Applied Mechanics and Materials Vols. 438-439

Abstract: The research status and progress, in China and overseas, of long-term deflection of FRP reinforced concrete beams are briefly introduced in this paper. The mechanism, influencing factors and calculation method of long-term deflection of FRP reinforced concrete beams are discussed and summarized. Meanwhile, some advices for long-term deflection research of FRP reinforced concrete beams are proposed.

Abstract: For considering the losses of pre-stress in suspend-dome structures, an improved rigid cable method was proposed. The main character of this method is the temperature stress is applied to corresponding element to compensate the loss of pre-stress. The relationship between temperature and pre-stress loss is deduced, which can give the definite num of temperature needed to add on the corresponding elements. An example and engineering application are discussed. Results show that the improved rigid cable method is effective and applicable.

Abstract: Basing on the practical engineering of elliptic paraboloid roof structural design in Qinyang Stadium, four structural schemes such as suspend-dome, single-layer latticed shell, double-layer latticed shell and rigid suspend-dome, are calculated and designed respectively. After satisfying the requirements of strength, stiffness and stability, the quantity of steel is compared. The advantages and disadvantages on mechanical performance, construction and cost of four schemes are discussed. Results of comparison provide the accordance for the final decision of structural schemes of Qinyang Stadium and can be referenced by other similar practical engineers.

Abstract: Based on the unified twin shear strength theory, a new earth pressure formula is deduced for the straight groove buried rigid pipes, with a straight slip plane soil pressure calculation model established. Compared with traditional earth pressure calculation method, the new formula which considers influence of intermediate principal stress on the pipeline earth pressure can obtain the result which is much closer to the actual pipeline stress situation. The results determined from the proposed formula with an engineering example show the influence law of slot width and the thickness of the overburden on tube top soil pressure. The conclusions have some guidance significance for optimization design of pipeline engineering.

Abstract: The construction of underground infrastructures often requires to excavate in close vicinity of existing structures. In these conditions, the main design requirement is that of limiting ground deformations caused by excavation to ensure the safety of the structure. The diaphragm wall was used to meet this requirement on the background of a hydropower station in China. In this paper, a series of 3D finite element analyses was carried out for modeling the installation of diaphragm walls based on ABAQUS. The contact pair between the wall, the pile and soil was built by the master-slave method. The elastic model is adopted for the diaphragm wall and the pile, the elastic-plastic model based Mohr-Coulomb was applied to soil. The construction process and the running state were also simulated to estimate whether the plan was appropriate while considering the initial ground stress. The results obtain by numerical simulation agree with the observed data, the deformation process can be satisfactorily modeled. So this simulation method of the diaphragm wall can be used as reference for similar hydraulic projects.

Abstract: Based on the ANSYS program, a numerical model of spiral case structure of hydropower station is built. The nonlinear contact characteristics are introduced in this model. For the working conditions under the different internal water pressure, structural simulation analysis is conducted. The effect of the internal water pressure on the structure, and the mechanical characteristics and stress of reinforcement are analyzed. The evolution process of concrete cracks, from microscopic period to macroscopic period is exhibited. The reasonable scheme of optimization under internal water pressure is attained.

Abstract: This paper takes cascade hydropower station project as the research object. It puts forward an economic post project evaluation of hydropower station`s analysis framework -- "static analysis and comprehensive evaluation" based on building the evaluation index set and data envelopment analysis. This paper takes economic post project evaluation of Yuanshui cascade hydropower station as an example to verify the science and effectiveness of the analysis framework and model. The results enrich the theory and model technique of economic post project evaluation of hydropower stations.

Abstract: ndependent evaluation of immigrants is conducted by independent and impartial monitoring mechanisms or synthetical supervision units to evaluate the results of resettlement and implementation of migrants lawful rights and interests, in order to get the information completely and objectively. According to the complete survey on the spot of migrants level of productive employment around the Shimenkan hydroelectric station at March 2012, and linking with the development of local society and economy, objective assessment was given to evaluate the state of resettlement, resumption of living standard and social adaptation. This paper sums up the experience and gives suggestions to the problems on this resettlement planning. At the implementation of the planning stage, resettlement points which were planned at the research phase were cancelled after investigating the remainder resources around reservoir and listening to the migrants opinions. Settling the problem right on the spot was chose to replace relocation. The plan after optimizing and adjusting was successful by way of practice.

Abstract: Low dam of the head complex of CCS hydropower station results in its small capacity, in order to reduce the wear of turbines, higher requirement is demanded for the head complex design. Water diversion and sediment prevention system design together with general layout of the project, a forward flushing, flood discharging, lateral intaking system is formed. The basic purpose of reducing sediment diversion is reached by the comprehensive measures of interception, sedimentation, ejection, combined with reasonable reservoir operation scheduling system.

Abstract: Aging reinforced concrete (R/C) bridge girders, currently in use, exhibit cracks wider than predicted at the design stage. Variation in material properties over time and increase in imposed live loads during service life can be the possible reasons for this behavioural difference. Visual condition monitoring reports of bridge assets do not seem to provide a more quantifiable explanation to this phenomenon. Therefore, authors propose a theoretical time dependent methodology, to predict the crack widths with age. The proposed method takes into consideration flexural stresses, shrinkage and creep. A bridge girder, currently in use, is analysed using proposed theoretical approach and the outcomes are compared with condition monitoring records available.