This study provides computational insights into the flexural strengthening of reinforced concrete (RC) T-beams in the negative moment region using steel-reinforced polymer cement mortar (PCM) overlays. A validated three-dimensional nonlinear finite element (FE) model was developed using the Advanced Tool for Engineering Nonlinear Analysis (ATENA) software (version 2023.0.0.22492) to simulate the behavior of beams retrofitted with 40 mm thick PCM layers embedded with 13 mm and 16 mm deformed bars. Model validation was performed against previously published experimental results reported by the authors, demonstrating excellent agreement, with normalized mean square error (NMSE) values expressed as fractions between 0.0001 and 0.0022, and experimental-to-numerical ultimate load ratios ranging from 0.99 to 1.01. Parametric analyses were then conducted to investigate the influence of key variables, concrete compressive strength, PCM overlay thickness, and longitudinal reinforcement ratio on the global flexural performance. The results revealed that increasing the overlay thickness raised the ultimate load capacity by up to 15.4% and improved energy absorption by 43%. Enhancing concrete strength led to gains of up to 12.5% in load capacity and 15.8% in stiffness. Variations in reinforcement ratio had the most significant impact, increasing peak load by up to a factor of 2.02 and improving energy absorption by up to a factor of 1.49. Despite these improvements, reductions in ductility were observed across all strengthening configurations, underscoring a strength–deformability trade-off critical for seismic applications. These findings affirm the efficacy of steel-reinforced PCM overlays and provide design-oriented insights for optimizing negative moment retrofitting strategies in RC bridge girders and continuous beam systems.

This study presented a comprehensive finite element (FE) investigation into the flexural behavior of RC T-beams strengthened in the negative moment region using near-surface mounted (NSM) carbon-fiber-reinforced polymers (CFRP) rods. A three-dimensional nonlinear FE model was developed and validated against experimental data, achieving close agreement with normalized mean square error values as low as 0.006 and experimental-to-numerical ratios ranging from 0.95 to 1.04. The validated model was then employed to conduct a systematic parametric analysis considering CFRP rod diameter, concrete compressive strength, longitudinal reinforcement ratio, and FRP material type. The results showed that increasing CFRP diameter from 6 to 10 mm enhanced ultimate load by up to 47.51% and improved stiffness by 1.48 times. Higher concrete compressive strength contributed to stiffness gains exceeding 50.00%, although this improvement was accompanied by reductions in ductility. Beams with reinforcement ratios up to 2.90% achieved peak loads of 309.61 kN, but ductility declined. Comparison among FRP materials indicated that CFRP and AFRP offered superior strength and stiffness, whereas BFRP provided a more balanced combination of strength and deformation capacity.

Near-fault earthquakes generate pulse-type ground motions that impose concentrated displacement demands on RC members, often leading to rapid degradation in stiffness and localized damage to negative-moment regions of T-beams. Although polymer-modified mortar (PMM) overlays with embedded reinforcement have demonstrated improved behavior under monotonic and cyclic loading, their response under seismic inputs with different characteristics remains insufficiently clarified. This study presents a parametric numerical investigation of RC T-beams strengthened with PMM overlays and embedded D13 and D16 steel bars and subjected to representative near- and far-field earthquake excitations. A three-dimensional nonlinear finite element model was developed and qualitatively validated against previously reported monotonic and reversed cyclic experimental results, with close agreement in the strength development and failure characteristics. The validated model was subsequently used in nonlinear time-history analyses. Under near-fault excitation, strengthening increased the peak load capacity by 52.40% (D13) and 73.30% (D16) relative to the control beam. For far-field motion, capacity gains of 53.77% and 65.85% were obtained, respectively. Near-fault input created pronounced localization in the compression zone, whereas far-field excitation resulted in more distributed cyclic deterioration. PMM strengthening substantially enhanced the flexural resistance and crack control, underscoring the importance of explicitly considering ground-motion type in performance-based seismic retrofit design.

The strengthening of reinforced concrete (RC) beams requires repair systems that can enhance strength, stiffness, and energy dissipation without significantly increasing self-weight or compromising durability. This study explores the structural response of RC beams strengthened using an integrated shear–flexure system combining near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) ropes and steel-reinforced geopolymer overlays in the compression zone. Monotonic three-point bending tests were performed on two RC beam specimens, one unstrengthened control and one strengthened beam, to obtain preliminary observations of load–deflection behavior, stiffness, ductility, and energy absorption. The strengthened specimen exhibited increases in ultimate load (28.6%), stiffness (13.6%), and energy absorption (7.65%) relative to the control beam, suggesting the potential for effective composite action between the CFRP ropes and geopolymer material. A three-dimensional nonlinear finite element model was developed using ATENA to support interpretation of the experimental response, incorporating detailed constitutive models for concrete, steel reinforcement, and CFRP ropes. The numerical predictions showed reasonable agreement with the experimental results. Within the limitations of the test matrix, the results indicate that the proposed dual strengthening system may offer a viable and sustainable approach for enhancing the shear–flexural performance of RC beams.

The field of structural engineering was focused on the growth of the latest technologies, materials, and techniques that promoted sustainability, and the use of Carbon Fiber Reinforced Polymer (CFRP) as well as geopolymer was a prime example of this effort. Several investigations and developments in composite materials have generated a wide range of materials that could be used to enhance the strength and durability of structures. This study introduces a novel approach to shear strengthening of reinforced concrete (RC) beams by utilizing Near Surface Mounted (NSM) CFRP ropes in combination with steel-reinforced geopolymer in the compressive zone. The investigation aims to assess the effectiveness of these advanced composite materials in enhancing the structural performance of RC beams, as opposed to conventional steel rebar. Three specimens were subjected to three-point bending tests, demonstrating that the NSM-CFRP ropes, paired with steel-reinforced geopolymer, significantly increased load-carrying capacity. Additionally, the results indicated substantial improvements in ductility and energy absorption. This research contributes to the field by providing a sustainable and efficient alternative to traditional strengthening techniques, supported by a comprehensive assessment of both experimental and numerical findings.