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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Structural Engineering and Mechanics
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Volume & Issues
Volume 56, Issue 6 - Dec 2015
Volume 56, Issue 5 - Dec 2015
Volume 56, Issue 4 - Nov 2015
Volume 56, Issue 3 - Nov 2015
Volume 56, Issue 2 - Oct 2015
Volume 56, Issue 1 - Oct 2015
Volume 55, Issue 6 - Sep 2015
Volume 55, Issue 5 - Sep 2015
Volume 55, Issue 4 - Aug 2015
Volume 55, Issue 3 - Aug 2015
Volume 55, Issue 2 - Jul 2015
Volume 55, Issue 1 - Jul 2015
Volume 54, Issue 6 - Jun 2015
Volume 54, Issue 5 - Jun 2015
Volume 54, Issue 4 - May 2015
Volume 54, Issue 3 - May 2015
Volume 54, Issue 2 - Apr 2015
Volume 54, Issue 1 - Apr 2015
Volume 53, Issue 6 - Mar 2015
Volume 53, Issue 5 - Mar 2015
Volume 53, Issue 4 - Feb 2015
Volume 53, Issue 3 - Feb 2015
Volume 53, Issue 2 - Jan 2015
Volume 53, Issue 1 - Jan 2015
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Effect of pile group geometry on bearing capacity of piled raft foundations
Fattah, Mohammed Y. ; Yousif, Mustafa A. ; Al-Tameemi, Sarmad M.K. ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 829~853
DOI : 10.12989/sem.2015.54.5.829
This is an experimental study to investigate the behaviour of piled raft system in different types of sandy soil. A small scale "prototype" model was tested in a sand box with load applied to the foundation through a compression jack and measured by means of load cell. The settlement was measured at the raft by means of dial gauges, three strain gauges were attached on piles to measure the strains and calculate the load carried by each pile in the group. Nine configurations of group (
) were tested in the laboratory as a free standing pile group (the raft not in contact with the soil) and as a piled raft (the raft in contact with the soil), in addition to tests for raft (unpiled) with different sizes. It is found that when the number of piles within the group is small (less than 4), there is no evident contribution of the raft to the load carrying capacity. The failure load for a piled raft consisting of 9 piles is approximately 100% greater than free standing pile group containing the same number of piles. This difference increases to about 4 times for 16 pile group. The piles work as settlement reducers effectively when the number of piles is greater than 6 than when the number of piles is less than 6. The settlement can be increased by about 8 times in (
) free standing pile group compared to the piled raft of the same size. The effect of piled raft in reducing the settlement vanishes when the number of piles exceeds 6.
Nonlinear large deflection buckling analysis of compression rod with different moduli
Yao, Wenjuan ; Ma, Jianwei ; Gao, Jinling ; Qiu, Yuanzhong ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 855~875
DOI : 10.12989/sem.2015.54.5.855
Many novel materials exhibit a property of different elastic moduli in tension and compression. One such material is graphene, a wonder material, which has the highest strength yet measured. Investigations on buckling problems for structures with different moduli are scarce. To address this new problem, firstly, the nondimensional expression of the relation between offset of neutral axis and deflection curve is derived based on the phased integration method, and then using the energy method, load-deflection relation of the rod is determined; Secondly, based on the improved constitutive model for different moduli, large deformation finite element formulations are developed and combined with the arc-length method, finite element iterative program for rods with different moduli is established to obtain buckling critical loads; Thirdly, material mechanical properties tests of graphite, which is the raw material of graphene, are performed to measure the tensile and compressive elastic moduli, moreover, buckling tests are also conducted to investigate the buckling behavior of this kind of graphite rod. By comparing the calculation results of the energy method and finite element method with those of laboratory tests, the analytical model and finite element numerical model are demonstrated to be accurate and reliable. The results show that it may lead to unsafe results if the classic theory was still adopted to determine the buckling loads of those rods composed of a material having different moduli. The proposed models could provide a novel approach for further investigation of non-linear mechanical behavior for other structures with different moduli.
Buckling analysis of functionally graded material grid systems
Darilmaz, K. ; Aksoylu, M. Gunhan ; Durgun, Yavuz ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 877~890
DOI : 10.12989/sem.2015.54.5.877
This paper aims to fill the technical gap on the elastic buckling behavior of functionally graded material (FGM) grid systems under inplane loads on which few research has been done. Material properties of an FG beam are assumed to vary smoothly in the thickness direction according to power and exponential laws. Based on a hybrid-stress finite element formulation, buckling solutions for FGM grid systems consisting of various aspect ratios and material gradation are provided. The numerical results demonstrate that the aspect ratio and material gradation play an important role in the buckling behavior of FGM grid systems. We believe that the new results obtained from this study, will be very useful to designers and researchers in this field.
