Mohammed Jalal Al-Ezzi

Glass fiber‐reinforced polymer (GFRP) composites have emerged as a promising alternative to conventional steel reinforcement in civil infrastructure because of their high strength‐to‐weight ratio, excellent corrosion resistance, fatigue durability, and extended service life. Their application has evolved from strengthening and rehabilitation systems to primary structural components in bridges, buildings, marine structures, and other aggressive environments. However, their widespread implementation remains constrained by relatively low elastic modulus, linear‐elastic brittle behavior, serviceability limitations, long‐term durability uncertainties, fire resistance, and inconsistencies among existing international design standards. This review presents a comprehensive and critical assessment of GFRP structural systems by integrating material characteristics, manufacturing technologies, mechanical and structural behavior, bond performance, durability, sustainability, analytical and numerical modeling, experimental characterization, and international design provisions within a unified engineering framework. A systematic review of approximately 190 peer‐reviewed publications, international codes, and technical reports published over the past three decades was conducted to evaluate recent developments, identify research gaps, and compare current design methodologies and engineering practices. The review demonstrates that GFRP structural systems significantly enhance corrosion resistance, reduce maintenance requirements, and improve life‐cycle performance compared with conventional steel‐reinforced structures, particularly in aggressive exposure conditions. Nevertheless, challenges associated with brittle failure, environmental degradation, creep, serviceability, and fire performance continue to influence structural design and long‐term reliability. Recent advances in hybrid composites, nano‐engineered matrices, structural health monitoring, artificial intelligence, digital twin technologies, and performance‐based design are improving predictive accuracy, durability assessment, and infrastructure management. Unlike previous reviews focusing on individual aspects of GFRP technology, this work provides an integrated multidisciplinary evaluation that combines material science, structural engineering, sustainability, design standards, experimental methods, and emerging digital technologies. The review identifies current knowledge gaps, highlights future research priorities, and provides guidance for researchers, designers, and code‐development organizations to support the broader implementation of durable, resilient, and sustainable GFRP structural systems.

Hollow filament-wound glass fiber-reinforced polymer (GFRP) tubes are known for their high specific strength, corrosion resistance, and structural efficiency. The nonlinear flexural response of these structures is controlled by the interaction of material and stability mechanisms, which are not well-captured by traditional linear sectional approaches. In this paper, a nonlinear sectional analytical model is proposed to determine the flexural response and the corresponding failure modes of hollow filament-wound GFRP tubes subjected to monotonic four-point bending. The formulation combines Euler–Bernoulli beam kinematics, layered numerical integration of the annular cross-section, asymmetric nonlinear tensile and compressive constitutive relations, iterative neutral-axis equilibrium, tangent-stiffness degradation, and compression-side local shell-buckling assessment in a curvature-controlled incremental solution routine. This framework captures progressive stress redistribution, neutral-axis migration, degradation of flexural rigidity and transition from material-controlled compression failure to local shell instability. Validation was performed against experimental results for five filament-wound glass/vinylester tube configurations with nominal ±55° winding and diameter-to-thickness ratios, D/t, ranging approximately from 20 to 75. The predicted load–deflection and moment–curvature responses were in good agreement with the experimental measurements with mean errors of about 1.6% for peak load, 1.8% for ultimate bending moment and 2.4% for peak curvature. The model also reproduces the experimentally observed governing failure mechanisms over the investigated configurations. The convergence study with sectional discretization showed that 200 integration layers provide a good compromise between numerical accuracy and computational efficiency, with less than 1% variation compared to the refined 500-layer reference solution. The proposed reduced-order formulation has low computational cost in the present implementation and provides a direct physical interpretation of the evolving sectional response. Because a directly comparable finite-element runtime was not reported for the benchmark model, no quantitative FE speed-up factor is claimed. Thus, the proposed framework provides an efficient analytical tool for the nonlinear flexural evaluation of hollow filament-wound GFRP tubes in the validated geometric, loading and laminate domain.

