Applied Mechanics and Materials Vols. 94-96

Abstract: It is an innovative work to make the electromagnetic damper with strong magnetic material. Firstly, the structural research and the experimental research on the basic performance of electromagnetic damper have been made. Then the theoretical research is conducted based on the above research results. Thus, the paper put forward and deduced the electromagnetic damper restoring force model and the motion parameter’s effects on its performance. Such as vibration frequency and amplitude are also studied in the paper. The results showed that the new electromagnetic damper is characteristic of simple structure and good performance and that the theoretical model coincides well with the results obtained from the experiments. Keywords：strong magnetic material, electromagnetic damper restoring force model, vibration frequency, motion amplitude value.

Abstract: Five-hundred-meter Aperture Spherical radio Telescope (FAST) is designed to be supported by geodesic form cable-net structure which is suspended from the ring beam. Based on the initial design, the present work has performed a further optimization to reduce the types and quantity of the connections between the cable-net and the ring beam. Furthermore, the finite element model has been established to study the influence of the deadweight of the reflector element on the force distribution of the cable-net structure, and the sensitivity of angle deviation of down tied cable to the control accuracy of cable net deformation has also been discussed.

Abstract: Abstract. Based on the concept of energy design, pushover analysis and elastoplastic dynamic response have been made under the earthquake. It is seen that the loading mode plays an important role in the pushover analysis. The loads in the pushover analysis distribute along the height of the structure that should reflect the distribution of the inertial forces under the earthquake so that the calculated displacements have a good accuracy in contrast to the real displacements. Only in such a way, the result by pushover analysis method is credible. On the other hand, it is found that the high order vibration modes can not be neglected in the pushover analysis for a continuous rigid frame bridges with long span and high piers. However, the bridge design codes have not told how to consider the effect of high order vibration modes. A simplified loading mode is then proposed in this work. A contribution ratio of vibration mode is defined to indicate whether the vibration mode should be considered or not in the pushover analysis. The proposed loading mode is applied to a real continuous rigid frame bridge with large span and high piers. The dynamic response and aseismatic property are evaluated and discussed. In addition, the results by pushover analysis are compared to the results by non-linear time-history analysis. The result shows that the high order vibrational modes indeed have a pronounced influence on the result. The proposed loading mode can give a reasonable result.

Abstract: The paper presents an experimental study on three-dimensional turbulence characteristics of curved channel flow by Doppler meter .Measured the time-average velocity and fluctuating intensity and so on. Analysised turbulence characteristics of curved channel flow by the experimental data,and also compared the flow distribution of vertical、horizontal fluctuating intensity,get the conclusion.

Abstract: Lead(Ⅱ) is a typical industrial pollutant which is harmful to people’s health. In this study, a new environmental-friendly material, the edible biopolymer poly--glutamic acid (-PGA) was applied to adsorb lead(Ⅱ). The results revealed that -PGA had pronounced binding effects on lead(Ⅱ) and its metal adsorption capacity was affected by lead(Ⅱ) concentration, -PGA dose and pH of the solution. For lead(Ⅱ) concentration, the removal rate of lead(Ⅱ) increased with the decrease of the metal concentration. For -PGA dose, the removal rate of lead(Ⅱ) increased with the increase of -PGA dose until the turning point at 4000 mg/L and then the tendency was adverse. The maximum removal rate was 92.8 % when lead(Ⅱ) and -PGA concentration was 1000 mg/L and 4000 mg/L separately. For pH, the metal adsorption capacity was weak when pH<4 and the optimal result occurred at pH 5-6.

Abstract: Autoregressive (AR) method can provide a simulation of random process with relatively short computational time and acceptable accuracy while Newmark-β Method is a quick way to accomplish the response analysis. Therefore in this paper, the combination of these two methods will solve the problem of wind-induced response analysis quickly and precisely. According to several theories, such as wind engineering, vibration theory and random process, we succeed to model 37-dimensional correlated random wind velocity and it is used for the response analysis. Then we utilize Newmark-β method to analyze successfully and the key results demonstrate that Guangzhou New TV Tower does not satisfy the requirements in the building code of China thus vibration control is needed.

Abstract: As for Beijing South Railway Station, railway track just lies on the roof slab of the basement, in railroad bridge or the railroad station orbit layer structure, the reinforcing bar designs general is used thick diameter reinforcing bar.However weld can’t assure the quality, and the reinforcing bar is dense, it is hard to site operation;But the mechanical connection has many advantages, such as have high quality, convenient construction,high productivity ,so now more and more project will choose it.Railroad station orbit layer has a total of 500 000 steel bar joints inside and directly bears the live load of moving trains,which need to do a fatigue search for assuring its satisfy use and specification request.Finally,through the test and application,the result is very good, gives reference for other construction projects of machinery connectivity on the live load.

Abstract: Theory equations and specification equations are currently main methods to calculate wall rock pressure. These equations are created in certain backgrounds, and are applicable in certain ranges, not fit for deep-buried or large span tunnels. Analysis methods combined with actual project are used, and measured data are contrasted with the theoretical results. Common used calculation equations are discussed from the aspects including calculation accuracy, the relationship with buried depth and the relationship with span of underground structure. Revised calculating equation for wall rock pressure of deep-buried and large-span tunnel are put forward, and is proved to be better on the aspects above. It has significance in theory and practice.

Abstract: The main form of interfacial bond stress between prestressed CFRP sheets and the beams of steel reinforced concrete(SRC) are interfacial shear and peel-off stress. The effective transfer of adhesive stress is the fundamental to ensure the structure bearing capacity improved after strengthened. According to the principle of minimum potential energy and combining with the mechanical behavior of prestressed CFRP sheets and the beams of SRC, the calculated formulas of interfacial shear and peel-off stress are deduced under symmetry concentrated loads. The influences of initial strain and the layer of CFRP sheets are discussed. The calculation results show that the effective availability of CFRP sheets is increased with the initial strain increasing under the load. And the interfacial shear and peel-off stress of beam-end are increased simultaneously with the initial strain and the layers of CFRP sheets increasing, which lead to the ends of beams occurred peel-off failure easily.

Abstract: In this paper a new type of reinforced concrete four-way rib hollow slab was proposed by the authors first. Further in order to research on the mechanical properties of the new floor slab the other two common slabs were compared with the new one, that was two-way rib hollow slab and solid slab. The rational finite element (FE) models of the three kinds of slabs supported by four corner columns were built up respectively by ANSYS. The deflection and stress of the three kinds of slabs under three load cases were calculated separately, on the basis of which thorough comparisons and analysis were carried out. The study results showed that the new reinforced concrete four-way rib hollow floor slab has superior mechanical properties.