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CONTENTS
Volume 32, Number 1, July 2023
 

Abstract
This paper discusses a framework for predicting the flexural strength of prestressed and non-prestressed FRP reinforced T-shaped concrete beams using soft computing techniques. An analysis of 83 tests performed on T-beams of varying widths has been conducted for this purpose with different widths of compressive face, beam depth, compressive strength of concrete, area of prestressed and non-prestressed FRP bars, elasticity modulus of prestressed and non-prestressed FRP bars, and the ultimate tensile strength of prestressed and non-prestressed FRP bars. By analyzing the data using two soft computing techniques, named artificial neural networks (ANN) and gene expression programming (GEP), the fundamental parameters affecting the flexural performance of prestressed and non-prestressed FRP reinforced T-shaped beams were identified. The results showed that although the proposed ANN model outperformed the GEP model with higher values of R and lower error values, the closed-form equation of the GEP model can provide a simple way to predict the effect of input parameters on flexural strength as the output. The sensitivity analysis results revealed the most influential input parameters in ANN and GEP models are respectively the beam depth and elasticity modulus of FRP bars.

Key Words
artificial neural network (ANN); flexural capacity; gene expression programming (GEP); prestressed and non-prestressed FRP bars; T-shaped concrete beam

Address
Danial Rezazadeh Eidgahee: Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Atefeh Soleymani: Department of Civil Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
Hamed Hasani and Hashem Jahangir: Department of Civil Engineering, University of Birjand, Birjand, Iran
Denise-Penelope N. Kontoni: 1) Department of Civil Engineering, School of Engineering, University of the Peloponnese, GR-26334 Patras, Greece, 2) School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece

Abstract
In order to study the anti-seismic performance of full light-weight concrete utility tunnel, EL Centro seismic waves were input, and the seismic simulation shaking table test was carried out on the four utility tunnel models. The dynamic characteristics and acceleration response of the system consisting of the utility tunnel structure and the soil, and the interlayer displacement response of the structure were analyzed. The influence law of different construction methods, haunch heights and concrete types on the dynamic response of the utility tunnel structure was studied. And the experimental results were compared with the finite element calculation results. The results indicated that with the increase of seismic wave intensity, the natural frequency of the utility tunnel structure system decreased and the damping ratio increased. The assembling composite construction method could be equivalent to replace the integral cast-in-place construction method. The haunch height of the assembling composite full light-weight concrete utility tunnel was increased from 30 mm to 50 mm to enhance the anti-seismic performance during large earthquakes. The anti-seismic performance of the full light-weight concrete utility tunnel was better than that of the ordinary concrete utility tunnel. The peak acceleration of the structure was reduced by 21.8% and the interlayer displacement was reduced by 45.8% by using full light-weight concrete. The finite element simulation results were in good agreement with the experimental results, which could provide reference for practical engineering design and application.

Key Words
dynamic response; finite element simulation; full light-weight concrete; shaking table test; utility tunnel

Address
Yanmin Yang, Qi Yuan, Jingyu Li, Yuan Gao and Yuzhe Zou: School of Civil Engineering, Jilin Jianzhu University, Changchun 130118, China
Yongqing Li: Xinlicheng Reservoir Management Center, Changchun City, Changchun 130119, China

Abstract
The current study targets to apply the adaptive neuro-fuzzy inference system (ANFIS) for the estimation of the shear resistance offered by the externally bonded fiber-reinforced polymer (EB-FRP) U-jackets. A total of 202 groups of data cumulated from previous investigations, were employed for the development and evaluation of the ANFIS model. A relative appraisal between the ANFIS predictions and the results of experiments has shown that the assessments by current ANFIS model are in good concurrence with the latter. In addition, assessment of the accuracy of the ANFIS model was done by relating the ANFIS predictions with the forecasts of eight extensively used design guidelines. Based on the examination of various performance measures, it has been derived that the adequacy of the ANFIS model is better than the available guidelines. A parametric investigation has additionally been done to reconnoiter the influence of individual parameters as well as their combined effects on the shear contribution of EB-FRP. Based on the observations made from the parametric study, it has been witnessed that the ANFIS model has incorporated the effect of different parameters more competently than the considered design guidelines.

