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CONTENTS
Volume 35, Number 4, April 2025
 

Abstract
A radial basis function-based meshless collocation (RBFMC) technique is developed for the initial buckling response of two-directional functionally graded material (TDFGM) plate. The collocation method in the strong form formulation is introduced into the framework of radial basis function (RBF) analysis as a viable replacement for the Galerkin method in the weak form formulation to lower the computing cost and increase the convergence rate. By considering the higher-order shear deformation theory (HSDT), the need for a shear correction factor is ignored. The governing differential equations of the TDFGM plate are obtained via the energy principle and discretized using RBF. The effectiveness and robustness of the introduced technique are demonstrated through several benchmark problems. It is observed that the suggested technique can yield more accurate results with a high convergence rate. Subsequently, the grading index, span-to-thickness ratio, and elastic foundation on the buckling analysis of TDFGM plates are thoroughly examined. The simulation results and benchmark solutions agree well.

Key Words
buckling; elastic foundation; RBF; RBFMC; TDFGM

Address
Manish C Srivastava and Jeeoot Singh: Department of Mechanical Engineering, Madan Mohan Malaviya University of Technology, Gorakhpur, U.P, 273010, India
Suraj Singh and Rahul Kumar: Department of Mechanical Engineering, IET, DDUGU Gorakhpur U.P, 273009, India
Basudeb Rajak: Department of Mechanical Engineering, IIT BHU, U.P, 221005, India
Harish K. Sharma: Department of Mechanical Engineering, GLA University, Mathura, India

Abstract
The strength and durability of geopolymer mortars with fly ash and rice husk ash (FA-RHA) (0 to 20%) mixed with polypropylene fibers (0 to 0.3%) were examined in this work through an experimental investigation. The mortar specimen's strength properties were assessed using flexural and uniaxial compressive strength tests. In contrast, tests for water absorption, sorptivity, and corrosion resistance to acids (10% concentration of H2SO4) were used to evaluate its durability attributes. Though there was a noticeable improvement in flexural behavior when PP fiber was added up to 0.3% by volume, the testing results showed that this addition had no meaningful effect on compressive strength. The maximum compressive strength values, measuring 62 MPa, were obtained by The M5 and M8 geopolymer mortars prepared using a 10 M sodium hydroxide solution concentration. The strength of the geopolymer mortar reduces when 20% rice husk ash is added. Due to its mechanical and durability properties, FA-RHA mixed geopolymer mortar was discovered by research and experimentation and was used to create the ANN architecture. The ANN framework's projected strength values for the durability and mechanical tests match the trial findings. Geopolymer mortar offers a great deal of promise for structural element restoration, and the application of this mortar for these repairs may be studied further.

Key Words
ANN method; cement mortar; fly ash; mechanical properties; polypropylene fiber; rice husk ash

Address
Vijayakumar A: Department of Civil Engineering, V.S.B. Engineering College, Karur - 639 111, Tamilnadu, India
Thiru S: Department of Mechanical and Materials Engineering, University of Jeddah, Jeddah - 21959, Kingdom of Saudi Arabia
Hemavathi S: Department of Civil Engineering, K Ramakrishnan College of Technology, Trichy - 621112, Tamilnadu, India
Priya R: Department of Civil Engineering, SNS College of Technology, Coimbatore - 641 035, Tamilnadu, India

Abstract
The importance of investigating the use of basalt fiber-reinforced polymers (basalt FRP) bars in lightweight self-compacting concrete (LWSCC) generally stems from its potential to offer more environmentally friendly, durable, and effective solutions for a variety of construction projects while addressing issues with conventional materials and methods. Literature shows that the use of basalt FRP along with spiral-hoops lateral strengthening in FRP-strengthened LWSCC columns has not been examined by researchers considering different formations. Therefore, the present study has endeavored to investigate the different configurations of lateral strengthening in FRP-strengthened LWSCC concrete rectangular columns including exterior basalt FRP hoops and interior basalt FRP spiral, interior and exterior basalt FRP hoops providing double restraints, and single basalt FRP hoops. Various parameters of fabricated columns are investigated including the diameter of crosswise strengthening, longitudinal strengthening material type, the vertical spacing of hoops, and different configurations of hoops. A new theoretical model is also suggested to predict the compressive load of LWSCC columns by involving the contribution of longitudinal and crosswise basalt FRP bars. The outcomes of the current investigation depicted that the use of basalt FRP along with spiral-hoops crosswise strengthening in FRP-strengthened LWSCC columns is the most efficient in terms of core restraint and compressive load compared with the other two configurations. The ductility of the samples reduced from 15.91 to 13.16 depicting a reduction of 20.89%, after lowering the pitch of hoops from 100 to 50 mm. By reducing the vertical distance between crosswise strengthening, the ductility of the columns improved with secondary peaks in the load-deflection curves. The proposed theoretical model performed well in capturing the compressive load of FRP-strengthened LWSCC columns.