Wind-induced vibration characteristics and parametric analysis of large hyperbolic cooling towers with different feature sizes
Ke, Shitang ; Ge, Yaojun ; Zhao, Lin ; Tamura, Yukio ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 891~908
DOI : 10.12989/sem.2015.54.5.891
For a systematic study on wind-induced vibration characteristics of large hyperbolic cooling towers with different feature sizes, the pressure measurement tests are finished on the rigid body models of three representative cooling towers with the height of 155 m, 177 m and 215 m respectively. Combining the refined frequency-domain algorithm of wind-induced responses, the wind-induced average response, resonant response, background response, coupling response and wind vibration coefficients of large cooling towers with different feature sizes are obtained. Based on the calculating results, the parametric analysis on wind-induced vibration of cooling towers is carried out, e.g. the feature sizes, damping ratio and the interference effect of surrounding buildings. The discussion shows that the increase of feature sizes makes wind-induced average response and fluctuating response larger correspondingly, and the proportion of resonant response also gradually increased, but it has little effect on the wind vibration coefficient. The increase of damping ratio makes resonant response and the wind vibration coefficient decreases obviously, which brings about no effect on average response and background response. The interference effect of surrounding buildings makes the fluctuating response and wind vibration coefficient increased significantly, furthermore, the increase ranges of resonant response is greater than background response.
Numerical and experimental study on dynamic response of moored spar-type scale platform for floating offshore wind turbine
Choi, E.Y. ; Cho, J.R. ; Cho, Y.U. ; Jeong, W.B. ; Lee, S.B. ; Hong, S.P. ; Chun, H.H. ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 909~922
DOI : 10.12989/sem.2015.54.5.909
The dynamic response and the mooring line tension of a 1/75 scale model of spar-type platform for 2.5 MW floating offshore wind turbine subject to one-dimensional regular harmonic wave are investigated numerically and verified by experiment. The upper part of wind turbine which is composed of three rotor blades, hub and nacelle is modeled as a lumped mass the scale model and three mooring lines are pre-tensioned by means of linear springs. The coupled fluid-rigid body interaction is numerically simulated by a coupled FEM-cable dynamics code, while the experiment is performed in a wave tank with the specially-designed vision and data acquisition system. The time responses of surge, heave and pitch motions of the scale platform and the mooring line tensions are obtained numerically and the frequency domain-converted RAOs are compared with the experiment.
A n-order refined theory for bending and free vibration of functionally graded beams
Hadji, Lazreg ; Daouadji, T. Hassaine ; Tounsi, A. ; Bedia, E.A. ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 923~936
DOI : 10.12989/sem.2015.54.5.923
In this paper, a simple n-order refined theory based on neutral surface position is developed for bending and frees vibration analyses of functionally graded beams. The present theory is variationally consistent, uses the n-order polynomial term to represent the displacement field, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The governing equations are derived by employing the Hamilton's principle and the physical neutral surface concept. The accuracy of the present solutions is verified by comparing the obtained results with available published ones.
Walking load model for single footfall trace in three dimensions based on gait experiment
Peng, Yixin ; Chen, Jun ; Ding, Guo ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 937~953
DOI : 10.12989/sem.2015.54.5.937
This paper investigates the load model for single footfall trace of human walking. A large amount of single person walking load tests were conducted using the three-dimensional gait analysis system. Based on the experimental data, Fourier series functions were adopted to model single footfall trace in three directions, i.e. along walking direction, direction perpendicular to the walking path and vertical direction. Function parameters such as trace duration time, number of Fourier series orders, dynamic load factors (DLFs) and phase angles were determined from the experimental records. Stochastic models were then suggested by treating walking rates, duration time and DLFs as independent random variables, whose probability density functions were obtained from experimental data. Simulation procedures using the stochastic models are presented with examples. The simulated single footfall traces are similar to the experimental records.
Influence of polled direction on the stress distribution in piezoelectric materials
Ilhan, Nihat ; Koc, Nagihan ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 955~971
DOI : 10.12989/sem.2015.54.5.955
In this paper, the influence of the polled direction of piezoelectric materials on the stress distribution is studied under time-harmonic dynamical load (time-harmonic Lamb's problem). The system considered in this study consists of piezoelectric covering layer and piezoelectric half-plane, and the harmonic dynamical load acts on the free face of the covering layer. The investigations are carried out by utilizing the exact equations of motion and relations of the linear theory of electro-elasticity. The plane-strain state is considered. It is assumed that the perfect contact conditions between the covering layer and half-plane are satisfied. The boundary value problems under consideration are solved by employing Fourier exponential transformation techniques with respect to coordinates directed along the interface line. Numerical results on the influence of the polled direction of the piezoelectric materials such as PZT-5A, PZT-5H, PZT-4 and PZT-7A on the normal stresses, shear stresses and electric potential acting on the interface plane are presented and discussed. As a result of the analyses, it is established that the polled directions of the piezoelectric materials play an important role on the values of the studied stresses and electric potential.
