Time filter

Source Type

Cui H.,Beijing Jiaotong University | Cui H.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Xu F.,Beijing Jiaotong University | Xu F.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Saha S.C.,University of Queensland
International Journal of Thermal Sciences | Year: 2017

Natural convection in a prismatic enclosure of triangular section with the top cooling and the bottom heating is investigated using three dimensional (3D) numerical simulations for a wide range of Rayleigh numbers from 100 to 1.25 × 106. The numerical result has been compared with the experiment. The development of natural convection flows in the cavity following sudden heating and cooling involves three stages: an initial stage, a transitional stage and a fully developed stage. Transition to unsteady natural convection flow in the fully developed stage, dependent on the Rayleigh number, is described. The flow structure including transversal and longitudinal rolls is characterized and the corresponding mechanism is discussed. The critical Rayleigh number for the transition to unsteady natural convection flow is obtained. The dependence of heat transfer on the Rayleigh number is quantified. © 2016 Elsevier Masson SAS


Jiang Z.Q.,Beijing University of Technology | Dou C.,Beijing Jiaotong University | Dou C.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Guo Y.L.,Tsinghua University | Zhang A.L.,Beijing University of Technology
Journal of Constructional Steel Research | Year: 2017

Seven pinned double-rectangular tube assembled buckling-restrained brace (DRT-ABRB) specimens are investigated by axial cyclic loading tests in this study. The core member of the specimen is a single flat-plate, with two rectangular tubes assembled to form the external restraining member by high-strength bolts. Each rectangular tube is composed of external channel steel and an external cover plate. The influence of end detailing of DRT-ABRBs on the energy dissipation is explored in the tests, which demonstrates that, compared with the end strengthening measure using an external hoop, the counterpart with a bench ribbed stiffener provides better energy dissipation capacity. In addition, the gap between the bench ribbed stiffener and the external channel steel should be controlled in design. All DRT-ABRBs studied exhibits excellent energy dissipation capacity, which proves the effectiveness of the DRT-ABRB end detailing proposed. © 2017 Elsevier Ltd


Dou C.,Beijing Jiaotong University | Dou C.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Jiang Z.-Q.,Beijing University of Technology | Pi Y.-L.,University of New South Wales | Guo Y.-L.,Tsinghua University
Engineering Structures | Year: 2016

This paper deals with elastic shear buckling behavior of infill panels in sinusoidally corrugated steel plate shear walls, and fitting equations predicting the shear buckling loads are presented. Firstly by using finite element analyses (FEA), the previous formulae for bending rigidities of sinusoidally corrugated plates are revised, then pure shearing model are established to study the effects of key parameters on elastic shear buckling of sinusoidally corrugated infill panels, such as the aspect ratio, corrugation ratio, corrugation depth to plate thickness ratio and corrugation repeating number. Based on extensive FEA numerical results, fitting equations with good accuracy are proposed to estimate elastic shear buckling loads of sinusoidally corrugated panels, which are improved much compared with the solutions in previous studies. It is found that, the formulae for bending rigidities of corrugated plates revised in this paper are accurate compared with the previous ones. For sinusoidal corrugated infill panels, only global buckling and local buckling can be observed in the lowest buckling mode of eigenbuckling analysis, while interaction buckling is not obvious. The parameter of corrugation repeating number has a significant influence on elastic shear buckling loads, whereas it was neglected in previous studies. © 2016 Elsevier Ltd.


