Applied Mechanics and Materials Vols. 405-408

Abstract: A justified assessment of the work of constructions and their elements should take into account physical and mechanical characteristics of construction materials. Although taking physical nonlinearity and anisotropic features into consideration will make the design more complicated, it is strongly needed to develop tools and methods that cover all the specific features of the material more precisely. Mathematical methods of construction design that take physical nonlinearity into account are quite well investigated. They are: Newton Raphson method; modified Newton Raphson method which differs from the original version by the fact that the stiffness matrix has to be calculated only once at the first iteration and remains the same for several further iterations and steps of load; the method of growing stiffness which is quite efficient in dealing with problems of physical nonlinearity, and so on. But certain difficulties appear as we consider these problems from the point of view of physics: the majority of strength and plastic-yield criteria are not implemented in design process yet. That is caused by complicated mathematics and a need for more experiment in order to determine the constants in use.

Abstract: Take advantages of concrete to improve the stiffness of fiber reinforced composite material(GFRP), reference to the existing dimensions of concrete-filled steel tube pole, applicate GFRP-concrete structure in 35 kV transmission line. Change the various parameters of the poles in ANSYS, compare the maximum deformations and the maximum stresses of GFRP tube-concrete pole and concrete-filled steel tube pole. Results show that different parameters have different impacts on the mechanical properties of the poles, suitable parameters of GFRP tube-concrete pole were got and the technical specifications of the application of GFRP in various voltage levels should be perfected.

Abstract: The green materials of alumina (Al₂O₃) and titania (TiO₂) are to be well received in the modern building. Control of fabrication parameters when preparing small-scale samples for academic research is not difficult. In mass production environments, however, maintenance of the stable parameters becomes the critical issues. An advance mold design may overcome the issues. In this article, we design the convenience molds that can maintain a constant current density and to facilitate the occurrence of electrochemical reactions in designated areas. The high quality and functional green building materials can therefore be easily fabricated.

Abstract: Since the invention of modern concrete, in the mid-nineteenth century until the early 80s, the concrete remained a mixture of aggregate, cement and water, with no major innovations that significantly alter the performance of its properties. But in recent decades, concrete technology has undergone tremendous development that has occurred due to the development of techniques and equipment for the study of the concrete and the use of new materials.The concrete with lightweight aggregate have been used, mainly due to the low values of density, thus demonstrating the great potential of using this material in several areas of construction ^[.With the objective of analyzing the influence of the consumption of cement in conventional concrete and light, were molded, tested and compared body-of-evidence containing two different values of cement consumption. The values were compared with those obtained by other researchers, as well as with the ABNT NBR 6118:2003 ^[ and ACI 213R-03:2003 ^[.

Abstract: The chloride concentration distribution is an efficient method of evaluating corrosion characteristics of concrete structures.A number of concrete samples at various positions were drilled in Zhuhai area and the free chloride concentration of concrete were determinated.Besides,the influences of elevations,distances from the sea and the local environment on chloride were analyzed.The value of chloride diffusion coefficient and surface chloride ion concentration along various elevation at the sea were calculated according to Fick's second law.The results show that chloride's erosion aciton tends to reduction with elevation and it is the most serious at an elevation of 1 meter for concrete by the sea.There is the large convective depth in alternate wetting-dry ares.Whereas it is just about 0.02%-0.05% on the road,at the distance of 15 kilometers from the seafront,which indicates that the father away from the seafront,the weaker chloride's erosion action becomes.

Abstract: New-to-old concrete freeze-thawing durability affects the safety and normal service of structure. In this paper, the freeze-thawing resistance of new-to-old concrete with different rough substrate surfaces was studied. The roughness of substrate surface was characterized by fractal dimension. Test results show that freeze-thawing damage of new-to-old concrete has two stage changes: first stage, freeze-thawing damage increases rapidly, mainly caused by the damage of interface; second stage, freeze-thawing damage increases slower, mainly reflects damage of substrate and overlay. Compared with smooth surface, rough surface can significantly improve freeze-thawing resistance of new-to-old concrete. In a certain range, with the increase of fractal dimension, the freeze-thawing resistance improves. When the fractal dimension is beyond the range, the freeze-thawing resistance impairs while the fractal dimension increases. A freeze-thawing damage model applied to new-to-old concrete is proposed, and a good correlation is found between the model and experimental results.

Abstract: Mechanical properties experiments of concrete after 0, 25, 50 and 75 freeze-thaw cycles under uniaxial and multiaixial compression were carried out. The uniaxial and multiaxial compressive strengths of ordinary concrete after freeze-thaw cycles were measured. According to the experiment results, the influence of freeze-thaw cycles on the ultimate compressive and tensile strength was analyzed systematically. The influence law of freeze-thaw cycles on compressive strength of concrete under multiaxial compression was obtained. The results indicate that the compressive strength of ordinary concrete after freeze-thaw cycles under multiaxial compression is higher than that under uniaxial compression, and the degree of improvement is depended on its stress ratio. This conclusion can propose theoretical foundation for design of concrete structures in cold environment

Abstract: Volume expansion is the distinguishing characteristic of concrete occurring AAR. Expansion performance of mortar with different particle size composition aggregate was tested in this paper. The result show that MR specimens with part alkali active sand and R specimens with total alkali active sand present obvious expansion. But expansion ratio of NR specimen with inactive sand remains generally stable and is only 0.02%. Ultimate expansion ratio of specimen due to AAR is not in proportion to content of alkali active aggregate. There is a possible ratio for alkali active aggregate and inactive aggregate to acquire a larger ultimate expansion account. Furthermore, expansion ratio of specimens due to AAR and reaction time present the exponential function relationship.

Abstract: To obtain the similarity relationship between the simulation experiment and the field experiment of chloride ion erosion in the concrete under the marine environment, on the basis of chloride ion ingress concrete under the onsite marine environment in Zhou Shan, a series of field corrosion tests involving the chloride ion ingression in the costal tidal zone are carried out. By simulating the environmental parameters of the tidal zone, the onsite environmental elements are simulated and modified in order to accelerate the ingress of chloride ion in the concrete. And the accelerated experiment is designed and completed. By comparing the results from the indoor accelerated experiment and the field test, the similarity of the main ingress parameters between the indoor and onsite durability experiment is analyzed.

Abstract: Recent years, massive projects construct in coastal zone in china , but soil in these coastal areas often contain organic matter.And the high levels of organic matter reduced soil strength which consolidated by concrete mixing pile.This paper take the organic sand as the research object,analysis the formation of such organic sand by electron microscopy scanning and indoor experiments.