Key Words
axial loading; axial strain; basalt FRP bars; basalt FRP spirals; ductility; theoretical model

Address
Khaled Mohamed Elhadi and Mohamed Hechmi El Ouni: 1) Department of Civil Engineering, College of Engineering, King Khalid University, PO Box 394, Abha, 61411, Saudi Arabia, 2) Center for Engineering and Technology Innovations, King Khalid University, Abha 61421, Saudi Arabia
Ali Raza: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan

Abstract
This research introduces a robust multilayer perceptron neural network model with a 6-7-4-1 configuration, designed to estimate the punching shear strength in flat slabs. The model's accuracy was evaluated using a validation technique called repeated random sub-sampling with a confidence level of 94.5% applied to filter the data. Numerical expressions considering factors such as slab depth, column dimensions, steel reinforcement ratio, concrete strength, steel yield, and the position of the contra flexural point were proposed to predict punching shear strength for design control purposes. Furthermore, a comparative analysis was performed between the robust multilayer perceptron neural network model and both the ACI and EC-2 codes for predicting the punching shear strength of flat slabs. The study revealed that while the different codes produced similar results for punching shear capacity, they diverged significantly from the actual experimental outcomes. In contrast, the introduced Artificial Neural Network (ANN) model provided predictions closely aligned with experimental results, underscoring its practical viability. The standard deviations (SD) of the differences between the experimental results and the predicted values were used as performance indicators. The ANN model exhibited a low SD of 53, while the ACI and EC-2 codes, serving as a reference for the comparative codes, showed a significantly larger SD, reaching 360.4 and 382.2 respectively. The ANN model also demonstrated superior performance in other error metrics, including the Mean Absolute Percentage Error (MAPE). The ANN model's MAPE was 13.3%, significantly lower compared to ACI 318-19's 78.3% and the EC-code's 80.1%. This highlights the ANN model's superior accuracy and practicality in estimating punching shear strength in flat slabs.

Key Words
comparative analysis; concrete compressive strength; design codes; flat slabs; neural network model; punching shear strength; slab depth

Address
Mohamed A. Farouk, Ahmed S: 1) Department of Civil Engineering, Faculty of Engineering, Delta University for Science and Technology, Gamasa, Egypt, 2) Department of Civil Engineering, Faculty of Engineering, Sphinx University, New Assiut, Egypt
Abd El-Maula: Department of Civil Engineering, Shoubra Faculty of Engineering, Benha University, Egypt
Mahmoud A. El-Mandouh: Department of Civil Engineering, Faculty of Engineering, Beni-Suef University, Egypt

Abstract
The frequency analysis of carbon nanotubes is the focus of this paper. For armchair single walled carbon nanotubes, the small size influence on the variation in density response is obtained using the nonlocal Euler beam theory. At the end of these tubes, two distinct immovable boundary constraints are applied. These boundary conditions appear to have a significant impact on SWCNT vibration. The content, size, structure, weight, and shape of the object all affect how frequently it occurs naturally. It is looked into how density affects natural frequency. The resonance frequency of the system is the same as the natural frequency of the nanotube. The influence of fundamental natural frequencies on the density of single-walled carbon nanotubes with C-C and C-F armchairs (3, 3), (9, 9), and (13, 13). Furthermore, the frequency values are influenced by the armchair tube's index order. In this work, the frequencies are given in THz. Therefore, a drop in resonance frequency is caused by an increase in density. Convergence of present study is done to view the accuracy. The available results are well matched with present provided results.

