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CONTENTS
Volume 18, Number 1, January 2015
 

Abstract
In this paper, the dynamic response of functionally gradient steel (FGS) composite cylindrical panels in steady-state thermal environments subjected to impulsive loads is investigated for the first time. FGSs composed of graded ferritic and austenitic regions together with bainite and martensite intermediate layers are analyzed. Thermo-mechanical material properties of FGS composites are predicted according to the microhardness profile of FGS composites and approximated with appropriate functions. Based on the three-dimensional theory of thermo-elasticity, the governing equations of motionare derived in spatial and time domains. These equations are solved using the hybrid Fourier series expansion-Galerkin finite element method-Newmark approach for simply supported boundary conditions. The present solution is then applied to the thermo-elastic dynamic analysis of cylindrical panels with three different arrangements of material compositions of FGSs including αβγMγ, αβγβα and γβαβγ composites. Benchmark results on the displacement and stress time-histories of FGS cylindrical panels in thermal environments under various pulse loads are presented and discussed in detail. Due to the absence of similar results in the specialized literature, this paper is likely to fill a gap in the state of the art of this problem, and provide pertinent results that are instrumental in the design of FGS structures under time-dependent mechanical loadings.

Key Words
functionally gradient steels; cylindrical panel; 3-D thermo-elasticity solution; thermoelastic dynamic response

Address
(1) S. Isavand, M. Bodaghi, M. Shakeri:
Thermoelasticity Center of Excellence, Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran;
(2) J. Aghazadeh Mohandesi:
Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran.

Abstract
With a quasi-three point bending apparatus, ratcheting deformation is studied experimentally on a pressurized austenitic stainless steel Z2CND18.12N pipe under bending load and vertical displacement control, respectively. The characteristic of ratcheting behavior of straight pipe under both control methods is achieved and compared. The cyclic bending loading and internal pressure influence ratcheting behavior of pressurized straight pipe significantly under loading control and the ratcheting characteristics are also highly associated with the cyclic displacement and internal pressure under displacement control. They all affect not only the saturation of the ratcheting strain but the ratcheting strain rate. In addition, ratcheting simulation is performed by elastic.plastic finite element analysis with ANSYS in which the bilinear model, Chaboche model, Ohno.Wang model and modified Ohno-Wang model are applied. By comparison with the experimental data, it is found that the CJK model gives reasonable simulation. Ratcheting boundaries under two control modes are almost same.

Key Words
ratcheting; cyclic loading; cyclic displacement; loading history; pressure piping

Address
(1) Xiaohui Chen:
School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China;
(2) Xiaohui Chen, Xu Chen, Gang Chen:
School of Chemical Engineering and Technology, Tianjin University, 300072, China;
(3) Duomin Li:
Guangdong University of Petrochemical Technology, Maoming 525000, China.

Abstract
In recent years, the use of fiber reinforced polymer composites has increased because of their unique features. They have been used widely in the aircraft and space industries, medical and sporting goods and automotive industries. Thanks to their beneficial and various advantages over traditional materials such as high strength, high rigidity, low weight, corrosion resistance, low maintenance cost, aesthetic appearance and easy demountable or moveable construction. In this paper, it is aimed to determine and compare the geometrically nonlinear static and dynamic analysis results of footbridges using steel and glass fiber reinforced polymer composite (GFRP) materials. For this purpose, Halgavor suspension footbridge is selected as numerical examples. The analyses are performed using three identical footbridges, first constructed from steel, second built only with GFRP material and third made of steel- GFRP material, under static and dynamic loadings using finite element method. In the finite element modeling and analyses, SAP2000 program is used. Geometric nonlinearities are taken into consideration in the analysis using P-Delta criterion. The numerical results have indicated that the responses of the three bridges are different and that the response values obtained for the GFRP composite bridge are quite less compared to the steel bridge. It is understood that GFRP material is more useful than the steel for the footbridges.

Key Words
finite element model; geometrically nonlinear static and dynamic analysis; glass fiber reinforced polymer; static analysis; suspension footbridge

Address
(1) M. Gunaydin:
Department of Civil Engineering, Gümüşhane University, Gümüşhan, Turkey;
(2) S. Adanur, A.C. Altunisik:
Department of Civil Engineering, Karadeniz Technical University, Trabzon, Turkey;
(3) B. Sevim:
Department of Civil Engineering, Yıdız Technical University, Īstanbul, Turkey.

