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CONTENTS
Volume 38, Number 1, January10 2021
 

Abstract
In this paper, a higher order shear deformation theory for bending analysis of functionally graded plates resting on Pasternak foundation and under various boundary conditions is exposed. The proposed theory is based on the assumption that porosities can be produced within functionally graded plate which may lead to decline in strength of materials. In this research a novel distribution of porosity according to the thickness of FG plate are supposing. Governing equations of the present theory are derived by employing the virtual work principle, and the closed-form solutions of functionally graded plates have been obtained using Navier solution. Numerical results for deflections and stresses of several types of boundary conditions are presented. The exactitude of the present study is confirmed by comparing the obtained results with those available in the literature. The effects of porosity parameter, slenderness ratio, foundation parameters, power law index and boundary condition types on the deflections and stresses are presented.

Key Words
functionally graded plate; pasternak foundation; porosity; boundary conditions

Address
Moustafa Guellil: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria;
Faculty of Engeneering, University of Temouchent, Temouchent, Algeria
Hayat Saidi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Fouad Bourada: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria;
Département des Sciences et de la Technologie, centre universitaire de Tissemsilt, BP 38004 Ben Hamouda, Algérie
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Abdelouahed Tounsi: YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
Mesfer Mohammad Al-Zahrani: Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran,
Eastern Province, Saudi Arabia
Muzamal Hussain: Department of Mathematics, Government College University Faisalabad, Punjab, Pakistan
S.R. Mahmoud: GRC Department, Jeddah Community College, King Abdulaziz University, Jeddah, Saudi Arabia



Abstract
Post-earthquake fire is a common disaster which causes serious safety issues to infrastructures. This study aims to investigate the residual loading capacities of circular concrete-filled steel tube (CFST) columns under post-earthquake fire experimentally and numerically. The experimental programme contains two loading steps - pre-damage cyclic loading at room temperature and transient state tests with constant compression loads. Three finite element models are developed and validated against the test results. Upon validation, a total of 48 numerical results were generated in the parametric study to investigate the effects of thickness and strengths of steel tube, axial compression ratio and damage degree on the fire resistance of circular CFST columns. Based on the analysis on experimental and numerical results, the loading mechanism of circular CFST columns is discussed. A design method is proposed for the prediction of fire resistance time under different seismic pre-damage and compression loads. The predictions by the new method is compared with the newly generated experimental and numerical results and is found to be accurate and consistent with the mean value close to the unity and a coefficient of variation around 1%.

Key Words
circular concrete-filled steel tube column; design method; experimental programme; finite element; post-earthquake fire; seismic damage

Address
Yu-Hang Wang, Ji-Ke Tan, Wei-Yong Wang, Yong-Tao Bai, Xiao-Hua Li and Jiu-Lin Bai: School of Civil Engineering, Chongqing University, Chongqing 400045, China
Qi Tang: CISDI ENGINEERING CO., LTD, Chongqing,400013, China
Mei-Ni Su: Department of Mechanical, Aerospace and Civil Engineering, University of Manchester, M1 3NJ, UK;
Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing 400045, China
Yong-Sen Lan and Wei Luo: CSIC HaiZhuang Wind power Co., Ltd, Chongqing 401122, China
Xiao-Wei Deng: Department of Civil Engineering, The University of Hong Kong, China

Abstract
The Runge-Kutta method of 6th-order has been employed in this paper to analyze the flow of Casson nanofluid along permeable exponentially stretching cylinder. The modeled PDEs are changed into nonlinear ODEs through appropriate nonlinear transformations. The aim of the paper is to investigate the effects of different parameters such as Casson fluid parameter, slip parameter, suction parameter, Prandtl number, Lewis number, Brownian motion parameter, and thermophoresis parameter, with the variation of mass concentration profile. Numerical results are attained using a renowned numerical scheme shooting technique and for the authenticity of present methodlogy, the results are verified with earlier open text.

