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Li G.-W.,Hohai University | Ni C.,Hohai University | Ni C.,Construction Administration of Huaihe River Water Resources Commission | Ge W.-M.,Hohai University | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Recently, due to their high specific strength, non-electric conductivity, non-magnetic nature and corrosion resistance, fiber reinforced polymer (FRP) bars are being used in engineering structures built in corrosive environments to enhance the durability of reinforced concrete (RC). Moreover, because of their high strength, small elastic modulus and remarkable size effect, the FRP bars are applied to pre-stressed structures, and their stress-relaxation feature is an important design parameter. The anchoring and measuring method for stress relaxation specimens with larger-diameter sand-surface FRP bars is studied. The results show that the modified steel sleeve-type anchoring method can reduce the slippage of the specimens, which meets the requirements of specification. The counterpart experimental method of anchoring concrete component with pre-buried loading devices can be used to test the relaxation behavior of anchoring structures. Furthermore, the fiber optic grating technology is employed to monitor the continuous long-term strain process of rod body. The measured strain data are accurate and stable.

Yang B.,Jiangsu Jinmai Engineering Investigation Co. | Yang B.,Nanjing University of Technology | Huang G.-L.,Nanjing University of Technology | Zhao S.-F.,Jiangsu Jinmai Engineering Investigation Co. | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

A new type of pile with rectangle and internal circular cross section is developed in recent years, which is named prestressed high strength concrete rectangular supporting pile (rectangular supporting pile for short). Compared with that of the pipe pile and square pile, the flexural stiffness of rectangular supporting pile is greatly improved in cross-section form. Thus it is more suitable to used as supporting structures in the excavation engineering in which the pile mainly bears horizontal force. An engineering case of the rectangular supporting piles used as the supporting structures of the excavation in soft soils is introduced, and the excavation is in good condition during its construction. The monitoring results indicate that the deformation of the supporting structures and the internal force of piles are in the controllable range. So the rectangular supporting piles have security assurance and greatly improve the economy and convenience for the pit excavation. Therefore this case study and the results may provide a reference for the application of rectangular supporting piles in excavation.

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