Abstract: This paper presents compressive and tensile constitutive law of UHPFRC used in numerical simulation. UHPFRC exhibits different constitutive law from normal and high strength concrete. A multi-directional fixed crack criterion that considers tensile strain hardening is defined to describe tensile behavior, and Drucker-Prager criterion with an associate d flow rule is adopted in the compressive region. The comparison of numerical results with experimental results indicates a good agreement.
Abstract: Low-carbon economy has become a hot research field in all walks of life currently. As a way to achieve low-carbon economy, industrial restructuring has been widely studied. In order to promote research in the field, and lead to the development of China's low-carbon economy, this article will give us a summary and a brief review of representative research achievements referring to industrial structure low-carbon adjustment in China's academia. They contain four aspects: intensions of industrial restructuring from the perspective of low-carbon economy, influence of industrial restructuring on carbon emissions, low-carbon industries, and strategies of industrial restructuring from the low-carbon economy aspect.
Abstract: Aiming at the problem of salt corrosion of concrete used in bridge and foundation in the salted areas of Qinghai province in our country,we study the performance of the prevention of salts corrosion and anti-freeze durability of concrete itself and concrete daubed waterproof materials outside or mixed the materials inside.The high-performance concrete made in this article used waterproof materials to prevent brine penetration and set multi-channel protection. The high-performance concrete specimens for comparison,the specimens daubed waterproof material, and rhe specimens mixed waterproof material inside are made to study the changing regularity under single factor and double factors(freeze and melt + chemical attack, carbonize + freeze and melt). The research results show the high-performance concrete made in this article has good anti-freeze durability and the protective covering of waterproof material can form multi-channel protection and effectively slow frozen corrosion of the concrete.
Abstract: Aiming at the corrosion problem of concrete structure of bridges in Chaerhan salt lake area, the paper puts forward a new method of using multi-defense lines against salt erosion, helpful to improve the durability of concrete structures. Single factor experiment of salt erosion and a dual-action experiment of salt erosion and drying-wetting cycles were conducted, using 3 kinds of concrete specimens, including simple high performance concrete (HPC), HPC coated with waterproof material outside and HPC mixed with waterproof material. Results of experiments show that high performance concrete prepared in the experiments has good anti-corrosion performance. Moreover, HPC with multi-defense lines application effectively delays salt erosion to concrete, and lengthens service life of concrete structures in saline-lake environment.
Abstract: Basic transfer differential equation and transferring model of load transfer method were given at first, and the pile-soil loading state was divided into five stages according to the increasing pile-head loading process. Next, based on the overall equilibrium of pile and boundary conditions, analytical stiffness expressions of single pile relating to these transferring model parameters were derived in stages. And then, the field static load test result, Q-s curve, was also divided into five corresponding stages and subsection fitting was suggested to be made for each stage. Finally, each model parameter was determined one by one in stages according to the corresponding relations between the measured Q-s curve and the proposed analytical solutions. This pile-soil parameters determination method would enhance the application value of the measured Q-s curve in some extent, and it would provide a theoretical basis for further study on mechanical properties of pile-soil system.
Abstract: According to a highway expansion project, this paper makes field obversations on earth pressrue of double-sided reinforcement retaining walls and studies distribution of it. Test results show earth pressure on the back of double-sided reinforcement retaining walls grows with increase of filling height during construction and the distribution is nonlinear along with height of the wall, the maximum is at the base. Measured values of vertical earth pressure are lower than theoretical ones. And this structure of double-sided reinforcement retaining walls has low requirement on bearing pressure of foundations. The results can be used as a reference for further application in future.
Abstract: The paper is supposed to establish a non-dimensional approach to analyze the free vibration of axially loaded beams with different kinds of boundary conditions, based on the Timoshenko’s beam theory and the method of separation of variables. When the mode-shapes and frequencies are known, it is convenient to get the equivalent load vector, equivalent mass matrix and the frequencies matrix, then, the characteristics of vibration of axially loaded beams will be obtained by the approach. The results and conclusions were also helpful to the anti-blast analysis of columns
Abstract: In this paper, a new shape classification method based on different feature sets using multiple classifiers is proposed. Different feature sets are derived from the shapes by using different extraction methods. The implements of feature extraction are based on two ways: Fourier descriptors and Zernike moments. Multiple classifiers comprise Normal densities based linear classifier, k-nearest neighbor classifier, Feed-Forward neural network, Radial Basis Function neural network classifier. Each classifier is trained by two feature sets respectively to form two classification results. The final classification results are a combined response of the individual classifier using six different classifier combination rules and the results were compared with those derived from multiple classifiers based on the same feature sets and individual classifier. In this study we examined the different classification tasks on Kimia dataset. For the tasks the best combination strategy was found using the product rule, giving an average recognition rate of 95.83%.
Abstract: Drying shrinkage is a critical factor influencing the long-term behavior of concrete. In this paper, related parameters for calculating moisture field are discussed based on the theory of nonlinear moisture diffusion. Numerical simulation of shrinkage tests of concrete blending with fly ash and ground granulated blast furnace slag is conducted by ANSYS, considering the solution analogy between moisture field and temperature field. The calculated shrinkage strains are in good agreement with experimental results and the adopted model and finite elements method can be used to predict the time-dependent moisture field and shrinkage strain field in the real structure.
Abstract: The numerical simulation calculation on round steel-tubes reinforced with CFRP sheets was done through the large-scale finite element software ANSYS. In this research, four factors were comparatively analyzed so as to obtain the influence of them on ultimate axial tensile bearing capacity of steel-tubes. These four factors are longitudinal reinforcement length rate , thickness , elastic modulus and circumferential reinforcement ways of CFRP sheets. The results show that the ultimate axial tensile bearing capacity of steel-tubes strengthened with CFRP sheets is enhanced significantly and the reinforcement effect is very good.