Papers by Author: Qing Shan Yang

Abstract: The enclosed air plays a significant role in form-finding and loading analysis of ETFE cushions. A new numerical model of ETFE cushions is proposed in order to consider the interaction effects between outer membrane and internal air. Then the form-finding and loading analysis of a regular hexagon ETFE cushion are performed and compared with experimental study. It is shown that the numerical results are in good agreement with the test results. The interaction FE model can be used in static analysis of ETFE cushions.

Abstract: For estimating seismic response of pier-structure under near-fault ground motion, The typical pulse-type near-fault ground motion records were chosen to establish a record base, and three pier models with different natural period were established; The non-elastic response spectral displacement of ground motion was used to estimate the nonlinear response; The yield displacement of the nonlinear oscillator was defined based on the static pushover analysis result, and its influence on response estimation was studied. The study result is important for structural seismic response estimation by using the non-elastic response spectral displacement and the probability-based seismic performance evaluation.

Abstract: With wind tunnel tests, simultaneous pressure measurements are made on 4 cylindrical roof models with different rise-span ratios and roof inclinations. Effects of these geometrical factors on wind pressure characteristics of the roofs are investigated, including mean pressure coefficients, RMS pressure coefficients, skewness, kurtosis, and probability distributions of wind pressure. Results show that the mean vertical wind force coefficient of high rise-span ratio roof is larger than that of the low rise-span ration roof; the mean pressure coefficient distribution of the low rise-span ratio roof is similar to that of RMS pressure coefficients and the skewness (or the kurtosis); the vortex center line occurs at the windward edge for the low rise-span ratio roof with inclination 0°, which occurs at the roof apex for the high rise-span ratio roof. The roof inclination has more effects on the low rise-span ratio roof, the vortex moves from the windward edge to the apex for the roof with inclination 7.2°when the wind flows from the low eave to the high eave. The distribution of the skewness is strongly correlative to that of the kurtosis. The probability distributions of the roof edges and corners deviate obviously from the Guass distribution. If this point is ignored, the peak suction pressure will be underestimated.

Abstract: The mechanical behaviors of intersecting joints considering damage accumulation in steel tube structures is analyzed through the FE-program ABAQUS. The stress characteristic and failure modes of these joints are concluded. Especially, it has been analyzed influence of the change of geometric parameters to mechanical behavior of joints. Finally, the results indicate the joints have a good mechanical performance and good plastic deformation as to excessive local buckling of chord under the loads.

Abstract: On the basis of the three-dimensional,compressible,unsteady-state,viscous N-S Equation and k-ε turbulence model,the simulation calculation is made with the finite volume method on the aerodynamic effect of two high-speed trains passing each other at the same speed through a tunnel,simulating the pressure change,analysising regularity of the pressure,researching comfort in the train.The following conclusions have been drawn from research:The maximum of transient pressure is concerned with the meeting point,when the two high-speed trains meet in tunnel.When the length,the speed and the sealing factor of the train are same,the transient pressure is maximum with the trains meeting at the midpoint of tunnel.When the tunnel length,the speed of the train,the sealing factor and the point of meeting are same,the transient pressure of the longer train is maximum.When the sealing factor is greater than 15s,the standard of permissible pressure (1250Pa\3s) can be satisfied with all circumstances.

Abstract: Pre-stressed spatial tubular truss system is adopted in steel roof truss structures of China International Exhibition Center New Venue. Bottom chord joints are multiplanar KK-joints consisting of chord with square hollow section and brace with circular hollow section. However, not only that relatively little research has been carried out on such joints, but also that no detailed design guidance on KK-type joints consisting of chord with square hollow section and brace with circular hollow section can be found Current design code for steel structure (GB 50017-2003). This paper reports the study into the strength of this type of KK-joints under axial loading. The numerical models were adopted, and several various geometric parameters which affect the strength and failure modes, were investigated. It was indicated that the geometric parameters affects significantly the ultimate capacity and failure modes of the joints. The varied relationship of the strength and failure mode with parameter varying was studied in detail. The results of the work presented provide initial discussion on behavior of this type of KK-joints and lay the foundation for a future large-scale parametric study and put out design formula.

Abstract: A large eddy simulation algorithm for numerically calculating unsteady wind field around complex geometry building was given. In this algorithm, a curvilinear coordinate system was used to formulate the numerical model, so the complex wind-structure interface could be described precisely. Governing equations were discretized by central differencing schemes with co-located grids. The convection velocity was interpolated by using Rhie-Chow method in order to avoid the inherent odd-even decoupling problem. A common Maker and Cell (MAC) scheme was used to split the velocity-pressure linkage in Navier-Stockes (NS) equation. An explicit Adams-Bashforth differencing scheme was applied for time marching. A corresponding computer code was developed and was validated by performing on simulation of wind field around full-scale Texas Tech University (TTU) building model. Furthermore, the simulation results were compared with corresponding field measure data and wind-tunnel experiment results reported by other authors. The comparison showed that this algorithm is feasible for numerical simulation of unsteady wind field around buildings.

Abstract: Railway wind-break wall is widely used, which is of significant importance to prevent running vehicles from suffering the risk of overturning. In the paper, application of railway wind-break wall and specific details of its structure are introduced. Wind tunnel test and CFD simulation are widely used in the researches on the performance of railway wind-break wall and some important results are summarized. Based on the review, developments of railway wind-break wall in the future are provided.

Abstract: Owing to some problems in the existent plywood products such as weak shear capacity and weak wear intensity, as while as the large consumption of crude wood resources, prestressed laminated strand lumber (PLSL) is proposed in this paper, in which the multiple integration method and prestressed technology are adopted to obtain a higher strength. More significantly, used wood can be reused as the raw material of PLSL, then the crude wood will be conserved and the cost will be lowered. To study its mechanical properties, the commercial software ANSYS is adopted to establish the finite element models of PLSL. The diameter and spacing of prestressed steel wire, the magnitude of the prestress and the width of the lumber are some factors considered. Based on the nonlinear finite element buckling analysis of these lumbers, some major conclusions are summarized as follows: (1) The improvement of strength is comparatively obvious to use PLSL compared with the traditional plywood products; (2) The ultimate bearing load is rising along with the increase of the diameter of the prestressed steel wire and the width of the lumber; (3) The ultimate bearing load is descending with the increase of the spacing of the prestressed steel wire; (4) The ultimate bearing load is rising along with the increase of the magnitude of the prestress at first, but when the prestress reaches a certain level, the ultimate bearing load starts to descend.

Abstract: The pounding between adjacent segments of bridge has significant influences on its seismic performance, which is a complex nonlinear phenomenon involving many parameters. Based on Kelvin impact model, a simple-supported girder bridge was introduced to discuss the effects of impact stiffness and initial gap between joints. With dynamic analysis, it can be drawn the reasonable range for impact stiffness ratio and initial gap at expansion joint are respectively 0.05~0.2 and 0.04m~0.05m, which make the earthquake response of bridge reach a good balance.