Applied Mechanics and Materials Vols. 166-169

Abstract: In order to analyze impact of roller loads applying in subgrade connecting, numerical software had been executed to calculate deformation caused by three types of roller loads to 6m subgrade. In this analysis, surface layer of the old subgrade, slope toe point and connecting point had been chosen as key points to study deformation under different construction processes. The results show that the displacement in the vertical direction of point A and point B increases with the roller load's increasing. Deformation of key points has the non-linear relationship with construction steps. According to the minimum deformation, the first scheme is chosen which is beneficial to the train’s safty and stability of whole subgrade. It will be instructive to control differentia deformation for the connecting subgrade projects in high-speed railway

Abstract: Based on the analysis of chaotic time sequence and the characterization to the system chaotic property from it’s characteristic index, we established finite element model about ASCE Benchmark. Then we got 4 acceleration time sequence of Benchmark model by simulation of instantaneous excitation. At last, we made a experimental analysis on the maximum Lyapunov exponent. As the result shows, all maximum Lyapunov exponents are above zero. It means that chaotic phenomenon appears in the structure system. At the same time, maximum Lyapunov exponent shows it’s sensitivity along with the evolution of structural condition. That is to say, the statement of structure could be reflected by the chaotic index of chaotic time sequence. Then we get new ideas on the study of safety assessment relied on the structural health monitoring.

Abstract: In this paper, the hybrid control method of earthquake excited high-raised buildings is put forword. The building is modeled as a shear-wall type structure with non-linear hysteretic restoring forces after the structure enters the period of nonlinear and plasticity. A passive base-isolation is combined with actuators applied at the basement of the structure. A candidate for Liapunov function is found out based on the theory of energy. A non-linear control law is designed following the theory of Liapunov, since small residual deformations have to be tolerated due to inelastic energy dissipation, asymptotic stability will not be required, but only stability in the sense of Liapunov has to be guaranteed. Computer simulations demonstrate the efficiency of the proposed control algorithm.

Abstract: Key technology of testing masonry shear strength with core drilling method is that standard shear strength of masonry is determined from the shear strength of masonry core sample, while current code or specification has not provided the corresponding calculating formula. To investigate their relationship, a series of tests have been carried out. Existing test result analysis shows that standard shear strength of masonry and shear strength of masonry core sample are closely related. By means of testing data regression analysis, this work can establish the relationship formula between shear strength of single core sample and standard shear strength of masonry. This Technology can be suitable both to traditional masonry structure and to new wall materials masonry structure, especially to seismic appraiser and reinforcement calculation of masonry structure. This technology can support scientific basis to quality examination and assessment of new wall materials and analysis of engineering quality accident.

Abstract: The lightweight steel portal frame structure has been extensively used in the industry and civil buildings in recent years, because of the rational force bearing, large numbers of tapered members appear in this kind of structure[1]. This part established the finite element model of tapered beam in the range of large-deflection and elastoplasticity by applying the theory of nonlinear finite element and ANSYS. Through the finite element calculation of this rate that wedge i-section beam elastic-plastic stability of the bearing capacity of influence.

Abstract: Based on the similarity between knowledge discovery from data bases (KDD) and Structural health monitoring (SHM), and considered the particularity of SHM problems, a four-step framework of SHM is proposed. The framework extends the final goal of SHM from detecting damages to extracting knowledge to facilitate decision making. The purposes and proper methods of each step of this framework are discussed. To demonstrate the proposed SHM framework, a specific SHM method which is consisted by second order structural parameter identification as feature extraction and statistical control chart analysis of identified stiffness for feature analysis is then presented. Through clarifying the goal and hierarchy of extracting useful knowledge of SHM problems, the framework has potential to facilitate the further development of SHM.

Abstract: In order to solve the problem that it need too large number of sensors and data of undamaged structure, the method of damage detection employ difference of deflection influence line under symmetrically load is proposed. theoretical derivation and finite element simulation shows that the curvature of the influence line is less than zero when the moving load is located in the damage region and it is no less than zero when the moving load is located in the other regions. so the damage location and extent can be detected by using this method, furthermore, this detection method is suitable for not only single damage but also multi damage.

Abstract: This paper combined the feature of Winkler foundation model and base model of limited compressible layer based on the layer-wise summation method, on condition that considering the feature of foundation soil, to derived from a newly foundation stiffness calculation model and to verify it.

Abstract: The damage identification research based on strain mode was discussed in this paper, and based on MATLAB, the models on the severy conditions of preset damaged was compared also. The results show that this method is more rapid, and the parameters impact of the strain mode is more intuitive than other finite element analysis software. The damage location and the extent of injury of simply beam can accurately determined by strain mode shapes. The conclusion is theoretical academic significance value of assess in service bridge structure examination.

Abstract: Damage identification method based on the change rate of strain mode is studied in this paper. Reinforced concrete frame structure as a researching object, true strain mode of structure is obtained by external excitation, graphics of strain mode and change rate of strain mode of the frame structure before and after the damage are established and analyzed. The results show that the change rate of strain mode is sensitive to the damage, and the location and extent of the damage can be judged through this method.