Stefano De Santis

Università Degli Studi Roma Tre | UNIROMA3 · Department of Civil Computer and Aeronautical Engineering

The seismic protection of historic stone masonry buildings has become one of the most challenging issues due to the systematic heavy damage suffered by stone buildings during earthquakes. The challenges lie in the need to improve their structural behavior while preserving the main features of the architectural heritage. To this purpose, two strengt...

Post-earthquake reconstruction activities need tools for assessing the vulnerability of structures, based on visual inspection and quick survey. So far, the public administrations in charge of granting the funds and monitoring reconstruction have adopted different methods taken from scientific literature or developed ad hoc for specific events. The...

The long-term performance of strengthening systems is of the utmost importance for the sustainable management of the building stock. Mortar-based composites have proved extremely effective for enhancing the ultimate strength of existing structures, but their durability has not been sufficiently investigated so far and still raises concern. This pap...

Detecting the onset of structural damage and its progressive evolution is crucial for the assessment and maintenance of the built environment. This paper describes the application of a computer-vision-based methodology for structural health monitoring to a shake table investigation. Three rubble stone masonry walls, one unreinforced and two reinfor...

Mortar-based composites are an emerging technology for the repair and strengthening of reinforced concrete and masonry structures. In most cases, the effectiveness of the retrofitting work relies on the substrate-to-composite bond capacity but in some applications, connectors are also used to prevent debonding and improve the performance of the ret...

There has been considerable attention drawn to the application of textile reinforced mortar ( TRM ) composites for strengthening existing masonry and concrete structures. These composites are made from textile fibers embedded in an inorganic matrix and act as externally bonded reinforcement ( EBR ). Therefore, a careful observation must be made of...

Steel reinforced grout is one of the most effective mortar-based composites for the strengthening of masonry structures. Nonetheless, the deterioration of steel cords, especially when embedded in lime-based matrices, may compromise the long-term effectiveness of the strengthening systems. The use of stainless-steel may overcome this drawback, but i...

Steel Reinforced Grout (SRG) is an effective, cost-efficient and versatile technology for strengthening existing structures. However, the high strength properties exhibited by steel textiles can rarely be fully exploited in design, due to the premature occurrence of bond failure and deterioration. Because of the small diameter of steel cords or wir...

The destruction of Amatrice and the surrounding villages in Central Italy after the 2016 seismic sequence was so impressive that engineers, authorities and local communities started sharing the common feeling that historical stone masonry buildings were too below current safety standards. The severe damage caused by the earthquakes led to a general...

Two techniques for the seismic strengthening of fair faced rubble masonry walls are proposed and tested on a shake table. The first solution entails the use of carbon fibre reinforced polymer connectors installed from outside through the natural stone units, without perforating the entire wall thickness, thus leaving the internal wall surface undis...

Fabric Reinforced Cementitious Matrix (FRCM) composites represent an innovative and effective retrofitting solution for masonry structures. The use of FRCMs as an external retrofitting technique requires an insight knowledge of their mechanical behavior, failure modes and masonry-to-FRCM bond properties. A Round Robin Test (RRT) programme was launc...

This paper presents an experimental investigation on Steel Reinforced Grout (SRG) systems comprising multiple layers of galvanized UHTSS textiles, with either 4 or 8 cords/in density, embedded within a geopolymer mortar. Lap-splice tests and single-lap bond tests were performed to develop an improved understanding of the textile-to-textile load tra...

The seismic vulnerability of unreinforced masonry structures threatens the life and health of people and the conservation of the built heritage in earthquake prone areas, highlighting the need of gaining a deeper understanding of their dynamic behaviour and of developing appropriate strengthening technologies. This work investigates the effectivene...

The structural effectiveness of textile reinforced mortar (TRM) composites relies on their load transfer capacity to the substrate and the interaction between textile and mortar. The bond plays a crucial role in mechanism of TRM composites. Despite some recent investigations, a deep understanding still needs to be gained on the textile-to-mortar bo...

Fabric reinforced cementitious matrix (FRCM) composites are widely used for retrofitting existing structures, especially in earthquake prone areas. After nearly two decades of scientific studies, experimental evidence proves their effectiveness for enhancing the ultimate strength and displacement capacity of masonry walls. There remains a need to d...

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...

Fabric Reinforced Cementitious Matrix (FRCM) composites represent an effective, compatible and cost-efficient solution for strengthening and retrofitting existing structures. A strong research effort was done to investigate the tensile and bond properties of these materials, as well as the overall behaviour of strengthened members. A Round Robin Te...

Fabric reinforced cementitious matrix (FRCM) composites, made of high strength textiles externally bonded with inorganic matrices, experimentally proved effective to enhance the capacity of masonry walls. With the aim of fostering the transfer of knowledge from scientific research to engineering practice, this paper proposes an approach for the des...

