Souzana Tastani

Souzana Tastani
Democritus University of Thrace | DUTH · Department of Civil Engineering

Assistant Professor, PhD Civil Engineering

About

68
Publications
31,524
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692
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Additional affiliations
December 2013 - February 2017
Democritus University of Thrace
Position
  • Lecturer

Publications

Publications (68)
Conference Paper
Full-text available
In corroded steel anchorages, radial pressures generated by corrosion and bond are balanced by hoop tension provided by the concrete cover; as concrete has negligible strain capacity, the exhaustion of its tensile strength results in instant cover spitting and consequent bond deterioration. This paper presents an experimental study of short steel a...
Conference Paper
Full-text available
The effect of steel corrosion on the structural response of reinforced concrete columns has been quantified in detail in a previously developed methodology, by considering cross-section loss, steel brittle-ness, induced cover cracking, and bond deterioration in the calculations of strength and deformation terms. In this work, the methodology is ext...
Conference Paper
Full-text available
In reinforced concrete, corrosion of steel results in rust of higher volume as per the consumed metal. When exceeding a certain amount of concentration, rust generates bursting pressure to concrete cover in a similar manner to the radial bond component. In the case of a corroded anchorage, both rust and bond radial pressures are balanced by concret...
Conference Paper
Full-text available
Η επίπτωση της διάβρωσης του χαλύβδινου οπλισμού στην αντοχή και ικανότητα παραμόρφωσης στοιχείου οπλισμένου σκυροδέματος (Ο.Σ.), λαμβάνοντας υπόψη παράγοντες όπως είναι η απώλεια διατομής και ολκιμότητας οπλισμού και η συνάφεια ράβδου – σκυροδέματος, έχει ποσοτικοποιηθεί σε αναλυτική μεθοδολογία που αναπτύχθηκε στο ΔΠΘ. Στην παρούσα εργασία διερευ...
Conference Paper
Full-text available
Τα μηχανικώς σχεδιασμένα σύνθετα τσιμεντοειδή (Engineered Cementitious Composites, ECC) αποτελούν ειδικά, «πλάστιμα» σκυροδέματα σύνθεσης από πολύ λεπτά ανόργανα υλικά (τσιμέντο, άμμος και τέφρες), πλαστικές μικρο-ίνες ως οπλισμός μάζας και πολύ λίγο νερό σε συνδυασμό με υπερ-ρευστοποιητή. Βασικό τους χαρακτηριστικό είναι η υψηλή ικανότητα σε εφελκ...
Chapter
Reinforced concrete (RC) columns undergoing lateral sway develop inelastic strains in the primary reinforcement after yielding at locations of maximum moment. The region where yielding develops in known as a plastic-hinge, the conventional definition of its length, ℓ pl , being the region where flexural moments exceed the member moment at yielding....
Conference Paper
Full-text available
Strain resilient cementitious composites are engineered-design concretes made with fine-grained inorganic materials with embedded plastic fibers as mass reinforcement. This novel material can be an attractive alternative to brittle concrete because it encompasses significant strain deformation capacity (larger than 3%) as a result of the confining...
Conference Paper
Full-text available
Ductile concrete with calcareous fly ash and polypropylene fibers I: tensile behavior Σουζάνα ΤΑΣΤΑΝΗ 1 , Ιωάννης ΣΑΒΒΙΔΗΣ 2 Λέξεις κλειδιά: πλάστιμο σκυρόδεμα, τέφρα, ίνες, εφελκυσμός, θερμοκρασία ΠΕΡΙΛΗΨΗ: Ως πλάστιμο σκυρόδεμα ορίζεται σύνθετο τσιμεντοειδές κονίαμα υψηλής ικανότητας παραμόρφωσης, η φιλοσοφία σχεδιασμού του οποίου αφορά μείξη ανό...
Conference Paper
Full-text available
Ductile concrete with calcareous fly ash and polypropylene fibers IΙ: compressive behavior and volumetric stability Σουζάνα ΤΑΣΤΑΝΗ 1 , Μαρία ΒΕΝΕΤΗ 2 , Βασίλειος ΖΑΠΡΗΣ 2 Λέξεις κλειδιά: πλάστιμο σκυρόδεμα, τέφρα, ίνες, θλίψη, συρρίκνωση ΠΕΡΙΛΗΨΗ: Ως πλάστιμο σκυρόδεμα ορίζεται σύνθετο τσιμεντοειδές κονίαμα με σύνθεση από ανόργανα λεπτόκοκκα υλικά...