A touch-off explosion on concrete slabs is considered one of the simplest yet most destructive forms of adversarial loading on building elements. It causes far greater damage than explosions occurring at a distance. The impact is usually concentrated in a small area, leading to surface cratering, scabbing of concrete, and even tearing or rupture of the reinforcement. Studies available on the behavior of reinforced concrete (RC) slabs under touch-off (contact) and standoff explosions commonly indicate that the maximum damage occurs when the blast is applied to the center of the slab. This observation raises an important question about how the position of an explosive charge, especially relative to the free edge of the slab, affects the overall damage pattern in slabs supported on only two sides with clamped supports. This study uses a modeling strategy combining Eulerian and Lagrangian domains using the finite element tools of Abaqus Explicit v2020 to examine the behavior of a square slab supported on two sides with clamped ends subjected to blast loads at different positions, ranging from the center to the free edge and beyond, under touch-off explosion conditions. The behavior of concrete was captured using the Concrete Damage Plasticity model, while the reinforcement was represented with the Johnson–Cook model. Effects of strain rate were included by applying calibrated dynamic increase factors. The developed numerical model is validated first with experimental data available in the published literature for the case where the explosive charge is positioned at the slab’s center, showing a very close agreement with the reported results. Along with the central blast position, five additional cases were considered for further investigation as they have not been investigated in the existing literature and were found to be worthy of study. The selected locations of the explosive charge included an intermediate zone (between the slab center and free edge), an in-slab region (partly embedded at the free edge), a partial edge (partially outside the slab), an external edge (fully outside the free edge), and an offset position (250 mm beyond the free edge along the central axis). Results indicated a noticeable transition in damage patterns as the detonation point shifted from the slab’s center toward and beyond the free edge. The failure mode changed from a balanced perforation under confined conditions to an asymmetric response near the free edge, dominated by weaker surface coupling but more pronounced tensile cracking and bottom-face perforation. The reinforcement experienced significantly varying tensile and compressive stresses depending on blast position, with the highest tensile demand occurring near free-edge detonations due to intensified local bending and uneven shock reflection.

Blast damage to structural members poses serious risks to both buildings and people, making it important to understand how these elements behave under extreme loads. Columns in reinforced concrete (RC) structures are especially critical, as their sudden failure can trigger progressive collapse, unlike beams or slabs that have more redundancy. This state-of-the-art review brings together the current knowledge of the blast response of RC columns, focusing on their failure patterns, dynamic behavior, and key loading mechanisms. The studies covered include experiments, high-fidelity numerical simulations, emerging machine learning approaches, and analytical models for columns of different shapes (square, rectangular, circular) and strengthening methods, such as fiber reinforcement, steel-concrete composite confinement, and advanced retrofitting. Composite columns are also reviewed to compare their hybrid confinement and energy-absorption advantages over conventional RC members. Over forty specific studies on RC columns were analyzed, comparing the results based on geometry, reinforcement detailing, materials, and blast conditions. Both near-field and contact detonations were examined, along with factors like axial load, standoff distance, and confinement. This review shows that RC columns respond very differently to blasts depending on their shape and reinforcement. Square, rectangular, and circular sections fail in distinct ways. Use of ultra-high-performance concrete, steel fibers, steel-concrete composite, and fiber-reinforced polymer retrofits greatly improves peak and residual load capacity. Ultra-high-performance concrete can retain a significantly higher fraction of axial load (often >70%) after strong blasts, compared to ~40% in conventional high-strength RC under similar conditions. Larger sections, closer stirrups, higher transverse reinforcement, and good confinement reduce spalling, shear failure, and mid-height displacement. Fiber-reinforced polymer and steel-fiber wraps typically improve residual strength by 10–15%, while composite columns with steel cores remain stiff and absorb more energy post-blast. Advanced finite element simulations and machine learning models now predict displacements, damage, and residual capacity more accurately than older methods. However, gaps remain. Current design codes of practice simplify blast loads and often do not account for localized damage, near-field effects, complex boundary conditions, or pre-existing structural weaknesses. Further research is needed on cost-effective, durable, and practical retrofitting strategies using advanced materials. This review stands apart from conventional literature reviews by combining experimental results, numerical analysis, and data-driven insights. It offers a clear, quantitative, and comparative view of RC column behavior under blast loading, identifies key knowledge gaps, and points the way for future design improvements.

