Papers by Parthena Maria Kosmidou
Δημοκρίτειο Πανεπιστήμιο Θράκης (ΔΠΘ). Σχολή Πολυτεχνική. Τμήμα Πολιτικών Μηχανικών. Τομέας Δομικών Κατασκευών. Εργαστήριο Οπλισμένου Σκυροδέματος και Αντισεισμικών Κατασκευών, 2020
Materials, 2019
Reinforced concrete (RC) beams under cyclic loading usually suffer from reduced aggregate interlo... more Reinforced concrete (RC) beams under cyclic loading usually suffer from reduced aggregate interlock and eventually weakened concrete compression zone due to severe cracking and the brittle nature of compressive failure. On the other hand, the addition of steel fibers can reduce and delay cracking and increase the flexural/shear capacity and the ductility of RC beams. The influence of steel fibers on the response of RC beams with conventional steel reinforcements subjected to reversal loading by a four-point bending scheme was experimentally investigated. Three slender beams, each 2.5 m long with a rectangular cross-section, were constructed and tested for the purposes of this investigation; two beams using steel fibrous reinforced concrete and one with plain reinforced concrete as the reference specimen. Hook-ended steel fibers, each with a length-to-diameter ratio equal to 44 and two different volumetric proportions (1% and 3%), were added to the steel fiber reinforced concrete (SF...
The use of composite materials (Fiber Reinforced Polymers - FRP) as internal and strengthening re... more The use of composite materials (Fiber Reinforced Polymers - FRP) as internal and strengthening reinforcement in concrete structural members is becoming increasingly apparent. The ageing of the materials, the poorly detailed concrete members of the existing old Reinforced Concrete (RC) structures designed prior to 1970, the exposure of extremely important (RC) structures (e.g. bridges, highways etc.) in high corrosive environment owing to climate conditions or chemicals and the design requirements of modern seismic codes have led since several years the scientific community to investigate alternative methods of reinforcing and strengthening of the structural elements. In some cases, the use of FRP materials seem to be more advantageous than the use of the conventional steel reinforcement. The present research focuses on the investigation of innovative materials as main internal reinforcement or strengthening reinforcement of RC members with shear problems under monotonic and cyclic l...
Fibers, 2018
The effectiveness of a new retrofitting technique to upgrade the structural behaviour of reinforc... more The effectiveness of a new retrofitting technique to upgrade the structural behaviour of reinforced concrete (RC) deep beams without steel stirrups using carbon fibre-reinforced polymer (CFRP) ropes as the only transverse shear reinforcement is experimentally investigated. Five shear-critical beams with rectangular and T-shaped cross-section are tested under monotonic loading. The strengthening schemes include (a) one vertical and one diagonal single-link CFRP rope that are internally applied through the web of the rectangular beam using an embedded through-section (ETS) system and (b) two vertical U-shaped double-link ropes that are applied around the perimeter of the web of the flanged beam using a near-surface-mounted (NSM) system. In both cases, the free lengths of the CFRP ropes have been properly anchored using epoxy bonded lap splices of the rope as NSM at (a) the top and the bottom of the web of the rectangular beam and (b) the top of the slab of the T-beam. Promising result...
An analytical methodology for the calculation of the flexural and the shear capacity of concrete ... more An analytical methodology for the calculation of the flexural and the shear capacity of concrete members with Fibre-Reinforced-Polymer (FRP) bars as tensional reinforcement is proposed. The flexural analysis is initially based on the design provisions of ACI 440.1R-15 which have properly been modified to develop general charts that simplify computations and provide hand calculations. The specially developed charts include non-dimensional variables and can easily be applied in sections with various geometrical properties, concrete grade and FRP properties. The proposed shear model combines three theoretical considerations to facilitate calculations. A unified flexural/shear approach is developed in flow chart which can be used to estimate the ultimate strength and the expected failure mode of a concrete beam reinforced with longitudinal FRP bars, with or without transverse reinforcement. The proposed methodology is verified using existing experimental data of 138 beams from the liter...
Fibers
Innovative reinforcement as fiber-reinforced polymer (FRP) bars has been proposed as alternative ... more Innovative reinforcement as fiber-reinforced polymer (FRP) bars has been proposed as alternative for the substitution of the traditional steel bars in reinforced concrete (RC) structures. Although the advantages of this polymer reinforcement have long been recognised, the predominantly elastic response, the reduced bond capacity under repeated load and the low ductility of RC members with FRP bars restricted its wide application in construction so far. In this work, the behavior of seven slender concrete beams reinforced with carbon-FRP bars under increasing static loading is experimentally investigated. Load capacities, deflections, pre-cracking and after-cracking stiffness, sudden local drops of strength, failure modes, and cracking propagation have been presented and commented. Special attention has been given in the bond conditions of the anchorage lengths of the tensile carbon-FRP bars. The application of local confinement conditions along the anchorage lengths of the carbon-FR...
Fibers
Innovative reinforcement as fiber-reinforced polymer (FRP) bars has been proposed as alternative ... more Innovative reinforcement as fiber-reinforced polymer (FRP) bars has been proposed as alternative for the substitution of the traditional steel bars in reinforced concrete (RC) structures. Although the advantages of this polymer reinforcement have long been recognised, the predominantly elastic response, the reduced bond capacity under repeated load and the low ductility of RC members with FRP bars restricted its wide application in construction so far. In this work, the behavior of seven slender concrete beams reinforced with carbon-FRP bars under increasing static loading is experimentally investigated. Load capacities, deflections, pre-cracking and after-cracking stiffness, sudden local drops of strength, failure modes, and cracking propagation have been presented and commented. Special attention has been given in the bond conditions of the anchorage lengths of the tensile carbon-FRP bars. The application of local confinement conditions along the anchorage lengths of the carbon-FR...
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Papers by Parthena Maria Kosmidou