Key Words
ANFIS; FRP composites; fuzzy logic; shear strengthening; U-wrap

Address
S Kar: Department of Civil Engineering, O P Jindal University, Raigarh, Chhattisgarh 496109, India
E. V. Prasad: Department of Civil Engineering, GITAM Deemed to be University, Hyderabad, Telangana - 502329, India
Nikhil P. Zade and K. C. Biswal: Department of Civil Engineering, National Institute of Technology, Rourkela 769008, India
Parveen Sihag: Civil Engineering Department, Chandigarh University, Punjab 140413, India

Abstract
Concrete in water environment is easily subjected to the attack of leaching, which causes its mechanical reduction and durability deterioration, and the key to improving the leaching resistance of concrete is to increase the compaction of its microstructure formed by the curing. This paper performs a numerical investigation on the intrinsic relationship between microstructures formed by the hydration of cement and slag and leaching resistance of concrete in water environment. Firstly, a shrinking-core hydration model of blended cement and slag is presented, in which the interaction of hydration process of cement and slag is considered and the microstructure composition is characterized by the hydration products, solution composition and pore structure. Secondly, based on Fick's law and mass conservation law, a leaching model of hardened paste is proposed, in which the multi-species ionic diffusion equation and modified Gérard model are established, and the model is numerically solved by applying the finite difference method. Finally, two models are combined by microstructure composition to form an integrated curing-leaching model, and it is used to investigate the relationship between microstructure composition and leaching resistance of slag-blended cement pastes.

Key Words
hydration; leaching; microstructure; model; slag-blended cement paste

Address
Department of Civil Engineering, School of Science, Nanjing University of Science & Technology, Nanjing 210094, China

Abstract
This article investigates the wave propagation analysis of the imperfect functionally graded (FG) sandwich plates based on a novel simple four-variable integral quasi-3D higher-order shear deformation theory (HSDT). The thickness stretching effect is considered in the transverse displacement component. The presented formulation ensures a parabolic variation of the transverse shear stresses with zero-stresses at the top and the bottom surfaces without requiring any shear correction factors. The studied sandwich plates can be used in several sectors as areas of aircraft, construction, naval/marine, aerospace and wind energy systems, the sandwich structure is composed from three layers (two FG face sheets and isotropic core). The material properties in the FG faces sheet are computed according to a modified power law function with considering the porosity which may appear during the manufacturing process in the form of micro-voids in the layer body. The Hamilton principle is utilized to determine the four governing differential equations for wave propagation in FG plates which is reduced in terms of computation time and cost compared to the other conventional quasi-3D models. An eigenvalue equation is formulated for the analytical solution using a generalized displacements' solution form for wave propagation. The effects of porosity, temperature, moisture concentration, core thickness, and the material exponent on the plates' dispersion relations are examined by considering the thickness stretching influence.

Key Words
FGM plate; hygro-thermal environment; porosity; quasi-3D HSDT; wave propagation

Address
Abdelouahed Tounsi and Trinh Do-Van: Center for Engineering Application & Technology Solutions, Ho Chi Minh City Open University, Ho Chi Minh City, Vietnam
Saeed I. Tahir: Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
Mohammed A. Al-Osta: 1) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia, 2) Interdisciplinary Research Center for Construction and Building Materials, KFUPM, 31261 Dhahran, Saudi Arabia
Fouad Bourada: 1) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria, 2) Science and Technology Department, Faculty of Science and Technology, Tissemsilt University, Algeria
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Abdeldjebbar Tounsi: Industrial Engineering and Sustainable Development Laboratory, University of Rélizane, Faculty of Science & Technology, Mechanical Engineering Department, Algeria

Abstract
This work utilizes simplified higher-order shear deformation beam theory (HSDBT) to investigate the vibration response for functionally graded carbon nanotube-reinforced composite (CNTRC) beam. Novel to this work, single-walled carbon nanotubes (SWCNTs) are distributed and aligned in a matrix of polymer throughout the beam, resting on a viscoelastic foundation. Four un-similar patterns of reinforcement distribution functions are investigated for the CNTRC beam. Porosity is another consideration taken into account due to its significant effect on functionally graded materials (FGMs) properties. Three types of uneven porosity distributions are studied in this study. The damping coefficient and Winkler's and Pasternak's parameters are considered in investigating the viscosity effect on the foundation. Moreover, the impact of different parameters on the vibration of the CNTRC beam supported by a viscoelastic foundation is discussed. A comparison to other works is made to validate numerical results in addition to analytical discussions. The findings indicate that incorporating a damping coefficient can improve the vibration performance, especially when the spring constant factors are raised. Additionally, it has been noted that the fundamental frequency of a beam increases as the porosity coefficient increases, indicating that porosity may have a significant impact on the vibrational characteristics of beams.

