The Effects of Loading Rate and Duration on the Axial Behavior of Low-Strength and Medium-Strength Noncircular Concrete Members Confined by Fiber-Reinforced Polymer Sheets

Polymers

Cem Demir¹  Aygul Kucukkapili¹  Alper Ilki¹  Duygu Doyrangol¹ 

[1] Department of Civil Engineering, Istanbul Technical University, Ayazaga, Sariyer, Istanbul 34469, Turkey;

关键词: concrete;    confinement;    creep;    fiber-reinforced polymer;    loading rate;    low strength;    medium strength;    strain rate;    sustained load;   

DOI  :  10.3390/polym6061685

来源: DOAJ

【 摘 要 】

In this study, 36 concrete specimens with square cross-sections and different concrete qualities were tested either under uniaxial compression at different loading rates or subjected to sustained uniaxial stresses after externally jacketing with carbonfiber-reinforced polymer (CFRP) sheets. The main test parameters were the loading rate and the applied sustained stress level. Among these parameters, the loading rate varied in the range of 0.0002 and 0.04 strain/min. In the case of short-term creep tests under sustained loads, three stress levels (between 0.73 f'cc and 0.90 f'cc or 2.76 f'cc and 3.37 f'cc) for low-strength and four stress levels (between 0.69 f'cc and 0.92 f'cc or 0.89 f'co and 1.20 f'co) formedium-strength prisms were applied. The test results showed that the stress-strain behavior of CFRP-confined concrete was affected by the change in loading rate, and external CFRP confinement enhanced the creep performance of concrete significantly. For low-strength concrete specimens, higher strain rates did not bring higher strength values; however, an increase in strength was obvious for medium-strength prisms. On the other hand, for both concrete qualities, the specimens loaded at slower strain rates exhibited better deformability. None of the specimens of the medium-strength concrete failed during the short-term creep tests; however, three of the low-strength concrete prisms failed during the tests. The results of residual strength tests showed that sustained loading did not cause a strength or ultimate deformation capacity loss, but affected the residual strain capacities.

【 授权许可】

Unknown