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Ren W.-X.,Central South University | Ren W.-X.,National Engineering Laboratory for High Speed Railway Construction | Fang S.-E.,Fuzhou University | Deng M.-Y.,Zhengzhou Institute of Aeronautical Industry Management
Journal of Engineering Mechanics | Year: 2011

With the aid of the response surface methodology, which is a combination of mathematical and statistical techniques, this paper presents a method for updating a finite-element model based on the measured static responses of structures. Unlike in the traditional model updating procedure, original finite-element models are replaced with response surface models constructed using the uniform design. By this means the complexity of a structure can be easily expressed by explicit functions with low dimensions. A parameter scope shrinking technique is also proposed to construct response surface models. The proposed method is verified against a numerical beam and an experimental full-scale continuous box-girder bridge. It is demonstrated that the proposed response surface-based finite-element-model updating in structural statics has the advantages of easy implementation, high cost-efficiency, and adequate updating accuracy. Once the response surface model that is formulated explicitly is constructed, no finite-element calculation is required in each optimization iteration during updating. Therefore, such finite-element model updating can be easily implemented in practice with available commercial finite-element analysis packages. © 2011 American Society of Civil Engineers.

Ren W.-X.,Central South University | Chen H.-B.,National Engineering Laboratory for High Speed Railway Construction
Engineering Structures | Year: 2010

Fast-running response surface models that approximate multivariate input/output relationships of time-consuming physical-based computer models enable effective finite element (FE) model updating analyses. In this paper, a response surface-based FE model updating procedure for civil engineering structures in structural dynamics is presented. The key issues to implement such a model updating are discussed such as sampling with design of experiments, selecting the significant updating parameters and constructing a quadratic polynomial response surface. The objective function is formed by the residuals between analytical and measured natural frequencies. Single-objective optimization with equal weights of natural frequency residual of each mode is used for optimization computation. The proposed procedure is illustrated by a simulated simply supported beam and a full-size precast continuous box girder bridge tested under operational vibration conditions. The results have been compared with those obtained from the traditional sensitivity-based FE model updating method. The real application to a full-size bridge has demonstrated that the FE model updating process is efficient and converges fast with the response surface to replace the original FE model. With the response surface at hand, an optimization problem is formulated explicitly. Hence, no FE calculation is required in each optimization iteration. The response surface-based FE model updating can be easily implemented in practice with available commercial FE analysis packages. © 2010 Elsevier Ltd.

Wang Z.-C.,Central South University | Wang Z.-C.,Missouri University of Science and Technology | Ren W.-X.,Central South University | Ren W.-X.,National Engineering Laboratory for High Speed Railway Construction
International Journal of Structural Stability and Dynamics | Year: 2011

A beam segment element formulation is presented for the dynamic analysis of prestressed concrete box-girder bridges, which can conveniently takes into account the effects of the restrained torsion, distortion, transverse local deformation, diaphragms, and prestressing tendons of prestressed concrete box-girder bridges. The spatial displacement field of the beam segment element is directly represented by the nodal degrees of freedom of the corner points. The stiffness matrix and mass matrix of such a segment element are formulated based on the principle of stationary total potential energy in elastic system dynamics. The proposed beam segment element formulation is then implemented to carry out the free vibration analysis of a real case prestressed concrete box-girder bridge. In terms of both natural frequencies and mode shapes, the formulation is verified by the three-dimensional (3D) finite element analysis using a commercial package. It is demonstrated that the proposed beam segment element formulation is suitable and efficient for the dynamic analysis of prestressed concrete box-girder bridges with the advantages of less element numbers and enough accuracy. It is expected that this methodology can be an effective approach for the further dynamic response analysis under all kinds of dynamic loads such as earthquakes, winds, vehicles, and their interaction. © 2011 World Scientific Publishing Company.

Dai G.,Central South University | Dai G.,National Engineering Laboratory for High Speed Railway Construction | Su M.,Central South University
Archives of Civil and Mechanical Engineering | Year: 2016

This paper presents the experimental observations and results of six full-scale field ballastless track structure specimens, and tested under longitudinal and transverse shear load. The tests aimed to examine the interfacial shear capacity of the continuous slab track structure and investigate the interfacial bond-slip behaviour. The results show that bond strength of the two interfaces which were on the top and bottom of mortar layer, respectively, have a large difference. Until the top interface of the mortar layer fractured, no slip displacement was observed in the bottom interface. In addition to the experimental study, a finite element model using nonlinear interface elements was employed to simulate the tests. The numerical calculated capacity agreed well with the experimental results, showing that the proposed bond-slip law is reliable. Finally, the track slab's evenness with the bond-slip effect under the dynamic load was studied. © 2016 Politechnika Wrocławska.

Ding F.-X.,Central South University | Li Z.,Central South University | Cheng S.,University of Sheffield | Yu Z.-W.,National Engineering Laboratory for High Speed Railway Construction
Thin-Walled Structures | Year: 2016

Four groups of axial compression tests on hexagonal CFT stub columns have been carried out aiming to investigate the effects of the concrete strength and steel ratio on the behaviour of hexagonal CFT stub columns. Studies on parametric analysis and composite action between core concrete and steel tube have been carried out using FE modelling which had been benchmarked using the test data. Based on the essential data obtained in this paper, the ratio of axial stress-yield strength of steel tube was determined at the ultimate state. The stress contour of core concrete was simplified to an unconfined area without constraint and a confined area with uniform constraint imposed by hexagonal steel tube. Eventually, a practical design equation of the ultimate bearing capacity of hexagonal CFT stub columns was proposed based on the superposition principle. An excellent agreement between the proposed equation and the experimental results was observed, with an average ratio of predicted to measured capacity of 1.08 and a standard deviation of 0.05. © 2016 Elsevier Ltd

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