Lu J.-S.,Shanghai Urban Construction Design and Research Institute |
Zhang Q.-L.,Tongji University
Gongcheng Lixue/Engineering Mechanics | Year: 2013
An efficient approach that employs a convex model to deal with the most unfavorable initial geometrical imperfection of spherical latticed shells is proposed. Initial geometric imperfection, as one of random variables, is a linear combination of N eigenmodes based on linear buckling analysis. The deviation of N dominant mode shapes is assumed to vary on an ellipsoidal set in the N-dimensional Euclidean space. The limit load of nonlinear buckling will be determined as a function of the N linear buckling mode amplitudes. This approach can replace the computationally expensive probabilistic approach, typically used in the study of imperfection sensitive structures. A Monte Carlo simulation has been performed to validate the results obtained by the convex model. ANSYS Parametric Design Language secondary development is used to carry out the finite element analysis.
Sun Y.,Shanghai JiaoTong University |
Shen S.-L.,Shanghai JiaoTong University |
Xia X.-H.,Shanghai JiaoTong University |
Xu Z.-L.,Shanghai Urban Construction Design and Research Institute
Materials and Design | Year: 2013
Studying the ratcheting and shakedown behavior of materials under cyclic loading is significant for controlling structural deformation and improving the service lifetime of materials. In this study, cyclic loading tests were performed on DH36 steel at room temperature under various conditions while evaluating the effects of the loading waveform, the loading rate and the stress ratio to reveal the material characteristics of ratcheting and shakedown behavior and to provide an experimental basis for proposing and implementing a numerical method that predicts the shakedown limit in this type of cyclic plastic behavior. A numerical analysis method using the plastic deformation energy as a shakedown criterion was proposed based on the energy dissipation phenomena observed in the tests. The method was then applied to two classic examples of shakedown analysis by computation and was compared with related results from the literature to evaluate its effectiveness and reliability. This method provides a new approach for the numerical analysis of the material shakedown limit. © 2012 Elsevier Ltd.
Jia R.Y.,Shanghai Urban Construction Design and Research Institute
Applied Mechanics and Materials | Year: 2013
Drop shafts, especially the vortex drop structure, are vertical conveyance conduits used in hydraulic engineering, water supply and drainage engineering, and so on. Because of complex flow properties and safety requirement, the system running security and reinforcement measure should be verified before it was built. In this paper, numerical and physical simulation methods were employed to verify mutually and analyze the hydraulic characteristics in a tangential vortex dropshaft. It is shown that the water carrying capacity of the dropshaft could be increased suitably and the safety freeboard of the conduit is the limiting factor. The air-water mixing at the junction may reduce the energy dissipation and reinforcement measure for the whole wall is necessary. © (2013) Trans Tech Pudlications, Switzerland.
Peng F.-L.,Tongji University |
Wang H.-L.,Tongji University |
Tan Y.,Tongji University |
Xu Z.-L.,Shanghai Urban Construction Design and Research Institute |
Li Y.-L.,Shanghai Foundation Engineering Company
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2011
Characterized by unmanned excavation and remote controlling, the new pneumatic caisson (NPC) method has advantages in deep excavation such as deep shield tunnel shafts and some underground construction close to the existing structures or facilities. When adopted in urban areas, it is very important to control the ground deformation during a caisson construction. For this purpose, field measurements of ground deformation were conducted during a tunnel shaft construction in Shanghai soft ground, in which the NPC method was used. On the basis of the particular construction procedure of a pneumatic caisson, one kinematic mechanical model was proposed for evaluating the influence of NPC construction on the surrounding strata. This model was incorporated into a finite-element (FE) program. By comparing the FE-predicted results of the proposed model and the field measurements, the accuracy and reliability of this model were verified. © 2011 American Society of Civil Engineers.
Bao L.,Shanghai Urban Construction Design and Research Institute
IET Conference Publications | Year: 2011
A knowledge-based prediction and evaluation system (KBPEs) for highway networks development planning is put forward, which is a decision support for transportation government. Firstly, the architecture of KBPEs is presented, and then with an example of Weihai city, the paper goes into more detail about how the system works. After analyzing current highway networks of Weihai city and concluding some factors that hold back transportation development, social and economic indexes (population, GDP) are predicted according to the statistics with the historical data. The regression formula among highway networks, national economy and population is presented. Furthermore, future highway networks are reasonably predicted quantitatively and qualitatively so as to meet the requirement of local social and economic development. According to the highway networks development planning of Weihai city, the total highway scale will reach to 2600 km in 2015, 3000 km in 2020 and about 3500 km in 2030. Finally, from the point of technical performance, besides macro-economy and social benefit, the paper gives evaluation of the adaptability of predicted highway networks in Weihai City.