Thanasis Triantafillou

University of Patras | UP · Department of Civil Engineering

Background This study explores the flexural behavior of unfired and fired one-way slabs constructed from reinforced ferronickel slag-based alkali-activated concrete (AAC). Despite growing interest in AAC as a sustainable alternative to ordinary Portland cement (OPC), limited research exists on large-scale structural elements, particularly under pos...

Masonry retrofitting systems combining seismic with energy upgrading features are increasingly gaining popularity in the scientific community during the past years since they simultaneously address two of the most pressing needs related to the existing building stock. This is commonly realized by applying textile reinforced mortar (TRM) overlays co...

Textile reinforced mortars (TRM) are materials whose mechanical behavior has been extensively investigated during the last few years. However, studies on the behavior of these materials after exposure to various aggressive environments are still limited and, hence, their performance during their entire service life remains to be determined. The pre...

This study aimed to develop optimized alkali-activated concrete using ferronickel slag for high-temperature applications, focusing on minimizing environmental impact while maintaining high compressive strength and slump. A response surface methodology, specifically the mixture design of experiments, was employed to optimize five components: water,...

This paper investigates the flexural behavior of unfired and fired one-way slabs constructed from reinforced ferronickel slag-based alkali-activated concrete. The study aims to expand the limited knowledge of large-scale testing of alkali-activated concrete structural elements, with a particular emphasis on their post-fire performance. Four slabs,...

The optimal combination of five components to develop a concrete for high-temperature applications was studied through a response surface methodology known as mixture design of experiment. The selected components were water, an alkali-activated binder based on ferronickel slag activated with potassium silicate and potassium hydroxide, and three agg...

Textile Reinforced Mortar (TRM) overlays have seen widespread usage in recent years for the strengthening of existing structures including reinforced concrete ones. However, little is known about the behavior of these materials in various harsh environments and their ability to serve as barriers against the ingress of chemicals harmful to concrete...

This paper discusses the integration of an alkali-activated mortar (AAM), based on industrial waste, into a novel composite material fit for structural upgrading purposes and rendered with high temperature endurance and a low CO2 footprint. The AAM combined with carbon fiber textiles form a new generation of sustainable inorganic matrix composites—...

The effect of in-plane damage on the out-of-plane response of retrofitted and thermally insulated masonry infills was examined in this paper through a set of experiments performed on a medium-scale reinforced concrete frame. Structural reinforcement was realized through the use of textile reinforced mortar (TRM), while expanded polystyrene boards w...

In view of the pressing need for strengthening old masonry structures, while considering the importance of reducing CO2 emissions in the construction sector, masonry retrofitting techniques with environmentally friendly (i.e., non-cementitious and non-corroding) materials need to be studied and developed. This paper discusses the mechanical perform...

The effectiveness of textile-reinforced mortars (TRM) utilized as jacketing overlays that are applied to short, shear-critical reinforced concrete (RC) columns was investigated experimentally and verified analytically in this study. Moreover, the possibility of replacing the standard ordinary portland cement (OPC) matrix with an alternative alkali-...

Textile reinforced alkali-activated mortars (TRAAM) constitute a new family of composite materials that combines the high mechanical performance of textile reinforced mortars (TRM) with the eco-friendly nature of alkali-activated materials (AAM). Moreover, the utilization of carbon fibers in TRAAM is likely to promote the fire endurance of the deve...

The effectiveness of textile reinforced mortars (TRM) in the form of thin overlays applied on reinforced concrete (RC) members is shortly reviewed in the oral presentation of this work, with emphasis on recent findings by the authors, including the development of integrated TRM-thermal insulation systems for the combined seismic and energy retrofit...

In this work, the optimal design of a mortar based on alkali-activated material technology is presented. Ferronickel slag, a byproduct of the ferronickel alloy industry, was used both as a binder component (in a finely ground form) and as fine aggregate in alignment with a circular economy approach. The proportions of binder, fine aggregate, and wa...

The present report provides a review of the seismic upgrading techniques for reinforced concrete, masonry and steel buildings, which constitute the majority of the building stock in the EU. Seismic upgrading techniques are divided in two major categories, depending on the way they “treat” the structure. The first category includes the ones that ope...

The renovation of existing buildings plays a key role in achieving the ambitious target of climate neutrality of the EU set out within the EU Green Deal. Through increased renovation of energy inefficient buildings, a reduction in energy consumption in the building sector can be achieved, as targeted by the Renovation Wave initiative. When consider...

To achieve the ambitious target of climate neutrality of the EU set out within the EU Green Deal, a reduction of energy use in the highly energy consuming building sector is critical. To achieve this, the renovation of existing buildings has been given a key role, starting with the Renovation Wave initiative. In fact, a large proportion of existing...

