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CONTENTS
Volume 55, Number 1, April 10 2025
 

Abstract
Development of new theories are essential for the analysis of laminated-composite-plates (LCPs) with modifications in reinforcements, matrix, aspect-ratios, and boundary-conditions. Here, a higher order shear-deformation-theory of fifth-order (MFSDT) is proposed for the static and modal analysis of LCPs modified with filler material (flyash/graphene; weight % range: 0% to 10%). The proposed MFSDT is compared to other plate-theories of past literature, and it reflects the robustness with a minimum error of 2.6%. Further, using this theory, the effect of filler on the modal response of LCPs (two different combinations (i) epoxy+ E-glass + flyash, and (ii) epoxy+ E-glass + graphene) are studied. The results are compared with results of experimental and finite element analysis. Further, using the proposed MFSDT, the static analysis of the LCPs are conducted to examine stress components, centre-deflection considering aspect ratio, load variation at the centre of the LCP, and filler percentage. Also, the effect of stacking sequences on the developed stress components, centre-deflection, and fundamental frequencies of LCPs are evaluated. It is observed that off-plane stresses are least affected by addition of filler content whereas fundamental frequencies, normal stresses, and centre deflection are significantly changed.

Key Words
fillers: graphene/flyash; Finite Element Method (FEM); frequency; hybrid structures, MFSDT; laminated composite plate; modal; non-linear analysis

Address
Sarada Prasad Parida:Department of Mechanical Engineering, Konark Institute of Science and Technology, Khordha, Odisha, 752050, India

Pankaj Charan Jena:Department of Production Engineering, Veer Surendra Sai University of Technology, Burla, Odisha, 768018, India

Debasish Mishra:Department of Production Engineering, Veer Surendra Sai University of Technology, Burla, Odisha, 768018, India

Abstract
Dust pollution has serious health implications on construction workers. Past research has shown that dust exposure data can help improve the construction workers' awareness of dust pollution and urge them to adjust their work behavior. Therefore, in order to control dust pollution on sites, accurate measurement of dust concentrations is very important. However, the current risk assessment of health damage to workers is mostly based on measured values of health hazards at the construction site, and the error between measured values and actual concentrations of pollutants are often ignored. To overcome the above limitation, the aim of this research is to obtain risk of health damage to construction workers by simulating the exposure dose of dust in construction sites. Using an experimental design, this research measured dust concentrations at a construction site in Nanchang city of China and simulated it using backpropagation neural network. This is a widely used technique in the field of pollutant concentration prediction because of its powerful computational ability to solve nonlinear relationships. The study used nine monitoring points representing different operations while capturing four types of construction dust. It found work faces that have high dust concentrations and the ones that are more hazardous to workers with stable results and relatively high accuracy levels. In addition, this paper showed that backpropagation neural network could be used to assess health risks of dust pollution which is often neglected as a mere nuisance or discomfort due to its slow onset. The results provide a number of practical implications for construction project managers who are very keen to mitigate its impact with the help of the worker.

Key Words
backpropagation neural network; construction dust; health damage risk; Monte Carlo Simulation

Address
Cheng Lin:School of Economics and Management, Beihang University, Beijing100191, China

Abstract
The center-to-center pitch (CCP) of shear connectors is specified to not exceed 0.61m in the AASHTO LRFD bridge design specifications to guarantee full composite action between steel girder and concrete deck. However, larger CCP of grouped shear connectors is in need in accelerated bridge construction to enhance efficiency and lower cost. In this study, the effects of CCP of grouped headed studs on shear force transfer and deck separation of simply-supported steel-concrete composite bridges were quantitatively investigated based on the refined finite element method. A typical simply-supported steel concrete composite bridge was designed based on the AASHTO LRFD code and modeled with the ANSYS. The accuracy of modeling skill was validated with published data. The HL-93 loading and fatigue design truck specified in the AASHTO LRFD code were adopted as design loading. The effects of three important parameters, including the diameter of headed studs, the CCP of grouped headed studs, and the arrangement of headed studs, on the shear force transfer and deck separation between steel girder and concrete deck were investigated. Results show that the three considered parameters have a coupling effect on the fatigue limit state and strength limit state of the bridge.