Abstract
Axial compression tests have been carried out on 18 rectangular concrete-filled cold-formed steel tubular (CFST) columns with the aim of investigating the axial behaviour of rectangular CFST columns under different loading methods (steel loaded-first and full-section loaded methods). The influence of different loading methods on the ultimate strength of the specimens was compared and the development of Poisson's Ratio as it responds to an increasing load was reported and analysed. Then, the relationship between the constraining factor and the strength index, and the relationship between the constraining factor and ductility index of the specimens, were both discussed. Furthermore, the test results of the full-section loaded specimens were compared with five international code predicted values, and an equation was derived to predict the axial carrying capacity for rectangular CFST columns with a steel loaded-first loading method.

Key Words
axial carrying capacity; constraining factor; ductility index; loading method; poisson's ratio; rectangular concrete-filled cold-formed steel tubular; strength index

Address
(1) Xiushu Qu:
School of Civil and Transportation Engineering, Beijing University of Civil Engineering and Architecture, Beijing, 100044, P.R. China;
(2) Xiushu Qu, Zhihua Chen, Guojun Sun:
School of Civil Engineering, Tianjin University, Tianjin, 300072, P.R. China.

Abstract
A refined higher-order shear deformation theory for bending, vibration and buckling analysis of functionally graded sandwich plates is presented in this paper. It contains only four unknowns, accounts for a hyperbolic distribution of transverse shear stress and satisfies the traction free boundary conditions. Equations of motion are derived from Hamilton\'s principle. The Navier-type and finite element solutions are derived for plate with simply-supported and various boundary conditions, respectively. Numerical examples are presented for functionally graded sandwich plates with homogeneous hardcore and softcore to verify the validity of the developed theory. It is observed that the present theory with four unknowns predicts the response accurately and efficiently.

Key Words
functionally graded sandwich plates; bending; buckling; vibration

Address
(1) Kien T. Nguyen:
Faculty of Civil Engineering and Applied Mechanics, University of Technical Education, Ho Chi Minh City, 1 Vo Van Ngan Street, Thu Duc District, Ho Chi Minh City, Viet Nam;
(2) Tai H. Thai:
School of Civil and Environmental Engineering, The University of New South Wales, NSW 2052, Australia;
(3) Thuc P. Vo:
Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK.

Abstract
This paper is to investigate the potentials of the elastic seismic design of twisted high-rise steel diagrid frame buildings in the strong wind and moderate/low seismicity regions. First, the prototypes of high-rise steel diagrid frames with architectural plans that have a twist angle of 0 (regular-shaped), 1, and 2 degrees were designed to resist wind. Then, the effects of the twist angle on the estimated quantities and structural redundancies of the diagrid frames were examined. Second, the seismic performance of the wind-designed prototype buildings under a low seismicity was evaluated. The response spectrum analysis was conducted for the service level earthquake (SLE) having 43-year return period and the maximum considered earthquake (MCE) having 2475-year return period. The evaluation resulted that the twisted high-rise steel diagrid frames resisted the service level earthquake elastically and most of their diagrid members remained elastic even under the maximum considered earthquake.

Key Words
high-rise steel diagrid frames; twist angle; quantities; redundancy; seismic performance; elastic seismic design

Address
(1) Seonwoong Kim:
Department of Architecture and Plant Engineering, Youngsan University, Yangsan, Kyungnam, South Korea;
(2) Kyungkoo Lee:
Department of Architectural Engineering, Dankook University, Yongin, Kyounggi, South Korea.

Abstract
The cutout hole locating at the place of rib-to-diaphragm welded connection is adopted to minimize the restraint, which is caused by the floor-beam web to rib rotation at the support due to the unsymmetrical loads in orthotropic deck. In practice, an inevitable problem is that there is a large number of welding joint's cracks formed at the edge of cutout hole. In this study, a comparative experiment is carried out with two types of cutout hole, the circular arc transition and the vertical transition. The fatigue life estimation of specimens is investigated with the application of the structural hot spot stress approach by finite element analyses. The results are compared with the ones of the fatigue tests which are carried out on these full-scale specimens. Factors affecting the stress range are also studied.

Key Words
finite elements; orthotropic deck; rib-to-diaphragm welded connection; fatigue; hot spot stress

Address
Mailbox 312, Chang'an University, The middle section of nan erhuan road, Xi'an City, Shaanxi Province 710064, P.R. China.

