Time-Dependent Behavior of Fiber-Reinforced Polymer-Confined Concrete Columns under Axial Loads

2002 ◽  
Vol 99 (2) ◽  



2012 ◽  
Vol 461 ◽  
pp. 682-685
Author(s):  
Yang Yang Han ◽  
Hao Zhang ◽  
Ya Qin Li ◽  
Jia Yao ◽  
Xiao Ping Hu

Abstract: Concrete members strengthened by fiber reinforced polymer (FRP) are increasingly becoming a popular retrofit technique in recent years due to the excellent material properties, convenient and easy construction methods, and outstanding strengthening effect. However, fundamental researches are incomplete; especially the characteristics research of square cross-section of FRP confined concrete has become a major obstacle for the development of further research and application. Therefore, the better understanding of the behavior of confined concrete becomes of paramount importance. A total of 10 concrete columns, which were reinforced with CFRP (carbon fiber reinforced polymer) and with filleted square sections, were fabricated and tested subjected to axial load to investigate the mechanical properties of FRP confined concrete. The mechanical behavior of FRP confined concrete has been further understood and some useful conclusions are obtained.



Author(s):  
Hai G. M. Doan ◽  
Hossein Ashrafizadeh ◽  
Pierre Mertiny

Abstract Piping made from thermoplastic fiber reinforced polymer composites (TP-FRPCs) is receiving increasing attention in the oil and gas industry. Creep and time-dependent behavior is one of the main factors defining the service life of TP-FRPC structures. The lifetime and time-dependent behavior of TP-FRPC structures can be predicted using simulation tools, such as finite element analysis, to aid in the design optimization by modeling the long-term behavior of the material. Composite material time-dependent properties are required inputs for such models. While there is previous research available on creep testing of TP-FRPCs in laminate geometry, such tests may not enable accurate determination of the composite properties due to edge effects. On the other hand, coupons with tubular geometry not only provide improved load distribution between the fibers and matrix with minimal end effects, they also enable certain loading conditions experienced during typical piping operations such as internal pressure. In this study, a testing method to capture the creep behavior of tubular TP-FRPC specimens subjected to multi-axial loading conditions was developed. Tubular coupons were prototyped by an automated tape placement process. Strain was measure using digital image correlation technique and strain gauges. The development of the test setup forms the foundation for further testing of tubular TP-FRPC coupons at different multi-axial loading conditions. As a preliminary test, the creep behavior of a TP-FRPC tube subjected to pure hoop stress condition was evaluated using the developed testing process.



2020 ◽  
Vol 7 ◽  
Author(s):  
Pengda Li ◽  
Yao Zhao ◽  
Xu Long ◽  
Yingwu Zhou ◽  
Zhenyuan Chen

The inherent defects of recycled aggregate concrete (RAC) include the complex interfacial transition zone (ITZ) and the many micro-cracks that appear during its producing process, which result in some inferior mechanical properties compared with natural aggregate concrete (NAC). This drawback usually prevents RAC from being selected for structural purposes. Existing research has shown that the strength and ductility of damaged concrete in compression members can be significantly enhanced through external confinement using fiber-reinforced polymer (FRP) wraps. This application has been widely used in concrete structural repair and retrofitting technology. However, research on the effects of RAC damage coupled with different load damage conditions is rare, as is information on the mechanical properties of RAC reinforced with FRP jackets. This paper presents the results of an experimental study on the behavior of pre-damaged recycled aggregate concrete cylinders that were repaired with carbon fiber-reinforced polymer (CFRP) or large rupture strain (LRS)-FRP jackets. Tests were conducted on 58 concrete cylinders with variations in the replacement ratio, damage levels, and FRP properties. Test results demonstrated that the ultimate strain and strength of damaged recycled aggregate concrete could be significantly enhanced by FRP jackets and that aggregate quality plays a vital role in the strength of confined concrete. Also, the energy absorption of CFRP- and LRS-FRP-confined RAC were evaluated. The analysis indicated that, compared with CFRP-confined RAC, LRS-FRP can greatly improve the energy absorption capacity of RAC; thus, LRS-FRP confined concrete has a good potential to achieve a ductile design for concrete columns, especially when used in seismic reinforcement.







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