Papers by Keyword: Concrete Material

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Authors: M. Kitahara, M. Onishi, Kouichi Nakahata, Masayoshi Yamada
Abstract: The Born inverse scattering method is applied to the shape reconstruction of flaws in the concrete materials. To accelerate the inversion process, the algorithm of the fast Fourier transform is introduced in the integration process of the scattering amplitude. The concrete specimens with flaw models are prepared and the scattered waveforms from flaws are acquired in the pulse-echo mode. The shape of flaws is reconstructed by using the measured waveforms and the performance of the inversion method is demonstrated experimentally.
Authors: Chuan Zhao, Guo Ping Cheng
Abstract: In recent years, with the development of engineering material technology and its application in project, a number of choices are available for the slope protection project in riverway. For the increasing number of applications of gabion and reno mattress in such engineering projects, as advanced flexible materials, which are also obviously competitive in protection effect and service life, they are more expensive comparing to the traditional masonry and concrete. Therefore, comprising AHP method and both the qualitative and the quantities analyses focusing on five major factors, the execution condition, construction cost, protection effect, service life and management & maintenance, this paper provides reference for decision-makers to choose the most appropriate material in the slope protection project.
Authors: Tao Chen, Qin Bing Li, Jun Feng Guan
Abstract: This paper extends the study of Dharan on the stress state in an elastic solid specimen subjected to axial strain acceleration to compressible materials. And an improved Dharan model is presented. Based on the Drucker-Prager strength criterion, analytical equations of the radial inertia confinement effect on dynamic compressive strength of concrete in split Hopkinson pressure bar tests is derived. Comparison and discussion on the analytical, experimental and numerical results are performed. It is proved that the strain rate effect of compressive strength of concrete materials is a pseudo material property partly caused by the radial inertia confinement. Special attentions should be paid to dynamic tests of low-strength concrete to get the real mechanical properties.
Authors: Yi Wei Tay, Biranchi Panda, Suvash Chandra Paul, Ming Jen Tan, Shun Zhi Qian, Kah Fai Leong, Chee Kai Chua
Abstract: 3D printing (3DP), commonly known as additive manufacturing (AM), is a promising technology that can fabricate three dimensional complex shape prototypes directly from computer-aided design (CAD) model without any tooling and human intervention. Owing to its peculiar characteristics, AM is widely used in many industries to assist in the design, manufacture and commercialization of a product. More recently, this technology has been extended to building and construction (B&C) application in order to mitigate some of the critical issues such as shortage of skilled labour, high production cost and construction time, health and safety concerns of the workers in the hazardous environment etc. However for successful implementation, proper selection of materials and their mix design is highly recommended, which is a challenging task. This paper summarizes the current available 3DP systems from literature and the respective materials that have been used thus far by various experts, industries for B&C purposes. Finally, the benchmarking properties of theses material and potential research directions are briefly discussed.
Authors: Ming Xie, Shan Suo Zheng
Abstract: The stochastic properties and discreteness of macroscopic property for concrete appear on mechanical property and fracture surface. In consideration of stochastik and discreteness of fracture surface, a class of mesoscopic damage mechanics model of concrete based on spring model, are put forward to understand the real damage evolution characteristics of concrete at the level of constitutional law. A kind of spring-slipper model is introduced to reflect the elastic-plastic damage behavior. It has been confirmed that fracture surface of concrete has self-affine fractal characteristic only on a certain spatial scale, but the actual fracture surface of concrete is a stochastic surface with multi-fractal characteristics. Uniaxial test was operated, combined with the Computerized Tomography test of concrete, to study the evolution of crack surface from mesoscopic level to macroscopic level. Compared with the existing damage constitutive law and experimental results preliminarily, the feasibility of fractal damage constitutive law is verified.
Authors: Qing Mei Kong, Hong Ju Lv
Abstract: The widening of expressway refers to many overpass, culvert and underpass made of concrete material. In order to make all the structures woke normally and safely after widening, it’s necessary to study the lengthening technique about concrete material for them. When overpasses are carried on lengthening, original structures should be used as more as possible. There are 3 main lengthening methods: direct use, rebuild in another field and use after lengthening. Lengthening technique about concrete material of culvert and underpass differs when the widening method of expressway is different. In the end, the application of lengthening technique about concrete material is introduced by engineering examples.
Authors: Ling Zhao, Guang Jun Zhang, Bai Sui Zhang, Wan Wen Wang
Abstract: Performance Based Design (PBD) is being developed as a more reasonable and flexible design method for a next generation of design method. To implement PBD, this paper presents a systematic approach (Bayesian method) for developing concrete material mixture design to satisfaction criterion level relationship. Satisfaction curves describe the probability of concrete reaching or exceeding different criterion level at specified levels of concrete material.
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