This paper presents a state-of-the-art review on the available seismic upgrading techniques of existing masonry structures, which comprise a very common structural material including most of the surviving historic structures worldwide. Due to their increased age and vulnerability, masonry buildings and structures are generally in greater need of st...

Ageing of the building stock is an issue affecting many regions in the world. This means a large proportion of existing buildings being considered energy inefficient, with associated high energy use for heating and cooling. Through renovation, it is possible to improve their energy-efficiency, hence reducing their significant impact on the total en...

The development of an optimal low-calcium alkali-activated binder for high-temperature stability based on ferronickel slag, silica fume, potassium hydroxide, and potassium silicate was investigated based on Mixture Design of Experiment (Mixture DOE). Mass loss, shrinkage/expansion, and compressive and flexural strengths before and after exposure to...

The need for repair and maintenance has become dominant in the European construction sector. This, combined with the urge to decrease CO 2 emissions, has resulted in the development of lower carbon footprint repair solutions such as textile reinforced mortars (TRM) based on alkali-activated materials (AAM). Life cycle studies indicate that AAM CO 2...

Development and use of preconstruction have been exhibited for several decades. Numerous modules, ranging from the simplest to the most advanced concepts, have been suggested to ameliorate the layout of building structures, with respect to a broad spectrum of needs. This study aims to unfold the fire defensiveness of an innovative precast concrete...

Short columns with deficiencies of low-strength concrete and large spacing of transverse reinforcement are quite common in construction practice in many developing countries in seismically active regions. Therefore, it is important to retrofit this type of column to avoid negative consequences in the case of severe damage. External fiber–reinforced...

In the present study, a total of 12 experiments were carried out in order to evaluate the effect of prior in-plane damage on the out-of-plane response of structurally and thermally retrofitted masonry wallettes, simulating in a that way the behavior of upgraded masonry infills in reinforced concrete or steel frame structures under seismic loading....

Taking into consideration the seismic vulnerability of older buildings and the increasing need for reducing their carbon footprint and energy consumption, the application of an innovative system is investigated; the system is based on the use of textile-reinforced mortar (TRM) and thermal insulation as a means of combined seismic and energy retrofi...

This paper presents investigations on the tensile behavior of several textile-reinforced concrete (TRC) material compositions after fire exposure. First, experimental investigations are presented, aiming to provide insights into the thermomechanical performance of fire-exposed TRC, and data that can be used for the development and implementation of...

The behavior of Textile Reinforced Concrete (TRC) under increased temperatures has been poorly investigated so far and has been a topic of increasing interest in the past decade. The lack of knowledge is even greater when it comes to the behavior of hybrid reinforcement layups, in which different fiber textiles are combined, and the effect of their...

The application of textile-reinforced mortars (TRM) on masonry walls constructed with natural stones was studied through a set of medium-scale experiments. Fourteen experiments were carried out in total, including in- and out-of-plane cyclic tests as well as two different strengthening configurations. The first consisted of a TRM made of a natural...

Textile-reinforced concrete (TRC) is a promising composite material with enormous potential in structural applications because it offers the possibility to construct slender, lightweight, and robust elements. However, despite the good heat resistance of the inorganic matrices and the well-established knowledge on the high-temperature performance of...

Collapses or serious damages of existing buildings during strong earthquakes have resulted in significant economic losses, severe injuries and loss of human lives. Given the late introduction of modern seismic standards and the large number of the existing under-designed buildings, the scientific interest has progressively been focusing on developi...

This study discusses a modelling technique of the thermomechanical behaviour of textile reinforced concrete (TRC) members, with finite elements. TRC specimens that were subjected to fire tests and subsequently to flexure tests are numerically simulated in a two-step procedure. The first step is a heat transfer analysis, where the temperature profil...

Taking into consideration the seismic vulnerability of older buildings and the increasing need for reducing their carbon footprint and energy consumption, the application of an innovative system is investigated; the system is based on the use of textile-reinforced mortar (TRM) and thermal insulation as a means of combined seismic and energy retrofi...

Taking into consideration the seismic vulnerability of older buildings and the increasing need for reducing their carbon footprint and energy consumption, the application of an innovative system is investigated; the system is based on the use of textile reinforced mortars (TRM) and thermal insulation as a means of combined seismic and energy retrof...

This guide addresses the use of externally bonded (EB) fabricreinforced cementitious matrix (FRCM) and steel-reinforced grout (SRG) systems for repair and strengthening of masonry structures. FRCM and SRG are composite materials composed of a reinforcement in the form of open fabric bonded on the masonry surface through an inorganic matrix. In part...

