrete beams August 29, 2018

Effect of Different Temperatures on FRP Beam 21
Testing first paper of reinforced concrete beams August 29, 2018
Testing second pair of reinforced concrete beams September 12,
2018
Creation of beams
To start with, the author carried out a design analysis so as to determine the shearing
reinforcement, ultimate limit states of the beams and quantity and arrangement of links that
were suitable for use in the reinforcement cages. The model that the author established
concluded that the links used should be 12 in number, spanning across the reinforcement
length, with a diameter of 3mm and spacing of 100 mm.
Details and creation of links used
As stated before, two types of links were used: steel reinforcement bars and glass fibre
reinforced polymer bars. The details of the links used for each of the reinforcements are as
follows:
Steel reinforced beam: 2 H10 bars 1480mm 2 mild steel top bars of diameter 6 mm, length
1480mm, and 12 links
Glass fibre reinforced polymer reinforced beam: 2 glass fibre reinforced polymer 10 bars length
1480mm 2 mild steel top bars 6mm diameter 1480mm, 12 links
Figure 5 below shows the design, dimensions and arrangement of links
Figure 5: Dimensions and arrangement of links prepared in AutoCAD (Author, 2018)
The links were constructed in the Kingston University lab using link bending device. Figure 6
below shows bent links.

Effect of Different Temperatures on FRP Beam 22
Figure 6: Bent links (Author, 2018)
Creation of reinforced beam cages
The cages were constructed I structures lab at Kingston University. These cages were
constructed by placing 4 bars of length 1480mm and diameter 10mm on two high ground
stands, placing 12 links around the bars and tightening them in place using smaller links
(stirrups), as shown in Figure 7 below. As the reinforcement cages were being constructed, the
lab technician was preparing the moulds after taking appropriate measurements to ensure that
the cages fitted perfectly in the moulds. After constructing the reinforcement cages, they were
placed in the moulds and fitted perfectly.
Figure 7: Construction of reinforced beam cages (Author, 2018)

Effect of Different Temperatures on FRP Beam 23
Figure 8 below shows the four prepared reinforced beam cages
Figure 8: Finished GFRP and steel reinforced beam cages (Author, 2018)
Installation of strain gauges
To measure strain experienced by the beams, strain gauges were fixed in the middle of
each of the four beams. One strain gauge was attached on the top side of the beam cage
(compression side) and the other on the bottom side of the beam cage (tension side), as shown
in Figure 9 below. The connected was then checked using an ammeter, as shown in Figure 10
below. Thermal output coefficient was then entered in the computing software to take into
account electrical resistance changing because of temperature and strain.

Effect of Different Temperatures on FRP Beam 24
Figure 9: Connection between strain gauges and reinforcement cages (Author, 2018)
Figure 10: Checking the connection of strain gauges (Author, 2018)
After connecting a strain gauge to a strain indicator and when the instrument is
balanced, any change in temperature results to a change in resistance in the gauge. The
resistance change due to temperature is not dependent on mechanical stress within the object
being tested (the object attached to the strain gauge). The resistance change is only due to the
temperature change, which is referred to as thermal output, and is different for different strain
gauges. The thermal output coefficient inserted into the computer software are as shown in
Figure 11 below

Effect of Different Temperatures on FRP Beam 25
Figure 11: Thermal output coefficients entered in the computer software (Author, 2018)
After fitting the strain gauges, the reinforcement cage beams were fitted into the moulds as
shown in Figure 12 below
Figure 12: Fitting reinforcement cages into moulds (Author, 2018)

Effect of Different Temperatures on FRP Beam 26
Casting of concrete
C30 concrete was prepared in the structures lab at Kingston University. The concrete
was needed to make 4 beams measuring 1500x125x75mm and 12 cubes measuring
150x150m. Considering the capacity of the mixing machine, the author made only one cast per
every mixture. Since only 1 mixture was enough, the possibility of having concrete with the
same strength across all beams and cubes was high.
The measurements of concrete ingredients used are as shown in Table 2 below
Table 2: Amount of concrete ingredients used
Per 1m3
Ingredient Amount
(kg)
Cement 425
Water 225
Fine aggregate (sand) 700
Coarse aggregates (within 10mm) 970
The measurements of concrete ingredients per beam are as shown in Table 3 below
Table 3: Amount of concrete ingredients per beam
Per beam
Ingredient Amount
(kg)
Cement 5.98
Water 3.17
Fine aggregate (sand) 9.85
Coarse aggregates (within 10mm) 13.65
The measurements of concrete ingredients per beam are as shown in Table 4 below
Table 4: Amount of concrete ingredients per cube
Per cube
Ingredient Amount