Abstract
Orthotropic steel highway bridges exist almost everywhere in world, especially in Europe. The design of these bridges started very early in 20th century and ended with a conventional orthotropic steel bridge structure, which is today specified in DIN FB 103. These bridges were mostly built in 1960's and exhibit damages in steel structural parts. The primary reason of these damages is the high pressure that is induced by wheel- loads and therefore damages develop especially in heavy traffic lanes. Constructive rules are supplied by standards to avoid damages in orthotropic steel structural parts. These rules are first given in detail in the standard DIN 18809 (Steel highway- and pedestrian bridges- design, construction, fabrication) and then in DIN- FB 103 (Steel bridges). Bridges built in the past are today subject to heavier wheel loads and the frequency of loading is also increased. Because the vehicles produced today in 21st century are heavier than before and more people have vehicle in comparison with 20th century. Therefore dimensioning or strengthening of orthotropic steel bridges by using stiffer dimensions and shorter spans is an essence. In the scope of this study the complex geometry of conventional steel orthotropic bridge is generated by FEProgram and the effects of cross beam web thickness and cross beam span on steel bridge are assessed by means of a parameter study. Consequently, dimensional and constructional recommendations in association with cross beam thickness and span will be given by this study.

Key Words
finite elements; orthotropic steel bridges; cross-beams

Address
Department of Civil Engineering, Yildiz Technical University, Esenler 34220, Istanbul, Turkey.

Abstract
The suspended zipper bracing system is suggested to reduce the flaws of ordinary zipper braced and concentric inverted V braced frames. In the design procedure of suspended zipper bracing systems, columns and top story truss elements are strengthened. This bracing system show different performances and characteristics compared with inverted V braced and ordinary zipper frames. As a result, a different response modification factor for suspend zipper frames is needed. In this research paper, the response modification factor of suspended zipper frames was obtained using the incremental dynamic analysis. Suspended zipper braced frames with different stories and bay lengths were selected to be representations of the design space. To analyze the frames, a number of models were constructed and calibrated using experimental data. These archetype models were subjected to 44 earthquake records of the FEMA-P695 project data set. The incremental dynamic analysis and elastic dynamic analysis were carried out to determine the yield base shear value and elastic base shear value of archetype models using the OpenSEES software. The seismic response modification factor for each frame was calculated separately and the values of 9.5 and 13.6 were recommended for ultimate limit state and allowable stress design methods, respectively.

Key Words
response modification factor; ductility factor; overstrength factor; suspended zipper bracing

Address
(1) Gholamreza Abdollahzadeh:
Faculty of Civil Engineering, Babol University of Technology, Babol, Iran;
(2) Mehdi Abbasi:
Civil Engineering Department, Shomal University, Amol, Iran.

Abstract
In this paper, various four variable refined plate theories are presented to analyze vibration of temperature-dependent functionally graded (FG) plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations for the present model is reduced, significantly facilitating engineering analysis. These theories account for parabolic, sinusoidal, hyperbolic, and exponential distributions of the transverse shear strains and satisfy the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Uniform, linear, nonlinear and sinusoidal thermal conditions are imposed at the upper and lower surface for simply supported FG plates. Equations of motion are derived from Hamilton's principle. Analytical solutions for the free vibration analysis are obtained based on Fourier series that satisfy the boundary conditions (Navier's method). Non-dimensional results are compared for temperature-dependent and temperature-independent FG plates and validated with known results in the literature. Numerical investigation is conducted to show the effect of material composition, plate geometry, and temperature fields on the vibration characteristics. It can be concluded that the present theories are not only accurate but also simple in predicting the free vibration responses of temperature-dependent FG plates.

Key Words
functionally graded plate; higher-order plate theory; vibration; temperature-dependent properties

Address
(1) Amina Attia, Abdelouahed Tounsi, E.A. Adda Bedia:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(2) Abdelouahed Tounsi:
Advanced Materials and Structures Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(3) S.R. Mahmoud:
Department of Mathematics, Faculty of Science, King Abdulaziz University, Saudi Arabia;
(4) S.R. Mahmoud:
Mathematics Department, Faculty of Science, University of Sohag, Egypt.

Abstract
A nonlinear finite element analysis (FEA) model is presented for simulating the behaviour of recycled aggregate concrete-filled steel tube (RACFST) beam-columns subjected to constant axial compressive load and cyclically increasing flexural loading. The FEA model was developed based on ABAQUS software package and a displacement-based approach was used. The proposed engineering stress versus engineering strain relationship of core concrete with the effect of recycled coarse aggregate (RCA) replacement ratio was adopted in the FEA model. The predicted results of the FEA model were compared with the experimental results of several RACFST as well as the corresponding concrete-filled steel tube (CFST) beam-columns under cyclic loading reported in the literature. The comparison results indicated that the proposed FEA model was capable of predicting the load versus deformation relationship, lateral bearing capacity and failure pattern of RACFST beam-columns with an acceptable accuracy. A parametric study was further carried out to investigate the effect of typical parameters on the mechanism of RACFST beam-columns subjected to cyclic loading.