A total of 12 experiments were carried out to evaluate the effect of prior in-plane damage on the out-of-plane response of structurally and thermally retrofitted masonry wallettes, simulating simply the behavior of upgraded masonry infills in frame structures under seismic loading. The specimens were retrofitted with textile-reinforced mortar (TRM)...

The mechanical behavior of Textile Reinforced Concrete after exposure to fire is poorly investigated so far. This study investigates the tensile and flexural capacity of carbon TRC at ambient conditions and after fire exposure, focusing on the influence of the surface treatment of the textiles and the thickness of the concrete cover. The results sh...

This paper presents the results of an experimental study investigating the seismic behavior of fiber reinforced polymer (FRP)-retrofitted shear-critical low-strength reinforced concrete (RC) short columns with or without moderate and heavy pre-damage. Towards this end, six nearly full-scale specimens were tested before and after retrofitting with F...

https://www.fib-international.org/publications/fib-bulletins/externally-applied-frp-reinforcement-for-concrete-structures-pdf-detail.html In December 1996, CEB established a Task Group with the main objective to elaborate design guidelines for the use of FRP reinforcement in accordance with the design format of the CEB-FIP Model Code and Eurocode2...

The concept of the combined seismic and energy retrofitting of existing reinforced concrete (RC) buildings was examined in this paper through a number of case studies conducted on model buildings (simulating buildings of the „60s-‟80s in southern Europe) constructed according to outdated design standards. Specifically, seismic and thermal analyses...

The mechanical behavior of textile reinforced cementitious composites (TRC) has been a topic of wide investigation during the past 30 years. However, most of the investigation is focused on the behavior under ambient temperatures, while only a few studies about the behavior under high temperatures have been conducted thus far. This paper focused on...

Textile reinforced mortars (TRM), also known in the international literature as textile reinforced concrete (TRC) or fabric reinforced cementitious matrix (FRCM) materials, have been widely studied during the last two decades as they constitute a promising alternative to the fiber reinforced polymer (FRP) retrofitting solution for strengthening of...

This investigation defines the problem and proposes guidelines for seismically upgrading masonry buildings using textile-reinforced mortar (TRM). The TRM technique in the form of externally applied jackets is appropriate for protecting masonry structures because it can provide sufficient strength and deformation capacity while satisfying the compat...

Textile reinforced mortars (TRM) and thermal insulating materials are integrated in a new system for structural (including seismic) and energy retrofitting of masonry. The proposed system is investigated experimentally by performing medium-scale tests on three series of masonry walls subjected to in-plane cyclic loading. Key parameters under invest...

The application of a new system, which combines textile reinforced mortars (TRM) and thermal insulating materials as a means of both structural (including seismic) and energy retrofitting of masonry walls is experimentally investigated in this study. Medium scale tests were carried out on masonry walls subjected to out-of-plane bending. Several par...

This paper studies the bond quality among Textile Reinforced Concrete and Extruded Polystyrene Foam, which can constitute the basic materials for construction of load-bearing elements, such as insulating sandwich panels. The bond properties were investigated experimentally and were monitored by Digital Image Correlation and Acoustic Emission. The r...

Textile Reinforced Mortar (TRM), also known as Fabric Reinforced Mortar or Fabric Reinforced Cementitious Matrix, composites are an emerging technology for the external repair and strengthening of existing structures. For most applications, the effectiveness of the TRM reinforcement relies on its bond performance. This recommendation identifies the...

Textile reinforced mortars (TRM), also known in the international literature as textile reinforced concrete (TRC) or fabric reinforced cementitious matrix (FRCM) materials, have been widely studied during the last two decades as they constitute a promising alternative to the fiber reinforced polymer (FRP) retrofitting solution for strengthening of...

Fire-testing of Textile Reinforced Concrete (TRC) is an interesting field in which quite limited research has been conducted so far. In this paper some preliminary tests are presented, where mortars used as binders are heated to 850 °C and their residual strength is tested, while the Ultrasonic Pulse Velocity (UPV) is also measured, before and afte...

An innovative concept is proposed to isolate – at low and moderate story drifts – infill panels from the surrounding steel frame, using thin layers of cellular materials. The concept is verified experimentally through testing of fully infilled frames under in-plane cyclic loading. A simple analytical model is developed and implemented in OpenSees;...

Textile reinforced mortar (TRM) is a promising alternative to the FRP retrofitting solution for shear strengthening of reinforced concrete (RC) beams, based on the experimental results presented so far in the literature. Thus, the development of reliable and accurate design models for shear strengthening of concrete members with TRM is required for...

The last decades, the introduction of fibre reinforced polymer (FRP) reinforcement has been proven instrumental for the strengthening and seismic retrofitting of a large number of ageing concrete structures. FRP reinforcement in the form of strips, sheets, fabrics and bars are used as externally applied reinforcement, by means of dedicated applicat...