Effect of Different Temperatures on FRP Beam 27
(kg)
Cement 1.44
Water 0.76
Fine aggregate (sand) 2.37
Coarse aggregates (within 10mm) 9703.28
After calculating the volume, the value obtained was multiplied by 10% as a safety factor to
cater for wastage.
The concrete was prepared by following Kingston University’s standard procedure of
preparing concrete, which is provided in Figure 13 below. First, coarse aggregates, sand and
cement were measured and poured into the mixing machine followed by adding half the water to
it. Figure 14 below shows measurement of aggregate. The ingredients were left to mix for a few
minutes after which they were mixed again then the remaining half water added to it. The
procedure was repeated for every mix. It took almost a day to complete mixing the required
volume of concrete. The prepared concrete was stored for casting the following day.
Figure 13: Kingston University’s standard procedure of preparing concrete (Author, 2018)

Effect of Different Temperatures on FRP Beam 28
Figure 14: Measurement of aggregate (Author, 2018)
Since four beams with different mixtures were needed, slump test was performed on
each mix so as to determine the strength of concrete. The benefit of slump test is that it helps in
checking the consistency or variability of water level or content in the concrete. The slump test
in this paper was performed in accordance with the guidelines of BS EN 12350-2: Testing Fresh
Concrete – Slump Test. The procedure of slump test was as follows: first, three layers of fresh
mixed concrete were filled equally into the steel slump cone, one at a time with each layer being
rodded about 25 times to ensure that the concrete is properly compacted. Second, the steel
slump cone was lifted up gently for the concrete to slump or collapse slightly. Third, the inverted
slump cone was placed on the base so as to act as reference then the difference in height
between the top of steel slump cone and the top of the concrete was measured and recorded.
The value recorded was equivalent to the slump of the concrete. Figure 15 below shows slump
test results. The height of first and second mixture was 15mm and 17mm respectively. Ideally,
the height of the two mixtures were expected to be the same but the results obtained show that
there was a difference of 2mm between the two. However, the difference of 2mm is small and
therefore it showed that workability and strength of the two mixtures were close.

Effect of Different Temperatures on FRP Beam 29
Figure 15: Slump test results (Author, 2018)
After completing the slump tests, the concrete was poured into the prepared moulds fitted with
reinforcement beams and 7 150x150mm cubes, as shown in Figure 16 below.
Figure 16: Concrete poured into the beam moulds (Author, 2018)
Figure 17 below shows preparation of concrete cubes. The steel reinforced concrete beams
were casted first then the GFRP reinforced concrete beams. The beams were then de-moulded

Effect of Different Temperatures on FRP Beam 30
and labelled (as shown in Figure 18 below) then placed in the curing room where they stayed
for 28 days to allow for adequate curing so that the concrete can attain maximum strength.
Figure 17 Preparation of concrete cubes (Author, 2018)
Figure 18: De-moulded and labelled beams
Testing of Concrete Cubes
Each concrete cube was tested one at a time. The setup of testing machine for concrete cubes
is as shown in Figure 19 below

Effect of Different Temperatures on FRP Beam 31
Figure 19: Testing machine for concrete cubes (Author, 2018)
Figure 20 below shows an example of reading from the testing machine. The reading means
that the cube failed at a maximum load of 692.5 KN at the stress of 30.8 N/mm2.
Figure 20: Example of reading on concrete cube testing machine (Author, 2018)
The results obtained from concrete cube testing are as provided in Table 5 below
Table 5: Concrete cube test results
First Batch Maximum load Stress

