作者: Wen Hui Bai, Bin Xiang Sun

摘要: In order to investigate flexural behavior of simply-supported beam using recycled coarse aggregate concrete, the difference of the component normal section stress distortion performance and failure characteristic between the recycled concrete beam and the normal concrete beam is researched. The approaches of testing the flexural behavior of 6 recycled course aggregate beams with the same section size, different replacement ratio of recycled coarse aggregate (0%, 50%, 70% and 100%) and different percentage reinforcement (0.68%, 0.89% and 1.13%). Based on the experimental the following conclusions are draw. There are also 4 phases of elasticity, cracking, yield and ultimate during the stress course of recycled concrete beam component normal section stress; the average strain measured on cross-section obliges to the plane section assumption; the characteristics of stress distortion and destruction of recycled concrete beam are basically the same as those of the normal concrete beam. Under same conditions, the cracking moment and the ultimate flexural carrying capability of recycled concrete beam is almost the same as those of normal concrete beam. The deformation of recycled concrete beam is larger than concrete beam. The conclusion of the paper is that it is still feasible to calculate the ultimate bending moment, cracking moment, and the biggest crack width of recycled concrete beam according to the formula in China Concrete Structure Design Code, but the deflection formula needs to be adjusted.

543

摘要: This paper mainly studies the deflection under short-term loading of recycled course aggregate reinforced concrete beam is calculated by using of the formula of short-dated rigidity in code for design of concrete structures. According to testing the flexural performance of 6 recycled course aggregate beams with the same section size, different replacement ratio of recycled coarse aggregate of 0%, 50%, 70%, 100% respectively and different percentage reinforcement of 0.68%, 0.89%, 1.13% respectively, analyzes relation between deflection and replacement ratio of recycled coarse aggregate, deflection and percentage reinforcement, compare measured value and calculated value using of current codes and make statistical analysis this data . By regressing and analyzing the experimental data from literature, supplied short-dated rigidity modified formula of recycled course aggregate beam. The calculation results are in good agreement with the experimental data. The formula of short-dated rigidity can accurately calculate deflection under short-term loading of recycled course aggregate reinforced concrete beam, and can be referenced in engineering practice and correlative regulations.

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作者: Xiu Qin Cui, Bing Guo, Zhong Ren Feng

摘要: The numerical analysis method is applied to simulate the whole process of bending. Keeping the section dimensions and the types of loads constant in prestressed concrete hollow slab with mid-strength spiral-rib steel wire, strength of concrete, strength of steel bar, reinforcement ratio, span-depth ratio and stretching control stress are analyzed and compared. The influence of strength of concrete, strength of steel bar, reinforcement ratio, span-depth ratio and stretching control stress on ratio of cracking bending moment and design bending moment of prestressed concrete hollow slab is discussed by numerical simulation.

136

作者: Xiao Meng Wang, Chu Wei Zhou

摘要: FRPhas been widely used in the strengtheningof RC structures because of its low density, high strength and anti-corrosion. Long term performance ofFRP/concrete interface is one of the keys for its successful engineering application, and however it has notbeen well studied. In this article a fractional derivative rheological model was proposed which is able to characterize the complicated creepdeformation of epoxy FRP/concreteinterface layer with simple expression. Numerical study revealed thatinterfacial creep might lead to notable stress redistribution and largeinterfacial deformation has possibility to cause weakening of FRPstrengthening.

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