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Volume 32, Number 3, August10 2019

In the present paper, the element free Galerkin (EFG) method is developed for geometrically nonlinear analysis of deep beams considering small scale effect. To interpret the behavior of structure at the nano scale, the higher-order gradient elasticity nonlocal theory is taken into account. The radial point interpolation method with high order of continuity is used to construct the shape functions. The nonlinear equation of motion is derived using the principle of the minimization of total potential energy based on total Lagrangian approach. The Newmark method with the small time steps is used to solve the time dependent equations. At each time step, the iterative Newton-Raphson technique is applied to minimize the residential forces caused by the nonlinearity of the equations. The effects of nonlocal parameter and aspect ratio on stiffness and dynamic parameters are discussed by numerical examples. This paper furnishes a ground to develop the EFG method for large deformation analysis of structures considering small scale effects.

Key Words
cnonlocal elasticity; element-free Galerkin (EFG) method; dynamic analysis; total Lagrangian approach; geometrically nonlinear analysis

(1) Mohammad Hossein Ghadiri Rad:
Civil Engineering Department, Quchan University of Technology, Quchan, Iran;
(2) Farzad Shahabian:
Civil Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran;
(3) Seyed Mahmoud Hosseini
Industrial Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.

In this study, we investigated the effect of fatigue crack propagation of the beams which have a vital importance in engineering applications, on the natural frequency of the system. Beams which have a wide range of applications, are used as fundamental structural elements in engineering structures. Therefore, early detection of any damages in these structures is of vital importance for the prevention of possible destructive damages. One of the widely used methods of early detection of damages is the vibration analysis of the structure. Hence, it is of vital importance to detect and monitor any changes in the natural frequencies of the structure. From this standpoint, in this study we experimentally investigated the effect of fatigue crack propagation on beams produced from 4140 steel, of the natural frequency of the beam. A crack was opened on the 8

Key Words
vibration analysis; cracked beam; fatigue crack propagation; natural frequency

(1) Habibullah Bilge, Murat Pakdil:
Department of Mechanical Engineering, Abant Izzet Baysal University, 14280, Bolu, Turkey;
(2) Habibullah Bilge:
Institute of Natural Sciences, Sakarya University, 54187, Sakarya, Turkey;
(3) Emre Doruk:
R&D Department, TOFAS-FIAT, 16369, Bursa, Turkey;
(4) Emre Doruk:
Department of Mechanical Engineering, Yalova University, 77200, Yalova, Turkey;
(5) Fehim F

Ratcheting boundary is firstly determined by experiment, elastic-plastic finite element analysis combined with C-TDF and linear matching method, which is compared with ASME/KTA and RCC-MR. Moreover, based on elastic modulus adjustment procedure, a novel method is proposed to predict the ratcheting boundary for a pressurized pipe subjected to constant internal pressure and cyclic bending loading. Comparison of ratcheting boundary of elbow pipe determined by the proposed method, elastic-plastic finite element analysis combined with C-TDF and linear matching method, which indicates that the predicted results of the proposed method are in well agreement with those of linear matching method.

Key Words
pressurized pipe; finite element analysis; constitutive model; ratcheting boundary; elastic modulus adjustment procedure

(1) Xiaohui Chen:
School of Control Engineering, Northeastern University, Qinhuangdao, 066004, China;
(2) Xiaohui Chen, Zifeng Li:
School of Mechanical Engineering & Automation, Yanshan University, Qinhuangdao, 066004, China;
(3) Xu Chen:
School of Mechanical Engineering & Automation, School of Tianjin University, Tianjin, 300072, China.

Concrete placement and temporary formwork of bridge deck overhangs result in unbalanced eccentric loads that cause exterior girders to rotate during construction. These construction loads affect the global and local stability of the girders and produce permanent girder rotation after construction. In addition to construction loads, the skew angle of the bridge also contributes to girder rotation. To prevent rotation (in both skewed and non-skewed bridges), a number of techniques have been suggested to temporarily brace the girders using transverse tie bars connecting the top flanges and embedded in the deck, temporary horizontal and diagonal steel pipes placed between the webs of the exterior and first interior girders, and permanent cross frames. This study includes a rigorous three-dimensional finite element analysis to evaluate the effectiveness of several bracing systems for non-skewed and several skewed bridges. In this paper, skew angles of 0°, 20°, 30°, and 45° were considered for single- and three-span bridges. The results showed that permanent cross frames worked well for all bridges, whereas temporary measures have limited application depending on the skew angle of the bridge.