The use of lightweight concrete is gaining prominence in civil engineering because of its effectiveness in minimizing dead loads. However, the increased reliance on concrete has accelerated the depletion of natural resources, raising environmental concerns. This challenge has led to a growing interest in finding sustainable alternatives within the field of civil engineering. This study focuses on the enhancement of bottom ash (BA) to develop a well-graded version (BAW). It examines the impact of replacing fine aggregates with BAW on the mechanical and thermal characteristics of lightweight concrete. The research experimented with different BAW incorporation levels, ranging from 5 % to 35 % by volume. The results showed a consistent decrease in concrete density with increasing BAW replacement, as well as varying changes in mechanical and thermal performance across the tested range of 0–35 % by volume. Mechanical and thermal properties peaked at 15 % before falling. Compressive strength peaked at 36.7 MPa at 15 % and dropped to 26.9 MPa at 35 %. Flexural strength increased to 2.85 MPa at 15 % and 2.57 MPa at 35 %. Split tensile strength increased to 0.76 MPa at 15 % and decreased to 0.63 MPa at 35 %. Ultrasonic pulse velocity reached a maximum speed of 3.86 km/s at 15 % and 3.18 km/s at 35 %. Thermal conductivity increased to 1.67 W/m·K at 15 % and dropped to 1.06 W/m·K at 35 %. The 15 % BAW level optimizes performance, whereas higher replacement rates increase porosity. These findings indicate that well-graded BA enhances the properties of concrete, offering reliable and sustainable material for use in modern construction.

To address the limitations of conventional concrete, such as low ductility and toughness, high-performance fiber-reinforced concrete (HPFRC) incorporates fibers into a cementitious matrix. However, traditional HPFRC production using natural aggregates and industrial fibers depletes resources and increases environmental impact. This study explores a sustainable alternative by developing high-performance coconut fiber-reinforced concrete with 35% and 70% coarse recycled aggregates (RA) as partial replacements for natural aggregates, combined with 0%, 1.5% and 3% coconut fibers (CFs) by binder volume. The addition of 0.6% polycarboxylate ether-based superplasticizer significantly enhanced mechanical and durability properties. Compressive strength increased by 14.3%, splitting tensile strength by 19.2% and shear strength by 41.4%. Durability against freeze–thaw cycles and acid attacks improved, with an 18.6% increase in residual compressive strength and 18.5% enhancement in acid resistance. While CFs and RA initially increased water absorption and chloride ion permeability, superplasticizers mitigated these effects, improving overall durability. The synergistic use of CFs and superplasticizers enhanced resistance to environmental degradation, enabling RA to perform effectively under harsh conditions. This approach demonstrates the potential of integrating recycled aggregates and waste coconut fibers to produce eco-friendly, high-performance concrete for modern construction. The study highlights the balance between mechanical performance, durability and sustainability, offering a cost-effective solution that reduces the carbon footprint and promotes circular economy principles in construction.

Pultruded glass fiber-reinforced polymer (GFRP) materials are increasingly recognized in civil engineering for their exceptional properties, including a high strength-to-weight ratio, corrosion resistance, and ease of fabrication, making them ideal for composite structural applications. The use of concrete infill enhances the structural integrity of thin-walled GFRP sections and compensates for the low elastic modulus of hollow profiles. Despite the widespread adoption of concrete-filled pultruded GFRP tubes in composite beams, critical gaps remain in understanding their flexural behavior and failure mechanisms, particularly concerning design optimization and manufacturing strategies to mitigate failure modes. This paper provides a comprehensive review of experimental and numerical studies that investigate the impact of key parameters, such as concrete infill types, reinforcement strategies, bonding levels, and GFRP tube geometries, on the flexural performance and failure behavior of concrete-filled pultruded GFRP tubular members in composite beam applications. The analysis includes full-scale GFRP beam studies, offering a thorough comparison of documented flexural responses, failure modes, and structural performance outcomes. The findings are synthesized to highlight current trends, identify research gaps, and propose strategies to advance the understanding and application of these composite systems. The paper concludes with actionable recommendations for future research, emphasizing the development of innovative material combinations, optimization of structural designs, and refinement of numerical modeling techniques.

Concrete is brittle; hence, it is incredibly likely that concrete buildings may fail in both local and global ways under dynamic and impulsive stresses. An extensive review investigation was carried out to examine reinforced concrete (RC) slab behavior under low-velocity impact loading. Significant past research studies that dealt with experimental and numerical simulations and analytical modeling of the RC slabs under impact loading have been presented in this work. As a result, numerous attempts to define failure behavior and to assess concrete structures’ vulnerability to lateral impact loads have been made in the literature. Based on analytical, numerical, and experimental studies carried out in previous research, this article thoroughly reviewed the current state of the art regarding the responses and failure behaviors of various types of concrete structures and members subjected to low-velocity impact loading. The effects of different structural and load-related factors were examined regarding the impact strength and failure behavior of reinforced concrete slabs reinforced with various types of strengthening procedures and exposed to low-velocity impact loads. The reviews suggested that advanced composite materials, shear reinforcement, and hybrid techniques are promising for effectively strengthening concrete structures.