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Author: search.filters.author.Nawaz, AdnanSubject: search.filters.subject.Concrete

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    Enhancing compressive behavior of concrete with novel low-cost hybrid passive confinement including large rupture strain cotton ropes: Experimental findings and a design-oriented model
    (2024-12-01)
    Saingam, Panumas
    ;
    Hussain, Qudeer
    ;
    Ejaz, Ali
    ;
    Nawaz, Adnan
    ;
    Joklad, Panuwat
    Recent research have highlighted the potential of hybrid confinement, combining high tensile strength fiber-reinforced polymers with large rupture strain confinement. This study presents experimental findings on 64 cylindrical and square-shaped specimens tested under axial compression, introducing a novel hybrid confinement method utilizing low-cost fiberglass chopped strand mat sheets and cotton ropes (COFS confinement). The experimental and analytical results yielded several key conclusions. Firstly, circular specimens exhibited significant peak strength increases in various subgroups, with enhancements ranging from 97.5 % to 285.5 %, and ultimate strain improvements ranging from 588.6 % to 1650.0 %. Similarly, square specimens under COFS confinement also demonstrated notable enhancements in ultimate strength and strain, with increases up to 244.7 % and 1083.0 %, respectively, particularly evident with higher levels of confinement. The influence of cross-sectional shape on compressive strength, strain, and energy dissipation was noted, with COFS confinement notably improving these factors for circular sections. Additionally, the study found that as the unconfined compressive strength increased, the enhancement in compressive strength, ultimate strain, and energy dissipation decreased. Moreover, the confinement ratio positively affected axial behavior improvement, with a proportional enhancement observed. However, the efficacy of the confinement ratio was influenced by cross-section type and plain concrete strength, emphasizing the need for considering these factors in COFS-based confinement design. Lastly, an analytical design-oriented model proposed for approximating stress vs. strain curves of COFS-confined concrete showed close agreement with experimental results, providing valuable insights for future design considerations.
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    Structural behavior of RC one-way slabs strengthened with ferrocement and FRP composites
    (2024-07-01)
    Joyklad, Panuwat
    ;
    Krishna Gadagamma, Chaitanya
    ;
    Maneengamlert, Bodee
    ;
    Nawaz, Adnan
    ;
    Ejaz, Ali
    Existing research lacks focus on the structural behavior of reinforced concrete (RC) one-way slabs reinforced with ferrocement, and there's a notable absence of comparative studies between fiber-reinforced polymers (FRPs) and ferrocement strengthening methods for these slabs. Given the cost-effectiveness and widespread use of ferrocement in structural reinforcement, this study aimed to address these gaps through an experimental program. Three sizes of wire mesh, categorized as Type-I (small), Type-II (medium), and Type-III (large), were employed in this study. Chemical or mechanical anchors were used to attach ferrocement jackets. Moreover, 6, 12, or 18 anchors were used to assess the effect of anchor configuration. The goal was to enhance the structural performance of slabs and compare them with slabs reinforced using FRP jackets. The study focused on preventing debonding of the strengthening layers, employing either mechanical or chemical anchors. All slabs exhibited ductile failure with flexural cracks. The peak load and ultimate deflection were enhanced by up to 49.00% and 109.07%, respectively, by the application of ferrocement jackets, whereas the dissipated energy was increased by up to 174.00 %. Notably, the use of chemical anchors demonstrated a superior ability to delay debonding and enhance ductility compared to mechanical anchors. Slabs reinforced with glass FRP (GFRP) showed delayed debonding relative to carbon FRP (CFRP) reinforced slabs, indicating the superior performance of chemical anchors with GFRP layers. Moreover, the type and size of wire mesh significantly influenced performance, with small and medium-sized mesh configurations enhancing ductility, while large-sized mesh exhibited relatively earlier debonding. The orientation of the wire mesh also played a crucial role, with parallel orientation to the longitudinal axis of slabs yielding better performance.