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CONTENTS
Volume 96, Number 1, October10 2025
 

Abstract
Bridges are the structures that connect communities. Monopile foundations are preferred for sea-crossing bridges. As a result of tidal variations and global warming, the characteristics of waves and ocean currents change frequently. Even welldesigned monopiles are vulnerable due to such variations. Ocean current fragility curves are developed for an existing highway bridge in Mumbai by taking account of various scenarios affected by factors such as wave height, water depth (mean sea level), and the effect of scouring around the monopile and wind speed. Computational Fluid Dynamics (CFD) is used to obtain the response of the monopile, and with this response, fragility curves are developed for this monopile foundation for design limit state function by considering ocean current velocity as an Intensity Measure (IM). The threshold mean current velocities for the design limit state are derived for the scenarios affected by factors like wave height, scouring, wind speed, and mean sea level. It is noted that the combination of loads have more effect than considering each of them separately. The fragility of the monopile structure increases by 50% when the wave height is increased to 2.5 m from 1.5 m at an intense mean current velocity of 2.6 m/s. The damage to the bridge increases by 10% when wind speed is raised from 6 m/s to 12 m/s. The vulnerability of monopile enlarges by 67% for the change in water depth from 6.5 m to 7.5 m at a particular mean current velocity of 2.6 m/s. The threat to the bridge increases by an amount of 133% when a scouring depth of 1.5 m around the monopile is considered at an intense mean current velocity of 2.6 m/s.

Key Words
CFD; fluid-structure interaction; monopile-supported sea crossing bridge; risk assessment and threshold mean current velocity (VTMC); scouring; wave, wind and ocean current fragility curve

Address
M.B. Praveen: Department of Civil Engineering, National Institute of Technology Calicut, Kozhikode, 673601, India; Indian Institute of Technology Madras, Chennai, 600020, India
R. Prethiv Kumar: Department of Civil Engineering, National Institute of Technology Calicut, Kozhikode, 673601, India
P. Robin Davis: Department of Civil Engineering, National Institute of Technology Calicut, Kozhikode, 673601, India

Abstract
In this study, clay soils were stabilized using fly ash (FA), ground blast furnace slag (GGBS) and alkaline activators in order to increase their mechanical and durability properties. The effects of different additive ratios on the soil were evaluated by unconfined compressive strength (UCS), and California Bearing Ratio (CBR) tests. The results showed that the combination of alkaline activators and FA significantly increased the strength of clay soils and reached a UCS value of 600 kPa at the end of 28 days. On the other hand, mixtures containing GGBS showed the highest strength and reached a value of 2470 kPa. Field Emission Scanning Electron Microscope (FE-SEM) analyses have confirmed that these mixtures have been geopolymerized successfully and sodium-alumino-silicate-hydrate (N-A-S-H) gel has been formed. Furthermore, the analysis carried out using the Artificial Neural Network (ANN) model showed a high level of predictive accuracy, with an R2 value of 0.86 and a Root Mean Square Error (RMSE) of 198.73, confirming the model's reliability for practical applications in soil stabilization. Overall, this study reveals that environmentally friendly binders offer a viable alternative in clay floor stabilization and have a wide potential in the field of civil engineering. The innovative aspect of the study is the comprehensive experimental investigation of the mechanical performance of clay soils stabilized with sustainable and environmentally friendly geopolymer binders using different proportions of fly ash and blast furnace slag and the use of these experimental data to make highly accurate predictions using artificial neural network (ANN)-based advanced modeling techniques as a practical and reliable forecasting tool in soil stabilization applications. Thus, both the reduction of environmental impacts and the integration of artificial intelligencesupported optimization in engineering applications have been achieved.

