Applied Mechanics and Materials Vols. 236-237

Abstract: Images of glass product that are captured under poor light usually make defected regions covered by dark pixels because of refraction and scattering brought about by defects on glass. On the other hand, image texture makes it unlikely to effectively identify defects accompanied by some texture by using commonly-used image segmentation and defects extraction algorithms. Watershed segmentation algorithm is proposed in this paper to extract catchment basin where defects characteristics in each image region will be calculated with the twofold application of gray level co-occurrence matrix(GLCM) and parameters characteristics . Defects will be finally identified using shape operator.

Abstract: The establishment of an effective finite element model for bridge structure is essential in the health monitoring system for Bridge. A new updating method for static model using response surface method is proposed in this paper, and the main procedures are given with an example of a special-shaped bridge. Firstly, the bridge deflection and strain data in designed load case are obtained. Several groups of combined parameters which are chosen based on the principle of uniform design method are selected to conduct calculation through finite element software. Finally through response surface fitting and optimization, the updated bridge finite element model is obtained. The results show that the updated model is approximate to the real bridge and this updating method is rational and practical.

Abstract: Presently, the study on damage identification of bridges is very popular and it has a wide range of applications. Also the related theory and technology are constantly developing and mature. The researches based on the dynamic response of bridge in frequency domain is more, but the dynamics theory is complex and difficult for the engineering personnel to grasp. On the opposite, although the damage identification method based on the dynamic response of bridge in time domain is easy to understand, it is difficulty for applications. The Auto Regressive Moving Average model (ARMA) of time series analysis can be used to settle this problem. It is a not very abstruse theory and it is already apply for the system identification of some Structures. In this paper, we use time series analysis for the damage identification of simply supported beam bridge combined with its own dynamic response in time domain.

Abstract: In the present study, a coupled numerical method is used to study EDZ (excavation damage zone) in a deep schist tunnel. Two codes, Fast Lagrangian Analysis of Continua (FLAC) and Particle Flow Code (PFC) are coupled to implement the simulation. The motive to apply the FLAC/PFC coupled approach is to take advantage of each modeling scheme while at the same time minimizing the requirement for computational resources. The coupling is realized through an exchange of displacements, velocities, and forces in each cycling step. Simulation results are found to be in good agreement with in site ultrasonic wave measured EDZ profile. The coupled PFC/FLAC model present more information than each uncoupled model individually, and these simulation results are very important in tunnel design.

Abstract: A grey relative degree assessment model for durability of concrete structure, based on the combinatorial weight, in which expert experience & information entropy are taken into account, is established after analyzing problems in existing durability assessment theory. Both the influence of subjective factors and the significance of objective factors are considered in this model, and to avoid assessment deviation for emphasizing one side or another. The model, which is testified by practical engineering example, provides a new approach to make durability assessment more scientifically and exactly.

Abstract: In two-dimensional space, an elasto-plastic finite element computational model was established to simulate inner support for excavation on the basis of the general-purpose finite element software ABAQUS. The soil was assumed to be a uniform and normally consolidated clay layer and strut was discreted by spring element. Compared with published case study, it can be concluded that FEM software AQAQUS can present one reliable simulation progress of inner support for excavation.

Abstract: This study includes the development of the seismic retrofit technology that structural frame of building is strengthened by installing additional wall with embedded form after demolition of the inner walls of unreinforced masonry wall including the exterior design walls. In addition, this paper involves the earthquake resistant performance evaluation of the system through an experimental work. From the test, it was turned out that as for the maximum strength of the specimens, the maximum load was similar regardless of whether using the embedded form. However, EF-IW-H1(embedded form) specimen with the form hardware embedded in the wall during retrofit resulted in ductile behavior of the, which shows the effect on the embedded form in a sense.

Abstract: When the frequency response function (FRF) and Back-propagation (BP) neural network are used to identify the structural damage, problems such as the excitation information can not be got easily, the network is difficult to converge and the network stability is poor as the oversize input vectors. So, in this paper, two node acceleration responses of the structure under the white noise are directly used to construct the vibration transmissibility, and principal component analysis (PCA) is pursued to the amplitude of the vibration transmissibility for dimensionality reduction. The combinations of principal component variation before and after damage are used as the damage characteristic vectors, and which are input into the BP neural network for damage identification, the influences of the different degrees of noise during the damage identification are considered simultaneously. The results of numerical simulation and model experiment of offshore platform show that the method can identify the different degrees of structural damage.

Abstract: The objective of this study is to investigate the file exchange compatibility of BIM based building energy simulation tools, especially focusing on various irregular building geometry shapes. As a base building modeling software, AUTOCAD Revit was selected and various building geometry shapes were created using Revit, such as curved and pitched walls, roofs, slabs with various air-conditioning zones. And these various shaped building zones were imported to ECOTECT, IES/VE and Openstudio for EnergyPlus, which are professional building energy simulation tools. Through this create-import process, the deformation of building shapes, change of zone volume, and compatibility to each simulation engine were investigated and analyzed.

Abstract: The objective of this study is to develop computational efficient and accurate stress stiffening models that can be used in the dynamical formulation for the analysis of two-dimensional beams. The model which accounts for the tangent stiffness of beam element are derived using second order theory and continuum mechanics approach. Then, three stiffness matrix and two different force models that include different degrees of complexity are presented by expanding it to power series and truncating at quadratic terms. It is shown that the finite-element formulation of multibeam system can be significantly simplified as compared to the classical geometrical nonlinear method developed for the formulation in local element frame. Despite the simplicity of the new models, they account for elastic non-linearity in the strain-displacement relationship, therefore, they lead to more accurate results as compared to the more complex models which does not exactly account for the non-linearity. Numerical results are presented in order to demonstrate the implementation of the new models and test their performances through dynamical analysis of crank-slider mechanism.