Applied Mechanics and Materials Vols. 444-445

Abstract: In order to solve 3-D dynamic problem for large-scale structure, based on HDDM (Hierarchical Domain Decomposition Method) method, 3-D dynamic finite element parallel computing method of large-scale structure is studied. In this paper, BDD method and Newmark-β average acceleration method in time integration is used. Based on ADVENTRUE program, the corresponding linear implicit transient dynamic parallel program which is based on the MPI parallel environment and can be used in shared memory and distributed memory parallel computer is prepared. Several pre-conditioners are contrasted using some examples, and the results show that BDD preconditioner or BDD-DIAG preconditioner can be used in 3-D dynamic analysis for large-scale structure.

Abstract: Based on an in-depth study on warning area security of radar network, this paper sets the cost of radar networks overall operation as the objective function and proposes mathematical models for management and control of radar under circumstances with interference, aiming at accomplish the security mission within warning area on the basis of the constraint condition that the warning areas at different height can satisfy joint probability of detection and coefficient of radar coverage. We use a modified genetic algorithm for the calculation of radar management and control model, save the feature of the optimized individuals via defining the probability, and improve the algorithm through setting reasonable parameter. The simulation calculation and practical application prove that the model and the scheme are effective because the qualified rate of radar management and control meet the requirement (reaches 100% from 36.54% with the increment of 63.46%), the number of operational radar reduced, and the anti-jamming measures are reasonable.

Abstract: The rotor shaft of a steam turbine generator consists of several masses, such as rotors of turbine sections, generator section and exciter section. When the generator is perturbed, it will cause torsional oscillation between different sections. In long-distance high-capacity transmission lines, series compensation with capacitors can enhance power transfer capability of power system, however it may cause subsynchronous resonance (SSR) between the turbine shaft and serial compensation., which produce large shaft torques can result in a reduction in the shaft fatigue life and possibly shaft failure, threatening the security of generator unit and stability of power system. In China the 1000kV HVAC transmission line with series compensation has been put in operation since 2009. Near the Nanyang substation, there has a power plant in Henan power grid. So it is necessary to model the power plant and HVAC transmission line to simulate the possibility of SSR problem. Based on the power system simulation software ADPSS developed by China Electric Power Research Institute (CEPRI), this paper built up the simulation model using the electromechanical-electromagnetic transient hybrid method, and simulated the SSR possibility between the power plant and HVAC transmission line series compensation. The simulation results showed that with the generator parameters given, there has no risk of SSR between them. This paper also gives an evaluation principle of generator SSR risk when connected into a power grid.

Abstract: The Yangtze River and its tributaries located in Three Gorges Project (TGP) reservoir was influenced by the operation of TGP reservoir, and the water quality problems were becoming serious these years. Mass transportation in the tributaries was interacted with the hydrodynamic field. Then, a parallelized three dimensional unstructured mesh water quality model was applied to Xiangxi River - one of tributaries of Yangtze River - to simulate the changing processes of flowing and nutrients including TP and TN. The results show that the parallelization model can enhance the simulation efficiency, especially when the computational scale is large. The parallelized model was executed in Windows operation system could make sufficient use of the resources of low-end multi-core personal computer. The parallelized model could provide a new tool for river water quality research and the information for management of TGP reservoir.

Abstract: In order to study whether foundation pit is stable or not after excavation, the article adopted the Duncan E-B model to make static analysis for the excavation scheme which considering the soil consolidation settlement and to make dynamic analysis under the action of earthquake wave of EL Centro. To make a slope stability of foundation pit analysis by calculating static and dynamic boundary conditions which further coupled with the Newmark method. The main study is the foundation settlement and earth-rock dams, slope stability of foundation pit conditions that considering unsaturated zone seepage conditions of earth-rock dams after the excavation. The results indicated that: in the static & dynamic analysis, the distribution about settlement is reasonable, earth-rock dam and foundation pit slope is in the steady state, the excavation scheme is reasonable and feasible.

Abstract: Based on the lower bound theory for the plastic limit analysis, rock slope is divided into rigid block and structural surface. And the mathematical programming model which takes the safety factor as the objective function is established for the calculation of slope stability. This model has to meet the balance equations of the blocks, the Mohr-Coulomb yield conditions and the boundary conditions of slope. In the end, a classic model of rock slope on consideration of the pore water pressure and earthquake force is analyzed, and its lower bound solution is worked out. This result is compared to the result worked out by limiting equilibrium to test the validity and correctness of the method and procedure used in this paper.

Abstract: The degradation of concrete structures due to steel reinforcement corrosion is a serious problem for durability and serviceability. Cracking behavior due to reinforcement corrosion is evaluated experimentally and analytically in this paper. In the experiments, in which corrosion was induced electronically, the structure proportion of corrosion product was analyzed. In the analysis, a micromechanical cracking mechanical analytic model, which considered the coupling effects of corrosion product and concrete protective layer was established. The initial cracks and crack growth process of smeared cracks in cover concrete were simulated and explored for the deterioration process of concrete structures due to corrosion expansion. It is indicated that the numerically predicted crack mode agrees well with the experimental results.

Abstract: In order to analyze the premature damage of dowel bar system in jointed concrete pavement, the eXtended finite element method (short for XFEM) coupled with submodeling method were employed to simulate the fracture process of concrete around the dowel bar under loading. This coupling method is based on 3-D finite element analysis for the whole concrete pavement structure. The initialization and evolution of the cracks on the concrete had been monitored in model simulation. The results demonstrate that the XFEM coupled with submodeling method is an efficient and accurate method to calculate the ultimate bearing capacity of dowel bar. Furthermore, the critical axle load could be back-calculated based on the former analyzing results. This study is expected to provide a valuable numerical analysis method to simulate the fracture process in stresses concentration region of the concrete structure.

Abstract: The massive rock slope is made up of rocks and structural surface. The existence and strength of the structural surface decides the stability of the rock mass. By adopting the lower bound method for the plastic limit analysis of wedge slope, we can easily calculate the stability of the rocky slope under various circumstances. To apply this method, we first took the wedge-shaped slide block as a complex of rigid block and structural surface for the analysis of the slope stress under the function of anchor bolts, the integrated function of rocks and structural surfaces being considered. Then, on the basis of the lower bound theory for the plastic limit analysis, a mathematical programming model which takes safety factor of slope stability as the object function is established. This model has to meet the equilibrium condition of the bolt, the Mohr-Coulomb yield condition and the boundary condition of slope. In the end, a classic model of wedge is analyzed and its lower bound solution is worked out. This result is compared to the result worked out by limiting equilibrium to test the validity of the measure and procedure used in this paper.

Abstract: Prestressed steel structure is the common form of space structure. BIM technology is used to every field of the construction industry. In order to apply BIM technology to the design and construction of prestressed steel structures, Xuzhou stadium prestressed structure was took as an example with BIM technology. Firstly, development standards of the family are created. Secondly, three-dimensional positioning technology and then establishing three-dimensional models of BIM are designed. Finally, the construction process of Xuzhou stadium is dynamically simulated.