Advanced Materials Research Vols. 250-253

Abstract: The constitutive relation of concrete under uniaxial tension and compression is an essential theoretical basis for structural analysis of concrete. Because of the lack of sufficient stiffness for ordinary test device, a stable decline branch of stress-strain curve could not be obtained. The condition of realizing the stress-strain complete curve for concrete uniaxial tension and compression is derived. The experiment device for uniaxial tension and compression was designed and fabricated with increasing stiffness method. Experiments were carried out for concrete with grade C30~C60 and strain rate 10^-5/s~10^-2/s. The equation for stress-strain curve in the rising branch were obtained and so were the complete stress-strain curve of uniaxial tension and compression under different strain ratio, which provide the theoretical basis for concrete structural analysis.

Abstract: Based on the theory of the landscape ecology , this paper puts forward the ways of the landscape ecological protection, repair and replacement of the urban river system and emphasizes adopting the holistic and systemic view, which integrates river with its catchment area and combines stormwater infiltration, storage and usage with these in the process of river harness.

Abstract: The reconstruction in the area of Wenchuan Earthquake strives to be eco-friendly and recalls the question of how green. Built environment, which is reconstructed according to the green of eco-architecture, must contribute more positively to the planet and the pleasure of place as well as answering the sustainable demands of comfort. To address both technic and poetic issues in eco-architectural practice, in the design proposal for a Rural Sunshine Primary School located at Barkam County of Sichuan Province, low technologically, sensory experience of sustainable strategies is widely introduced to reinforce the meaning of green building and encourages the children in disaster area to make friends with nature and future. Three interactive issues, eco site plan, sustainability strategy and green environment, are introduced as the core concepts in the design, while the children in disaster area comfortably and sensorily experience daylighting, ventilation and thermal performance of green building.

Abstract: The unfired bricks which regarded as a new green wall material are produced by fly ash, shell ash (renewable resources), cement and lime as the main raw materials, and together with the chemical activator. The essential mixture ratio is designed on the experimental result of its mechanical properties and durability. The bricks are water conserved in the condition of normal temperature and pressure. We respectively research the compressive and flexural strength and frost resistance of the unburned brick. The results show that the optimum mixture ratio for unburned bricks are: fly ash 41%, cement 25%, lime 15%, shell ash 15%, gypsum 4%, SBR 3%, fiber 0.10%, water-reducing admixture 0.5%, sand cement ratio 0.5 and water cement ratio 0.3. We obtain the properties of unburned bricks that produced by vibration with the optimum mixture ratio. The minimum compressive strength of one brick more than 30MPa, the mass loss of one brick after 15 times freezing and thawing cycles is only 1%, and the compressive strength after frost reaches 26MPa, the overall performance of bricks can satisfy the requirement of " China Fly Ash Brick " standard.

Abstract: Cold-formed steel structure is suitable for post-earthquake reconstruction since its good seismic performance and construction speed. Analyzing the dynamic characteristic of a two story office building by using the finite element software ANSYS. And the results show that: (1) in the time history analysis based on three types of seismic waves the lateral displacement of the structure and rotation between layers to meet the relevant specifications when confront the rare earthquake (2) Under the seismic loads, earthquake response acceleration amplification factor is smaller which indicating better seismic performance and it can be used in areas with high seismic intensity.

Abstract: Powder of Ti-46at%Al alloy was synthesized through mechanical activation (MA) and then sintered and concurrently consolidated in a short sintering time of 900 s by using spark plasma sintering (SPS) process. The XRD and SEM profiles show that the microstructures of TiAl alloys contained γ TiAl and small amount α-2 Ti₃Al phase, whose amount can be controlled by the sintering temperature. The compacts retained the original fine-grained fully densified bodies by avoiding an excessively high sintering temperature. The alloys sintered at higher temperature with this process showed a coarser microstructure. So it is possible to produce dense nanostructured TiAl alloys by mechanically activated spark plasma sintering (MASPS) within a very short period of time.

Abstract: Mullite nanocomposites powders have been successfully synthesized from high-aluminium coal fly ash via hydrothermal crystallization process. The mullite nanocomposites powders are investigated and charactered by laser particle size analysis, BET surface area analysis, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) analysis, selected area electron diffraction (SAED) analysis and energy-dispersive X-ray (EDX) analysis. Moreover, the reaction mechanism is speculated according to MAS-NMR results. The experimental results show that mullite nanocomposites powders can be prepared at 80-90 °C for 3 h with NaOH concentration of 2-4 mol/L and L/S ratio (liquid/solid ratio in mass) of 10 mL/g. The powder size of D₅₀ is about 1.88-3.27 mm. Mullite nanocomposites are mainly rod-like, acicular and fibroid in shape with an range of 30-80 nm in length and an range of 4.5-30 nm in diameter. MAS-NMR analysis indicates that the nano-size mullite grow around the central atom-Al, Si of [AlSi]O₄ tetrahedral and the growth unit Al[OH]₄^- is existed in this process definitely.

Abstract: The research conducts the numerical analysis of the fatigue performance of precracked concrete beams strengthened with prestressed CFRP, establishing the static analysis model (SM) and fatigue analysis model (FM) respectively, examining the change of the static loading and fatigue performance before and after CFRP strengthens precracked concrete beams in the different prestressed situations, and analyzing the relevant fatigue performance parameters through comparing FEM analysis with experimental results. The research results demonstrate that the method of strengthening concrete beams with prestressed CFRP can improve the static loading and fatigue performance; the increased rate of fatigue performance of precracked concrete beams is parallel to the CFRP prestress; the fatigue life of precracked concrete beams increases with the raising of the CFRP prestress; FEM analysis is in close agreement with experiment results; the fatigue properties of precracked concrete beams strengthened with prestressed CFRP can be analyzed effectively by the finite element method.

Abstract: With the water tourism developed, making the development of water landscape rising rapidly. How to ensure the safety of hydraulic engineering technology under normal circumstances, and protect the ecological environment, play tourism economic benefits are an important problem in landscape design. Under the premise of following the principle of water conservancy landscape planning and design, applying AHP to research Xiya ditch waterfall landscape and optimize design program, then set up the preferred plan from ecological effect, waterfalls and technological factors three aspects of evaluation index. This provides theory basis for model test and engineering implementation in Xiya ditch waterfall landscape. In recent years, water conservancy projects relying on water industry form a large number of humanities landscape, natural landscape. The development of water tourism, gradually achieved a certain economic, social and environmental benefits. Giving full play to the comprehensive benefits of water conservancy projects, Ministry of Water Resources has granted water tourism as three major elements in water economy with water supply, power generation.

Abstract: This paper explores some strategies and concepts, for the design of mobile ecological buildings in the Qinling mountain area. The special environmental features of the Qinling Mountain area are first introduced, based on which general strategies, which emphasize structural portability and space flexibility, for the design of buildings in such areas are provided; the merits of the selected type of structure as well as the possible operation/function of the external and internal movable walls are then discussed in detail; The direction for further exploration in the relevant area is also recommended.