Effect of Different Temperatures on FRP Beam 32
(KN) (N/mm2)
Pre experimental samples
785.2 34.9
692.5 30.8
742.8 33
Post experimental samples (cubes stored in the
environmental chamber)
875.3 38.9
804.8 35.77
767.4 34.1
Post experimental samples (cubes stored out of the
environmental chamber)
862.1 38.1
676.7 30.07
716.2 31.83
Second Batch Maximum load
(KN)
Stress
(N/mm2)
Pre experimental samples
640.2 28.5
693.4 30.8
666 29.6
Post experimental samples (cubes stored in the
environmental chamber)
685 30.48
713.6 31.72
651.9 28.97
Post experimental samples (cubes stored out of the
environmental chamber)
529.2 23.52
539.8 23.99
685.8 31.48

Effect of Different Temperatures on FRP Beam 33
Beam Results Hypothesis
It is expected that all beams, regardless of the type of reinforcement bars used, will
record their best performance under normal temperature. But the aim of this paper is to analyze
the effect of seasonal or environmental temperatures on the behaviour or properties of FRP
reinforced concrete beams (GFRP reinforcement and steel reinforcement) under extreme
environmental temperatures and controlled loads. According to the study conducted by Wang et
al. (2014), the beams are expected to perform poorly in fluctuating temperature conditions. The
researchers of the study found that the ratio of tensile strength of basalt reinforced concrete
beams decreased drastically as a result of high temperature (Wang, et al., 2014). Therefore it is
expected that high temperature will have more damaging effects on the beams under 4-point
bending load than low temperature. Another research by Adam et al. (2015) showed that glass
fibre reinforced concrete had a lower ultimate load than steel reinforced concrete. In relation to
flexural behaviour, glass fibre reinforcement also revealed a worse deflection with increase in
loads than steel reinforcement. This study concludes that steel reinforcement is a better
reinforcement material than glass fibre reinforcement material (Adam, et al., 2015). But, the
main advantage of fibre reinforcement is its high corrosion resistance and strength-to-weight
ratios than steel reinforcement. This major advantages make FRP one of the most viable
options for use as concrete reinforcement material. Also, beams tested under normal
temperature are expected to perform better than those tested in the environmental chamber,
which has freezing and thawing effect. This is because temperature has an effect on the
performance of reinforcement materials.
Testing of Beams
The testing was done using devices available in Kingston University’s structure lab.
During testing, the beams were supported with concrete cubes. Applying loads on the beams
was done by tightening the steel plate supports with a spanner. This induced the same
deformation as it would have been by applying a load on simply supported beam under four
point bending.
Testing system of beams
After the beams had been cured for 28 consecutive days, they were taken from the
curing room and placed into the environmental chamber for testing. The beams were properly
positioned followed by wiring the strain gauges on them using a solder iron, as shown in Figure
21 below

Effect of Different Temperatures on FRP Beam 34
Figure 2: Setup of beam testing (Author, 2018)
Deflection of the beam at mid-span was the most important part of this test. This is
because maximum deflection was expected to occur at the middle of the beam. Nevertheless,
there was the possibility of the beam moving inside the environmental chamber, which could
lead to errors. To prevent this error, linear variable differential transformers (LVDTs) were added
on the supports at the distance of 100mm from the ends and another one at the middle of the
beam, as shown in Figure 22 below. A stand was used to hold every two LVDTs in place.
Figure 22: Position of LVDTs on each beam (Author, 2018)
Testing process
The environmental chamber was calibrated such that the temperature varied from 50 °C
TO -20 °C. A testing thermal cycle was performed for 22 hours before the start of actual testing.