Masonry walls are particularly vulnerable against out-of-plane seismic actions. Fabric Reinforced Mortars (FRM) composites, comprising high strength fabrics applied with inorganic matrices, may be used to prevent or delay the onset of collapse mechanisms, and integrated with traditional techniques in compliance with the preservation criteria requir...

Masonry walls are particularly vulnerable against out-of-plane seismic actions. Steel tie-bars and crowing beams in reinforced masonry can prevent their overturning, but collapse may take place also by bending, leaf separation or disaggregation. Textile Reinforced Mortar (TRM) composites, comprising high strength fabrics and inorganic matrices, can...

Recent earthquakes have dramatically shown the seismic vulnerability of existing masonry structures and highlighted the urgent need of developing suitable strengthening solutions. In order to gain an improved understanding of the seismic response of masonry constructions and of the most appropriate technologies for their retrofitting, a shake table...

The post-earthquake inspections for the assessment of buildings’ usability have a key role in the post-earthquake emergency phases. In particular, a primary importance is given to the damage and usability assessment of public buildings, which is crucial for a quick recovery of the social activity. A significant contribution in the usability evaluat...

The out-of-plane vulnerability of masonry walls plays a crucial role in the seismic response of existing structures. Depending upon mechanical properties and section morphology, collapse may occur by the onset of a mechanism or, as historic constructions often exhibit, leaf separation, disaggregation or sliding. In these latter cases, structural an...

In a period characterized by the urgent need of enhancing the safety level of the building stock, including architectural heritage, externally bonded textile-reinforced mortar (TRM) systems are emerging as a particularly advantageous strengthening solution. Their use on unreinforced masonry arched members appears one of the most promising fields of...

Masonry vaults are dramatically vulnerable against non-symmetric loads, relative support displacements and earthquakes. In numerous existing structures, retrofitting is needed to improve the safety level and, for this purpose, externally bonded composites are particularly useful and have already been installed in the field. This paper describes an...

The out-of-plane vulnerability of perimeter walls is one of the main issues in the seismic response of historic masonry structures. Their dynamic behaviour is highly non-linear and is influenced by the discontinuous nature of the material. A range of failure modes may occur, such as onset of a mechanism, leaf separation, disaggregation, or sliding....

Higher stiffness and strength achieved with a reduced overall weight together with an extensive use of prefabrication justify the growing diffusion of Steel-Concrete Composite (SCC) bridges since the early 2000s, especially for the 20 ÷ 80 m span range. Former experimental campaigns aimed at investigating the static response of simply supported con...

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...

Steel reinforced polyurethane (SRPU) is an innovative composite material which comprises a unidirectional steel textile and a polyurethane matrix. By the virtue of the high flexibility of the polyurethane, which redistributes the shear stresses between reinforcement and substrate, SRPU has recently proved effective for specific externally bonded st...

The use of externally bonded Steel-Reinforced Grout (SRG) composites, comprising Ultra High Tensile Strength Steel (UHTSS) textiles embedded in an inorganic mortar matrix, has been shown to provide an effective and costefficient solution for the repair and strengthening of existing structures. Although several studies have been carried out in the l...

Masonry walls are particularly vulnerable against out-of-plane seismic actions. Steel tie-bars can prevent their overturning, but collapse may take place also by bending, leaf separation or disaggregation. Textile Reinforced Mortar (TRM) composites can be applied to improve their seismic capacity. Nevertheless, a deeper knowledge still needs to be...

Fabric Reinforced Cementitious Matrix (FRCM) composites are a new class of materials used to repair and strengthen existing structures. Mechanical performance vary widely based on the type and volume of fibers, fabric architecture, mortar properties, and bond characteristics. Moreover, test setup and boundary conditions are of the utmost importance...

Masonry vaults can be particularly vulnerable against unsymmetrical service loads, support displacements and seismic actions. Retrofitting is often needed to ensure an adequate safety level according to current standard codes. Externally bonded composites are emerging as a possible retrofitting technique, but no experimental evidence is still avail...

Digital Image Correlation (DIC) is a full-field contactless optical method for measuring displacements in experimental testing, based on the correlation of the digital images taken during test execution. It is used in several fields of experimental solid mechanics, but its potential application to the characterization of composite reinforcements ha...

Recent earthquakes have shown the key role of post-earthquake technical inspections aimed at assessing the seismic safety and/or usability of buildings and the functionality of infrastructural systems, in order to minimize the impact of losses on citizens as fast as possible. The AeDES form is used to evaluate the safety conditions of buildings in...

An increasing interest and application is nowadays found for composite systems in construction and rehabilitation industry. The consensus on fibre reinforced composite systems was mainly based on high tensile strength, light weight, relative ease of installation, and resistance to corrosion. However, some drawbacks related to the epoxy (hence, orga...