Key Words
bracing systems; deck overhang deck; exterior girder rotation; skewed bridge; non-skewed bridge; construction loads; steel girders; finite element analysis

(1) Md Ashiquzzaman:
DOTec Corp., St. Charles, MO, 63301, USA;
(2) Ahmed Ibrahim:
University of Idaho, Moscow, ID, 83844, USA;
(3) Will Lindquist:
William Jewell College, Liberty, MO 64068, USA;
(4) Riyadh Hindi:
Saint Louis University, St. Louis, MO 63103, USA.

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component ‘side walls of rectangular hollow sections (RHS) in tension/compression’. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component ‘side walls of RHS in tension/compression’ to be applied in a further unified global proposal for the application of the component method to RHS.

Key Words
connections; component method; stiffness; side walls; RHS

(1) Carlos López-Colina, Miguel A. Serrano, Miguel Lozano, Fernando L. Gayarre, Jesus M. Suárez:
Department of Construction and Manufacturing Engineering, University of Oviedo, Building DO7, Pedro Puig Adam St. 33204 Gijón/Xixón, Spain.
(2) Tim Wilkinson:
School of Civil Engineering, University of Sydney, J05 Civil Engineering Building, Shepherd St, Darlington NSW 2006, Australia.

Modular construction has been increasingly used for mid-to-high rise buildings attributable to the high construction speed, improved quality and low environmental pollution. The individual and repetitive room-sized module unit is usually fully finished in the factory and installed on-site to constitute an integrated construction. However, there is a lack of design guidance on modular structures. This paper mainly focuses on the evaluation of the initial stiffness of corrugated steel plate shears walls (CSPSWs) in container-like modular construction. A finite element model was firstly developed and verified against the existing cyclic tests. The theoretical formulas predicting the initial stiffness of CSPSWs were then derived. The accuracy of the theoretical formulas was verified by the related numerical and test results. Furthermore, parametric analysis was conducted and the influence of the geometrical parameters on the initial stiffness of CSPSWs was discussed and evaluated in detail. The present study provides practical design formulas and recommendations for CSPSWs in modular construction, which are useful to broaden the application of modular construction in high-rise buildings and seismic area.

Key Words
modular steel construction; corrugated steel plate; initial stiffness; finite element analysis; theoretical deviation; design recommendation

(1) En-Feng Deng:
School of Civil Engineering, Zhengzhou University, 100 Kexue Road, Zhengzhou, China;
(2) Liang Zong, Yang Ding:
School of Civil Engineering, Tianjin University / Key Laboratory of Coast Civil Structure Safety (Tianjin University), Ministry of Education, 92Weijin Road, Tianjin, China.

Tubular joints are used in the construction of offshore structures and other land-based structures because of its ease of fabrication. These joints are subjected to different environmental loadings in their lifetime. At the time of fabrication or modification of an existing offshore platform, tubular joints are usually strengthened to withstand the environmental loads. Currently, various strengthening techniques such as ring stiffeners, gusset plates are employed to strengthen new and existing tubular joints. Due to some limitations with the present practices, some new techniques need to be addressed. Many researchers used Fibre Reinforced Polymer (FRP) to strengthen tubular joints. Some of the studies were focused on axial compression of Glass Fibre Reinforced Polymer (GFRP) strengthened tubular joints and found that it was an efficient technique. Earlier, the authors had performed studies on Carbon Fibre Reinforced Polymer (CFRP) strengthened tubular joint subjected to axial compression. The study steered to the conclusion that FRP composites is an alternative strengthening technique for tubular joints. In this work, the study was focused on axial compression of Y-joint and in plane and out of plane bending of T-joints. Experimental investigations were performed on these joints, fabricated from ASTM A106 Gr. B steel. Two sets of joints were fabricated for testing, one is a reference joint and the other is a joint strengthened with CFRP. After performing the set of experiments, test results were then compared with the numerical solution in ANSYS Parametric Design Language (APDL). It was observed that the joints strengthened with CFRP were having improved strength, lesser surface displacement and ovalization when compared to the reference joint.

Key Words
tubular joints; in-plane bending; out-of-plane bending; CFRP; Ansys; experimental and numerical investigation

(1) P.S. Prashob:
Department of Mechanical Engineering, MPSTME, NMIMS University, Mumbai - 400 056, India;
(2) A.P. Shashikala:
Department of Civil Engineering, National Institute of Technolgy Calicut - 673 601, India;
(3) T.P. Somasundaran:
Department of Civil Engineering, Hindustan Institute of Technology and Science, Chennai - 603 103, India.