Article
Full-text available
The required confined zone in critical regions of columns and piers undergoing lateral sway during earthquakes is related to the plastic hinge length where inelastic deformation and damage develops. The exact definition of the plastic hinge length stumbles upon several uncertainties, the most critical being that the extent of the inelastic region e...
Conference Paper
Strain Resilient Cementitious Composites (SRCC) is a class of ECCs, following the design philosophy in terms of grain fineness of mixing materials and the high dosage of plastic fibers, but differentiating in the tensile response: after first cracking they develop a wide parabolic response sustaining adequate tensile strength up to high levels of s...
Conference Paper
Full-text available
In order to advance the use of Strain Hardening Cementitious Composites (SHCC) in structural applications it is essential to understand the mechanics of bond of reinforcement anchored in this type of material. The strength of the cover against splitting as well as the strain development capacity of bars anchored in SHCC are studied in the present e...
Conference Paper
Full-text available
Strain resilient cementitious composites (SRCC) is a class of ECCs; their high deformation capacity as a result of the fiber reinforcement along with the limited porosity render these concretes as highly durable materials with increased cracking resistance. In this experimental study four SRCCs were made with Greek unclassified calcareous fly ash (...
Article
Experiments on deformed reinforcing bar anchorages developed in strain-resilient cementitious composites (SRCCs) with high tensile deformation capacity illustrate that the bar-matrix assembly may respond in a ductile manner marked by pullout failure with no cover splitting - even in the absence of external confinement. This ductile bond-slip respon...
Conference Paper
Full-text available
When a reinforced concrete (RC) column is subjected to lateral sway as a result of earthquake action, the large strain demand in the end sections is supported by development of strains in the anchorage. This causes the bars to displace (or slip) relative to the anchoring concrete at the column fixed end(s). The lumped slip causes rigid-body rotatio...
Conference Paper
Full-text available
The plastic hinge length is defined as the length over a seismically swaying column, where flexural moments exceed the yielding capacity. This length, measured from the critical section towards the shear span, signifies the region where intense inelasticity occurs during the earthquake, and is determined in design codes through calibrated empirical...
Conference Paper
Full-text available
Ως μήκος πλαστικής άρθρωσης σε υποστύλωμα οπλισμένου σκυροδέματος υπό σεισμική φόρτιση ορίζεται το διάστημα όπου οι καμπτικές ροπές υπερβαίνουν την αντοχή διαρροής. Αυτό το μήκος, μετρούμενο από την κρίσιμη διατομή προς το διατμητικό άνοιγμα, σηματοδοτεί την περιοχή όπου εμφανίζεται έντονη ανελαστικότητα κατά την διάρκεια ενός σεισμού. Καθορίζεται...
Conference Paper
Full-text available
The introduction of engineered cementitious composites (ECC) as a patch repair technique in providing confinement of inadequate anchorages or lap-splices has been studied only lately as one of the ap-plications of ECCs in concrete members and as an alternative to the externally bonded FRP jacketing. This paper analytically investigates the bond – s...
Conference Paper
Full-text available
This paper presents an analytical investigation of geo-materials through F.E. simulations, as per the mechanical interaction of polypropylene geo-textiles with the soil substrate in which these materials are to operate as reinforcement. Critical for these analyses was deemed the investigation of the constitutive mechanical properties of woven geote...
Conference Paper
Full-text available
Improved mechanical behavior of unpaved roads is encompassed by the use of geotextiles. Geotextiles are manufactured from polymers having high tensile strength and strain capacity relative to the soil. For this reason they cooperate with the soil in strengthening road surfaces, temporary or permanent. They are placed between soil subgrade and stone...
Article
Stress transfer between reinforcing bars and concrete is engaged through rib translation relative to concrete, and comprises longitudinal bond stresses and radial pressure. The radial pressure is equilibrated by hoop tension undertaken by the concrete cover. Owing to concrete’s poor tensile properties in terms of strength and deformability, the equ...
Article
Full-text available
This paper is a comprehensive state of the art background document which was assembled in support of the development of design guidelines by the Fib Committee 9.3 regarding the use of externally applied Fiber Reinforced Polymers (FRP) materials in the seismic retrofitting of reinforced concrete structures. In the context of developing design guidel...
