Applied Mechanics and Materials Vols. 94-96

Abstract: On the basis of analysis on the geological environment of highway loess landslide, three in-situ loess samples,500mm×600mm×600mm, were cut on the shear crack of landslide. The residual shear experiment of soil samples were accomplished in native state and saturated case. Compared with the residual cohesive force and residual internal friction angle of slide face soil in native state by indoor shear experiment, that of landslide shear crack soil in saturated state by in situ shear experiment is grater with the degree of 12.25% and 29.38%.The reason of difference between two experimental methods is proposed. It shows that in situ shear experiment is very important to the landslide stability analysis and the optimization of landslide engineering treating, specially to the creep landslide.

Abstract: The structural form of a kind of cellular hollow flat slab floor using thin wall plastic boxes was introduced. The equivalent frame method, which was used to analyze the internal force of this kind of cellular hollow flat slab floor, was discussed. Finally, the method to calculate the deflection of cellular hollow flat slab was investigated and some improvements in this method were presented. The effects of the cracks on the stiffness and deflection of hollow flat slabs were taken into account in this method to decrease the error of elasticity calculation results.

Abstract: Based on the finite element software ANSYS, an electromechanical impedance (EMI) model for a cracked beam with imperfectly bonded piezoelectric patches is established in the paper. The property of bonding layer between the PZT sensor/actuators and the host beam is taken into account and thus the three-dimensional (3D) model of piezoelectric patch-adhesive-cracked beam coupled system is developed. Comparison with existing numerical results validates the effectiveness and accuracy of the present analysis. Then, parameter study is conducted by considering effects of the vibration mode of the host beam, the mass density of the adhesive and crack depth etc. on EMI signatures. The numerical results indicate that the present EMI model can be used to detect the cracks in the structures.

Abstract: An explosion is defined as a large-scale, rapid and sudden release of energy. Explosions, such as a bomb explosion within or immediately nearby a building and a gas-chemical explosion, can cause catastrophic damage on the building's frames, collapsing of walls, blowing out of large expanses of windows, and shutting down of critical life-safety systems. In fact, an explosion may result in large dynamic loads, greater than the original design loads, of many structures. Blast phenomenon and blast efforts have been made during the past several decades to develop methods of structural analysis and design to resist blast loads. The analysis and design of structures subjected to blast loads require a detailed understanding of blast phenomena and the dynamic response of various structural elements. This paper introduces different methods to estimate blast loads, also presents a comprehensive overview of the effects of explosion on RC structures.

Abstract: The impact of blast load is always taken into consideration in significant building and protective construction. In order to study the mechanical behavior of the concrete slab under blast load, the dynamic responses of a square concrete slab under surface explosion are simulated by the nonlinear finite element program ANSYS/LS-DYNA. The JOHNSON_HOLMQUIST_CONCRETE model is used for concrete material and the damage and strain rate effect are considered in this mode1. The simplified exponential load is used as blast load. The Z-displacement,Mises effective stress and damage state of concrete slab under different blast load of corresponding scaled distance are investigated and discussed. It can be found from the results that the influence of blast pressure can be neglected when scaled distance is around 2.0 and the damage of slab is beginning from the edge.

Abstract: Starting from the principle of three-dimensional laser scanner and after analyzing the positioning error of point cloud, in this paper the following key problems confronted in data processing are researched ,the problems are range image segmentation, point cloud registration, point cloud filtering, absolute positioning and stitching data, modeling in AutoCAD or 3Dmax. Then, examples were introduced in constructing three-dimensional model using laser scanning technology. The results showed that the use of this technology can provide high-precision building models, which is important in constructing three-dimensional models and very helpful of digital cities.

Abstract: Abstract: This paper mainly studies the application effects of calcium sulfate whisker, a new kind of high-modulus and inorganic-modified material in asphalt mixture. According to the Marshall test, this research designs the ratio of the mixed material, so as to determine the mixed quantity of calcium sulfate whisker. Based on the related studies about road performance, it makes a comparative study among these three mixed materials. The results indicate that the high-modulus asphalt mixture with modified calcium sulfate whisker can effectively improve the mixed materials’ stability in high temperature, water stability and anti-fatigue performance; meanwhile, it doesn’t decrease their performance in low temperature. Therefore, it is helpful to solve the common problems in highway engineering, such as rutting, water damage and so on. The feasibility analysis proves that the application of high-modulus asphalt mixture with modified calcium sulfate whisker could achieve greater economic and social benefits while ensuring the good road performance of the road.

Abstract: It is serious problem of the deficiency of high quality embankment filling in the expressway construction in shanghai, the Yangtze estuary fine sand has been extensive applied as the substitute filling material to avoid destroying the cultivated land and cropland. It is signality of the fine sand filling embankment technique popularization and application to the improvement of highway construction level, the protection of the cultivated land and the protection of the eco-environment. For the natural sand is no-viscous bulk solid material with great variation on mechanical properties to traditional embankment filling, now there are some problems on the application of fine sand filling embankment engineering haven’t been analyzed such as the standardization of highway optimum structure system and road performance of fine sand filling embankment. In the paper, it analyzed the fine sand filling embankment stability by considering with the shape of landslide and safety factor by using the combination method of the strength reduction method and Fast Lagrange method. The analysis included geometrical and material properties of the slope ratio, the subgrade height, the presence or absence of the surrounding soil and the thickness of it, the top seal coat, pavement structure etc. and proposed the design suggestions of the optimum fine sand filling embankment based on the analysis above.

Abstract: he steel lined reinforced concrete penstocks (SLRCP) is always looked as an axisymmetric structure according to the design code, which can not show the true load-carrying capacity when considering the dam’s constraint to the SLRCP. In this paper, the physical non-axisymmetric property of the structure is simulated using the finite element method. The internal force distribution of every cross section in the SLRCP is studied, and a design method for steel arrangement based on axial force is proposed. When considering the non-axisymmetric property, the axial force in those cross sections approaching the bottom of the structure may be reduced more than 30% to the calculated value by the axisymmetric analysis. The larger the inner radius of the penstock or the thickness of the concrete wall is, the more marked the non-axisymmetric property of the SLRCP is.

Abstract: To control thermal cracks of concrete of thick arch lining of tunnel of big pan, based on basic assumption, the formula calculating thermal stress of arbitrary position and the maximal stress in arch lining restricted by surrounding rock is deduced. Moreover, the formula of thermal stress of arbitrary position, the maximal thermal stress is also presented, when the thick of arch lining varies according to the law of cosine. The change of temperature of concrete of arch lining in practical engineering is monitored. The maximal thermal stress in arch crown surface and the thermal stress in surface along the axis of arch are calculated using the formula deduced above is presented and is contrasted with its real strength. Conclusions show that the thermal stress in arch crown is the maximal stress, concrete lining do not crack under the condition of thermal stress less than its strength.