Understanding the compressive behavior of shape memory alloy (SMA)-confined normal- and high-strength concrete

2018 ◽  
Vol 202 ◽  
pp. 943-953 ◽  
Author(s):  
Aliakbar Gholampour ◽  
Togay Ozbakkaloglu
2011 ◽  
Vol 82 ◽  
pp. 57-62 ◽  
Author(s):  
Sha Sha Wang ◽  
Min Hong Zhang ◽  
Ser Tong Quek

This paper presents a laboratory experimental study on the effect of high strain rate on compressive behavior of plain and fiber-reinforce high-strength concrete (FRHSC) with similar strength of 80-90 MPa. Steel fibers, polyethylene fibers, and a combination of these were used in the FRHSC. A split Hopkinson pressure bar equipment was used to determine the concrete behavior at strain rates from about 30 to 300 s-1. The ratio of the strength at high strain rates to that at static loading condition, namely dynamic increase factor (DIF), of the concretes was determined and compared with that recommended by CEB-FIP code. Fracture patterns of the specimens at high strain rates are described and discussed as well. Results indicate that the CEB-FIP equation is applicable to the plain high strength concrete, but overestimates the DIF of the FRHSC at strain rates beyond a transition strain rate of 30 s-1. Based on the experimental results, a modified equation on DIF is proposed for the FRHSC.


2013 ◽  
Vol 743 ◽  
pp. 45-49
Author(s):  
Jian Chin Lim ◽  
Togay Ozbakkloglu

This paper presents a study on the axial compressive behavior of fiber reinforced polymer (FRP)-confined high-strength concrete (HSC). A large experimental test database assembled from the published literature was used to investigate and quantify factors influencing the compressive behavior of FRP-confined HSC. The database consisted of 976 test data having unconfined concrete strength ranging from 6.2 to 169.7MPa. Based on the analysis results of the database, it was found that the threshold confinement stiffness increases significantly with an increase in concrete strength, which in turn adversely affects the strength enhancement of confined concrete. It was also observed that the hoop rupture strain of FRP shell decreases with an increase in concrete strength. Existing confinement models that are applicable to FRP-confined HSC were assessed using the database. Finally, a new simple design-oriented model for FRP-confined HSC developed on the basis of the database is presented.


2013 ◽  
Vol 671-674 ◽  
pp. 1860-1864 ◽  
Author(s):  
Thomas Vincent ◽  
Togay Ozbakkloglu

It is well established that external confinement of concrete with fiber reinforced polymer (FRP) sheets results in significant improvements on the axial compressive behavior of concrete. This understanding has led to a large number of experimental studies being conducted over the last two decades. However, the majority of these studies have focused on normal strength concretes (NSC) with compressive strengths lower than 55 MPa, and studies on higher strength concretes have been very limited. This paper presents the results of an experimental study on the compressive behavior of FRP confined high- and ultra high-strength concrete (HSC and UHSC) with average compressive strengths of 65 and 100 MPa. A total of 29 specimens were tested under axial compression to investigate the influence of key parameters such as concrete strength and method of confinement. All specimens were cylindrical, confined with carbon FRP and were 305 mm in height and 152 mm in diameter. Results obtained from the laboratory testing were graphically presented in the form of axial stress-strain relationships and key experimental outcomes are discussed. The results of this experimental study indicate that above a certain confinement threshold, FRP-confined HSC and UHSC exhibit highly ductile behavior. The results also indicate that FRP-wrapped specimens perform similar to concrete-filled FRP tube (CFFT) specimens at ultimate condition, however notable differences are evident at the transition region when comparing stress-strain curves.


2020 ◽  
Vol 230 ◽  
pp. 117043 ◽  
Author(s):  
Muhammad Usman ◽  
Syed Hassan Farooq ◽  
Mohammad Umair ◽  
Asad Hanif

2014 ◽  
Vol 501-504 ◽  
pp. 963-968
Author(s):  
Thomas Vincent ◽  
Togay Ozbakkaloglu

This paper presents an experimental investigation on the influence of specimen slenderness on axial compressive behavior of concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs). A total of 18 aramid FRP- (AFRP) confined high-strength concrete (HSC) specimens with circular cross-sections were tested. Specimens with height-to-diameter ratios of 1, 2, 3 and 5 were manufactured and tested, with all specimens maintaining a nominal diameter of 150 mm. The results indicate that specimens with an H/D of 1 exhibit significantly higher strength and strain enhancements compared to specimens with H/D ratios of 2 to 5. The influence of slenderness on specimens with H/D ratios between 2 and 5 was found to be significant in regards to axial strain enhancement, with a decrease observed as specimen slenderness increased. On the other hand, the influence of slenderness on axial strength enhancement of specimens with H/D ratios between 2 and 5 was found to be negligible.


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