Key Words
center-to-center pitch of grouped headed studs; deck separation; refined finite element method; shear force transfer

Address
Wei Wang:1)Key Laboratory for Damage Diagnosis of Engineering Structures of Hunan Province, Hunan University, Changsha, Hunan 410082, China
2)College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China

Jun Wang:College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China

Xiuyuan Zeng:College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China

Huicong Xiang:College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China

Wei Ji:1)Key Laboratory for Damage Diagnosis of Engineering Structures of Hunan Province, Hunan University, Changsha, Hunan 410082, China
2)College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China

Abstract
As a green and innovative structure, FRP–rubber concrete–steel double-skin tubular columns (RC-DSTCs) not only reduce the environmental harm caused by waste rubber and promote its recycling, but also enhance their own ductility by utilizing the high toughness of rubber concrete. However, current research has been limited to the axial compressive behaviour of short columns, without addressing the stability issues of RC-DSTCs at higher slenderness ratios. Therefore, this study investigates the influence of slenderness ratio (6.69, 13.39, 20.08, 26.78, and 33.47), rubber volume replacement rate (0%, 5%, and 10%), GFRP tube thickness (2, 4, and 6 mm), and void area ratio (0.3, 0.4, and 0.5) on the axial compressive performance of RC-DSTCs. Experimental results indicate that with an increase in the slenderness ratio, the failure modes of RC-DSTCs transition from axial compressive failure to flexural instability failure and their peak load, GFRP tube confinement effect, and ductility significantly decrease. When the rubber volume replacement rate is 5%, the ductility coefficient of RC-DSTCs increases by 15%, and its peak load does not change significantly. Furthermore, the effect of GFRP tube thickness and void area ratio on the peak load of RC-DSTCs is insignificant, but their ductility notably increases. Ultimately, the theoretical axial compressive capacities of RC-DSTCs consider the cross-sectional shape and stability factors, showing good agreement with the experimental results. This study can provide a valuable reference for future engineering applications.

Key Words
axial compressive behaviour; double-skin tubular column; long column; rubber concrete; stability; theoretical capacity formula

Address
Jiahui Wang:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Feng Liu:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Zhezhou Pan:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Genghao Chen:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Hongming Li:1)School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China
2)Guangdong Zhongdu Construction Group Co. Ltd, Lianjiang 524499, China

Zhichao Wu:1)School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China
2)Guangdong Zhongdu Construction Group Co. Ltd, Lianjiang 524499, China

Zhenpeng Luo:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Lijuan Li:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Mingli He:Guangdong Yonghe Construction Group Co. Ltd, Guangzhou 510330, China

Zhe Xiong:School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China

Abstract
In this research, the post-buckling analyses of multilayer porous sigmoid functionally graded (PSFG) cylindrical shells with two-layered FG porous (FGP) cores resting on elastic foundations (EF) exposed to external excitation are examined using an analytical method. The research focuses on two distinct variations of FG layers: those with evenly distributed porosities (FG-EPD) and those with unevenly distributed porosities (FG-UEPD). Additionally, the FGP cores are explored in two forms: one with uniform porosity distribution (UPD) and another with non-symmetric porosity distribution (NSPD). This analysis includes eight different configurations of these layers. The equilibrium equations have been formulated using the classical shell theory, incorporating geometrical nonlinearity in the von Kármán-Donnell framework. An approximate solution for deflection, involving three terms, has been selected for greater accuracy. Additionally, explicit formulas for determining the post-buckling load-deflection relationships and the critical load are provided through the use of Galerkin's method. The influences of various parameters, including geometry, EF coefficients, and material properties, on post-buckling behaviors of the multilayer PSFG cylindrical shells with two-layered FGP cores resting on EF are investigated.

Key Words
elastic foundation; external excitation; multilayer porous sigmoid FG shells; post-buckling; two-layered FG porous cores

Address
Kamran Foroutan:Energy Systems Engineering, University of Regina, Regina, SK S4S 0A2, Canada

Farshid Torabi:Energy Systems Engineering, University of Regina, Regina, SK S4S 0A2, Canada

Abstract
In this study, design abacuses were proposed to evaluate the possibility of replacing the minimum shear reinforcement of reinforced concrete beams with steel fibers. For this purpose, computations were made to evaluate the shear strength of 240 experimental tests of concrete beams reinforced with steel fibers (SFRC) using code formulations, literature, and international standards to define which model is in better agreement with the experimental data. Thus, once this expression was identified, SFRC beam design abacuses were developed to determine the amount of steel fibers needed to replace the minimum shear reinforcement according to the Brazilian Standard. Through statistical analysis, the model that best correlated with the experimental test results was selected. In the last section, the selected model is applied to the SFRC beam with rectangular sections, and the design abacuses are shown. Finally, it is concluded that the developed abacuses facilitate decision-making in the design of SFRC beams and, may become an essential tool for the design of these structural elements.

Key Words
design abacus; reinforced concrete beam; shear; steel fibers

Address
Gustavo Bono:Núcleo de Tecnologia, Centro Acadêmico do Agreste, Universidade Federal de Pernambuco, CEP: 55014-900, Caruaru, Pernambuco, Brazil

Giuliana F.F. Bono:Núcleo de Tecnologia, Centro Acadêmico do Agreste, Universidade Federal de Pernambuco, CEP: 55014-900, Caruaru, Pernambuco, Brazil

Marinaldo dos Santos Júnior:Instituto Federal da Paraíba, Campus Monteiro, CEP: 58500-000, Monteiro, Paraíba, Brazil

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