Dou C.,Beijing Jiaotong University | Dou C.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Pi Y.-L.,University of New South Wales
Journal of Structural Engineering (United States) | Year: 2016

This paper presents the flexural-torsional buckling resistance and design of steel circular arches subjected to uniform compression with elastic end bending restraints by using finite element (FE) numerical analyses. Firstly, effects of geometric and mechanical parameters such as initial imperfections, section types, material properties, slenderness, rise-to-span ratios, and end restraints on flexural-torsional buckling resistances of arches are investigated and are found to be eliminated to a large extent by introducing the normalized slenderness. Then, on the basis of extensive numerical results, a design method is proposed to predict the flexural-torsional buckling resistances of circular arches in uniform compression with elastic end restraints by the column curves according to the normalized slenderness and a specific section type, namely curve 'a' for hollow sections, curve 'b' for welded box sections, and curve 'c' for welded I-sections. Next, the flexural stiffness of an arch is studied, taking the destabilizing effect of the axial force into account to calculate the end restraining provided by adjacent arch segments to the adverse segment in a laterally-braced arch in uniform compression to obtain the flexural-torsional buckling resistance using the normalized slenderness and the column curve analytically. The result shows a good agreement with that gained from finite element numerical analyses, and proves it very conservative when the adverse segment is assumed to be hinged without any end restraining. © 2015 American Society of Civil Engineers.


Dou C.,Beijing Jiaotong University | Dou C.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Pi Y.-L.,University of New South Wales
Journal of Structural Engineering (United States) | Year: 2016

This paper deals with the effects of geometric imperfections on flexural inelastic buckling resistance of axially loaded columns with equally spaced lateral braces and presents a simplified way of forming the critical geometric imperfection for finite-element analyses, which leads to rational results for buckling resistances. First, laterally braced columns with geometric imperfections formed by the traditional single half sine wave or the eigenbuckling modes were analyzed by FEM to illustrate the effect of different imperfection shapes. Second, geometric imperfections of columns acquired from measurements in laboratory tests were adopted, and the statistical characteristic and probability distribution of initial deflections along the column length were obtained; then, extensive numerical results from finite-element analyses were obtained through random imperfection simulations. Last, the comparison was made between statistical results based on the random imperfections and those based on eigenbuckling modes to propose a critical geometric imperfection shape as a linear superposition of a limited number of scaled eigenbuckling modes, making it possible to obtain a rational buckling resistance result by one-time analysis, which is safe but not too conservative. The commonly used lowest eigenbuckling mode or equivalent sine shape for initial geometric imperfections do not provide a rational prediction for the inelastic buckling resistance of laterally braced columns. The critical geometric imperfection shape presented in this paper can be used in advanced analysis for inelastic buckling resistance of braced columns. © 2016 American Society of Civil Engineers.


Li B.,Beijing Jiaotong University | Li B.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Zhang J.,Beijing Jiaotong University | Yang Q.-S.,Beijing Jiaotong University | Yang Q.-S.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2016

Wind tunnel velocity tests have been carried out to investigate the windbreak performance of wind barriers on bridges considering different barrier porosities and widths, the wind barrier wind tunnel simulation method and evaluation parameter of windbreak performances are discussed in the paper. Test results show that the shielding region of wind barriers is about 2.0 H (H is the height of wind barrier) and that wind speed decreases significantly when the height is below 1.0 H. The turbulence intensity of the downstream flow on the wind barrier reaches the maximum at a height of 1.0 H. Windbreak performance depends on porosity of wind barrier, wind speed will rise and turbulence intensity decreases with increasing porosity. Barrier width seems to have no relationship with windbreak performance; when porosity is the same, the effect of barrier width can be ignored. The wind speed reduction coefficient can be used to evaluate windbreak performance, which is defined by pressure equivalence. © 2016, Editorial Office of Journal of Vibration and Shock. All right reserved.


