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Enhancement of Flexural Strength Capacity of RC-Beams using LC-GFRP Plates with Effective Debonding Techniques
(2026-07-01)
Rodsin, Kittipoom
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Ngamkam, Kunanon
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Parichatprecha, Rattapoohm
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Pongpeng, Jakrapong
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Mehmood, Tahir
Strengthening of reinforced concrete (RC) beams by externally bonded Carbon Fiber Reinforced Polymer (CFRP) is found to be a very effective method to increase their flexural strength capacity. However, the strengthening cost of the CFRP technique is very high and clients tend to avoid such expensive retrofitting methods. An alternative strengthening material, such as Glass Fiber Reinforced Polymer (GFRP), is a much less expensive material compared to CFRP. The GFRP strengthening method can achieve comparable strength gain and is an effective solution for strengthening RC beams. However, due to the lower strength and stiffness, a larger thickness of GFRP is required to obtain the target tensile strength. This increase in fiber thickness results in the commonly observed debonding failure of the GFRP-plated RC beams. Therefore, this study investigates the end anchoring technique by testing five beams under three-point bending. The first beam served as a controlled beam, while the second and the third beams were strengthened with one and three layers of GFRP to investigate the effect of the number of GFRP layers on debonding behavior. Anchored bolts were used to prevent debonding in the fourth specimen. The innovative W-shape inclined jacket technique was used for the last specimen. The test results revealed that the GFRP could effectively increase the beam's flexural strength. Nevertheless, when a larger number of GFRP layers was used, the debonding of GFRP occurred at an early loading stage. With the anchored bolted technique, the flexural strength of the RC beam was found to increase twice compared to the controlled specimen before failure due to the pulling off of the anchored bolts. Widespread shear cracks were observed near the failure stage. For the W-shape inclined jacket strengthening technique, the flexural strength was increased to a similar order as the anchored bolted technique, but the failure mode was due to slippage of the GFRP against the W-shape inclined jacket. Due to the use of a W-shape inclined jacket, the shear strength of the beam increased significantly. Therefore, the crack patterns near the final stage were controlled by flexure. The test results revealed that both techniques are effective methods to enhance the flexural strength of the GFRP-strengthened beam by achieving a similar magnitude of strength gain but failing in different failure mechanisms.
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Detection of Isolated Track Defects Using Axle Box Acceleration from Multibody Simulation and Recurrent Neural Network
(2026-01-23)
Plodphai, Kritat
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Petcharat, Thitiwut
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Suthasupradit, Songsak
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Parichatprecha, Rattapoohm
Railway track inspection is typically conducted cyclically, which is slow, budget-intensive, and time-consuming, as it can only be performed during non-service periods when trains are not in operation. Currently, there are emerging concepts and research studies utilizing railway defect detection through acceleration measurements from axle box mounted on service trains, as this approach offers easier implementation, reduced costs, and time efficiency compared to conventional methods. However, the diagnostic process remains challenging due to the high complexity and large volume of data involved. This research presents a method for applying Recurrent Neural Network (RNN) that works with time-series data in diagnosing railway defects by classifying three specific types of isolated defects: squats and corrugation. The training samples for the neural network were derived from axle box acceleration data obtained through multibody simulation analysis that modeled various railway conditions, speeds, and defect characteristics. A total of 360 samples from the multibody model were used for training, validation, and testing. The study results showed that the Recurrent Neural Network (RNN) achieved an average defects classification accuracy of 91.67%. Furthermore, the study findings revealed that the developed RNN model can accurately predict the location and classify defects, with particularly high accuracy in predicting the location and defects caused by long-pitch corrugation. The study concluded that the developed RNN model can efficiently learn and classify defects from axle box acceleration data obtained from multibody simulation. This approach can be applied as a guideline for railway damage diagnosis in future maintenance applications.
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Low-Cost Glass Fiber-Reinforced Polymer Composite Wraps for Strengthening Deep Beams with and without Longitudinal Openings
(2025-08-01)
Rodsin, Kittipoom
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Ejaz, Ali
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Hussain, Qudeer
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Suthasupradit, Songsak
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Parichatprecha, Rattapoohm
This is a preliminary work on the application of low-cost glass fiber-reinforced polymer composites (Lo-Gs) wraps to enhance the structural response of shear-critical deep beams with and without openings. This study explores the performance of nine deep beams divided into three groups depending on the existence and number of longitudinal openings: solid section beams (Group 1), beams with one opening (Group 2), and beams with two openings (Group 3). Each group consisted of one unstrengthened beam and two beams strengthened with either one or two layers of Lo-Gs wraps. The results showed that Lo-Gs confinement effectively delayed failure in strengthened beams, while having minimal impact on the sudden failure behavior of unstrengthened specimens. Solid section beams exhibited peak load increases of 12.1% and 20.2% with one and two wraps, respectively. In contrast, beams with openings demonstrated higher but more variable strength gains. The presence of longitudinal openings diminished the effectiveness of the wraps in improving ultimate deflection and energy dissipation. While solid beams achieved up to a 130.1% increase in energy dissipation, beams with one and two openings showed lower gains of 63.4% and 57.0%, respectively. Existing design models, calibrated for synthetic FRPs, poorly predicted the behavior of beams with Lo-Gs wraps and neglected the effects of openings, emphasizing the need for further research and model development to address these limitations.
