Loading...

Experimental and Code-Based Assessment of the Axial Behavior of Geopolymer and Cement Concrete Confined with UPVC Tubes and FRP

Hosseinzadeh, Ali | 2025

0 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58387 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khaloo, Alireza
  7. Abstract:
  8. In the first part of this study, the axial performance of unplasticized polyvinyl chloride (UPVC) tubes filled with slag-based geopolymer concrete was investigated experimentally, analytically, and in accordance with design codes. The effects of concrete compressive strength (20 to 60 MPa), tube thickness (4.8 and 7.6 mm), height-to-diameter ratio (2 and 4), and specimen age (7, 28, and 90 days) on ultimate capacity, ductility, and confinement efficiency were evaluated. The results showed that increasing concrete strength, specimen age, and height-to-diameter ratio reduced confinement efficiency, while increasing tube thickness improved it. To complement the study, data from 523 concrete-filled thermoplastic tube (CFTT) specimens collected from previous works were combined with the experimental results to evaluate international design codes. Although these codes were mainly developed for concrete-filled steel tubes, EC4 and AS-NZS demonstrated higher accuracy in predicting the results. Finally, modified formulations based on the findings and EC4 provisions were proposed. In the second part, the axial behavior of cement-based and geopolymer concrete columns (normal- and high-strength) confined with FRP, using either natural or recycled aggregates, was studied analytically and code-based. A database comprising 1381 specimens from previous studies was used to assess the accuracy of established design codes in estimating axial capacity. Although these codes were mostly developed for normal-strength cement concrete, fib Bulletin 90 and CNR-DT 200 provided the most accurate predictions, while some codes underestimated capacity due to limitations in accounting for FRP properties. In addition to the codes, predictive models proposed by researchers in the literature were also evaluated. These models showed good agreement with experimental results for normal-strength cement and geopolymer concretes with natural or recycled aggregates, but their accuracy needs improvement for high-strength concretes. Ultimately, formulations were proposed based on experimental results and existing models, which showed good consistency with the experimental data
  9. Keywords:
  10. Geopolymer Concrete ; Unplasticized Polyvinyl Chloride (UPVC) Tube ; Fiber Reinforced Polymer (FRP)Confinement ; Axial Loads ; Ductility ; Ultimate Strength ; Seismic Design Codes ; Ultimate Strength Prediction

 Digital Object List

 Bookmark

No TOC