Applied Mechanics and Materials Vols. 71-78

Abstract: Recycled concrete aggregates have large porosity, large water absorption and high crush index. The performance reduces dramatically compared with ordinary aggregates. Mechanical properties of recycled concrete aggregates could be improved by adding sugar water reducer. On the basis of the experimental studies, this paper analyzes the influences on recycled concrete setting time and its compression strength at different ages when various amounts of sugar water reducer are used. The mechanism of strength increase is also discussed on the view of porosity. The results show that sugar water reducer has a high enhancement on compressive strength of recycled aggregate concrete, which provides the experimental and theoretical foundation for the application of recycled concrete aggregates in practical engineering.

Abstract: In recent years, as the portal frame’s height toward higher and the span toward wider, the influence of wind vibration becomes more and more prominent among the portal frame structure. In the design of the portal frame, there are many different opinions on whether considering the impact of the vertical wind vibration to the portal frame. This paper taking a true engineering as an example, using finite element software to establish the solid model of the portal frame structure, selecting the junction of purlin and roof as a node of imposing vertical fluctuating wind load, we made numerical simulation analysis of vertical wind vibration. The simulation results will be compared with data of the internal forces and deformation under the average wind pressure. The results showed that: vertical wind vibration has a prominent effect to the portal frame and should be considered in the design.

Abstract: Wind-induced dynamic responses of light-weight steel structures with gabled frames are significant because of their light weight, small stiffness and long natural period, according to Reference [1]. While the current "Technical specification for steel structure of light-weight buildings with gabled frames" (CECS102:2002) and "Lode code for the design of building structures” (GB50009-2001) generally don’t consider the wind-induced vibration influence of gabled frames. Based on rational model, the light-weight steel structure with gabled frame subjected to wind load is simulated by finite element software. The numerical simulation about horizontal wind-induced vibration response is carried out. Calculated results show that the influence of horizontal fluctuating wind load is harmful for light-weight steel plants with gabled frames and suggest that more attention should be paid in design.

Abstract: In the process of the highway building, especially in mountain region the some complex geological conditions often appears. In this paper, using the slope of highway with weak interlayer as the research subject, systematically analyzing the stress field and plastic field during the excavation of the slope, obtained the failure mechanism of the slope with weak interlayer, which is a cyclic process that weak interlayer shear failure led to the tensile failure of its upper mass rock. It has extraordinarily important guiding significance for the protection and reinforcement of similar slope.

Abstract: The performance of buckling-restrained brace and the stress mechanism of interior joints in RC frame are both briefly introduced,based on which interior joints strength of buckling-restrained braced frame of reinforced concrete is studied，and contributions to the shear strength of the joint made by brace is therefore summarized. These results can serve as references for the design of interior joints strength of buckling-restrained braced frame of reinforced concrete to meet the “strong connection-weak connected member” requirement.

Abstract: In order to analyse the potential of reducing energy consumption of the system ,which based on evaporative cooling and radiant air condition in civil building.In this paper,firstly,calculated cooling load of a office building in Xinjiang, China.Then analysed and compared the design methods,operating cost and investment cost of three semi-central air conditioning systems. The result shows that radiant air conditioning based on evaporative is low energy consumption , operation cost is 43 percent of conventional primary air fan-coil system .

Abstract: Electrokinetic removal is a new kind of technology and it is paid close attention in many countries. This work shows the laboratory results of electrodialytic removal experiments about the fly ash from municipal solid waste in Chongqing. The characterization parameters of the electrolyte solution pH, electric current, electrical conductivity, voltage gradient were discussed after the experiment. The pH value changed smoothly in the cathode compartment, while it changed abruptly in the first 6 hours, but it changed smoothly in the rest time in the anode compartment. The electrical current increased in the first 50 hours, then gradually decreased in the rest time. The higher the electrical current is, the better the removal effect is. The electrical conductivity in the anode compartment increased while the electrical conductivity decreased in the cathode compartment. The higher the electrical conductivity is, the better the removal effect is. The metal hydroxide precipitation was the most serious factor that influenced the removal rate.

Abstract: This paper discusses particle deposition in rectangle air-conditioning duct using RSM (Reynold Stress Model) and random trajectory particle model. Particle with nominal diameters of 10-200μm are simulated at each of three nominal air speed: 4m/s, 6m/s and 8m/s, respectively, in the cross-section sizes of 160×120, 500×250, 1000×320mm. In simulation, the paper compares and analyzes the influence factors of particles deposition in volume surface ratio of the given duct. The results show that: 1) particle deposition velocity increases with volume surface ratio; 2) As the inlet air speed increasing, when the particles deposited to floor and vertical wall, the image of dimensionless deposition velocity Vs dimensionless relaxation time shows a coincident trend when the duct cross-section sizes are 500×250, 1000×320mm, but has great differences with the image of 160×120mm.

Abstract: The historic towns in Yuan River basin, with the same origin in water and mountain, has similar geographical environment, interlinked regional economy and inclusive multi-ethnic culture, all of which have a large contribution to both similarities and differences of the space forming of the historic towns. The space form respects for nature with the flexible layout and embodies the leading role of the water transport economy for space form of ancient town. The towns have Similarity of space form elements, convergence of space combinations, ecological of spatial layout and other features. At the same time, diverse types of spatial forms showed peoples wisdom and courage of adapting to nature and working out measures to suit local conditions in Yuan River basin. All these previous experiences supply valuable experience for construction of the small historic town in the present.

Abstract: In view of the characteristics of the natural conditions in tidal zones, systematic innovation and improvement have been made in the techniques to execute conventional vacuum preloading technology in combination with sand cushions, technology for installation of prefabricated drains, sealing membrane and technology for laying sealing membrane, and technology for vacuum pumping, to overcome the difficulties in improving underground soft soils in tidal zones. Key techniques in improving underwater soft soils in tidal zones have been solved and the vacuum preloading technique was successfully used in improving soft soils in tidal zones, producing very good results.