This study proposes a new concept of an axial damper using the combination of shape memory alloy (SMA), friction devices, and polyurethane springs. Although there are many kinds of dampers to limit the damages, large residual deformation may happen and it causes much repairing cost for restoring the structure to the initial position. Also in some of the dampers, a special technology for assembling and fabricating is needed. One of the most important advantages of this damper is the ability to remove all the residual deformation using SMA plates and simple assembling without any special technology to fabricate. In this paper, four different dampers (in presence or omission of friction devices and polyurethane springs) are investigated. All four cases are analyzed in ABAQUS platform under cyclic loadings. In addition, the SMA plates are replaced by steel ones in four cases, and the results are compared to the SMA dampers. The results show that the axial polyurethane friction (APF) damper could decrease the residual deformation effectively. Also, the damper capacity and dissipated energy could be improved. The analysis showed that APF damper is a good recentering damper with a large amount of energy dissipation and capacity, among others.

Key Words
smart material; shape memory alloy (SMA); damper; residual deformation; finite element analysis

(1) Nadia M. Mirzai:
School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran;
(2) Nadia M. Mirzai:
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam;
(3) Jong Wan Hu:
Department of Civil and Environmental Engineering, Incheon National University, Incheon 22012, South Korea;
(4) Jong Wan Hu:
Incheon Disaster Prevention Research Center, Incheon National University, Incheon 22012, South Korea.

In this article, a simple quasi-3D shear deformation theory is employed for thermo-mechanical bending analysis of functionally graded material (FGM) sandwich plates. The displacement field is defined using only 5 variables as the first order shear deformation theory (FSDT). Unlike the other high order shear deformation theories (HSDTs), the present formulation considers a new kinematic which includes undetermined integral variables. The governing equations are determined based on the principle of virtual work and then they are solved via Navier method. Analytical solutions are proposed to provide the deflections and stresses of simply supported FGM sandwich structures. Comparative examples are presented to demonstrate the accuracy of the present theory. The effects of gradient index, geometrical parameters and thermal load on thermo-mechanical bending response of the FG sandwich plates are examined.

Key Words
sandwich plate; thermo-mechanical; quasi-3D HSDT; functionally graded material

(1) Djaloul Zarga, Abdelouahed Tounsi, Fouad Bourada:
Civil and Environmental Engineering Department, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia;
(2) Abdelouahed Tounsi:
Civil and Environmental Engineering Department, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia;
(3) Abdelmoumen Anis Bousahla:
Laboratoire de Modélisation et Simulation Multi-échelle, Faculté des Sciences Exactes, Département de Physique, Université de Sidi Bel Abbés, Algeria;
(4) Abdelmoumen Anis Bousahla:
Centre Universitaire Ahmed Zabana de Relizane, Algeria;
(5) Fouad Bourada:
Département des Sciences et de la Technologie, centre universitaire de Tissemsilt, BP 38004 Ben Hamouda, Algérie;
(6) S.R. Mahmoud:
Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.

Six shear-critical square tubed steel reinforced concrete (TSRC) columns using the high-strength concrete (fcu,150 = 86.6 MPa) were tested under constant axial and lateral cyclic loads. The height-to-depth ratio of the short column specimens was specified as 2.6, and the axial load ratio and the number of shear studs on the steel shape were considered as two main parameters. The shear failure mode of short square TSRC columns was observed from the test. The steel tube with diagonal stiffener plates provided effective confinement to the concrete core, while welding shear studs on the steel section appeared not significantly enhancing the seismic behavior of short square TRSC columns. Specimens with higher axial load ratio showed higher lateral stiffness and shear strength but worse ductility. A modified ACI design method is proposed to calculate the nominal shear strength, which agrees well with the test database containing ten short square TSRC columns with shear failure mode from this study and other related literature.

Key Words
tubed steel reinforced concrete (TSRC) column; square cross-section; shear studs; high-strength concrete (HSC); seismic test; shear failure mode

(1) Xiang Li, Xuhong Zhou, Jiepeng Liu, Xuanding Wang:
School of Civil Engineering, Chongqing University, Chongqing 400045, China;
(2) Xiang Li, Xuhong Zhou, Jiepeng Liu, Xuanding Wang:
Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing 400045, China.

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