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Collapse prevention of pre-stressed electric transmission poles using glass fiber reinforced polymers
(2025-07-01)
Parichatprecha, Rattapoohm
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Rodsin, Kittipoom
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Suthasupradit, Songsak
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Mehmood, Tahir
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Nawaz, Adnan
Natural hazards such as strong winds, typhoons, and earthquakes have caused massive economic losses in the form of damage to residential and life-line structures. Electric transmission infrastructures are life-line structures susceptible to severe damage under lateral loads like wind and earthquakes. This study focused on vulnerability assessment and measures to reduce the expected damage to the prestressed electric transmission poles under lateral loads. The Glass Fiber Reinforced Polymer (GFRP) sheet is selected as a strengthening material because the fiber cost is affordable but still has acceptable high tensile strength. A full-scale 12-meter-long prestressed transmission pole was tested under reversed cyclic lateral loading. Furthermore, another specimen strengthened with the GFRP sheet was tested to quantify the effectiveness of this technique. The experimental results show significant improvement in the lateral response behavior of prestressed poles in terms of lateral drift capacity, ductility, and energy dissipation characteristics. The GFRP-strengthened specimen exhibited a significantly enhanced lateral drift capacity (more than 100 %) compared to the control specimen. The performance of GFRP in preventing the collapse of a full-scale transmission pole is proved experimentally in this study. Finally, a numerical model based on the fiber modeling concept was also implemented in the open-source platform OpenSees to simulate the observed hysteretic behavior for strengthened and unstrengthened prestressed electric transmission poles. The application of this strengthening method is shown to be very practical for collapse prevention of existing PC poles both in terms of performance and budget.
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Influence of Recycled Fine Aggregates on the Structural Behavior of Reinforced Concrete Beams
(2025-06-01)
Rodsin, Kittipoom
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Ejaz, Ali
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Shrestha, Kriti
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Hussain, Qudeer
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Parichatprecha, Rattapoohm
The research specifically focuses on the effects of recycled fine aggregates as partial replacements for natural aggregates, contributing to the growing body of knowledge on sustainable construction materials. This study contributes to the understanding of how recycled materials can be effectively utilized in concrete construction, promoting sustainability while maintaining structural integrity. The testing program includes 13 beams, all designed with a target compressive strength of 15 MPa, using seven different types of fine aggregates. All tested beams experienced mixed shear failure, starting with flexural cracks beneath the loading point and progressing to flexural-shear and diagonal shear cracks as the load increased. Failure was marked by significant diagonal cracks leading to brittle collapse and reduced beam capacity. Recycled aggregate beams exhibited a slight increase in flexural cracks, with critical shear cracks widening significantly when loads exceeded 50% of ultimate strength. The use of recycled brick aggregates, recycled concrete aggregates, fly ash, and sugarcane bagasse ash led to reduced shear strength and deflection capacity. Notably, recycled fine aggregate concrete beams with 10% cement clay interlocking bricks performed better than the control beam. The load-deflection response was similar across beams, indicating no impact on elastic stiffness.
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Experimental and Theoretical Analysis of a Hybrid FRP Strengthening Technique for Reinforced Concrete Circular Columns
(2025-01-01)
Rodsin, Kittipoom
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Parichatprecha, Rattapoohm
This study presents a preliminary experimental and analytical investigation into the effectiveness of newly developed hybridized basalt fiber-reinforced polymers and e-glass (B-CHSM) jackets. Twenty-four RC specimens were fabricated, with variables including unconfined compressive strength and the number of B-CHSM layers. The experimental results demonstrated significant enhancements in compressive strength and strain, with improvements of up to 325% and 322%, respectively, compared to unconfined specimens. Specimens with an unconfined strength of 15.5 MPa achieved a 325% increase in ultimate strength with three-layer B-CHSM confinement. For low unconfined strength specimens, strain improvements of 135%, 218%, and 322% were observed with 1-, 2-, and 3-layer B-CHSM confinement, respectively. Low-strength specimens strengthened with 1-, 2-, and 3-layer confinement showed 30%, 22%, and 88% higher ultimate strength than medium-strength specimens and 75%, 75%, and 165% higher strength than high-strength specimens. The study evaluated existing analytical models for FRP strengthening, revealing their limitations in accurately predicting the performance of B-CHSM-confined concrete. Consequently, regression-based expressions were developed, achieving coefficients of determination exceeding 0.80. These expressions were utilized to idealize the stress-strain curves, enabling precise representation of B-CHSM-confined concrete behavior. The predicted curves closely matched experimental results, confirming the reliability of the proposed methodology.