Effect of Different Temperatures on FRP Beam 35
This was done so as to ensure that the environmental chamber was functioning properly. Since
the steel reinforced beams were the first to be cast, they were also the first pair of beams to be
tested. The researcher started with a 0 KN cycle. This means that the beams were not
subjected to any loading and therefore their behaviour was observed under temperature
changes only. The cycle was then followed by 2KN cycle, 4 KN cycle, 6 KN cycle, 8 KN cycle
and 10 KN cycle. Since the two beams were put in one load cell, the value of load on the
computer was doubled to ensure that the beams were getting the right values of loads. Every
load cycle took about 22 hours (almost a day) to complete. After completing a cycle, the loading
device had to be calibrated for the next load cycle (loading condition). The loading condition was
changed by tightening the nuts positioned at the top of the steel plate. To achieve greater
accuracy by having better calibration, the nuts were tightened equally. To have a better
understanding of the strain values of concrete under fluctuating temperatures, 3 concrete cubes
were put in the environmental chamber for testing so as to determine their compressive strength
at the end of the six-day cycle. The beams’ loading was attached to the loading cell that was
connected to the logging device outside the environmental chamber.
During thermal cycle testing, more focus was put on the two hours that the temperature
of the environmental chamber reached 50 °C and -20 °C. At these temperatures, the beams
were left at a constant temperature for 2 hours. This enabled removal of thermal gradients and
facilitated attainment of stable behaviour. After completing testing the two steel reinforced
beams, they were removed from the environmental chamber and replaced with GFRP beams.
The GFRP beams were placed in the environmental chamber ensuring that they were put in the
right position and that LVDT’s were the same as those used when testing steel reinforced
beams. The same loading pattern of 0 KN, 2 KN, 4 KN, 6 KN, 8 KN and 10 KN was used, just
like for the steel reinforced beams. At the end of every 22 hours (after completing each cycle),
LVDT’s displacement values were reset followed by observing cracks especially in steel support
area under the load cell. Predominantly, there were no cracks seen for all the cycles, both for
steel reinforced and GFRP reinforced beams under all loading conditions.
Values of different parameters were measured from the testing and used to model the
beams’ behaviour in ANSYS software. The particular values measured include the following:
mid-span deflection, strain (at top and bottom of the beam) and deflection at different points
along the beams. The values obtained were also used to calculate specific parameters that are
needed as input data for ANSYS software. The specific parameters include: elastic modulus,
ultimate uniaxial tensile strength, ultimate uniaxial compressive strength, Poisson’s ratio, stress-

Effect of Different Temperatures on FRP Beam 36
strain relationship and shear transfer coefficient of concrete; Poisson’s ratio and elastic modulus
of steel reinforcement bars and GFRP reinforcement bars; and Poisson’s ratio and elastic
modulus of steel plates.
All these parameters were measured and recorded for the two types of beams (steel
reinforced beams and GFRP reinforced beams) at different loading conditions (0 KN, 2 KN, 4
KN, 6 KN, 8 KN and 10 KN) and at all thermal cycles (50 °C to -20 °C). These parameters were
then used to analyze the beams in ANSYS software.
ANSYS software
There are different methods used for modeling the behaviour of reinforced concrete
components through numerical and analytical approaches (Moharrami & Koutreomanos, 2017).
One of the widely used numerical methods is finite element analysis (FEA) (Tahmasebinia,
2008); (Tan & Zhang, 2013). This is basically a computerized approach of predicting the
behaviour of a component when it is subjected to real-world physical effects such as forces,
fluid flow, heat and vibration (Dragos, et al., 2014). The method divides a structural component
into sub-components after which it simulates each sub-component’s static loading conditions
(Subramani, et al., 2014). In this study, the FRP reinforced concrete beams were analyzed
using ANSYS software – a general purpose FEA package. This software is a commonly used
and reliable FEA package for analyzing the behaviour of reinforced concrete components under
different physical effects (Dahmani, et al., 2010).
Experimental program
The experimental program in this study comprised of four beams: 2 made with steel
reinforced concrete and 2 made with FRP reinforced concrete. The details of dimensions of the
beams and properties of concrete used have been provided in the first sections of methodology.
To start with, a finite element model was created in ANSYS software, which is a 3D finite
element program. In this analysis, the researcher used apposite material models provided in the
software to represent the behaviour of steel reinforcement, FRP reinforcement, concrete and
steel plates (provided at loading point and support locations in the finite element model). The
steel plates are used for ensuring even distribution of stress over loading points and support
locations in the finite element model. Details of these material models are provided in the
ANSYS manual. The concrete was modeled in ANSYS software using a solid element,
SOLID65. This element is a non-linear model that simulates brittle materials. It has 8 nodes with
each node having 3 intermediate degrees of freedom (DOF). The element can simulate cracking
of concrete in 3 orthogonal directions, plastic deformation of concrete and crushing of concrete.

