Applied Mechanics and Materials Vols. 105-107

Abstract: This paper describes the agent construction system of development and the associated building regulations in China. A brief overview of the South-to-North Water Diversion Project and the practical application of agent construction system in the Beijing-Shijiazhuang section of the South-to-North Water Diversion Middle Route Project (SNWDMRP) is made and specific recommendations to carry out the system to the next diversion project construction is put forward. Existent problems and corresponding measures applied to the agent construction system are discussed, such as the situation and choice of agent construction corporation, agent construction project selection, responsibilities and rights of the agent construction corporation, incentive and punishment mechanism, construction supervision and management and so on. Useful exploration on the application of agent construction system is made in hydraulic and hydroelectricity engineering field.

Abstract: Based on the reliability-based optimization design theory, the reliability sensitivity technique and the robust design method, the reliability-based robust design of rubbing rotor system is extensively discussed and a numerical method for reliability-based robust design is proposed. The reliability sensitivity is added to the reliability-based optimization design model and the reliability-based robust design is described as a multi-objection optimization. On the condition of known first four moments of basic random variables, the respective program can be used to obtain the reliability-based robust design information of rubbing rotor system accurately and quickly using the fourth moment technique. According to the numerical results, the approach proposed is a convenient and practical reliability-based roust design method.

Abstract: Throughout history till today, earthquake prevention and disaster mitigation has been the eternal subject in engineering field. Security is the very premise for the subsistence and development of human beings. Entrusted with government correlation department, the examination of seismic safety and structural health diagnosis will be done in relation to the type, characteristic feature and damage, etc. of current masonry structure in Minnan District, which is in the spirit of “Emphasis on hedge against disaster relief”. According to current criteria as well as considering the actual situation of construction, various constructions will be evaluated scientifically by the on-the-spot survey, investigation, evaluation and analysis, from which get the various morbid state and principle of constructions in concordance with the differences of severity. On the other hand, in line with “rescuing” principle in order of importance and urgency, corresponding classification of disaster prevention and certain applicable and practical disposal ideas will be put forward in order to provide references for engineering practice and application as well as management and policy making for relevant department.

Abstract: Lattice light steel frame is a new type of structural system, combining general steel framework which is composed of lattice column and lattice beam with lattice light steel keel of the partitions and floors, the system takes full advantages of both structural systems, with high speed construction, less steel consumption, good earthquake-resistance etc., and possesses good prospects. The paper describes the system construction approach and the characteristics of lattice light steel frame system, and provides a project example of a villa. The design method and calculation model of the project are presented. Calculation results meet the specifications’ requirements, proving the new system can be applied to practical engineering. The paper gives guidance for application and research of this new system.

Abstract: For present-day bridges.cable tensions test is a vitally important job in course of construction.The tensions condition of cables plays an especially important part in the course of construnction and operation.In order to ensure the safety of operation and lengthen the service life,the exact testing result is being required to obtain.In cable stayed bridges and arch bridges, the boundary condition as well as the bending rigidity has an greater effect on the cable forces testing of the short boom.This paper based on Additional Mass Method,using the method of GA-BP Neural network after Genetic Algorithm optimization to identify the cable forces of short boom and a preferable research result is obtained.

Abstract: The construction of precast box girder plays a pivotal role in the process of building passenger dedicated lines. But the high temperature and low-speed of cooling rate inside the box girder will seriously reduce the box girders’ quality and delay the project duration. So, some methods such as cooling by means of circulating water in drill way etc. are presented in this paper. Then temperature tests are carried out for the box girders with different cooling measures, and the respective data are analyzed. The results show that the proposed cooling methods can effectively reduce the highest temperature, speed up the cooling rate inside the box girder and decrease the temperature difference between the interior and the exterior of the concrete.

Abstract: The paper presents a dynamic computational model and field test for analyzing the relationship between the rail natural frequencies and the longitudinal temperature stress by means of the finite element method. The essay use the infinite Timoshenko beam as the plane model to simulate continuous welded rail track structure and the rail model by means of the finite element method in order to its unit as a division of space elastomer. The test uses vertical incentive and horizontal incentive to encourage continuous welded rail track structure to get the rail natural frequencies. The measured data and the result of finite element analysis are compared, finds the results are consistent. The paper not only investigates the relationship between the rail’s dynamic characteristics and the longitudinal stress, but also provides a feasible method for test longitudinal stress of continuous welded rail track.

Abstract: Fluid scour is one of the major causes for bridge failure. To prevent this type of failure, even the catastrophic accidents, it is necessary to make a further study on the effect of fluid scour on mechanic behavior of bridge pier. In this paper, the 3-D finite element model of piled pier and soil interaction is established. The scouring process is simplified for the soil excavation, and the effect of scour on overall stability of piers and bearing behavior of piled pier structure is simulated and discussed. The curves of horizontal, vertical displacement and carrying capacity under various scour depths are drawn in the article. It demonstrates that the effect of fluid scour on piled pier bridge is bad. With these analyses, some useful conclusions in engineering practice are obtained.

Abstract: Bridge plays an important role in modern transportation. Once it is damaged, there will be great loss. So assessment of bridge state has become more and more important in modern society. Ambient around bridge always are very complex and bridge is affected by many factors. So in all response of bridge, noise and useful signals mixed together. The noise generally includes temperature effect, wind load effect, live-load effect, and so on. In order to get the useful signals we must separate the live-load effect from the total effect by using multi-scale analysis firstly. EMD brought a new method for multi-scale analysis and it is superior to wavelet to some extent. But it has some shortcomings also. In order to improve the performance of the EMD further, EEMD is introduced to extract live-load effect of bridge. The practical and simulation results verified the feasibility of the new method based on EEMD and the results is much better than those based on wavelet.

Abstract: A method based on ultimate limit analysis (ULA) was proposed to identify collapse pattern for cable-stayed bridges. The proposed method had no need to model the whole process of structural progressive failure, but assumed plastic hinge model of cable-stayed bridges, which had two sets of variables describing plastic hinges’ positions and rotational angles. By a two-stage sequential optimization, the variables could be solved to reveal the bridge collapse pattern. Parametric studies could be further conducted to identify the bridge critical components, and explore the effects of some design parameters on collapse pattern and ultimate load-carrying capacity (ULC). The proposed technique was illustrated on a twin-pylon cable-stayed bridge. Comparing with the results of nonlinear finite element analysis (FEA), the yielded components forming collapse pattern can be correctly extracted from the plastic hinge model. This technique results in small errors (less than 3.1%) for estimating the ULCs.