Applied Mechanics and Materials Vols. 556-562

Abstract: Microwave curing of PU/EP IPN was studied in this paper. Microwave curing IPN was prepared by means of intermittent microwave heating, The results indicates that microwave curing technique can shorten curing time remarkably. The microwave curing and thermal curing IPN have identical structure, tensile property of microwave curing IPN is better than that of thermal curing IPN, Impact strength of thermal curing IPN is slightly higher.

Abstract: When long-span pre-stressed concrete bridges are subjected to concrete creep and temperature load , bridge deck deformation will be aroused. Then the additional track irregularity will be generated. It brings about the result that the dynamic response of train-track-bridge system will be influenced. In this paper, with the train-track-bridge coupling vibration theory, a (90+180+90) m continuous beam-arch combination bridge located on a certain passenger line is analysised comparatively, by considering the effect of concrete creep and temperature deformation. The results show that, the track irregularity caused by the concrete creep and temperature deformation influence the wheel unloading rate and the vertical accelararion of the train so obviously with the speed increasing. It can be concluded that the track irregularity need to be considered, especially for high-speed trains.

Abstract: To study the grouting detection standard of Karst roadbed based on resistivity method, transient Surface wave method and electromagnetic wave CT, the typical test areas in the Karst roadbed of NANNING-GUANGZHOU railway are selected, and the field test research of grouting detection standard of Karst roadbed was studied by the above three geophysical methods. The grouting qualified Karst roadbed was determined by multiple methods of borehole coring and field water pressure after grouting, and the test results of Karst roadbed grouting qualified was confirmed effective sample. The difference value of resistivity, surface wave velocity and electromagnetic wave absorption coefficient of limestone layer, clay, pebble soil and Karst cave was statistical analyzed based on the effective test data, and preliminarily obtained the detection standard of Karst roadbed grouting effect based on the above three geophysical methods.

Abstract: Studied a variety of factors that affect the efficiency of electrochemical desalination. Using electrochemical methods and analytical chemistry methods etc. depth studied efficiency of electrochemical desalination on different energizing time, current density. Through comparative analyzing, evaluated these factors influencing preliminarily.

Abstract: Slow strain rate tension tests were carried out in order to investigate effect on new corrosion inhibitor to stress corrosion cracking of prestressed steel wire in simulated concrete pore solution. Indeed, the results suggest that C₄H₁₃N₃ can form adsorption film on the metal surface, prevent chloride ion erosion. Meanwhile, MoO₄^2- may make the passive film become denser. The synergistic effect of C₄H₁₃N₃ with MoO₄^2-, can reduce the prestressed steel wire SWRH77B in 3.5%NaCl+ saturated Ca (OH)₂ solution stress corrosion sensitivity, prevent stress corrosion cracking effectively.

Abstract: To analyze the axial compression bearing capacity of concrete filled double skin steel tubular (CFDST) stub columns which are filled with demolished concrete lump, twelve stub columns are tested. The main experimental parameters were the diameter-to-thickness ratio, mixing ratio and hollow section ration.Load-displacement curves and failure mode were analyzed, the compressive capacity determined from related design rules were compared with the peak load obtained in the tests. All specimens have a good performance of ductility and late bearing capacity. When the width-thickness is 72 and have a same mixing ratio, CFDST have the same bearing capacity with CFT. When the mixing ratio is 0 and width-thickness is 120, the bearing capacity of CFDST increase 16% than CFT. When the new concrete have similar compressive strength with old and mixing ratio is 25%, the bearing capacity of CFDST increase 18.8% than CFT.

Abstract: Using large-scale finite element analysis software ANSYS analyzes seismic respons of prestressed concrete bridge, respectively establish finite element model under viscoelastic boundary conditions and elastic boundary conditions, compare and analyze seismic respons of bridge structure under two kinds of boundary conditions. Compared with elastic boundary conditions, viscoelastic boundary conditions not only can simulate elastic recovery performance of foundation, but also can realize infinite medium radiation damping. The research results provide the basis for the seismic design and protection of bridge.

Abstract: In this paper, finite element model of the Qingyi River rectangular section reinforced concrete aqueduct is set up by using three-dimensional finite element analysis software ANSYS. Considering the conventional static load, the seismic loads which use quasi-static method, and considering five combinations of operation condition of aqueduct in operation process, the structure stress and displacement rules of aqueduct are obtained in the different conditions. The results show that the rectangular cross-section aqueduct in the water level under the action of the full tank, the vertical displacement of the aqueduct body structure is nearly doubled than the empty slot, indicating the water load have a significant impact on the aqueduct. The calculated results has a good precision, can meet the needs of practical engineering, can provide a reference basis for the design of thin-walled rectangular aqueduct and the theoretical basis for engineering practice and guidance recommendations.

Abstract: Temperature is one of the main loads of concrete dam, adverse temperature load can lead to the dam body cracks, this paper study temperature load’s influence on concrete gravity dam. This paper use finite element method, it adopts finite element calculation software to establish concrete gravity dam’s finite element model of Jiangya hydropower station. Based on monitoring data of water temperature, air temperature, dam body temperature, foundation temperature about Jiangya hydropower station, calculates and analyzes temperature field of dam during operation period, researches stress variation law of dam under the influence of temperature field. The results showe that, temperature load has a great influence on the dam operation, but dam still meet code design requirements; when continuous high temperature during summer, dam should avoid operate under high water level; when continuous low temperature during winter, dam should avoid operate under low water level. Research results provide theoretical according for concrete gravity dam’s safe operation of Jiangya hydropower station.

Abstract: The splitting tensile method for the tensile strength of concrete is usually used in structural applications, so it is great important in the investigating the relation between the direct tensile strength and the splitting strength. But the relationship between the splitting strength and the direct tensile strength is not consolidatly confirmed at home and abroad. In order to obtain the exact results, the experimental apparatus for concrete of the direct tension are designed, which resolves the difficulty of ensuring that the load is truly axial. Tests of the direct tension are performanced on three different concrete mixes (C20,C40,C60) at 3, 7, 14 , 28 and 60 days and the test data do not scatter. The relations between the tensile strength and the cube compressive strength are obtained and a formula for investigating the relation between the direct tensile strength and the splitting strength are proposed.