Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment

Beijing, China

Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment

Beijing, China
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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


Zhang J.,Beijing Jiaotong University | Zhang J.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Yang Q.,Beijing Jiaotong University | Yang Q.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment
Journal of the Balkan Tribological Association | Year: 2016

Inflow rate and environment air temperature are the keys to answer several important questions related to natural draft dry cooling tower (NDDCT) working, safety and optimization. A featured NDDCT building has been numerically embedded in a Computational Fluid Dynamics (CFD) model in order to test inflow rates and environment air temperatures under various conditions. And some special cases are simulated to determine the working limits of NDDCT during winter days. A parametric study has been carried out to examine the effect of crosswind velocity profile and air dry-bulb temperature on the thermal performance of an NDDCT. Based on quantifying the effect of the environment effects on the thermal performance, CFD results showed that both inflow rates and environment air temperatures have great influences on the emissions discharge paths, inner temperatures and velocity profiles in NDDCT. The effect of crosswind velocity on the thermal performance of an NDDCT has been investigated numerically. From the numerical simulations it has been confirmed that crosswind velocity has great effects on the thermal performance of the NDDCT. Moreover, the effect of air dry-bulb temperature has been confirmed in this study. The thermal performance is affected in the same manner under different crosswind velocities at different environment air temperatures. © 2016, Scibulcom Ltd. All rights reserved.


Bai F.,Beijing Jiaotong University | Bai F.,Beijings Key Laboratory of Structural Wind Engineering and Urban Wind Environment | Yang N.,Beijing Jiaotong University | Wang X.-F.,Beijing Jiaotong University
Gongcheng Lixue/Engineering Mechanics | Year: 2017

The stability problem is a key concern for the performance of C-section purlins under wind loading. Aiming at this problem, a semi-analytical model is proposed for predicting the longitudinal stresses of simply supported C-section purlins considering both lateral and rotational restraints by sheeting. Formulae used to calculate the longitudinal stresses of the roof purlins are derived by using the classical bending theory of the thin-walled beams. To validate the accuracy of the present model, a comparison is made between the analytical results data obtained from software Maple and the test data from related literatures. It is shown that the results calculated from the proposed model agree well with the data from these two methods. Thereafter, the parameter analyses on the stress and displacement are conducted, and the effects of lateral and rotational stiffness on the limit states are investigated. The results also shows that the bracing restraint can change the buckling mode of purlins. The model proposed can be used to calculate the longitudinal stresses distribution and displacement of simply supported purlins under uplift loadings. © 2017, Engineering Mechanics Press. All right reserved.


Zhang A.L.,Beijing University of Technology | Li S.H.,Beijing University of Technology | Jiang Z.Q.,Beijing University of Technology | Fang H.,Beijing University of Technology | And 2 more authors.
Engineering Structures | Year: 2017

Prefabricated steel structure systems have become a new trend in the development of steel structures. In particular, earthquake-resilient steel structures have become a hot issue in the field of structural seismic research. Based on the idea of damage control and a new kind of energy-saving, material-saving and environmentally friendly sinusoidal corrugated web, this paper put forward a new type of earthquake-resilient prefabricated sinusoidal corrugated web beam-column joint (PSCWJ). Then, its constitution, its mechanics mechanism and its seismic design requirements are introduced. After considering the influence of the bolt binding coefficient, the overall bending of the binding section and the overall instability of the flange cover plate, the design theory of the earthquake-resilient PSCWJ is established. Through 55 examples of PSCWJs, the rationality of the design theory proposed in this study is verified, and a reasonable value range of the middle bolt interval on the flange cover plate is determined. During the process of theoretical derivation, the influences of many design parameters are considered, such as the section parameters of the sinusoidal corrugated web beam and cantilever beam, the thickness of the flange cover plate, the material properties of the flange cover plate, the diameter of bolts, the middle bolt interval and the weaken rate of the cover plate. Research shows that the design theory proposed in this paper can predict the yield load of PSCWJ accurately and effectively control the ultimate bearing capacity of PSCWJ. The PSCWJ designed through this theory has good bearing behaviour and ductility, which can make sure the main members, such as the beam and the column, remain in an elastic range and meet the requirements of earthquake resilience. © 2017


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.


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.


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.

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