Article
Seismic-design procedures for walls require that the confinement in the critical (plastic hinge) regions should extend over a length in the compression zone of the cross section at the wall base where concrete strains in the Ultimate Limit State (ULS) exceed the limit of 0.0035. In a performance-based framework, confinement is linked to required cu...
Chapter
Full-text available
This chapter reviews the issues of confinement in plain and reinforced concrete under concentric compression and summarizes the state of the art regarding the available confinement models for strength and stress-strain behaviour of encased confined concrete, and the corresponding magnitude of dependable strain capacity. The mechanisms of confinemen...
Article
Full-text available
Design requirements for development length of lap-spliced reinforcing bars in concrete refer to the associated rules for anchorage, practically treating the two problems as one. This was based on the empirical observation that development capacity of reinforcement obtained from both lap-splice and anchorage tests converge to the same experimental v...
Conference Paper
Full-text available
Stress transfer between reinforcing bar and the surrounding concrete or other cementitious matrices is engaged through rib translation relative to the concrete cover, and comprises longitudinal bond stresses and radial pressure exerted by the bar on concrete. Pressure is balanced by media hoop tensile stresses, which, in conventional concrete with...
Conference Paper
Full-text available
Stress transfer between reinforcing bar and the surrounding cementitious matrix is engaged through rib translation relative to the concrete cover, and comprises longitudinal bond stresses and radial pressure exerted by the bar on concrete. Pressure is balanced by matrix hoop tensile stresses, which, in conventional concrete, result in instant radia...
Article
Development of flexural yielding and large rotation ductilities in the plastic hinge zones of frame members is synonymous with the spread of bar reinforcement yielding into the supporting anchorage. Yield penetration where it occurs, destroys interfacial bond between bar and concrete and reduces the strain development capacity of the reinforcement....
Article
Full-text available
The distribution of bond on the lateral surface of steel reinforcement embedded in concrete is explored through systematic solution of the governing field equations of the associated mechanical problem. By separating the variables, the state of stress in the concrete surrounding the bar is represented by coupling two independent solutions, each des...
Conference Paper
Full-text available
An endeavor to understand the mechanics of bond between a steel reinforcing bar and engineered cementitious composites (ECC), is attempted through this paper. The tensile response of the ECC material deviates from that of the ordinary concrete; after an initial elastic ascending branch, the tensile stress-strain response demonstrates plastic behavi...
Article
Well-established confinement models can adequately estimate the axial strain capacity of FRP-strengthened columns with low-to-moderate confinement, but there is a tendency for overestimation of the effect of FRP-induced confinement on deformation capacity in the range of high confining pressures. Results are particularly evident in the case of exis...
Conference Paper
Full-text available
The distribution of bond on the lateral surface of steel reinforcement embedded in concrete is explored through systematic solution of the governing field equations of the associated mechanical problem. By separating the variables, the state of stress in the concrete surrounding the bar is represented by coupling two independent solutions, each des...
Conference Paper
Full-text available
The development length of lap-splices is defined in codes with reference to the required development length of the associated anchorage, although the similarity between the states of stress of these two situations is only partly understood. To track the relationship between the two seemingly different stress conditions, the differential equation of...
Conference Paper
Full-text available
Retrofits of initially damaged brittle r.c. columns through FRP jacketing of plastic hinge zones fall within two categories when considering the damage attained during the pre-repair phase; the first includes specimens that attained a premature mode of failure without developing any ductility and the second one refers to columns that underwent inel...
Chapter
Full-text available
Seismic retrofits with FRP-jacketing for confinement of plastic hinge zones ride on the spectacular improvements in strength and deformation capacity reported in lightly reinforced column tests after strengthening. In these tests damage is effectively suppressed in the wrapped region at the expense of increased pullout contribution from the anchora...
Chapter
Full-text available
Review of previous experiments on brittle R.C. columns through FRP jacketing illustrates that the efficiency of FRP jacketing in strengthening applications is superior to that which is observed when jacketing is used as a repair means. Actually, performance of the repair appears to be related to the state of damage along the anchorage or lap splice...
Article
Full-text available
The effective strain of FRP wraps used as confining jackets of substandard reinforced concrete members in seismic strengthening applications is studied with the objective to establish the associated plastic compression strain capacity of the encased concrete core. For imposed strains exceeding the effective value, failure owing to compressed bar bu...
