Advanced Materials Research Vols. 919-921

Abstract: The parabolic trough-type collectors and new bracket system were accounted for the research object; static load and structural optimization were analyzed by ANSYS, and selected the best section size of the bracket with meet the strength and stiffness requirements. The results show that the original bracket structure almost meet the strength and stiffness requirements under normal working conditions; After optimization design, the weight of bracket system decreased by 10.68%, so greatly save the production cost under meeting the conditions of strength and stiffness requirements.

Abstract: Based on the project of construction monitoring for cable structure of the roof of Shenzhen Baoan stadium, the displacement and stress of outer compressive ring caused by temperature change were monitored before the radial cable was tensioned, analyzed and compared the monitoring results. Comparing the measured results and simulation results shows the temperature change characteristics of outer compressive ring and the temperature change characteristics are valuable for delicacy construction of other similar projects.

Abstract: The complex modal analysis is developed to study the transverse vibration of Timoshenko beams resting on viscoelastic Pasternak foundation. Complex frequency equations and modal function expressions are obtained for pinned-pinned ends. In numerical examples, the characteristics of natural frequencies and decrement coefficients of Timoshenko beams are compared with Euler-Bernoulli beams. The numerical results show that with increase in the length, the natural frequencies of Timoshenko beams are slightly less than Euler-Bernoulli beams, and the decrement coefficients of Timoshenko beams are not constant as that of Euler-Bernoulli beams.

Abstract: The author puts forward a new insulation cross arm, uses the insulation and high strength composite materials (FRP), to replace the steel applied to the RPC pole cross arm, this not only has a full bar maintenance-free features, and can shorten transmission corridor again, for the construction of resource intensive transmission lines has important practical significance. In addition, this paper uses finite element analysis software ANSYS, considering the influence of fluctuating wind, in the modal analysis and dynamic response illustrates the actuality of cross arm application of composite materials.

Abstract: In accordance with the technical specifications of existing concrete structure construction template and an arched structure concrete pouring process, the exterior-template design for concrete of the project has been done, which contents the requirements of the of engineering concrete on construction quality.

Abstract: Based on experimental study of 9 full-scale high-strength concrete(HSC) rectangular frame columns with high axial compression ratios, high-strength longitudinal reinforcements and transverse reinforcements and rectangular interlocking ties, their strain change rules of longitudinal reinforcement, stirrups and concrete were discussed and analyzed. The main results indicate as follows. The maximum tensile strain of longitudinal reinforcement decrease and the tensile strain of concrete increase quickly as the axial compression ratios and the strength grades of concrete are higher; the strains of outer stirrups are all the time greater than those of inner stirrups; the single brace stirrups have the same action with the closed stirrups.

Abstract: Nonlinear finite element upheaval buckling model of buried offshore pipelines under HT/HP is built using ABAQUS. The petroleum is defined as uniform flow; temperature field of offshore pipelines produced in the process of petroleum transportation is obtained by heat transfer analysis; offshore pipelines are buried in trench of sandy seabed, interaction between seabed and offshore pipelines is defined as friction, seabed interaction with offshore pipelines will limit the movement of offshore pipelines; coupled fluid-structure analysis for three phase model of oil-pipe-soil is conducted to obtain stress under HT/HP. Initial imperfection of pipeline is introduced to calculate upheaval buckling of buried offshore pipeline under HT/HP. Through numerical analysis, the axial force of pipelines under HT/HP is obtained and thus resulted in upheaval buckling.

Abstract: Given the global trend toward the expansion of the use of nuclear power, Koreas nuclear power industry has begun to work actively to make inroads into foreign countries. As formwork accounts for about 25 percent of the entire duration of a construction project, including nuclear power plant construction, and requires considerable efforts, to achieve a reduction in construction duration, it is necessary to reduce the duration of formwork. In this study, an actual site where Alumimum Form (AL-Form) was used as a system form in a nuclear plant construction site was investigated and analyzed. Through the analysis, AL-Form was found to be sufficiently economically feasible to be utilized in nuclear power plant construction. However, there are slight differences between general system form and AL-Form, and to activate the utilization of AL-Form skilled workers should be cultivated for the formwork and specific technologies for the AL-Form work should be additionally studied in the future.

Abstract: The development of a methodology for the accurate and reliable assessment of structural damages, as one crucial step in the structural health monitoring (SHM) field, is very important to ensure the safety, integrity and stability of structures. An improved adaptive differential evolution (IADE) algorithm is proposed for structural damage detection (SDD) based on DE algorithm and FE model-updating techniques. An objective function is defined as minimizing the discrepancies between the experimental and analytical modal parameters (namely, natural frequencies and mode shapes). It is set as a nonlinear least-squares problem with bound constraints. Unlike the commonly used line-search methods, the IADE approach, a heuristic method for the direct search of the optimal point of the given objective function, is employed to make the optimization process more robust and reliable. Some numerical simulations for single and multiple damage cases of a 25-bar space truss frame structure have been conducted for evaluation on the reliability and robustness of the proposed method. The illustrated results show that the IADE algorithm is very effective for SDD. It can not only locate the structural damages but also quantify the severity of damages. Regardless of slight damage or multiple damages, the identification accuracy is very high and noise immunity is better, which shows that the IADE algorithm is feasible and effective for SDD.

Abstract: The creep of concrete structure has a prodigious effect on bridge alignments and the stress control during the bridge construction. In the meantime, the problems such as pre-stress losses, bearing asymmetry sink ,the concrete box-beam deflection, box-beam web cracks, structure stress redistributing and so on, which make the bridge structure lose functions or even invalid early when it works. For these reasons, the construction monitor of the deformation and the long-term deflection of long-span bridges with high piers have important practical significance. Construction monitoring of prestressed concrete continuous beam bridge - new Tongyang canal bridge which adopt cantilever construction work is made.