Abstract
The main objective of this paper is to study the effect of porosity on the buckling behavior of thick functionally
graded sandwich plate resting on various boundary conditions under different in-plane loads. The formulation is made for a newly developed sandwich plate using a functional gradient material based on a modified power law function of symmetric and asymmetric configuration. Four different porosity distribution are considered and varied in accordance with material propriety variation in the thickness direction of the face sheets of sandwich plate, metal foam also is considered in this study on the second model of sandwich which containing metal foam core and FGM face sheets. New quasi-3D high shear deformation theory is used here for this investigate; the present kinematic model introduces only six variables with stretching effect by adopting a new
indeterminate integral variable in the displacement field. The stability equations are obtained by Hamilton's principle then solved by generalized solution. The effect of Pasternak and Winkler elastic foundations also including here. the present model validated with those found in the open literature, then the impact of different parameters: porosities index, foam cells distribution, boundary conditions, elastic foundation, power law index, ratio aspect, side-to-thickness ratio and different in-plane
axial loads on the variation of the buckling behavior are demonstrated.
Key Words
buckling behavior; functionally graded materials; metal foam; porosity; sandwich plate
Address
Abdelkader Tamrabet: Department of Civil Engineering, University of Ferhat Abbas-Setif1, Faculty of Technology, Algeria; Research Unit of Emerging Materials, University of Ferhat Abbas-Setif1, Algeria
Belgacem Mamen: Department of Civil Engineering, Faculty of Science and Technology, University of Abbes Laghrour Khenchela, Algeria; Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abderrahmane Menasria: Department of Civil Engineering, Faculty of Science and Technology, University of Abbes Laghrour Khenchela, Algeria; Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelhakim Bouhadra: Department of Civil Engineering, Faculty of Science and Technology, University of Abbes Laghrour Khenchela, Algeria; Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Mofareh Hassan Ghazwani: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Saudia Arabia
Ali Alnujaie: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Saudia Arabia
S.R. Mahmoud: GRC Department, Jeddah Community College, King Abdulaziz University, Jeddah, Saudi Arabia
Abstract
The article is about the theoretical analysis of the transmission and reflection of elastic waves through the interface of perfectly connected materials. The solid continuum mediums considered are piezoelectric semiconductors and transversely isotropic in nature. The connection among the mediums is considered in such a way that it holds the continuity property of field variables at the interface. The concept of strain and stress introduced by non-local theory is also being involved to make the study more applicable It is found that, the incident wave results in the generation of four reflected and three transmitted waves including the thermal and elastic waves. The thermal waves generated in the medium are encountered by using the concept of three phase lag heat model along with fractional ordered time thermoelasticity. The results obtained are calculated graphically for a ZnO material with piezoelectric semiconductor properties for medium M1 and CdSc material with transversely isotropic elastic properties for medium M2. The influence of fractional order parameter, non-local parameter, and steady carrier density parameter on the amplitude ratios of reflected and refraction waves are studied graphically by MATLAB.
Key Words
fractional order time derivative; nonlocal theory; piezoelectric semiconductor; refraction; Thermoelasticity
Address
Adnan Jahangir: Department of Mathematics, COMSATS University Islamabad, Wah Campus, Pakistan
Abdul Waheed: Department of Mathematics, COMSATS University Islamabad, Islamabad Campus, Pakistan
Ying Guo: School of Civil Engineering, Henan University of Science and Technology, Luoyang 471023, Henan, China
Abstract
Limited studies are available on the mathematical estimates of the compressive strength (CS) of glass fiberembedded polymer (glass-FRP) compressive elements. The present study has endeavored to estimate the CS of glass-FRP normal strength concrete (NSTC) compression elements (glass-FRP-NSTC) employing two various methodologies; mathematical modeling and artificial neural networks (ANNs). The dataset of 288 glass-FRP-NSTC compression elements was constructed from the various testing investigations available in the literature. Diverse equations for CS of glass-FRP-NSTC compression elements suggested in the previous research studies were evaluated employing the constructed dataset to examine their correctness. A new mathematical equation for the CS of glass-FRP-NSTC compression elements was put forwarded employing the procedures of curve-fitting and general regression in MATLAB. The newly suggested ANN equation was calibrated for various hidden layers and neurons to secure the optimized estimates. The suggested equations reported a good correlation among themselves and presented precise estimates compared with the estimates of the equations available in the literature with R2= 0.769, and R2 =0.9702 for the mathematical and ANN equations, respectively. The statistical comparison of diverse factors for the estimates of the projected equations also authenticated their high correctness for apprehending the CS of glass-FRP-NSTC compression elements. A broad parametric examination employing the projected ANN equation was also performed to examine the effect of diverse factors of the glass-FRP-NSTC compression elements.
