Advanced Materials Research Vols. 378-379

Abstract: It is a knotty problem in the actual project, that contraction deformation produce stretching stress on the concrete engineering. To counter deformation characteristic of the large-scale concrete foundation mat in construction temperature field,this paper has put a complete set of compute mechanics model of stress analysis and influence limits of constrained deformation on the basis of Saint-Venant’s principle. A number of computing formulas were inferred with theory of materil mechanics and structural mechanics,so that have obtained a set of analysis methods.By theory analysing and computing an actual project, it was that compute result accorded with structure law and the seat of compute crack was identical with cracking seat of the actual project.So, the achievement has the same values about the theory and the engineering application.

Abstract: In this paper, a storage cell for the high level radioactive wastes is studied in order to identify and demonstrate the coupled phenomena evolving in the high level radioactive wastes (HLW) storage. According to the various important processes in the storage structures, special attention is paid on the coupling elastoplastic and viscoplastic damage processes in short and long term. In the calculations, the complicated thermo-hydro-mechanical coupling process has been taken into consideration. These numerical calculations allow us to obtain some quantitative results describing the mechanical behaviour and coupling thermo-hydro-mechanical processes for a short-and long-term in the storage cell.

Abstract: In order to analyze the distributing condition of urban passenger flow scientifically and correctly, the disaggregate Dogit model is presented to predict the public transportation share ration in city, which is carried out by means of analysis of the outer and inner factors that affect the choice of modes of transportation and is based on the random utility theory. Establishment of the model, parameter identification and the process of calculation are described in detail. Finally, according to the proposed algorithm, the public transportation share ratio forecast test is carried out using the field survey data. The results of independent sample test indicate that the model has a finer precision and stability.

Abstract: How to accurately predict peak traffic is difficult for various forecasting models. In this paper, least squares support vector machines (LS-SVMs) are investigated to solve such a practical problem. It is the first time to apply the technique and analyze the forecast performance in the domain. For comparison purpose, other two non-parametric predictors are selected because of their effectiveness proved in past research. Having good generalization ability and guaranteeing global minima, LS-SVMs perform better than the others. Providing sufficient improvement in stability and robustness reveals that the approach is practically promising.

Abstract: At present, many experts and scholars use theory way to search the concrete’s dry shrinking stress. According to action and in-action principle, the writer designed one experiment model indoor to test the concrete’s stress variety in construction stage by the stress and strain apparatus. In this experiment, successfully collected the data of the stress variety with the time in 0~24 hours of concrete plank-placing in unit width. Through analysis the data, discover the regulation that dry shrinking cause crack in concrete’s construction stage.

Abstract: Based on the purpose of the bridge health monitoring, a new health monitoring system, including hardware and software part, is proposed for cable-stayed bridges in detail. The system is categorized as five sub-systems covering sensor system, data acquisition system, data analysis system, simulation analysis system, and warning system. Many monitoring parameters including environment wind, temperature field, humidity field, strain, deflection, cable forces, and traffic can be obtained by those five sub-systems. The purpose and monitoring content of each parameter are illustrated in the paper, and moreover, the method of the layout of the measuring points is put forward.

Abstract: Dynamic stability of suspen-domes is analyzed in the paper. Theoretical investigation is conducted based on the Lypumov dynamic stability theory. Based on B-R criterion, an improved method to evaluate the dynamic stability of suspen-domes is proposed. According to the method and time-history response curves, the dynamic stability of the suspen-domes is evaluated under horizontal seismic excitations. The dynamic stability characteristics, stability mode and cable mechanical behavior of the suspen-domes with different rise-span ratios are analyzed. The results show that the effect of the rise-span ratios on the dynamic stability is different. When the exciting acceleration approaches the critical point, some cables may relax, but they may be tensed again.

Abstract: The scaled boundary finite element method (SBFEM) was extended to solve dam-reservoir interaction problems in the time domain and a dynamic stiffness used in the SBFEM of semi-infinite reservoir in the time domain was proposed, which was evaluated by the Bessel function. Based on the dynamic stiffness, transient responses subjected to horizontal ground motions were analyzed through coupling the SBFEM and finite element method (FEM). A dam was modeled by FEM, while the whole fluid in reservoir was modeled by the SBFEM alone or a combination of FEM and SBFEM. Two benchmark examples were considered to check the accuracy of the dynamic stiffness. Results were compared with those from analytical or substructure methods and good agreements were found.

Abstract: The changes of tunnel rock stress caused by dynamic load is a hot point in geotechnical engineering. The paper introduces seismic methods of seismic design codes in China. The paper select state road 318(Huangcaoping part)as an example. Using finite difference software to analyze the rock pressure changes around the lining-tunnel with different seismic inputs. Comparing the results the rock static pressure and find the relative amplification factor between dynamic pressure and static pressure. Based on the results of analysis, we can obtain the following conclusions: As the peak ground motion acceleration increases, the peak value of tunnel rock increases, too. The amplifications change in a small range. The oblique parts of tunnel are the weakest parts of the tunnels. In different areas, the amplifications change a lot. The maximum ones are in the area of oblique.

Abstract: Considering the grey feature of traffic accident occurrence, grey model optimized by least-square theory is introduced to prejudge the future trend of traffic accident. To improve the prediction precision of this model, an amendment factor of boundary value and Markov chain are proposed and the numerical application proves the effectiveness of this Grey –Markov predict model.