Key Words
CNT-reinforced beam; free vibration; functionally graded materials; porosity; viscoelastic foundation

Address
Abdulmajeed M. Alsubaie, Ibrahim Alfaqih, Ismail M. Mudhaffar and Saeed Tahir: Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Mohammed A. Al-Osta: 1) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia, 2) Interdisciplinary Research Center for Construction and Building Materials, KFUPM, 31261 Dhahran, Saudi Arabia
Abdelouahed Tounsi: 1) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia, 2) Interdisciplinary Research Center for Construction and Building Materials, KFUPM, 31261 Dhahran, Saudi Arabia, 3) YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea, 4) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Abdelbaki Chikh: 1) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria, 2) Universite Ibn Khaldoun, BP 78 Zaaroura, 14000 Tiaret, Algerie

Abstract
The bending of a porous FG plate is discussed in this study using a novel higher quasi-3D hyperbolic shear deformation theory with four unknowns. The proposed theory takes into consideration the normal and transverse shear deformation effect and ensures the parabolic distribution of the transverse stresses through the thickness direction with zerotraction at the top and the bottom surfaces of the structure. Innovative porous functionally graded materials (FGM) have through-thickness porosity as a unique attribute that gradually varies with their qualities. An analytical solution of the static response of the perfect and imperfect FG plate was derived based on the virtual work principle and solved using Navier's procedure. The validity and the efficiency of the current model is confirmed by comparing the results with those obtained by others solutions. The comparisons showed that the present model is very efficient and simple in terms of computation time and exactness. The impact of the porosity parameter, aspect ratio, and thickness ratio on the bending of porous FG plate is shown through a discussion of several numerical results.

Key Words
bending analysis; porous FG plate; Quasi-3D HSDT

Address
Farouk Yahia Addou: 1) Civil Engineering Department, Faculty of Science and Technology, University of Mostaganem, Algeria, 2) Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Fouad Bourada: 1) Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria, 2) Science and Technology Department, Faculty of Science and Technology, Tissemsilt University, Algeria
Mustapha Meradjah and Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Abdelouahed Tounsi: 1) Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria, 2) YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea, 3) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia, 4) Interdisciplinary Research Center for Construction and Building Materials, KFUPM, Dhahran, Saudi Arabia
Mofareh Hassan Ghazwani and Ali Alnujaie: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Kingdom of Saudia Arabia

Abstract
The crack under the influence of the higher intensities of the stresses grows and the structure gets collapsed with the time when the crack length reaches to critical value. Therefore, the fracture behavior of a structure in terms of stress intensity factors (SIF) becomes important to determine the remaining fracture strength and capacity of material and structure for avoiding catastrophic failure, increasing safety and further improvement in the design. The robustness of the method has been demonstrated by comparing the numerical results with analytical and experimental results of some problems. XFEM is used to model cracks and holes in structures and predict their strength and reliability under service conditions. Further, XFEM is extended with a stochastic method for predicting the sensitivity in terms of output COVs and fracture strength in terms of mean values of stress intensity factors (SIFs) of a structure with discontinuities (cracks and holes) under tensile loading condition with input individual and combined randomness in different system parameters. In stochastic technique, the second order perturbation technique (SOPT) has been used for the predicting the fracture behavior of the structures. The stochastic/perturbation technique is also known as Taylor series expansion method and it provides the reliable results if the input randomness is less than twenty percentage. From the present numerical analysis it is observed that, the crack tip near to the hole is under the influence of the stress concentration and the variational effect of the input random parameters on the crack tip in terms of the SIFs are lesser so the COVs are the less sensitive. The COVs of mixed mode SIFs are the most sensitive for the crack angles (a=45o to 90o) for all the values of c1 and d1. The plate with the shorter distance between hole and crack is the most sensitive with all the crack angles but the crack tip which is much nearer to the hole has the highest sensitivity.

Key Words
COV; discontinuities; MMSIF; randomness; SIF; stochastic; XFEM

Address
Khubi Lal Khatri: Department of Mechanical Engineering, Swarrnim institute of Technology, Gandhinagar, Gujarat, India
Kanif Markad: Department of Mechanical Engineering, DVVP College of Engineering, Ahmednagar, Maharashtra (India)-414111

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