Applied Mechanics and Materials Vols. 71-78

Abstract: The EPS concrete with 10%，20%，30%，40%，50% EPS volume fraction were prepared. Taking critical strain as the index, the deformation property of EPS concrete with different EPS volume fraction under impact loading were studied using a 100-mm-diameter split Hopkinson pressure bar(SHPB) apparatus. The results show that the deformation property of the EPS concrete increases with the average strain rate for the strain rate effect, which takes on obvious strain rate dependency. For the EPS microscopic structure effect, the deformation property of the EPS concrete increases with the EPS volume fraction in 0~40%. Its deformation property reduces somewhat when the EPS volume fraction reaches 50%. To improve the deformation property, the optimum volume fraction of EPS is 40%.

Abstract: The mechanical properties of high-strength reinforced concrete beams strengthened with FRP ( fiber reinforce polymer) are further investigated theoretically including it s failure mechanism and loadability,based on earlier theoretical works on RC beams. And the correlation equation of flexural capacity on the cross section of high-strength reinforced concrete beams strengthened with FRP is deduced according to different types of failure.The correlation equation is shown to be in good agreement with the experimental results, which can be referred to engineering application.

Abstract: The curing characteristic of phenol-formaldehyde resol resins catalyzed with magnesium hydroxide, calcium hydroxide and barium hydroxide was studied in this study.The effects of catalysts on chemical structure of phenol formaldehyde resin was investigated by fourier transform infrared.The results indicated that divalent metal ions catalysts played an important role influence both the cure rate and cure time.Phenol formaldehyde resin catalysed by diffierent catalysts showed diffierent addition of formaldehyde onto ortho positions of phenolic rings.The order of the divalent metal ions effectiveness studied in alkaline conditions is calcium hydroxide, barium hydroxide and magnesium hydroxide.

Abstract: By means of XRD, SEM, FE-SEM, and TEM, the microstructures and growth morphology features of icosahedral quasicrystal for rapidly solidified Mg-Al-Zn system were investigated. It was found that, single icosahedral quasicrystal can be obtained in the Mg-Al-Zn alloys. The icosahedral quasicrystal reveals three typical morphologies: well developed dendrites, coral-like, and petal-like, and its compositions are in a wide range composition with 42.87-48.89 at.%Mg, 13.78-17.03 at.%Al, and 34.22-40.60 at.%Zn. Pentagonal dodecahedron with icosahedral symmetries is seen, and certain steps in pentagonal faces suggest that the planar growth occurs on the pentagonal faces.

Abstract: In recent 10 years, inclined concrete-filled steel tubular (CFST) columns are applied for some real engineering projects in China. And so a total of 10 specimens were experimented to study the behaviors of the rectangular inclined CFST stub columns. The main parameters were the inclined angle (0 degree and 9 degree), the inclined orientation (major axis and minor axis) and with or without infilling concrete. Comparisons with predicted sectional strengths were made using the existing codes. The results clearly show that all the codes were conservative and available for predicting the capacities of the specimens.

Abstract: Through determining Ca(OH)₂ content and chemically combined water content, hydration degree of cement with added-calcium thermal activated coal gangue may be analyzed. Variation of mineral composition during hydration process of system was analyzed by X-ray diffraction(XRD) method. Simultaneously, specific strength index was applied to study pozzolanic effect of activated coal gangue. The results can show high contribution of added-calcium coal gangue calcined at 1050°C for pozzolanic properties and high hydration reaction degree in this kind of activared coal gangue cement system, with fewer Ca(OH)₂ content, more chemically combined water content and obviously reduced hydration product Ca(OH)₂ at each age.

Abstract: Two industrial produced non-quenching and non-tempering steels 40Mn2V and 36Mn2V had been tested by Gleeble-1500 thermal simulation machine to simulate MPM rolling, sizing and cooling process. The cooling rate in the air noticeably affected the final property of different size pipes. According to the measured practical cooling rates of different size pipes, appropriate size pipes with cooling rate at range of 0.9°C/s~1.6°C/s and 1.6 °C/s~2.1°C/s can be picked out to use steel 40Mn2V and 36Mn2V to produce grade N80 OCTG(Oil Country Tubular Goods) with steady property respectively. This result had been used in practical production, which greatly improved the property stability of grade N80 OCTG.

Abstract: Flue gas desulphurization (FGD) gypsum and fly ash are two kinds of solid waste in coal-fired power plant. The possible displacement content of fly ash in gypsum plaster was investigated in this paper. The effect of various chemicals retarders, such as Citric acid, sodium citrate and SC gypsum retarder, and water retention agent on the setting time, flexural strength and compressive strength of gypsum plaster was also studied. The results demonstrate that gypsum plaster has maximum mechanical properties and enough setting time at the rate of 20% fly ash replacing calcined gypsum; SC gypsum retarder effectively delays the setting time and has lower strength loss; The optimum level of water-retention agent for effective utilization of gypsum plaster is 0.2%.

Abstract: Concrete filled steel tubes of square columns under axial load are in complicated stress, the influence of every factor on mechanics performance is difficult to ascertain accurately. Neural network performs well obtaining the relationship between input and output variables by self-studying, self-organizing, self-adapting and nonlinear mapping. In this paper a three-layer back-propagation model of network is successfully trained and set up according to experimental data of square CFT columns under load. Ten groups of experimental data were verified by the model, the results show the predicted values are in accord with test values, precision in calculation is good enough for structure design. So the neural network model can be used as an auxiliary method to calculate the capacity of square concrete filled tube columns in the project. With the increase of experimental data, the neural network precision of prediction will be improved in the future.