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The current situation and the directions of changes in rail freight transport in Thailand
(2024-01-01)
Hengsadeekul, Thammanoon
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Chaosakul, Thitirat
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Parichatprecha, Rattapoohm
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Pakdeenarong, Paveerat
The purpose of the article is to present the current situation in the rail freight transport in Thailand and the direction of changes in this area. Firstly, Thailand statistics in volume of freight transport by rail and modal share of freight transport have been presented. Afterwards, problems and obstacles in railway operational practices and in using rail transport services have been identified to improve railway system in Thailand and the outcome was assessed in terms of railway capacity and utilization. The findings were used to outline the direction of changes in rail freight transport. The results show that the rail transport capacity in double-track would increase by 48% (at present by 15.5% and as plan by 30%) and the ratio by rail transport to total freight transport would increase from at present by 1.87% to 10% in 2037.
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Experimental and Analytical Studies on Low-Cost Glass-Fiber-Reinforced-Polymer-Composite-Strengthened Reinforced Concrete Beams: A Comparison with Carbon/Sisal Fiber-Reinforced Polymers
(2023-10-01)
Rodsin, Kittipoom
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Ejaz, Ali
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Hussain, Qudeer
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Parichatprecha, Rattapoohm
This study presents an experimental framework with seventeen beams to investigate the impact of loading type, configuration, and through-bolt anchorage on LC-GFRP (Low-Cost Glass-Fiber-Reinforced Polymer) confinement performance. Beams underwent three-point and four-point bending, with LC-GFRP applied in various ways, including U-shaped, side-bonded, and fully wrapped, with and without anchors. The performance of LC-GFRP was compared to CFRP (Carbon-Fiber-Reinforced Polymer) and sisal wraps. LC-GFRP in side-bonded and U-shaped configurations without anchors under three-point bending showed no shear failure, while those under four-point bending without anchors experienced shear failure. With anchors, U-shaped configurations successfully prevented shear failure. The side-bonded, U-shaped, and U-shaped configurations along the full span with anchors demonstrated peak capacity enhancements of 72.11%, 43.66%, and 68.39% higher improvements than the corresponding configurations without anchors, respectively. Wrapping all sides of the beam with LC-GFRP or CFRP prevented shear failure without additional anchors, with complete wrapping being the most efficient method. When anchors were used, significant capacity enhancements were observed. Existing shear strength prediction models were evaluated, highlighting the need for more tailored expressions for LC-GFRP confinement, especially for non-U-shaped configurations.
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Monotonic and cyclic axial compressive responses of concrete specimens externally confined with different types of FRP composites: experimental and analytical investigations
(2023-10-01)
Rodsin, Kittipoom
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Hussain, Qudeer
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Parichatprecha, Rattapoohm
The main objective of this study was to investigate the monotonic and cyclic axial stress versus strain response of the concrete confined with different types of fiber reinforced polymer (FRP) composites such as cotton fiber rope reinforced polymer (CFRRP), glass fiber reinforced polymer (GFRP) composites and carbon fiber reinforced polymer (CFRP) composites. Another objective was to investigate the applicability of existing ultimate strength models to predict the ultimate strength of concrete confined with CFRRP, GFRP and CFRP composites. For this, a total number of 28 concrete cylinders were cast, strengthened and tested under pure axial compression. The concrete cylinders were strengthened with two and four layers of FRPs. The experimental results indicate that all kinds of FRPs are very useful to alter the ultimate strength and strain of the confined concrete. The highest increase in ultimate strength was recorded for CFRP composite confined specimens and the highest increase in ultimate strain was observed for CFRRP composite confined specimens. Further, both ultimate strength and ultimate strains are found higher in the case of cyclic loads compared with the monotonic load. In general, the stress versus strain curves of cotton fiber rope and glass FRPs are found trilinear. Whereas, stress versus strain curves of CFRP confined specimens are observed to be bilinear. Existing ultimate strength models developed for CFRRP and CFRP composites are found well accurate to predict the ultimate strengths of CFRRP and CFRP confined concrete specimens tested in this study.
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Use of viscoelastic polymer sheet as an acoustic control treatment in ceramic tiles to improve sound insertion loss
(2023-03-01)
Sukontasukkul, Piti
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Tontiwattanakul, Khemapat
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Puttiwongrak, Avirut
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Zhang, Hexin
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Parichatprecha, Rattapoohm
Ceramic tiles are commonly used in non-structural components of a building such as walls, partitions, floors, and roofs. However, due to their high surface hardness and density, ceramic tiles are not an ideal soundproof material. To improve the sound properties, this study introduced the use of a viscoelastic polymer sheet (VPS) as an acoustic control treatment. The VPS was attached to ceramic tiles in 4 different patterns: X, Cross, Corner, and Strip. The ceramic tiles with VPS were tested for the damping property and sound insertion loss (IL) and then compared to the ones without VPS. Results indicated that the attachment of VPS improved the damping property of the ceramic tiles. All tiles with VPS exhibited higher damping loss indexes than the ones with no VPS. The highest damping loss index of 0.017–0.018 was observed in the specimens with VPS in X and Cross patterns. In the case of IL, the performance of all ceramic tiles was indifferent when tested at sound frequencies smaller than 1000 Hz. At the sound frequencies above 1000 Hz, the best performance was observed in the specimen with VPS in the Cross pattern, followed by X, Strip, and Corner patterns, respectively. This concluded that the use of VPS can improve the damping property of a ceramic tile which also leads to the improvement in sound insertion loss.

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