Applied Mechanics and Materials Vol. 454

Abstract: The calculations of plan truss and beam-girder method on straight bridge were analyzed, which determined right beam-girder method calculation model of the box-girder bridge. Based on this model, the different radius continuous curved box-girder bridges were simulated by finite element, and then the internal forces of the bridge were obtained. The calculations of inner beam and outer beam show the change rule of internal force and bridge radius. The reasonable calculation methods of continuous curved box girder bridges are obtained, which can offer help to the bridge designers.

Abstract: Modification of pine woods which impregnated with formaldehyde-urea resin and subsequently cured by electron-beam (EB) radiation was studied. The results showed that the impregnated wood samples can easily cured by EB radiation under dose of 40~60kGy in air. And the water resistance and tensile strength of the wood samples were both improved significantly with proper treatments of impregnation and EB radiation curing.

Abstract: Energy is the material basis for human survival, economic development, and the social progress. With the growth of population and the improvement of per capita living standards in developing countries, energy becomes scarce. To improve the energy structure and seek sufficient stability in energy supplies has become issues of concern. Ground source heat just to meet the people's demand for energy, ground surface of shallow geothermal energy is a renewable energy stored. The ground source heat pump system pile are caring for two aspects: whether the pipes will influence the bearing capacity of the pile and whether the deformations of the pile will influence the buried pipes．In this paper, the bearing capacity influenced by the buried pipes is analyzed through the variation of the moment of inertia and the area of the pile．The results show that the buried pipes in the pile have little influence on the structures．

Abstract: The impurities removed from the vein quartz sands were investigated with six complexing agents (citric, oxalic, acetic, humic acid, EDTA and thiourea). So as to optimized the leaching reaction parameters and to reach a high rate of impurities removal, the kinds and concentration of complexing agents, reaction temperature and time were also discussed. The results shown that the impurities can be dissolved very effectively by both oxalic acid and acetic acid, and then, the citric, humic acid, EDTA and thiourea can also be increased partly rate of impurities removal. At the same time, the interior impurities of the vein quartz sands has been dissolved out that primary depended on the mixed acids which were 2.0M HCl, 0.5M HF, and 0.8M oxalic acid complexing agent at 80°Cfor 8h. The removal rate of elements Fe, Al, K, Na, Ca, and Mg were respectively 93.31, 47.06, 17.28, 28.82, 12.58 and 62.44 percent.

Abstract: With more and more precise calculation and analysis to the bridge, and its carrying capacity assessment and repair reinforcement universal attention, it is necessary to acquire the influence line of bridge responses corresponding with moving-load position. A method is presented to obtain the influence line by experiment. A laser rangefinder with large range is added to original test instruments. The moving load position parameter can be looked on as displacement after the signal conversion, which can be synchronously collected together with the response signal. The inverse function principle is introduced to process the data. The examples indicate that the present approach can accurately measure the influence line.

Abstract: The accurate sine-swept function is proposed by theoretic derivation. The natural frequencies of five-story steel frame structure in transverse direction were identified by modal test. Based on the numerical simulation results of steel frame structure excited by sine-swept vibration, it is proved that the difference of structural response between forward excitation and backward excitation is little,and both the results of them can be used to evaluate the dynamic property of structure. However, it is proper to decide whether the response results of structure should be modified or not based on the dynamic properties of table-board. The conclusions above can provide basis for design and dynamic time-domain analysis of shaking table test in sine-swept excitation.

Abstract: The effect of carbonation on compressive strength of cement-fly ash mortar which subjected to freeze-thaw cycles were investigated by means of orthogonal design method. The results show that carbonization time is the main factors affecting compressive strength of cement-fly ash mortar subjected to freeze-thaw cycles, followed by the water-cement ratio, the number of freeze-thaw cycles and mix amount of fly ash. Carbonization improves the frost resistance of concrete in some extent, and in a reasonable range, the longer carbonation time is, the stronger frost resistance capacity is.

Abstract: The different effect of chemical activators on mechanical properties and microstructure of cement-base repair materials were investigated. The microstructure of repair concrete was also analyzed by using scan electronic microscope (SEM). Test of mechanical properties indicate that the optimum chemical activator suitable to repair concrete with nearly 30% mineral materials replacement of cement is the type J-B, and the optimum addition is 5% dosage by weight of binders. The presence of chemical activator J-B increase the early strength and exert significantly advantageous affect on the later strength. Measurement of microstructure indicates that the surface of fly ash particle can be seen obvious pozzolanic reaction, and this is due to the presence of chemical activator which accelerate the pozzolanic reaction and densify the mortar pore structure.

Abstract: Stress analysis of the bolts used for Φ1.3m parabolic antenna was conducted in this article, and the strength of bolts was checked, the results indicated that the bolts can meet the strength requirements. This calculation result was verified by the static load experimental test of Φ1.3m parabolic antenna, and the experiment results agreed well with the calculation results. The calculation and verification methods provided a reference for the structure design and bolts strength check of the same type of antenna.

Abstract: In seasonal frozen regions, shallow landslide hazards in soil slopes usually happen. The type of failure surface is always on the freezing and thawing surface in the soil slope. So the direct influence factor of soil slope failure is the soil shear strength of the freezing and thawing (F-T) surface. The shear strength of the soil is determined by the two parameters of Cohesion c and Friction angle φ. In this study model experiment of F-T soil interface with different aggregate materials is designed by alternating the F-T cycle times, then the parameters c and the φ were obtained. Finally the deterioration modal of the two shear strength parameters of soil interface was put forward. The results demonstrated when the slope stability in the seasonal frozen regions was analyzed using shear strength reduction method, the two deterioration modals can provide the data reference for the analysis.