Effect of Different Temperatures on FRP Beam 37
The steel plates were modeled in the ANSYS software using SOLID45 element. The element
has a total of 8 nodes with each node having 3 DOF that transition in x, y and z directions. To
ensure that the reinforcement bars remain in their right positions and to measure internal strains
within the reinforcement bars, the researcher used discrete method of three dimensional spar
link8 element. The element has 2 nodes with 3 DOF transitions in the x, y and z directions. The
element can also measure plastic deformation of the reinforcement bars.
The FRP reinforcement bars were modeled using SOLID46, a layered solid element.
This element is basically a layered version of SOLID45 that is designed to model layered solids
or thick shells. It can be used to model up to 250 layers of different materials. It has 3 DOF at
each node, which transitions in all three directions: x, y and z directions. Figure 23 below is an
example of modeling a concrete beam in ANSYS.
Figure 23: Example of modeling a concrete beam in ANSYS software (Singh, et al., 2016)
A square mesh was used so as to increase the accuracy of results. A FEA requires that
the model be meshed i.e. divided into smaller parts. Figure 24 below is an example of a
meshing of a beam in ANSYS software. The environmental temperatures were modeled using
SOLID70 and LINK33 of the ANSYS software. SOLID70 has a total of 8 nodes with one DOF at
each node that is defined as temperature (and sometimes referred to as three dimensional
thermal conduction capability).

Effect of Different Temperatures on FRP Beam 38
Figure 24: Example of meshing a beam in ANSYS software (Singh, et al., 2016)
Finite element model input data
ANSYS software works based on the input data for finite element model. When modeling
concrete, the software requires input data for the following concrete properties: elastic modulus,
ultimate uniaxial tensile strength, ultimate uniaxial compressive strength, Poisson’s ratio, stress-
strain relationship of concrete and shear transfer coefficient. The steel reinforcement bars and
FRP reinforcement bars used in this study were assumed to be elastic-perfectly plastic
materials. They were also assumed to be identical in both compression and tension. When
modeling the reinforcement bars, the ANSYS software requires input data for the following
reinforcement properties: Poisson’s ratio and elastic modulus (Badiger & Malipatil, 2014). The
researcher assumed that the steel plates used in this study were linear elastic materials. When
modeling the steel plates, the ANSYS software requires input data for the following properties:
Poisson’s ratio and elastic modulus. All the input data for concrete, steel reinforcement bars,
FRP reinforcement bars and steel plates used in this study were obtained from results in the two
case studies aforementioned: a study by Waqas Khattak and a similar study by Atikom
Ongphichetmetha. The input data is then used to simulate the relationships between load and
deflection, temperature ad deflection, load and strain, and temperature ad strain. Figure 25 and
26 below shows examples of total deflection and elastic strain of a beam simulated in ANSYS
software.

Effect of Different Temperatures on FRP Beam 39
Figure 25: Example of total deflection of a beam in ANSYS software (Singh, et al., 2016)
Figure 26: Example of elastic strain of a beam in ANSYS software (Singh, et al., 2016)
Boundary and loading conditions
The developed finite element model was exposed to different thermal cycles and loads.
The beams were tested at temperatures ranging between 50 °C and -20 °C. To start with, the
first steel reinforced beam model was subjected to a load of 0 KN and tested under different
temperatures (50 °C and -20 °C). The process was repeated by changing loads to 2 KN, 4 KN,
6KN, 8 KN and finally 10 KN. The results of various properties that demonstrated the behaviour
of the reinforced concrete beams under varied loads and temperatures were automatically
recorded in the ANSYS software. At each cycle, the software was set such that the temperature
variation between 50 °C and -20 °C took 22 hours. But at 50 °C and -20 °C, the temperature
was held constant for 2 hours each. The same modeling process was repeated for the second
steel reinforced concrete beam and the two other FRP reinforced beams. The program
produced finite element models showing how the behaviours of beams under different loading
conditions and at different temperatures.