Key Words
mass concentration; nanofluid; R-K method of 6th-order; fluid flow

Address
Waheed Iqbal, Muzamal Hussain and Muhammad N. Naeem: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Mudassar Jalil: Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, 44000 Islamabad, Pakistan
Mohamed A. Khadimallah: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 16273, Saudi Arabia;
Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia
Abdullah F. Al Naim: Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa 31982, Saudi Arabia
S.R. Mahmoud: GRC Department, Faculty of Applied studies, King Abdulaziz University, Jeddah, Saudi Arabia
Abdelouahed Tounsi: 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


Abstract
This work addresses the free vibration analysis of Functionally Graded Porous (FGP) nanocomposite truncated conical shells with Graphene PLatelet (GPL) reinforcement. In this study, three different distributions for porosity and three different dispersions for graphene platelets have been considered in the direction of the shell thickness. The Halpin–Tsai equations are used to find the effective material properties of the graphene platelet reinforced materials. The equations of motion are derived based on the higher-order shear deformation theory and Sanders's theory. The Fourier Differential Quadrature (FDQ) technique is implemented to solve the governing equations of the problem and to obtain the natural frequencies of the truncated conical shell. The combination of FDQ with higher-order shear deformation theory allows a very accurate prediction of the natural frequencies. The precision and reliability of the proposed method are verified by the results of literature. Moreover, a wide parametric study concerning the effect of some influential parameters, such as the geometrical parameters, porosity distribution, circumferential wave numbers, GPLs dispersion as well as boundary restraint conditions on free vibration response of FGP-GPL truncated conical shell is also carried out and investigated in detail.

Key Words
free vibration; fourier differential quadrature; functionally graded material; graphene platelet reinforcement; higher-order shear deformation theory; truncated conical shell

Address
Majid Khayat, Abdolhossein Baghlani, Seyed Mehdi Dehghan
and Mohammad Amir Najafgholipour: Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran

Abstract
The use of composite beams with partial interaction, with less shear connectors than those required for full interaction, may be advantageous in many situations. However, these beams tend to show higher deflections compared to beams with full interaction, and codified expressions for the calculation of such deflections are not fully developed and validated. Thus, this paper presents a comprehensive numerical study on the deflections of steel-concrete composite beams with partial interaction. Efficient numerical models of full-scale composite beams considering material nonlinearities and contact between their parts have been developed by means of the advanced software ABAQUS, including a damage model to simulate the concrete slab. The FE models were validated against experimental results, and subsequently parametric studies were developed to investigate the influence of the shear connection degree and the coefficient of friction in the deflection of composite beams. The comparison of predicted deflections using reference codes (AISC, Eurocode-4 and AS-2327.1) against numerical results showed that there are still inaccuracies in the estimation of deflections for the verification of the serviceability limit state, according to some of the analyzed codes.

Key Words
deflections; steel-concrete structures; partial interaction; composite beams; shear connectors

Address
Enrique Mirambell: Department of Civil and Environmental Engineering, Polytechnic University of Catalunya, Spain
Jorge Bonilla and Beatriz Clero: Group for Numerical Methods in Engineering, University of Ciego de Ávila, Cuba
Luciano M. Bezerra: Department of Civil and Environmental Engineering, University of Brasília, Brazil

Abstract
Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0X104 ue and have a similar trend as that in the numerical simulation.

