Advanced Materials Research Vols. 255-260

Abstract: The uniform design is a new design method for investigating the experiment with many factors and levels, which can get enough experiment information with less experiment times. The advantages of uniform design are introduced in the paper, it can seek experimental points to be uniformly scattered in the experimental domain, which reduce experiment times greatly and get good experiment results. The new polymeric grouting experiment is designed by uniform design and the experiment data has been studied by regression analysis. It is proved that distinct influencing factor on grout diffusion radius are grouting pressure and permeability, but the influences of grouting time and grout temperature are smaller, their relation has been obtained through regression analysis, uniform design is efficient and credible method of experimental design by the experiment results.

Abstract: Cyclic stresses around welding joint-part affect the strength of mechanical components. In order to understand the fatigue phenomena caused by the cyclic stresses, non-destructive methods that can be related to number of stress cycles are necessary. In the present work, we used a newly developed scanning Hall probe microscope (SHPM) equipped with a GaAs film sensor and observed three dimensional magnetic fields of the specimen before and after four point fatigue testing at room temperature in air. Low carbon steel plates (JIS, SS400) were used in the experiments. It was found that the intensity of the magnet field in a direction perpendicular to the specimen surface was strongly affected by the fatigue testing. This result means that we can evaluate the fatigue in welding-joint area using quantitative magnetic field measurements. Furthermore, it was discovered that the key factor to evaluate the fatigue is the range between “S” and “N” (“peak-to-bottom” values) of the magnetic fields.

Abstract: Using BFRPS to increase strength and durability of the structure has recently started to be used as a new technical mean. In this paper, eight BFRPS timber columns under axial compressive loads are tested, and damage characteristics and mechanical properties are studied based on the testing results. Compared with the components which are reinforced and not, the relationship between the effects of bearing factors and increasing degrees can be concluded, providing reference for the similar engineering problems.

Abstract: Prestress suspendome structure is a new two-double space structure system, which is composed of single-layer spherical reticulated shells and cable-strut tensile structure, and taking full advantages of two systems. Compared to single-layer shells, stiffness and stability are improved effectively. Compared to cable dome, designing, constructing and joint treatments are simplified much more easily. In this paper, taking geometrical nonlinearity and material nonlinearity into account, the stable ultimate bearing capacity of Schwedler suspendome was analyzed theoretically by employing a nonlinear finite element method. Structural parameters of the suspendome, such as prestresses of cables, heights of struts, rise-span ratio and cable layout, which influence the structural stable ultimate load-carrying capacity, having been analyzed by employing the two-double computational mode of Schwedler suspendome of 40m span. Some valuable and reasonable conclusions are drawn for practical engineering design by theoretically analysis.

Abstract: The area of mountain ridge accounts for the most part of our country land. With the development of economic construction, more and more long span bridges have been built in the mountainous region of the western in China.. Combining live observed wind with numeric simulation, the wind characteristics on the western gap of valley areas are studied. On the one hand through the self-development processing of the bridge speed data to analyze massive wind observation data, the parameters (such as wind speed profile, turbulence intensity, power spectral density) used as the main basis for calculating wind loads are achieved. On the other hand wind flow around the bridge site as well as the environment around the mountain wind flow, wind speed field and the distribution of turbulent flow, etc is obtained by using CFD technology. Based on the results that is compared with that of numerical simulation by FLUENT, the reliability and efficiency of the program is testified. It would be provided with great theoretical significance and practical engineering value passes through the foregoing study.

Abstract: South pile foundation of Ma On Shan Yangtze River Highway Bridge is big, deep, soft soil, groundwater rich. In order to guarantee the safeties of the foundation, its foundation pit supporting schemes are compared, selected and calculated, finally lock mouth steel pipe support is selected as the design and construction scheme. The three-dimensional simulation analysis of the scheme is calculated by using MIDAS software, simulated four construction condition is presented, and stress and deformation results of retaining structure on various operating conditions is obtained. The calculation results show that the palisade structure basic satisfies the requirements of caps excavation and caps concrete construction. The results of construction show that the construction method, model and parameters used in this paper are basic right, the reasonableness of Supporting is confirmed and for the similar large foundation pit construction provides useful reference.

Abstract: Risk matrix is applied to evaluate seismic risk on mountainous bridge. In this article, a continuous bridge is used as example to analyze the seismic risk of key position under a usual earthquake. Related control method is proposed to provide technical support for bridge seismic design and operation maintenance.

Abstract: The collapse of structures caused by earthquakes causes catastrophic loss of life. Such collapse is typically caused by the inability of the structural system to redistribute its loads following the failure of one or more structural members to carry gravity loads. To study its mechanism in detail, numerical simulation is a significant method to reproduce the whole process of collapse in structural level. However, the traditional method was based on macro factors for collapse analysis and energy change in collapse process was less analyzed before, in fact, the kinds of energy components change with earthquake acceleration inputted and therefore it is necessary to analyze structural whole collapse process in terms of energy method. A three-dimensional computer simulation of the collapse of a real steel frame structure has been conducted using the LS-DYNA computer program in this paper. The responses and kinds of energy components of the structure under seismic loads are analyzed at different ultimate plasticity strain values and the strain energy change rate method for evaluating structure collapse is proposed in this paper. At last, the three main collapse patterns of structures are proposed.

Abstract: The removal efficiencies of sulfamerazine (SMR) and sulfamethoxypyridazine (SMP) in aqueous solutions were studied using advanced oxidation technologies. The results show similar removal kinetics for two sulfa pharmaceuticals and that complete removal of all is achieved within 90 min of ozonation at the concentration of O3 (1 mgL^-1) without controlling the pH. The rate constants were calculated as 0.0143 and 0.0113 min^-1 for SMR and SMP, respectively. The catalysts exhibited a superior removal efficiency of SMP to those of SMR with a TiO₂ concentration of 2.0 gL^-1. The disappearance of these two sulfa pharmaceuticals follows a pseudo-first-order kinetics according to the Langmuir-Hinshelwood (L-H) model. The rate constants were calculated as 5 × 10^-3 and 6 × 10^-4 min^-1 for SMR and SMP, respectively. Advanced oxidation processes (AOPs), such as O₃ and UV/TiO₂ processes should be an effective treatment for removing these sulfa pharmaceuticals.

Abstract: Exampled with the project of front slope for Deng cao-tang tunnel outlet, the front slope is treated with prestressed anchorage cables. The reason of front slope cracking is analyzed. Moreover, the stress distribution of anchorage cables has been monitored so as to obtain the stress distribution in time. The results offer scientific basis with the treatment effect of front slope so that the safety of tunnel construction in ensured. The study has been great theoretical significance and practical value.