Effect of Different Temperatures on FRP Beam 40
RESULTS ANALYSIS
Strain of steel reinforced beams at varied loads and temperature
The beams experienced very minimal strain at 0 KN. The minimal strains were as a
result of temperature changes, which shows deformation of the beam when particles in the steel
materials get displaced when temperature is changing. The general behaviour of steel
reinforced beams was that an increase in temperature and load resulted to a corresponding
increase in strain. At the highest temperature of 50 °C, the steel reinforced beam was in
expansion and therefore strain values were high. On the other hand, at the lowest temperature
of -20 °C, the beams were in compression and the strain values were low. At constant load, the
values of strain increased gradually as temperature rose from 20 °C and reached the maximum
value at 50 °C. The strain values then started decreasing as temperature dropped from 50 °C to
-20 °C. The strain started increasing again as temperature rose from -20 °C to 20 °C. The
simulation also showed that strain values were directly proportional to the applied load – 10 KN
load recorded the highest strain values while 2 KN load recorded the smallest strain values.
Additionally, it was noted that strain values at the top of the beams were lower than those at the
bottom of the beam. This is expected because the top experiences compression thus strain is
expected to be lower while the bottom experiences tension thus strain is expected to be higher.
Strain of GFRP reinforced beams at varied loads and temperature
The behaviour of the GFRP reinforced beams was identical to that of steel reinforced
beams. This is because strain increased with increasing load from 20 °C to reach maximum
value at 50 °C. The strain values then started decreasing as temperature dropped from 50 °C to
-20 °C where minimum strain values were recorded. The strain started increasing again as
temperature rose from -20 °C to 20 °C. When temperature increases, the beam experiences
tension and therefore it expands resulting to an increase in strain. On the other hand, when
temperature drops, the beam experiences compression and therefore it contracts resulting to a
decrease in strain. The simulation also showed that strain values at the top of GFRP reinforced
beams were smaller than those at the bottom of the beams. The strain values for GFRP
reinforced beams were greater than those for steel reinforced beams at the same loading
condition and temperature.
Deflection of steel reinforced beams at varied loads and temperature
The aim of this simulation was to find out how loads and temperature affects deflection
in beams. The beams were subjected to different loading conditions and thermal expansion
rates. Theoretically, when a material is exposed to thermal expansion, it tends to expand when

Effect of Different Temperatures on FRP Beam 41
it is heated and contract when it is cooled. The simulation showed that maximum positive
deflection was recorded at 50 °C, which was the highest temperature of the test while maximum
negative deflection was recorded at -20 °C. Every thermal cycle started at room temperature of
about 20 °C, increased to 50 °C (and held constant for 2 hours), dropped to -20 °C and finally
increased to 20 °C. At maximum and minimum temperature (50 °C and -20 °C), temperature
was held constant for 2 hours. This was necessary to allow adequate stabilization of
temperature and remove strains that were produced by thermal gradients so as to give actual
values of maximum and minimum deflection. It was found that deflection increased with
increase in temperature, and vice versa. Also, deflection was proportional to load – 10 KN load
produced the highest deflection values, followed by 8 KN load, 6 KN load, 4 KN load and lastly
the 2 KN load produced the least deflection.
Deflection of GFRP reinforced beams at varied loads and temperature
The deflection behaviour of FRP reinforced beams was similar to that of steel reinforced
beams. In both types of beams, the maximum positive deflection was recorded at 50 °C
whereas the maximum negative deflection was recorded at -20 °C. Deflection was also
proportional to the amount of load applied on the beam at the same temperature – 10KN load
produced the highest deflection, followed by 8 KN load, 6 KN load, 4 KN load and lastly 2 KN.
However, there was a significant difference in values of maximum positive and negative
deflection between steel reinforced beams and GFRP reinforced beams. The GFRP reinforced
beams recorded slightly higher deflection values than steel reinforced beams. This basically
means that steel and FRP beams deflect at different rates when exposed to the same
temperature variations.
One common trend that was realized when simulating deflection of both steel reinforced
and GFRP reinforced beams was that maximum deflection was attained during the lowest
temperature of -20 °C. The deflection also increased with increase in load, and vice versa.
In this study, the FEA software was used to show the relationship between load and
deflection, temperature and deflection, load and strain and temperature and strain.
CONCLUSION
A study was conducted to create a model of reinforced concrete beams using ANSYS
software to help in determining the effects of temperature on the behaviour of steel and GFRP
reinforced concrete beams. Two class 30 (C30) steel reinforced concrete beams, two GFRP
reinforced concrete beams and 12 concrete beams were prepared and various parameters of

