Applied Mechanics and Materials Vols. 405-408

Abstract: Against the background of applying geographic information system (GIS) technology in the water industry, the application of Web-based GIS (Web-GIS) for displaying and managing the safety of cascade reservoirs is introduced. Moreover, the system architecture and development platform, together with the design of the database, function, and user interface for a safety monitoring and early warning system for cascade reservoirs based on the Web-GIS platform are put forward and illustrated. The key technologies, which include data fusion and a monitoring index system involved in system development, are also proposed. The system is capable of visualization design and improves the ability of realizing real-time early warning for cascade reservoirs.

Abstract: With the development of the earth penetration weapon, the research interest has gradually changed from low velocity impact to high velocity or hypervelocity penetration. This paper reviews the the theoretic research status on velocity region ascertaining of penetration, the target material properties near penetration cavity and mass abrasion of projectiles in high velocity penetration, and makes suggestions on the future research.

Abstract: Authors studied variation characteristics of dynamic strain amplitude of frozen clay with different temperatures by MTS-810 vibration tri-axial material testing machine. Results show that the variability is carried by instrument errors, operation errors, and so on. The average values are used to eliminate the variability of test results. With the increasing of the load levels, dynamic strain amplitude increases gradually. Negative temperature has a lager influence on the variation characteristics of dynamic strain amplitude, however, the influence is smaller when temperature above freeze points of water in the soil; when the temperature below it, dynamic strain amplitude changes with decreasing temperature; when temperature below-4°C, dynamic strain amplitude has no change with decreasing temperature. Dynamic strain amplitude grows with increasing dynamic stress amplitude.

Abstract: The basic frequency of masonry specimens can be obtained by dynamic tests with ambient or artificial excitation. The elastic modulus of masonry structures, as well as the damage factors, can then be determined by training their finite element models and make the calculated frequencies agree with the measured ones. Using 530 groups of dynamic test data, the damage factors of four masonry specimens were identified. The Bayesian inferences of the highly diverse measured results were conducted through a Markov Chain Monte Carlo (MCMC) sampling method, and the location of the damage was identified. The methodology was applicable, and can be used in the damage identification for other materials or structures.

Abstract: The shear thickening phenomenon was explained in this paper. The characteristics of shear thickening fluids (STFs), including reversibility and liquid to solid transition at critical shear rate were presented. Also, the applications of STFs for protective clothing and equipment were discussed. Since little references can be found which concern the effect of interparticle forces like Van der Waals forces on the performance of cementitious materials subjected to impact loading, understanding the mechanism of STF and knowing how its structure affects the properties, behaviors, and resulting applications is expected to inspire potential designs for building cementitious materials.

Abstract: A method for the box girders creep calculation considering the hydration heat is proposed and the effect of the hydration on the creep is discussed. The box girder is divided into several components and the average hydration temperature of the component is defined to represent the general condition resulted in the hydration. The formulae of the average hydration temperature have been recommended based on the discussion with respect to the formulae accuracy. The effect of the hydration on the creep is changed into that of the variable age of loading and the relationship between them is also given. It has been found that the hydration decreases the creep stress obviously.

Abstract: Based on the low cyclic loading experiments on prestressed high strength concrete pipe piles, in which one of them was reinforced by steel fiber, another stirrup ratio, the other was not reinforced, the authors compare the results in terms of damage characteristic, hysteretic curve, bearing capacity, displacement and ductility. It is shown that the bearing capacity and ductility of prestressed high strength concrete pipe piles reinforced by steel fiber increases. With the increase of stirrup ratio, the hysteretic behavior and the deformation behavior of prestressed high strength concrete pipe piles improves.

Abstract: To realize the automatic transmission for present digital image capture test system, a new system which consists of laptop computer, camera, fixing device and mechanical testing machine was presented and designed. The Monitor software, which was developed using MATLAB to realize automatic transmission function for the system, includes slow and high speed. The general stage and key stage for quasi-brittle materials can be effectively captured by the software. With MATLAB, the digital image correlation software (DIC) was developed. In DIC the first image is used as the base image. The images are sorted by photographing time (or file name), and the listing file is generated. The grid is drawn on the base image to divide the area into ‘facets’, the size of which can be adjusted between 1pixel and 100 pixels. Based on fast Fourier transform and convolution algorithm, the image comparison is realized and the deformation of the material is calculated. The designed system is applied to the compression test of a concrete specimen, and the results show that the system realizes automatic transmission image capture, and calculates accurate displacement. The displacement distribution is uniform in linear elastic stage, and varies in yielding stage. This is mostly due to localized failure and displacement discontinuity.

Abstract: Corrosion experimental were conducted in order to study concrete samples of two strength grades during different erosion period under the condition of designed artificial chloride erosion.Through drilling powder of concrete surface at various depths,chloride ions’concentration at different depths of corroded samples were determinated,and the diffusion coefficients of chloride ion after 90,180,240 days of corrosion were calculated on the basis of Fick’s second law.It turns out that obvious convection zone exitsin corroded concrete,and the thickness of convection zone increases with the erosing time and the reduction of concrete strength grade.In addtion,fitted datas of chloride ion diffusion coefficient increases with the reduction of concrete strength grade.

Abstract: The basic Construction principle of southern Hunan vernacular architecture is suiting the concrete circumstance of the site, making use of the local material, and building with the resources accessible. The material such as brick, stone, tile, wood, soil etc. come from local site, which are adapt to the southern Hunan natural conditions and low cost, as well as sustainable and easy to merge into the circumstance.