Liu P.,Beijing Jiaotong University | Liu P.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

An approach based on Bayesian theorem and structural vibration test data was presented for reliability updating. The approach takes account of uncertainties of the excitation, structural model and its parameters. Structural model parameters were identified based on the vibration test data and Bayesian parameter identification. According to Laplace asymptotic approximation, the dynamic reliability estimated purely in the light of design conditions was updated. The reliabilities of a truss structure subjected to dynamic random loading were calculated for three cases. Only the uncertainty of the loading was considered for the first case. The uncertainties of the loading and the prior probability distribution of model parameters were considered for the second case. The uncertainties of the loading and the updated probability distribution of model parameters were considered for the third case. Natural frequencies and mode shapes of the actual structure and the updated model were compared. Discussions about the updated reliabilities were made. The results show that the updated failure probability of the tested DOF agrees better with the actual value compared with that by deterministic nominal models. The updated failure probability of untested DOFs may deviate from the actual values. Increasing tested DOFs may have no effect on the updated failure probability. ©, 2015, Chinese Vibration Engineering Society. All right reserved.


Chang P.,Beijing Jiaotong University | Chang P.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Yang N.,Beijing Jiaotong University | Yang N.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Shi H.,Beijing Jiaotong University
Journal of Computational and Theoretical Nanoscience | Year: 2016

To identify the damage location in structures, energy curvature changing rate method (ECCR) was given in this paper. And a reduced-scale five-story composite wall structure, which consists of spacial frame shear walls and composite walls, was taken as the research object in the shaking table test to verify the validity of the method. To get the accelerate data of the damaged and undamaged composite wall structure, 6 accelerometers were fixed at each floor. Signal components on different scales were got using wavelet decomposition, and then the energy of the signal components of each floor could be calculated. At the same time, finite element model was developed and the numerical simulation data showed that this method could detect the position of the damages correctly as well. The comparison of simulation results with measured ones showed that damage location could be accurately detected in terms of spikes extracted directly from the accelerate data using energy curvature changing rate method. Copyright © 2016 American Scientific Publishers. All rights reserved.


Liu P.,Beijing Jiaotong University | Liu P.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Lian P.-Y.,Beijing Jiaotong University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2016

Ambient vibration tests of a frame structure consisting of the main building and podium without seismic joint were conducted and the dynamic characteristics of the structure were analyzed. The sensors employed in the tests were mounted on the right and left stairwells, the fourth floor of the main building and the large span floor of the podium with grillage beams. With the measured acceleration data and by using an improved frequency domain decomposition method, the modal parameters of five modes were identified. Consistent identification results were obtained by different test schemes. The fluctuation of identified natural frequencies is smaller than that of damping ratios. The first four modes are induced by the vibration of the main building. The fifth mode is the first vertical bending mode of the podium. The torsional behavior appears in the first three modes due to the asymmetry of the structure. The spurious modes during identification may be due to the dynamic interactions between the main building and podium. A finite element model of the tested structure was constructed and five modes were obtained, which agree well with the identification results. The influence of different connection forms between the main building and podium on the natural frequencies and mode shapes of the structure were analyzed. Results show that fixed or pinned connections between the main building and podium have almost no influence, while presence of seismic joint has large influence on the natural frequencies of the structure. The order of the mode shapes does not change for all the cases. © 2016, Chinese Vibration Engineering Society. All right reserved.


Li B.,Beijing Jiaotong University | Li B.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Yang Q.-S.,Beijing Jiaotong University | Yang Q.-S.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Feng S.-H.,Beijing Jiaotong University
Gongcheng Lixue/Engineering Mechanics | Year: 2015

The windbreak performance of the wind fence on a high speed train is investigated by CFD numerical simulation method. Firstly, a wind fence is equivalent to porous media and the additional source method is explored to simulate its windbreak performance. By comparing of the results drawn from simulation and wind tunnel tests, the provided method is validated. Based on the given method, the windbreak performance of a wind fence with different porosity is investigated, the results show that optimal porosity is 40%. The aerodynamic forces of a train are simulated by the moving grid method, which agree with the results drawn from the site measurement. Finally, the safety of a high speed train is evaluated in the action of across wind. The results show that a wind fence can improve the efficiency of a train. © 2015, Engineering Mechanics Press. All right reserved.

Loading Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment collaborators
Loading Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment collaborators