Effect of Different Temperatures on FRP Beam 42
mechanical properties determined. The procedure followed was the one used by two researcher
sin their past similar studies: “Investigation on influence of freeze/thaw on reinforced concrete
beams with GFRP” by Waqas Khattak, and “Effect of environmental temperature on FRP
reinforced concrete beams” by Atikom Ongphichetmetha. Therefore the main focus of this paper
was to use ANSYS software to show results obtained from the two papers.
Finite element models of steel reinforced and GFRP reinforced beams were constructed
in ANSYS software using particular elements for concrete, steel reinforcement bars, FRP
reinforcement bars and steel plates. The input data from the two past papers that was used to
model various components of the beams are as follows: concrete – elastic modulus, ultimate
uniaxial tensile strength, ultimate uniaxial compressive strength, Poisson’s ratio, stress-strain
relationship of concrete and shear transfer coefficient; steel reinforcement bars and FRP
reinforcement bars – Poisson’s ratio and elastic modulus; and steel plates – Poisson’s ratio and
elastic modulus. After creating the models of steel reinforced and GFRP reinforced concrete
beams in ANSYS software, they were simulated under different loading conditions and thermal
cycles. One beam was simulated at a time. Each beam was subjected to a loading of 0 KN
followed by 2 KN, 4 KN, 6 KN, 8 KN and then 10 KN. Every loading cycle lasted for 22 hours.
During this period, temperature was varied between 50 °C and -20 °C. The analysis started at
20 °C. The temperature was then raised to 50 °C where it was held constant for 2 hours. It was
then dropped to -20 °C where it was again held constant for another 2 hours. Thereafter, the
temperature was increased to 20 °C. The main area of focus was on the relationship between
load and strain, load and deflection, temperature and strain, and temperature and deflection.
The simulation showed that the behaviour of steel reinforced concrete beam and GFRP
reinforced concrete beam was similar but identical. Strain of the two beams changed with
varying loads and temperature. Generally, an increase in temperature resulted to a
corresponding increase in strain and vice versa. Also, strain was proportional to load with the 10
KN load cycle producing the greatest strain while the 2 KN load cycle producing the least strain.
Steel has a higher coefficient of expansion than GFRP thus it is expected that when these two
types of materials are subjected to the same loading conditions and temperature, steel will have
a smaller reaction of strain than GFRP. The deflection of GFRP reinforced beam was greater
than that of steel reinforced beam. These results are as expected because GFRP has a higher
Young’s modulus (606 GPa) than that of steel (210 GPa). Therefore when steel and GFRP are
subjected to the same load and environmental conditions, GFRP is likely to deform more than
steel.

Effect of Different Temperatures on FRP Beam 43
ANSYS software is a FEA package that is commonly used in analyzing behaviour of
components when subjected to different physical effects. In this study, the software was used to
analyze the behaviour of steel reinforced concrete beam and GFRP reinforced concrete beam
when subjected to varying forces (loads) and temperature. The beam models created in the
software were simulated and they clearly showed that temperature affects the behaviour of steel
and GFRP reinforced concrete beams. The behaviours of these two beams were similar but
identical because the curves or graphs of temperature against defection, temperature against
strain, load against deflection and load against strain had similar trends even though the values
of deflection and strain at each loading condition and temperature cycle were different. The
differences in values of strain and deflection for steel and GFRP reinforced concrete beams was
due to these two types of materials having different values of coefficient of expansion and
Young’s modulus. Therefore the results obtained from this study proved the hypothesis that
temperature changes have a significant effect on properties of FRP reinforced concrete
elements.
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