In this study an innovative concept is proposed to isolate-at low and moderate storey drifts-infill panels from the surrounding reinforced concrete (RC) frame, using thin layers of cellular materials. The concept is verified experimentally through testing of three fully infilled (i.e. at full height) and two partially infilled (i.e. at reduced heig...

Analysis-oriented model (AOM) is a theoretical approach intended to analyze and design systems by applying the notions throughout the organization of a series of equations in one or more iterative cycle. The stress–strain curve of an fiber reinforced polymer (FRP) confined column is evaluated using an incremental procedure, which takes into account...

The application of a new system, which combines textile reinforced mortars (TRM) and thermal insulating materials as a means of both structural (including seismic) and energy retrofitting of masonry walls is experimentally investigated in this study. Medium scale tests were carried out on 17 masonry walls subjected to out-of-plane bending. Several...

In this chapter, the author presents the basic principles and behavioral aspects of reinforced concrete (RC) strengthening with textile-reinforced mortar (TRM); the author also reviews a number of studies that have provided fundamental knowledge on the use of TRM as a strengthening and seismic retrofitting material of RC structures. In most cases,...

Building on the concepts presented in the previous chapter, this chapter aims to present simplified design procedures and models for unreinforced masonry structures strengthened with fiber composites comprising textiles in inorganic matrices (textile-reinforced mortar). The following topics are covered: general safety principles and safety verifica...

One interesting solution to the problems associated with current strengthening techniques for unreinforced masonry walls involves the use of textile-reinforced mortar (TRM) overlays. In this chapter, the author presents concepts for the strengthening of masonry structures with TRM, as well as key aspects of structural behavior. The following topics...

This paper presents the experimental procedure for damage detection on concrete cylinders retrofitted with TRM (textile-reinforced mortar) or FRP (fiber-reinforced polymer) jackets. The strengthening systems were equivalent so that a direct comparison of the results were possible. A comparison between the two composite materials (TRM and FRP) was m...

Textile reinforced concrete (TRC) is a high performance cementitious composite using straight and parallel aligned fibers of suitable materials, e.g. ARglass and carbon, as continuous reinforcement in form of textiles. Textile reinforced concrete is usually used for thin concrete elements or as strengthening layers for concrete structures. Textile...

The effectiveness of using textile-reinforced mortar (TRM) as a means of improving the mechanical behaviour of reinforced concrete (RC) or masonry elements has been experimentally verified in the recent past. In this study TRM was employed for the first time in the case of substandard masonry-infilled RC frames representing structural detailing of...

Fibre-reinforced polymer (FRP) composites have been employed in the last few decades largely for the strengthening and seismic retrofitting of existing reinforced concrete (RC) structures. Several studies are available in the literature and different analytical models have been proposed for evaluating the FRP contribution in strengthened RC element...

This chapter gives an overview on the state-of-the-art of the Near-Surface Mounted (NSM) technique for structural retrofitting of reinforced concrete structures using Fibre Reinforced Polymers (FRP). The chapter is divided in 5 sections. Firstly, general aspects of the technique are introduced, including main advantages, nomenclature adopted, type...

Textile Fibre Composites in Civil Engineering provides a state-of-the-art review from leading experts on recent developments, the use of textile fiber composites in civil engineering, and a focus on both new and existing structures. Textile-based composites are new materials for civil engineers. Recent developments have demonstrated their potential...

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...

This paper investigates the use of innovative, cost-effective techniques to protect ancient monuments consisting of multi-drum columns from seismic excitations. The proposed approach includes the use of particle dampers in the form of classical drums, with a hollow part containing particles. These can substitute damaged or missing drums. Their effe...

The contribution of masonry infills to the seismic resistance of existing reinforced concrete structures is significant, both before separation of the infill from the surrounding frame occurs and during large cycles of imposed deformations near collapse. Strengthening of this type of structures usually aims at increasing the resistance and deformat...

A passive control methodology to increase the seismic safety of multi-drum columns is presented. The response of a large scale column-model to dynamic excitations is investigated experimentally. A particle damper is used to replace one of the columns’ original drums. The influence of the system parameters on the response of the column is also exami...

Contemporary externally bonded structural upgrading schemes for masonry structures employ Fiber Reinforced Polymer (FRP) systems (a technique that was extended from concrete to masonry structures) and technical textiles (structural fiber grids) embedded in inorganic matrices. The latter account for a multitude of systems depending on the type of gr...

The paper presents the results of a comprehensive experimental program aiming to provide a fundamental understanding of the behavior of reinforced concrete (RC) columns under simulated seismic loading, strengthened in flexure (of crucial importance in capacity design) with different types and configurations of near-surface mounted (NSM) reinforcing...