Key Words
ANN equation; compression element; compressive strength; glass-FRP; mathematical equation
Address
Selmi Abdellatif: Department of Civil Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Alkharj, 11942, Saudi Arabia; Civil Engineering, Laboratory, Ecole Nationale d'Ingénieurs de Tunis (ENIT), B.P. 37, Le belvédère 1002, Tunis, Tunisia
Ali Raza: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan
Abstract
In this paper, the shear behavior of soft filling in rectangular-hollow concrete specimens was simulated using the 2D particle flow code (PFC2D). The laboratory-measured properties were used to calibrate some PFC2D micro-properties for modeling the behavior of geo-materials. The dimensions of prepared and modeled samples were 100 mmx100 mm. Some disc type narrow bands were removed from the central part of the model and different lengths of bridge areas (i.e., the distance between internal tips of two joints) with lengths of 30 mm, 50 mm, and 70 mm were produced. Then, the middle of the rectangular hollow was filled with cement material. Three filling sizes with dimensions of 5 mmx5 mm, 10 mmx5 mm, and 15 mmx5 mm were provided for different modeled samples. The parallel bond model was used to calibrate and re-produce these modeled specimens. Therefore, totally, 9 different types of samples were designed for the shear tests in PFC2D. The shear load
was gradually applied to the model under a constant loading condition of 3 MPa (oc/3). The loading was continued till shear failure occur in the modeled concrete specimens. It has been shown that both tensile and shear cracks may occur in the fillings. The shear cracks mainly initiated from the crack (joint) tips and coalesced with another one. The shear displacements and shear strengths were both increased as the filling dimensions increased (for the case of a bridge area with a particular fixed length).
Address
Lei Zhou: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China; Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province,
Southwest University of Science and Technology, Mianyang 621010, Sichuan,China; MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
Vahab Sarfarazi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran
Hadi Haeri: Department of Mining Engineering, Higher Education Complex of Zarand, Zarand, Iran
Amir Aslan Naderi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran
Mohammad Fatehi Marji: Department of Mining Engineering, Yazd University, Yazd, Iran
Fei Wu: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Abstract
An extended parametric study based on nonlinear finite element analyses is performed to assess the key factors
affecting the shear behaviour of exterior beam-column joints of unbraced reinforced concrete frames. Extensive results are presented, the major conclusion being that the few shear behaviour models for exterior reinforced concrete beam-column joints available in the literature do not properly account for some of the most influential factors. The present results are also compared with recently published results for interior joints, showing that while some factors have a similar influence on interior and exterior joints others are relevant for only one of these types of joints. This also confirms, numerically, that some resisting
mechanisms of exterior joints differ from those of interior joints.
Key Words
beam-column joint; finite element method; reinforced concrete; shear behavior
Address
Ricardo Costa: Department of Civil Engineering, University of Coimbra, ISISE, Rua Luis Reis Santos, 3030-788, Coimbra, Portugal
Paulo Providência: University of Coimbra, INESC Coimbra, DEC, 3030-290, Coimbra, Portugal
Abstract
Reliability-Based Design Optimization (RBDO) is an appropriate framework for obtaining optimal designs by taking uncertainties into account. Large-scale problems with implicit limit state functions and problems with discrete design variables are two significant challenges to traditional RBDO methods. To overcome these challenges, this paper proposes a hybrid method to perform RBDO of structures that links Firefly Algorithm (FA) as an optimization tool to advanced (finite element) reliability methods. Furthermore, the Genetic Algorithm (GA) and the FA are compared based on the design cost (objective function) they achieve. In the proposed method, Weighted Simulation Method (WSM) is utilized to assess reliability constraints in the RBDO
problems with explicit limit state functions. WSM is selected to reduce computational costs. To performing RBDO of structures with finite element modeling and implicit limit state functions, a First-Order Reliability Method (FORM) based on the Direct Differentiation Method (DDM) is utilized. Four numerical examples are considered to assess the effectiveness of the proposed method. The findings illustrate that the proposed RBDO method is applicable and efficient for RBDO problems with discrete and continuous design variables and finite element modeling.
Address
Ali Khodam: Department of Civil and Geomechanics Engineering, Arak University of Technology, Arak, Iran
Mohammad Saeid Farajzadeh, Mohsenali Shayanfar: School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
Abstract
The seismic performance of the tall building equipped with a tuned mass damper (TMD) considering soil-structure interaction (SSI) effects is well studied in the literature. However, these studies are performed on the nominal model of the seismic-excited structural system with SSI. Hence, the outcomes of the studies may not valid for the actual structural system. To address the study gap, the reliability theory as a useful and powerful method is utilized in the paper. The present study aims to carry out reliability analyses on tall buildings equipped with TMD under near‐field pulse-like (NFPL) ground motions considering SSI effects using a subset simulation (SS) method. In the presence of uncertainties of the structural model, TMD device, foundation, soil, and near‐field pulse-like ground motions, the numerical studies are performed on a benchmark 40-story building and the failure probabilities of the structures with and without TMD are evaluated. Three types of soils (dense, medium, and soft soils), different earthquake magnitudes (MW=7,0. 7,25. 7,5 ), different nearest fault distances (r=5. 10 and 15 km), and three seismic performance levels of immediate occupancy (IO), life safety (LS), and collapse prevention (CP) are considered in this study. The results show that tall buildings built near faults and on soft soils are more affected by uncertainties of the structural and ground motion models. Hence, ignoring these uncertainties may result in an inaccurate estimation of the maximum seismic responses. Also, it is found the TMD is not able to reduce the failure probabilities of the structure in the IO seismic performance level, especially for high earthquake magnitudes and structures built near the fault. However, TMD is significantly effective in the reduction of failure probability for the LS and CP performance levels. For weak earthquakes and long fault distances, the failure probabilities of both structures with and without TMD are near zero, and the efficiency of the TMD in the reduction of failure probabilities is reduced by increasing earthquake magnitudes and the reduction of fault distance. As soil softness increases, the failure probability of structures both with and without TMD often increases, especially for severe near-fault earthquake motion.