Key Words
recycled aggregate concrete-filled steel tube (RACFST); finite element analysis (FEA); beam-columns; cyclic loading; bearing capacity; mechanism

Address
State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, 116024, China.

Abstract
In this research, a simple but accurate sinusoidal plate theory for the thermomechanical bending analysis of functionally graded sandwich plates is presented. The main advantage of this approach is that, in addition to incorporating the thickness stretching effect, it deals with only 5 unknowns as the first order shear deformation theory (FSDT), instead of 6 as in the well-known conventional sinusoidal plate theory (SPT). The material properties of the sandwich plate faces are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is made of an isotropic ceramic material. Comparison studies are performed to check the validity of the present results from which it can be concluded that the proposed theory is accurate and efficient in predicting the thermomechanical behavior of functionally graded sandwich plates. The effect of side-to-thickness ratio, aspect ratio, the volume fraction exponent, and the loading conditions on the thermomechanical response of functionally graded sandwich plates is also investigated and discussed.

Key Words
sandwich plate; thermomechanical; analytical modelling; functionally graded material; stretching effect

Address
(1) Ahmed Hamidi, Abdelouahed Tounsi:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(2) Mohammed Sid Ahmed Houari, Abdelouahed Tounsi:
Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Université de Sidi Bel Abbes, Faculté de Technologie, Département de Génie Civil, Algeria.
(3) S.R. Mahmoud:
Department of Mathematics, Faculty of Science, King Abdulaziz University, Saudi Arabia;
(4) S.R. Mahmoud:
Mathematics Department, Faculty of Science, University of Sohag, Egypt.

Abstract
This paper presents the natural frequency of a composite girder with corrugated steel web (CGCSW). A corrugated steel web has negligible in-plane axial stiffness, due to the unique characteristic of corrugated steel webs, which is called the accordion effect. Thus, the corrugated steel web only resists shear force. Further, the shear buckling resistance and out-of-plane stiffness of the web can be enhanced by using a corrugated steel web, since the inclined panels serve as transverse stiffeners. To take these advantages, the corrugated steel web has been used as an alternative to the conventional pre-stressed concrete girder. However, studies about the dynamic characteristics, such as the natural frequency of a CGCSW, have not been sufficiently reported, and it is expected that the natural frequency of a CGCSW is different from that of a composite girder with flat web due to the unique characteristic of the corrugated steel web. In this study, the natural frequency of a CGCSW was investigated through a series of experimental studies and finite element analysis. An experimental study was conducted to evaluate the natural frequency of CGCSW, and the results were compared with those from finite element analysis for verification purpose. A parametric study was then performed to investigate the effect of the geometric characteristics of the corrugated steel web on the natural frequency of the CGCSW. Finally, a simplified beam model to predict the natural frequency of a CGCSW was suggested.

Key Words
natural frequency; corrugated steel web; steel-concrete composite structures

Address
(1) Jiho Moon:
New Transportation Research Center, Korea Railroad Research Institute (KRRI), Uiwang-si, Gyeonggi-do, Republic of Korea;
(2) Hee-Jung Ko, Hak-Eun Lee:
School of Civil, Environmental & Architectural Engineering, Korea University, Seoul, Republic of Korea;
(3) Ik Hyun Sung:
Department of Civil Engineering, Hanseo University, Chung Nam, Republic of Korea.

Abstract
As one of the most common failure types of arch bridges, stability is one of the critical aspects for the design of arch bridges. Using 3D finite element model in ABAQUS, this paper has studied the stability performance of an arch bridge with inclined arch ribs and hangers, and the analysis also took the effects of geometrical and material nonlinearity into account. The impact of local buckling and residual stress of steel plates on global stability and the applicability of fiber model in stability analysis for steel arch bridges were also investigated. The results demonstrate an excellent stability of the arch bridge because of the transverse constraint provided by transversely-inclined hangers. The distortion of cross section, local buckling and residual stress of ribs has an insignificant effect on the stability of the structure, and the accurate ultimate strength may be obtained from a fiber model analysis. This study also shows that the yielding of the arch ribs has a significant impact on the ultimate capacity of the structure, and the bearing capacity may also be approximately estimated by the initial yield strength of the arch rib.

Key Words
stability; asymmetric steel arch bridge; inclined arches; elasto.plastic large deformation; local buckling; residual stress

Address
(1) Xinke Hu, Xu Xie, Zhanzhan Tang, Yonggang Shen:
Department of Architecture & Civil Engineering, Zhejiang University, China;
(2) Pu Wu, Lianfeng Song:
Architectural design and Research Institute of Zhejiang University, Hangzhou, Zhejiang, China.


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