Biaxial creep property of ethylene tetrafluoroethylene (ETFE) foil
Li, Yintang ; Wu, Minger ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 973~986
DOI : 10.12989/sem.2015.54.5.973
Ethylene tetrafluoroethylene (ETFE) foil is a novel structural material which has being used in shell and spatial structures. This paper studies biaxial creep property of ETFE foil by creep tests and numerical simulation. Biaxial creep tests of cruciform specimens were performed using three stress ratios, 1:1, 2:1 and 1:2, which showed that creep coefficients in biaxial tension were much smaller than those in uniaxial one. Then, a reduction factor was introduced to take account of this biaxial effect, and relation between the reduction factor and stress ratio was established. Circular bubble creep test and triangle cushion creep test of ETFE foil were performed to verify the relation. Interpolation was adopted to consider creep stress and reduction factor was involved to take account of biaxial effect in numerical simulation. Simulation results of the bubble creep test embraced a good agreement with those measuring ones. In triangle cushion creep test, creep displacements from numerical simulation showed a good agreement with those from creep test at the center and lower foil measuring points.
An analytical study on the nonlinear vibration of a double-walled carbon nanotube
Hajnayeb, Ali ; Khadem, S.E. ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 987~998
DOI : 10.12989/sem.2015.54.5.987
In this paper, free vibrations of a clamped-clamped double-walled carbon nanotube (DWNT) under axial force is studied. By utilizing Euler-Bernoulli beam theory, each layer of DWNT is modeled as a beam. In this analysis, nonlinear form of interlayer van der Waals (vdW) forces and nonlinearities aroused from mid-plane stretching are also considered in the equations of motion. Further, direct application of multiple scales perturbation method is utilized to solve the obtained equations and to analyze free vibrations of the DWNT. Therefore, analytical expressions are found for vibrations of each layer. Linear and nonlinear natural frequencies of the system and vibration amplitude ratios of inner to outer layers are also obtained. Finally, the results are compared with the results obtained by Galerkin method.
A new block assembly method for shipbuilding at sea
Zhang, Bilin ; Boo, Seung-Hwan ; Kim, Jin-Gyun ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 999~1016
DOI : 10.12989/sem.2015.54.5.999
In this paper, we introduce a new method for assembly of shipbuilding blocks at sea and present its feasibility focusing on structural safety. The core concept of this method is to assemble ship building blocks by use of bolting, gluing and welding techniques at sea without dock facilities. Due to its independence of dock facilities, shipyard construction capability could be increased considerably by the proposed method. To show the structural safety of this method, a bulk carrier and an oil tanker were employed, and we investigated the structural behavior of those ships to which the new block assembly method was applied. The ship hull models attached with connective parts are analyzed in detail through finite element analyses, and the cargo capacity of the bulk carrier is briefly discussed as well. The results of these studies show the potential for applying this new block assembly method to practical shipbuilding.
Random vibration analysis of train-slab track-bridge coupling system under earthquakes
Zeng, Zhi-Ping ; He, Xian-Feng ; Zhao, Yan-Gang ; Yu, Zhi-Wu ; Chen, Ling-Kun ; Xu, Wen-Tao ; Lou, Ping ;
Structural Engineering and Mechanics, volume 54, issue 5, 2015, Pages 1017~1044
DOI : 10.12989/sem.2015.54.5.1017
This study aimed to investigate the random vibration characteristic of train-slab track-bridge interaction system subjected to both track irregularities and earthquakes by use of pseudo-excitation method (PEM). Each vehicle subsystem was modeled by multibody dynamics. A three-dimensional rail-slab- girder-pier finite element model was created to simulate slab track and bridge subsystem. The equations of motion for the entire system were established based on the constraint condition of no jump between wheel and rail. The random load vectors of equations of motion were formulated by transforming track irregularities and seismic accelerations into a series of deterministic pseudo-excitations according to their respective power spectral density (PSD) functions by means of PEM. The time-dependent PSDs of random vibration responses of the system were obtained by step-by-step integration method, and the corresponding extreme values were estimated based on the first-passage failure criterion. As a case study, an ICE3 high-speed train passing a fifteen-span simply supported girder bridge simultaneously excited by track irregularities and earthquakes is presented. The evaluated extreme values and the PSD characteristic of the random vibration responses of bridge and train are analyzed, and the influences of train speed and track irregularities (without earthquakes) on the random vibration characteristic of bridge and train are discussed.