Advanced Materials Research Vols. 631-632

Abstract: In order to investigate factors influencing workability of recycled aggregates (RA) concrete, such as water amount, sand ratio and RA replacement percentage, 10 pitch of RA concrete was prepared for measurement of workability and a formula was used for calculating effect of water amount on slump of RA concrete. Experimental results and formula induction indicated that there are logarithmic relationship between flowability of fresh concrete and water amount and ratio of aggregates to cement . The flowability will logarithmically increase with increase of water amount and decrease of aggregates cement ratio. The optimum sand ratio for RA concrete can be determined by measurement of slump. Slump decreases with RA replacement percentage and there is a very good linear relationship between them. When water amount increases, slump increases and when replacement percentage of RA increases, slump decrease. Under different water amount, effect degrees of replacement percentage of RA on slump are very similar and under different replacement percentage of RA, effect degrees of water amount on slump are also very similar.

Abstract: The research on the history of load and temperature to the influence of rock’s damage and fracture is rare. Commonly, it takes no account of the order of load and temperature and despite how the load’s history which arose its damage of thermal fracture is, the process of damage evolvement and the intensity of fracture is same as long as adds of carry is similar to temperature value. However, the thermal influenced by the history of adds of temperature and the result will be different under different order of adds of carry. This paper carries through meso-structure experiment of different order of adds of carry and temperature by the numbers, observe the process of limestone’s thermal crack damage under the different order of adds of temperature and carry on real time with instrument such as DaoJin High Temperature Fatigue Testing System with Scanning Electron Microscope. In the view of the rock’s tiny crack growth, compute its crack tip energy release rate under different order of adds of carry. The result of theory and experiment indicate that the fracture of rock’s thermal cracking are intensively influenced by the history of adds of carry.

Abstract: There are some disadvantages in the concrete pouring method of column beam joints of super high-rise structures. If the concrete of joint core use the same strength grade with beams and plates, and pouring with them together, the construction process will be simplified and the construction quality will be easier to ensure. But the concrete strength of joint core is reduced, so whether the resistant behavior of the structure can be able to meet the design requirements is the key problem we focus on. The finite element model of a super high-rise structure was established by MIDAS software, the holistic resistant behavior of the structure was analyzed to study the effect of joint core concrete strength on the whole structure. The study provides the basis for further exploring a more reasonable pouring method of the concrete of the joints.

Abstract: A dual-zone reinforcement ply stacking sequence optimization method used for comosite laminate with large cutout is present. The optimization method utilized a new Genetic Algorithm. The new Genetic Algorithm introduced a new strategy which can improve the efficiency of the traditional Genetic Algorithm and overcome the shortages of the worse convergency and prematurity of the Simple Genetic Algorithm. In the new Genetic Algorithm, the selection probability and the mutation probability are self-adaptive. Compared with the Simple Genetic Algorithm, the new Genetic Algorithm method shows good consistency, fast convergency and practical feasibility. By using the new Genetic Algorithm, the reinforcement ply stacking sequence optimization method got reasonable symmetric and balance stacking sequence which could meet the design requirements.

Abstract: A nonlinear analysis program for the capacity of L-shaped columns with numerical integral method is complied. Using the program, the Date of Mx-My curves under different axial compression ratios is obtained for five different reinforcement of equi-eimb L-shaped reinforced concrete columns.The maximum moments in various loading angles are analyzed, the cross-section’s ability to bear load influenced by different reinforcement is discussed, The rational reinforcement of equi-limb L-shaped reinforced concrete columns is derived. The date shows that the theoretical values and experimental results meet closely. Finally, Some suggestions in practice design for equi-limb L-shaped columns are given.

Abstract: Cement bonded particleboards were manufactured form grapevine stalk particles. The physical and mechanical properties of the boards were assessed. Results revealed that the mixture of grapevine-cement for either treatment of particles, was graded as “low inhibition” when CaCl₂ was incorporated, as determined by the hydration tests. Three factors namely grapevine-cement ratio, water-cement ratio and particle size were applied in this study for the board manufacturing. Increase in grapevine-cement ratio caused decrease in Modulus of rupture (MOR), Modulus of elasticity (MOE), Internal bond (IB), thermal conductivity and increase in Thickness swelling (TS). Increase in water-cement ratio caused decrease in MOR, MOE, IB, TS and thermal conductivity. The particle size resulted in little change in all, but TS. The MOR, MOE, IB of the boards were significantly affected by grapevine-cement and water-cement ratios except for TS. Only the effect of particle size on thermal conductivity is significant at 0.05 level significance.

Abstract: Dynamic mechanical properties of silica fume concrete in a number of strain rate under the conditions of dynamic compression mechanical properties subjected to various strain rates were studied, and gained the stress versus strain curves, details of an experimental investigation using 74 mm-diameter split Hopkinson pressure bar(SHPB) apparatus were presented. The results showed that: The admixture of silica fume concrete impact resistance, especially under the impact of the performance of high-speed has a very important influence, with the impact velocity increased, the strain rate increase, and its impact more obvious.

Abstract: This paper deals with the influence of the steel-concrete interface quality on the steel bar corrosion. Electrochemical methods including linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) were comparatively used to monitor the corrosion process of reinforcing steel in cement mortar. Experimental results show that a good quality of steel-concrete interface can significantly delay the corrosion initiation and reduces the corrosion rate. The results highlight the reasonable correlation between the impedance response and the Rp values by LPR method, but the corrosion rates obtained by EIS are lower than those results of LPR.

Abstract: Soils have nonlinear stiffness and develops irrecoverable strains even at very small strain levels. Accurate modeling of stress-strain behaviour at various strain levels is very important for predicting the deformation of soils. Some existing stress-strain models are reviewed and evaluated firstly. And then a new simple non-linear stress-strain model is proposed. Four undetermined parameters involved in the proposed model can be obtained through maximum Young’s module, deformation module, and limit deviator stress and linearity index of soils that can be measured from experiment directly or calculated by empirical formulas indirectly. The effectiveness of the proposed stress-strain model is examined by predicting stress-strain curves measured in plane-strain compression test on Toyota sand and undrained triaxial compression test on London clay. The fitting results of the proposed model are in good agreement with experimental data, which verify the effectiveness of the model.

Abstract: As the core elements of competition, Industrial design plays a great role in product innovation and management innovation and incentive. In recent years the integrated ceiling market develops rapidly in our country in which the industrial design of integrated ceiling product innovation has played a huge role in promoting. The application of industrial design in integrated ceiling product innovation is mainly divided into four aspects: technical innovation, market innovation, design innovation, design management innovation. As a result of these four aspects of innovation, integrated ceiling industry successfully realizes upgrading.