Key Words
near‐field pulse-like ground motion; reliability analysis; seismic performance level; soil-structure interaction effect; subset simulation method; tuned mass damper
Address
Sadegh Etedali: Department of Civil Engineering, Birjand University of Technology, P.O. Box 97175-569, Birjand, Iran
Mohammad Seifi, Morteza Akbari: Independent Researchers, Birjand, Iran
Abstract
Smart structures are those structure that could adopt some behavior to prevent instability in their responses. The recognition of stability deterioration has been performed through rigid mathematical formulations in control theory and unpredicted results could not be addressed in control systems since they are able to only work under their predefined condition. On the other hand, incorporating all affecting parameters could result in high computational cost and delay time in the response of the systems. Artificial intelligence (AI) method has shown to be a promising methodology not only in the computer science by at everyday life and in engineering problems. In the present study, we exploit the capabilities of artificial intelligence method to obtain frequency response of a smart structure. In this regard, a comprehensive development of equations is presented using Hamilton' principle and first order shear deformation theory. The equations were solved by numerical methods and the results are used to train an artificial neural network (ANN). It is demonstrated that ANN modeling could provide accurate results in comparison to the numerical solutions and it take less time than numerical solution.
Key Words
artificial intelligence; mathematical modeling; piezoelectric materials; problem-solving; smart problem
Address
Kaiwen Liu: School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
Jun Gao: School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China; National Railway Group Wu-Guang High Speed Railway Company, Wuhan, 430212, Hubei, China
Ruizhe Qiu: School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
Abstract
Precast assembled bridge piers with hybrid connection (PASP) use both tendons and socket connections. To study the seismic performance of PASP, a full-scale in-situ test was performed based on an actual bridge project. The elastic-plastic fiber model of PASP was established using finite element software, and numerical analyses were performed to study the influence of prestress degree and socket depth on the PASP seismic performance. The results show that the typical failure mode of PASP under horizontal load is bending failure dominated by concrete cracking at the joint between the column and cushion cap. The cracking of the pier concrete and opening of joints depend on the prestress degree and socket depth. The prestressing tendons
and socket connection can provide enough ductility, strength, restoration capability, and bending strength under small horizontal displacements. Although the bearing capacity and post yield stiffness of the pier can be improved to some extent by increasing the prestressing force, ductility is reduced, and residual deformation is increased. Overall, there are reasonable minimum socket depths to ensure the reliability of the socket connection.
Address
Shuang Zou, Heisha Wenliuhan, Yanhui Liu, Zhipeng Zhai: Earthquake Engineering Research & Test Center, Guangzhou University, China; China Guangdong Provincial Key Laboratory of Earthquake Engineering and Applied Technology, Guangzhou, China; Key Laboratory of Earthquake Resistence, Earthquake Mitigation and Structural Safety, Ministry of Education, Guangzhou, China
Chongbin Zhang: China Railway Engineering Design and Consulting Group Co., Ltd., Beijing, China
Abstract
This paper studies the effects of porosity distributions on buckling and post-buckling behaviors of a functionally graded saturated porous (FGSP) circular plate. The plate is under the uniformly distributed radial loading and simply supported and clamped boundary conditions. Pores are saturated with compressible fluid (e.g., gases) that cannot escape from the porous solid. Elastic modulus is assumed to vary continuously through the thickness according to three different functions corresponding to three different cases of porosity distributions, including monotonous, symmetric, and asymmetric cases. Governing equations are derived utilizing the classical plate theory and Sanders nonlinear strain-displacement relations, and they are solved numerically via shooting method. Results are verified with the known results in the literature. The obtained results for the monotonous and symmetric cases with the asymmetric case presented in the literature are shown in comparative figures. Effects of the poroelastic material parameters, boundary conditions, and thickness change on the post-buckling behavior of the plate are discussed in details. The results reveal that buckling and post-buckling behaviors of the plate in the monotonous and symmetric cases differ from the asymmetric case, especially in small deflections, that asymmetric distribution of elastic moduli can be the cause.
Address
Khaled Alhaifi: Department of Automotive and Marine Engineering, College of Technological Studies-PAAET, El-Shuwaikh, Kuwait
Ahmad Reza Khorshidvand: Department of Mechanical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
Murtadha M. Al-Masoudy: Air Conditioning and Refrigeration Technique Engineering Department, Al-Mustaqbal University College, 51001 Hillah, Babylon, Iraq
Ehsan Arshid: Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, Iran; Production and Recycling of Materials and Energy Research Center, Qom Branch, Islamic Azad University, Qom, Iran
Seyed Hossein Madani: Department of Mechanical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
