Advanced Materials Research Vols. 255-260

Abstract: Tree-root drying can reduce the water content of a soil in a significant manner and cause foundation settlement in expansive soil. Distortions of lightly loaded structures caused by tree root absorption are often observed in areas of expansive soil. Interest in numerical modeling of the influence of trees on soil shrinkage settlements has intensified recently. Nevertheless, no prescriptive method is given to describe the parameters and conditions in a tree-root-soil-water interaction model. In this paper, a general description of the factors involved in a tree root-absorption model is discussed. The estimation of transpiration, rainfall, evaporation and root distribution is provided. Flow equation and constitutive equation are also explored to describe the soil water interactions.

Abstract: In recent year,the epidemic situation of schistosomiasis has been recurring, the spreading of oncomelania is obvious, and the schistosomiasis problem is quite serious in Yangtze river basin. In such case, kinds of water conservancy measurement combined with schistosomiasis control are introduced. Considering that various measures of oncomelania interception are mainly suitable for low-head project, the reliability is poor and the management operation is with high difficulty at present, the technology of interception of oncomelania snail with hydraulic separation which is suitable for high-lift and medium-head (3meters) projects and the technology of interception of oncomelania snail with net cage that can be applied to low-head projects are proposed. According to the research, we can discover the interception of oncomelania snail with hydraulic separation oncomelania snail and the interception of oncomelania snail with net cage is efficient in intercepting oncomelania snail, and can be applied to practical projects.

Abstract: Dam security is the key of concrete high dam. This thesis proposes design flow chart in high arch in service, according to researches of dam brought performance-based design theory. The reliability method is adopted, based concrete behavior of change by strain rate and hold time of load influence in seismic action. In elastic stage, using control total cost formulas get corresponding deformation of arch dam under the minimum total, provided a reference for project.

Abstract: This study proposed a method to reinforce existed structures. Nonlinear analysis for the rectangle axially loaded column with CFRP considering secondary load was done by the finite element analysis software ANSYS. The ultimate limit strengthen for seven rectangle axially columns with CFRP which compared with normal axial column respectively (one of them is comparative column no secondary) was estimated under different level secondary loads. This paper mainly investigated the influence of CFRP under secondary load. Coefficient of CFRP was given.

Abstract: This paper mainly studied of the carbon fiber reinforced plastic (CFRP) reinforced concrete columns to improve its capacity．First，the CFRP strengthened concrete columns reinforced by the force derived mechanism to improve the theoretical foundation of the bearing capacity. On this basis，study of eight reinforced concrete columns were tested. The actual strength reinforcement component results compare with the theoretical results, this paper got the law of the CFRP reinforced small concrete columns, provided a reference for project．

Abstract: This paper was combined with a real bridge to construct a carbon fiber arch bridge scale test model according to similar principles, thereby testing and researching on its mechanical properties. Space finite element analysis software Midas / Civil was adopted for space simulation study of all working conditions in each use stage of the model bridge. The test results showed that: CFRP hanger tension and load in all working conditions of the model experience were basically changed in a linear mode, its working conditions were normal, all working conditions were basically matched with the theoretical calculation values except the hanger whose specific anchors were provided with slight slip, which indicates that it is feasible to allocate CFRP hanger in bowstring arch bridge while indicating that calculation and analysis results of finite element program can be used to guide loading work, measuring point selection and other work of the model bridge, and the experimental data and analysis results are correct.

Abstract: Four medium -scale reinforced concrete beams were constructed and tested to investigate the effectiveness of external poststrengthening with prestressed carbon fiber reinforced polymer (CFRP) plates. The various variables included the strengthening method and the amount of prestressing. The experiments consisted of one control beam, one nonprestressed CFRP-bonded beam, and two prestressed CFRP-bonded beams, all the beams were subjected to four-point bending tests. In comparison to the control beam and the nonprestressed CFRP-bonded beam, the cracking load, yield load, ultimate load and stiffness of the beams with bonded prestressed CFRP plates were increased. The failure mode of the prestressed CFRP-plated beams was not debonding, but concrete crushing. After the debonding of the CFRP plates, the behaviour of the bonded CFRP-plated beams changed to that of unbonded CFRP-plated beams due to the effect of the anchorage system. The ductility of the beams strengthened with CFRP plates having the anchorage system was considered high if the ductility index was above 3.

Abstract: Polypropylene fibrous concrete is a new kind of composite material. Polypropylene fiber leads to an increase in the resisting strength, cracking resistance performance, resistance to impact performance and permeability reducing performance of the concrete, thus reduces the shrinking and deformation of the concrete. This paper uses the method of numerical analysis, assisted by the software of finite element analysis, makes both static and dynamic analysis on the polypropylene fibrous concrete ditch with different volume mixing. It results in the stress and strain table of the head and base plates of the polypropylene fibrous concrete ditch in the case of 0.1%, 0.5%, and 1% volume mixing of polypropylene fibers. The paper provides technological basis for formation design of the polypropylene fibrous concrete materials, and laids technological foundation for the further developments of polypropylene fibrous concrete in hydraulic engineering.

Abstract: This paper deals with high-strength concrete structure with carbon fiber reinforced plastic (CFRP) strips bonded to the shear face. The first part deals with an experimental study. The fiber reinforced plastics strengthened concrete member test presents a failure mode with debonding of the external CFRP strips from the concrete member. The second part deals with a nonlinear FE analysis with LS-DYNA . Considering of the adhesive layer, explicit finite element is used for simulating the shear failure of CFRP-strengthened concrete, obtain the whole process of structure deformation development and describe the conformation and development of crack and the failure mode. The FE results are compared with the experimental results.

Abstract: A new type of composite sandwich hollow column is prepared through using glass fiber and paulownia wood by the way of vacuum infusion resin method for the first time. The structure of the column is cylindrical sandwich shell. After preparation of columns, mechanical properties under axial compression of the composite column are also studied. The results show that increasing the core material thickness or the surface material thickness can improve the load-carrying capacity of the composite column under axial compression. The characteristics of the column are low-price, cost-effectiveness, fast preparation, product stability, lightweight, high strength and corrosion- resistance, so it can be widely used as a building’s column, a supporting column of coalmine’s roadway, and a part of retaining structure of deep excavation.