Key Words
carbon nanotube; density; Euler beam theory; nano-material; order of index; vibration

Address
Muzamal Hussain: Department of Mathematics, University of Sahiwal, Sahiwal, 57000, Pakistan
Mohamed A. Khadimallah: Department of Civil Engineering, College of Engineering in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj, 11942, Saudi Arabia
Abdelouahed Tounsi: 1) Department of Civil Engineering, Faculty of Engineering, Beni-Suef University, Egypt, 2) Department of Civil and Environmental Engineering, King Fahd University of Petroleum and Minerals,31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
This study examines the behavior of shear keys under the combined effect of CFRP strengthening and temperature values. The interfacial shear strength behavior was captured using the three-dimensional nonlinear finite element analysis (NLFEA) technique with a newly proposed theoretical model. The simulated models were verified using experimental push-off tests published in the literature. This is followed by expanding the validated specimens to examine the effect of the high temperatures (20, 250, 500, and 750 oC), the number of CFRP strips provided at the interface connection (1, 2, 3, a, 5, and 6), and the number of internal steel stirrups (0, 1, 2, 3, 4, and 5). Results revealed that reinforcing the shear keys with CFRP strips reduces the propagated crack widths and the associated slip compared to the control one. This proves the proposed CFRP strengthening configuration's role and effectiveness in enhancing the structural performance of the interfacial shear strength. In addition, it has been shown that the exposure temperature's value directly affects the longitudinal shear strength, failure mode, slippage, and toughness.

Key Words
CFRP sheets; heat-damage; NLFEA; push-off; shear key

Address
Department of Civil Engineering, Jordan University of Science and Technology, Irbid, Jordan

Abstract
This study provides an in-depth assessment of the influence of the Seismic Vertical Component (SVC) on the seismic behavior of continuous reinforced concrete (RC) highway bridges retrofitted with Partially Restrained Seismic Isolation (PRSI). Focusing on a representative isolated bridge, the study utilizes a detailed three-dimensional numerical model to simulate nonlinear material behavior and structural collapse mechanisms. The seismic performance of the PRSI-rehabilitated RC bridge is assessed by analyzing its dynamic response under major earthquake records, considering both the presence and absence of the SVC. The response of the original unrehabilitated bridge serves as a comparison reference. The results reveal a brittle collapse mechanism influenced by the SVC, and significant alterations in axial forces within the central column. In summary, both the SVC and the friction coefficient of the isolation device exert substantial influence on seismic performance.

Key Words
highway RC bridges; nonlinear dynamic analysis; partially restrained seismic isolation; seismic vertical component

Address
1) Universidad Nacional de Cuyo, Mendoza, Argentina, 2) CONICET, National Research Council, Argentina

Abstract
This study experimentally and analytically evaluated the structural performance of prestressed concrete (PSC) beams deteriorated by aging and other factors. A PSC beam specimen was designed and fabricated, with accelerated corrosion applied to the prestressing (PS) steel strands under tension at the bottom of the beam. Using the Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST) computer program, the PS steel element was modified to simulate the interaction between concrete and PS steel in deteriorated PSC members. The damage modeling considered the reduction in the cross-sectional area of the PS steel, loss of bond strength, reduction in the ductility of the PS steel, and deterioration of concrete strength. The experiment and analysis results revealed a nonlinear correlation between the maximum load and corrosion level. The deterioration model accurately predicted the performance degradation of the structure. Moreover, the 0.05 coefficient of variation of the experiment/analysis values for ultimate load in the tested deteriorated PSC beam specimens indicated that the behavioral characteristics of PSC beams according to different corrosion levels were well represented. This study facilitated deformation, cracking, and damage predictions of deteriorated PSC structures under various loading scenarios based on the level of corrosion exposure, PS level, and localized corrosion in PSC beams. The findings of this study emphasize the significance of bonded PS steel deterioration, such as corrosion, addressing the research gap regarding the detrimental effects of corrosion on structural performance.

Key Words
damage modeling; deteriorated; prestressing steel element; prestressed concrete beams; structural performance

Address
Tae-Hoon Kim, Choon-Seok Bang and In-Ho Yeo: Advanced Railroad Civil Engineering Division, Korea Railroad Research Institute, 176, Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do, 16105, Republic of Korea
Chang-Ho Sun and Ick-Hyun Kim: Department of Civil and Environmental Engineering, University of Ulsan, 93, Daehak-ro, Nam-gu, Ulsan-si, 44610, Republic of Korea

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