Article
A c c e p t e d M a n u s c r i p t N o t C o p y e d i t e d ABSTRACT Results from fifty bond tests conducted using the so-called direct tension-pullout (DTP) specimen type are presented. Anchorages of steel bars with machined deformations were tested so as to enable a targeted study of the effect of rib height and related rib area on bond behavio...
Conference Paper
Full-text available
80 δεν συνάδουν με τις σύγχρονες προδιαγραφές αντισεισμικότητας. Συνήθης τύπος δομήματος της περιόδου είναι τα κτίσματα με pilotis, όπου στα υποστηλώ-ματα του μαλακού ορόφου συγκεντρώνεται η μεγαλύτερη απαίτηση για ικανότη-τα σεισμικής παραμόρφωσης. Ωστόσο, λόγω ανεπαρκών συνδετήρων, τα κατα-κόρυφα στοιχεία αδυνατούν να παραλάβουν τέτοιου μεγέθους...
Conference Paper
Full-text available
Post earthquake reconnaissance studies on masonry buildings have revealed as primary modes of failure diagonal cracking, out-of-plain bending and detachment of perpendicular connected walls. The rehabilitation of seismic resistance of these structures, the importance of which lies in maintenance and survival of the historical and cultural informati...
Conference Paper
Full-text available
With reference to seismic upgrading of poorly detailed reinforced concrete frame members using FRP jackets, the effective design strain of the jacket material (and the commensurate increase of compression strain ductility) are explored for confining applications in compressed members. For strain demands exceeding the effective value in some cases r...
Conference Paper
Full-text available
1. ΕΙΣΑΓΩΓΗ Η αντικατάσταση ακατέργαστης αργίλου με ξηραμένη λυματολάσπη προερχόμενη από αστικά απόβλητα για την παρασκευή κεραμικών οπτόπλινθων μπορεί να αποτελέσει μέρος της λύσης ζητημάτων που αφορούν στην απόθεση και διαχείριση των αποβλήτων, στον περιορισμό της περιβαλλοντικής μόλυνσης και δευτερευόντως στη μείωση του κόστους παραγωγής με τη χ...
Article
Fiber reinforced polymer jackets (FRP sheets) offer great advantages as confining devices of damaged or substandard reinforced concrete (r.c.) members and are already used extensively as local interventions in seismic rehabilitation of existing construction. The design issues and detailing rules related to this seismic repair/strengthening techniqu...
Conference Paper
Full-text available
Mohr-Coulomb, επιπεδότητα διατομών κατά Bernoulli) εκτιμάται η διατμητική αντοχή V Rd τυπικού κτιρίου φέρουσας τοιχοποιίας έναντι οριζόντιας σεισμικής τέμνουσας V Sd. Το μέγεθος της V Rd συναρτάται των φορτίων βαρύτητας, του μεγέθους της επιβαλλόμενης σεισμικής τέμνουσας, των μηχανικών ιδιοτήτων των επιμέρους υλικών καθώς και της γεωμετρίας της κατ...
Article
An analytical model is developed to describe the mechanics of corrosion-induced bond strength degradation and its implications on development capacity of bar anchorages. The model is a frictional construct whereby bond strength is estimated from the coefficient of friction and the normal confining pressure along the anchorage. Both variables are ev...
Conference Paper
Full-text available
This paper aims to evaluate a limit-state model for the local bond-slip relationship of fiber reinforced polymer bars (FRP) as a useful tool for design purposes. This attempt is motivated by the absence of such a relationship even though there is ample experimental evidence in the international literature. The lack of a well defined bond law is att...
Article
Full-text available
This paper explores the structural behavior of corroded reinforced concrete (r.c.) members and the efficacy of repair schemes that include FRP jacketing, both as a means of curbing the corrosion process and for strength recovery. Corrosion of steel reinforcement is a critical issue in the assessment of old construction, because its harmful influenc...
Article
Full-text available
This paper explores the structural behavior of corroded reinforced concrete (r.c.) members and the efficacy of repair schemes that include FRP jacketing, both as a means of curbing the corrosion process and for strength recovery. Corrosion of steel reinforcement is a critical issue in the assessment of old construction, because its harmful influenc...
Article
The local bond mechanics of glass-fiber reinforced polymer GFRP bars in normal strength concrete was investigated through experimental testing and analytical modeling. The experimental program was comprised of 30 direct tension pullout specimens with short anchorages. A novel test setup, specially designed so as to minimize the spurious influence o...