Key Words
composite materials; UCS tests; crushing effects; strain waves

Address
Fei Liu: Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China;
Shenzhen Key Laboratory of Deep Underground Engineering Sciences and Green Energy,
Shenzhen University, Shenzhen, 518060, China
Lianghui Li: College of Energy & Mining, China University of Mining & Technology, Beijing 100083, China


Abstract
To investigate the failure form, bending stiffness, and residual bearing capacity of monolithic composite beams with laminated slab throughout the fire process, fire tests of four monolithic composite beams with laminated slab were performed under constant load and temperature increase. Different factors such as post-pouring layer thickness, lap length of the prefabricated bottom slab, and stud spacing were considered in the fire test. The test results demonstrate that, under the same fire time and external load, the post-pouring layer thickness and stud spacing are important parameters that affect the fire resistance of monolithic composite beams with laminated slab. Similarly, the post-pouring layer thickness and stud spacing are the predominant factors affecting the bending stiffness of monolithic composite beams with laminated slab after fire exposure. The failure forms of monolithic composite beams with laminated slab after the fire are approximately the same as those at room temperature. In both cases, the beams underwent bending failure. However, after exposure to the high-temperature fire, cracks appeared earlier in the monolithic composite beams with laminated slab, and both the residual bearing capacity and bending stiffness were reduced by varying degrees. In this test, the bending bearing capacity and ductility of monolithic composite beams with laminated slab after fire exposure were reduced by 23.3% and 55.4%, respectively, compared with those tested at room temperature. Calculation methods for the residual bearing capacity and bending stiffness of monolithic composite beams with laminated slab in and after the fire are proposed, which demonstrated good accuracy.

Key Words
monolithic composite beam with laminated slab; fire test; static test; bearing capacity; bending stiffness; calculation method

Address
Junli Lyu: School of Civil Engineering, Shandong Jianzhu University, Jinan, 250101, China;
Key Lab of Building Structural Retrofitting and Underground Space Engineering, Ministry of Education, Jinan 250101, China
Shengnan Zhou and Qichao Chen: School of Civil Engineering, Shandong Jianzhu University, Jinan, 250101, China
Yong Wang: School of Mechanics & Civil Engineering, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China

Abstract
This research examines the eccentric compression performance of composite columns composed of recycled aggregate concrete (RAC)-filled square steel tube and profile steel. A total of 17 specimens on the composite columns with different recycled coarse aggregate (RCA) replacement percentage, RAC strength, width to thickness ratio of square steel tube, profile steel ratio, eccentricity and slenderness ratio were subjected to eccentric compression tests. The failure process and characteristic of specimens under eccentric compression loading were observed in detail. The load-lateral deflection curves, load-train curves and strain distribution on the cross section of the composite columns were also obtained and described on the basis of test data. Results corroborate that the failure characteristics and modes of the specimens with different design parameters were basically similar under eccentric compression loads. The compression side of square steel tube yields first, followed by the compression side of profile steel. Finally, the RAC in the columns was crushed and the apparent local bulging of square steel tube was also observed, which meant that the composite column was damaged and failed. The composite columns under eccentric compression loading suffered from typical bending failure. Moreover, the eccentric bearing capacity and deformation of the specimens decreased as the RCA replacement percentage and width to thickness ratio of square steel tube increased, respectively. Slenderness ratio and eccentricity had a significantly adverse effect on the eccentric compression performance of composite columns. But overall, the composite columns generally had high-bearing capacity and good deformation. Meanwhile, the mechanism of the composite columns under eccentric compression loads was also analysed in detail, and the calculation formulas on the eccentric compression capacity of composite columns were proposed via the limit equilibrium analysis method. The calculation results of the eccentric compression capacity of columns are consistent with the test results, which verify the validity of the formulas, and the conclusions can serve as references for the engineering application of this kind of composite columns.

Key Words
recycled aggregate concrete; recycled concrete-filled steel tube; steel reinforced recycled concrete; composite column; eccentric compression performance

Address
Hui Ma: School of Civil Engineering and Architecture, Xi'an University of Technology, Xi'an, 710048, China;
State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, 710048, China
Jiacheng Xi and Jikun Dong: School of Civil Engineering and Architecture, Xi'an University of Technology, Xi'an, 710048, China
Yaoli Zhao: Research and Design Institute of water conservancy and hydropower, Xi'an University of Technology, Xi'an, 710048, China



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