Key Words
alkali activators; ANN; geopolymerization; soil stabilization; UCS

Address
Ali Ulvi Uzer: Vocational School of Technical Sciences, Department of Construction, Kayseri University, Kayseri, 38280, Turkey
Ufuk Tunç: Tomarza Mustafa Akincioglu Vocational School, Department of Construction, Kayseri University, Kayseri, 38940, Turkey; Graduate School of Natural and Applied Sciences, Department of Civil Engineering, Erciyes University, Kayseri, Turkey
Mehmet Cemal Acar: Department of Construction, Yatağan Vocational School, Muğla Sitki Koçman University, Muğla 48500, Turkey
Ali İhsan Çelik: Tomarza Mustafa Akincioglu Vocational School, Department of Construction, Kayseri University, Kayseri, 38940, Turkey

Abstract
This study investigates the torsional behavior of reinforced concrete beams strengthened using the near-surface mounted technique with steel bars. Eight full-scale reinforced concrete beams were tested under pure torsional loading to evaluate the effectiveness of this strengthening method. Two beams served as reference specimens, while the remaining six beams were reinforced using different configurations of steel bars embedded within the concrete cover. The key parameters investigated included the influence of variations in bar spacing and diameter and the effectiveness of different configurations of U-shaped stirrups which are used for strengthening. The experimental results demonstrated that beams strengthened with nearsurface mounted steel bars exhibited significantly enhanced torsional resistance compared to the reference beams. Beams reinforced with four faces of double U-shaped stirrups increased their ultimate torsional capacity by up to 58 percent, while those with three faces of U-shaped stirrups exhibited enhancements ranging from 6 to 41 percent. Reducing the spacing between the steel stirrups resulted in improved load-carrying capacity, and increasing the diameter of the embedded steel bars also contributed to higher torsional strength. However, the addition of longitudinal near-surface mounted steel bars had minimal impact on ultimate torsional resistance. The study concludes that the near-surface mounted strengthening technique using steel bars is an effective and economically viable method for enhancing the torsional performance of reinforced concrete beams, particularly when applied with optimal spacing and configuration of U-shaped stirrups.

Key Words
concrete beams; experimental study; near surface mounted; pure torsion; torsional strengthening

Address
Adel A. Al-Azzawi: Department of Forensic Engineering, Higher Institute of Forensic Sciences, Al-Nahrain University, Jadriya, Baghdad, Iraq
Mariam I. Ali: Department of Civil Engineering, College of Engineering, Al-Iraqia University, Baghdad, Iraq

Abstract
For over a century, equivalent static analysis has been a straightforward method for evaluating the impact of earthquake loads. Seismic codes specify the ratio between the base shear force and the building's weight, V/W. These suggested ratios mainly depend on the seismicity of the area and the building's importance and are unaffected by the number of floors, seismic load direction, or plan configuration. This study examined the V/W ratio for 36 unreinforced masonry (URM) building models, comprising nine different plan configurations and ranging from one to four stories. To assess the effect of seismic activity, the research was conducted at two peak ground acceleration levels: 0.3 g and 0.25 g. The structures were modeled using macroelements, and their capacity was evaluated using nonlinear static analysis. The results demonstrate that the V/W ratio is highly sensitive to building height and plan geometry, decreasing significantly as the number of stories increases. The ratio peaks at 0.51 for a one-story, regular (Class B) building and drops to as low as 0.08 for a four-story, irregular (Class D) building. Furthermore, slender rectangular plan configurations (Class A) were found to be unstable beyond one story. A comparison with four national seismic codes reveals that these codes do not account for such variations. Some codes suggest V/W ratios as high as 0.75-0.82, potentially overestimating the seismic capacity of multi-story or irregular URM buildings by a significant margin. This study provides more realistic, configuration-dependent V/W ratios, which are essential for safer preliminary design and vulnerability assessment.