Conference Paper
Full-text available
OBJECTIVES: In this paper local bond-slip relationships for specially machined steel reinforcement are derived through coordinated experimental and analytical investigations. Rather than guiding the proposed design expressions for bond, experiments are used here in order to corroborate the analytical model, which is formulated from first principles...
Article
The efficacy of fiber-reinforced polymer FRP confinement as a means of repairing/strengthening reinforced concrete mem-bers with nonductile details is explored in this paper with particular emphasis on the interaction between jacket and the embedded longitudinal compression reinforcement at the onset of bar buckling. To this end, a total of 27 shor...
Article
Externally-bonded Fiber Reinforced Polymers (FRPs) when used as jackets in reinforced concrete (r.c.) members are effective in increasing shear, lap-splice strength and deformation capacity. For this reason they are currently used extensively as a fast remedy in earthquake-damaged structures, or to strengthen under-designed structures in areas of h...
Article
Full-text available
An analytical model is developed to describe the mechanics of corrosion-induced bond strength degradation and its implications on development capacity of bar anchorages. The model is a frictional construct whereby bond strength is estimated from the coefficient of friction and the normal confining pressure along the anchorage. Both variables are ev...
Conference Paper
Full-text available
Synopsis: In this paper local bond-slip relationships of GFRP bars in normal strength concrete are evaluated experimentally through testing of 30 direct-tension pullout specimens. In all cases short anchorages are examined. A novel type of test specimen was used in the study specially designed so as to minimize the spurious influence of testing con...
Conference Paper
Full-text available
This paper explores the structural behavior of corroded reinforced concrete (r.c.) members and the efficacy of repair schemes that include FRP jacketing both as a means of curbing the corrosion process and for strength recovery. Corrosion of steel reinforcement is a critical issue in assessment of old construction because its harmful influence on s...
Article
Corrosion of steel reinforcement is a critical issue in assessment of exposed reinforced concrete (r.c.) structures because its harmful influence on stiffness, strength and ductility may drastically limit their service life. In assessing residual strength several parameters need be considered: loss of flexural strength due to bar section loss, burs...
Article
Full-text available
The 'classical' model for the estimation of crack widths and the ratio φ/ρeff and influence of bond characteristics of reinforced concrete elements are discussed. The result from tests with shallow beams reinforced with different types of 12mm steel, made up of same batch of concrete delivered in ready-mix batch showed that crack widths are signifi...
Article
Reinforced concrete columns designed and built prior to the introduction of modern detailing practices are often susceptible to the compounded influences of reinforcement corrosion owing to carbonation or exposure to the marine environment, a circumstance that decimates even further the limited safety reserves of old-type construction. This problem...
Article
Full-text available
Reinforced concrete columns designed and built prior to the introduction of modern detailing practices are often susceptible to the compounded influences of reinforcement corrosion owing to carbonation or exposure to the marine environment, a circumstance that decimates even further the limited safety reserves of old-type, non-conforming constructi...
Article
Full-text available
The formulation of a design strategy for the seismic upgrading of existing R.C. structures using externally-bonded FRPs as jacketing devices is the subject of this paper. Considering that FRP wraps impart little or no stiffness to the jacketed elements, the objective is to achieve through intervention a reasonable increase of the deformation capaci...
Article
Full-text available
Externally-bonded FRPs offer great advantages as jacketing devices in repair/ strengthening schemes of reinforced concrete members that seek to increase strength and deformation capacity at failure, and for this reason they are currently used extensively as a fast remedy in earthquake-damaged structures built with non-conforming detailing rules. Th...
Conference Paper
Full-text available
This paper presents results of an experimental investigation of the performance of an alternative bond test known as DTP-BT (Direct Tension Pullout Bond test) designed to quantify the lower bound bond properties of steel and GFRP bars embedded in normal strength concrete. Objective of an alternative test setup was to simulate the stress field that...
Conference Paper
Full-text available
This paper presents results of an experimental investigation regarding the anchorage strength of GFRP bars embedded in concrete. Objective of this study was the experimental evaluation of bond of nonmetallic reinforcement when the surrounding concrete is subjected to a tension stress field, such as would occur in the tension zone of a beam in flexu...

Questions

Question (1)
Question
Has anyone in your laboratory equipment a VERSA TESTER? made by SOILTEST.Inc (Evanston Ill. USA)? I am looking for its user manual... Any help is greatly appreciated!!!
See the attached file.