Key Words
base shear coefficient; masonry buildings; push-over analysis; regular and irregular plans; seismic codes

Address
Mahnoosh Biglari: Department of Civil Engineering, School of Engineering, Razi University, Taq-e Bostan, Kermanshah, Iran
Huseyin Bilgin: Faculty of Architecture and Engineering, Department of Civil Engineering, Epoka University, Tirana, Albania
Dorin Radu: Faculty of Civil Engineering, Transilvania University of Brașov, Brașov, Romania
Marijana Hadzima-Nyarko: Faculty of Civil Engineering and Architecture Osijek, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia

Abstract
To study the seismic response law of Gas-Insulated Metal-Enclosed Transmission Line (GIL), the seismic simulation vibration table test and finite element analysis of a 550 kV GIL pipeline unit were conducted, and the partial GIL finite element model under the whole station domain was established based on the tested and verified GIL pipeline unit model, and the seismic response was analyzed. The results show that the safety factor of the three pillar insulators under the test and finite element analysis is the weak part of GIL; the finite element analysis result of GIL pipeline unit is in good agreement with the vibration table test result, and the maximum error of mode analysis, peak acceleration response and Von-Mise stress are 8.5%, 8% and 12%, indicating that the established finite element model and parameter setting are reasonable; The stress response of GIL key parts under YZ 2D multi-point input is greater than the consensus input, And the displacement peak response was increased by 31% over the consistent input, therefore, The influence of multi-point input should be considered in the GIL seismic design; The seismic response at 3D of 150 m/s) GIL only increased by 6.4% compared to YZ 2D multipoint input, The increase was smaller, Therefore, in the engineering design, Only considering the two-dimensional multi-point input can meet the requirements of the engineering calculation.

Key Words
finite element; gas insulated transmission line; multi-point input; shaking table test; wave-passage effect

Address
Haoran Yang: China Railway 23rd Bureau Group Co. Ltd., Chengdu 610072, China

Abstract
The research work mainly deals with the mechanical behaviour and performance characteristics of conventional and aluminium-reinforced honeycomb structures under different parameters and loading conditions. Honeycombs with varying cell sizes, node lengths, and cell-wall thicknesses were fabricated and tested to observe their interaction with quasi-static, impact, and blast loads. The deformation mode under in-plane and out-of-plane quasi-static loads provided an idea about the structural soundness and adaptability of reinforced honeycombs under static conditions. Low-velocity impacts were performed to investigate the energy absorption and impact resistance of reinforced honeycomb structures, which are very suitable for aerospace and transportation sectors where impact mitigation is highly required. Comparisons between conventional honeycomb cores and the reinforced counterparts were made, with a focus on parameters such as weight, stiffness, and strength to help engineers in the optimization of designs for particular applications. Crashworthiness studies showed how cell size, node length, and cell-wall thickness influence energy absorption in impacts and provided a basis for the fulfillment of strict crash-resistance standards. Further understanding of the behaviour of these structures in dynamic scenarios was advanced by FEM simulations of blast loads, thus enabling the development of blast-resistant designs. The aluminium-reinforced honeycombs possessed an ultimate strength of 145.28 MPa, a yield strength of 98.15 MPa, and a modulus of elasticity of 69 GPa. Under low-velocity impact, the peak force of a reinforced honeycomb with cell size 10 mm and wall thickness 0.1 mm was 1456.8 N, which agreed very well with numerical prediction with an error of less than 5%. Blast tests showed that reinforced honeycomb cores reduced back-face sheet deformation by up to 37% compared to conventional honeycombs for a variety of explosive masses, with improved blast resistance and energy absorption. The results add much value to the design and optimization of honeycomb structures for various engineering applications and also form a basis for future research on wider manufacturing parameters, dynamic loading conditions, and environmental effects.

Key Words
aluminium-reinforced honeycomb; energy absorption; FEM; impact resistance; mechanical behaviour

Address
Lovlish Sharma: Department of Civil Engineering, Punjabi University, Patiala, India
Anhad Singh Gill: Department of Civil Engineering, Punjabi University, Patiala, India
Prashant Kumar: Department of Civil Engineering, COER University, Roorkee, India

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