Mortar-based reinforcements are an innovative solution for retrofitting existing structures that combine effectiveness, compatibility, and sustainability. Despite the recent spreading of field applications, there is still insufficient knowledge on their fundamental mechanical properties, and a regulatory gap for experimental procedures and design c...

Steel Reinforced Grout (SRG), consisting of ultra high tensile strength steel cords embedded in a mortar matrix, is an effective solution for the upgrade of existing structures. Among its various applications, it can be applied to the extrados and the intrados of masonry vaults to improve their load-carrying and seismic capacity. Nevertheless, its...

Steel Reinforced Grout (SRG), consisting in Ultra High Tensile Strength Steel unidirectional textile embedded into lime mortar, is an effective and cost efficient solution for the reinforcement of existing structures. Nevertheless, the existing knowledge is still insufficient for its confident in the field, especially for some applications, as thos...

Due to their slenderness, masonry vaults are particularly vulnerable against unsymmetrical service loads, support displacements and seismic actions. Retrofitting works are therefore needed in numerous existing structures to ensure an adequate safety level according to current standard codes. This paper describes an experimental investigation carrie...

Steel Reinforced Grout composites have become a popular technique for strengthening masonry arches and vaults. The SRG composites are made of Ultra High Tensile Strength Steel unidirectional textiles applied to the substrate by means of inorganic mortar. The structural performance is generally controlled by the bond properties of the interface betw...

The use of Fabric Reinforced Cementitious Matrix (FRCM) composites appears as a compatible and effective technique to strengthen masonry structures. The use of FRCM composites in place of FRP (fiber reinforced polymer) composites provides noticeable advantages in terms of fire and heat resistance and vapor permeability. These characteristics are of...

TTextile Reinforced Mortar (TRM), also named Fabric Reinforced Cementitious Matrix (FRCM), composites, comprise high strength textiles embedded into inorganic matrices, and have been recently developed for the repair and rehabilitation of structures. Their effectiveness and compatibility with the substrate fostered the industrial development of a w...

Despite the high vulnerability to earthquakes of historic structures, the approaches for evaluating seismic demand and capacity still appear inadequate and there is scarce consensus on the most appropriate assessment methods to use. To develop an improved knowledge on the seismic behaviour of masonry structures and the reliability of analysis tools...

Steel Reinforced Polymer (SRP) is an innovative system for the external strengthening of structures, which comprises unidirectional textiles of High Tensile Strength Steel applied with polymeric resin. The first applications of SRP in civil engineering date back to 2004, and, since then, a number of studies have been carried out on both mechanical...

The out-of-plane vulnerability of masonry walls is one of the main causes of earthquake induced damage for both masonry buildings and reinforced concrete infilled frame structures. Aiming at increasing their seismic capacity, composite materials comprising either epoxy resin (Fibre Reinforced Polymers, FRP) or mortar matrix (Fabric Reinforced Cemen...

Fabric Reinforced Cementitious Matrix (FRCM) composites are currently receiving great attention for strengthening reinforced concrete and masonry structures, as they improve the capacity with minimum mass increase. Despite a large number of FRCM systems, supplied by several companies, are nowadays available in the market and have already been insta...

Field tests were carried out to investigate the bond behaviour of Steel Reinforced Grout (SRG) systems, making use of Ultra High Tensile Strength Steel cords embedded into a lime based mortar, bonded to the extrados of masonry vaults. Test outcomes provided the SRG-to-substrate shear bond strength after the development of a crack at the extrados of...

The paper presents a brief overview of the experimental works carried out over the last eleven years on SRP systems, to provide an updated knowledge on the behaviour of SRP strengthened structures and identify areas of future research. First, the studies devoted to the mechanical characterization under tensile loading, to the durability of steel te...

Fabric Reinforced Cementitious Matrix (FRCM) composites are currently receiving great atten-tion for strengthening existing structures, as they provide a significant improvement of the structural capacity with minimum mass increase. Despite a large number of FRCM systems, supplied by several companies, are today available in the market and have alr...

Steel Reinforced Polymer (SRP) systems, consisting of Ultra High Tensile Strength Steel cords and epoxy resin, are emerging as an effective and cost efficient solution for the externally bonded strengthening of structures. Their applications in civil engineering are more recent than those with Fibre Reinforced Polymers (FRP) employing carbon, glass...

An innovative solution for the seismic protection of existing masonry structures is proposed and investigated through shake table tests on a natural scale wall assemblage. After a former test series carried out without reinforcement, the specimen was retrofitted using Steel Reinforced Grout. The strengthening system comprises horizontal strips of u...

Masonry arch bridges constitute a significant proportion of European road and rail infrastructures. Most of them are well over 100 years old and are supporting traffic loads many times above those originally envisaged. The inherent variation in their constituent materials, the traditional design criteria and methods used for their construction, the...

Unconventional computer vision and image processing techniques offer significant advantages for experimental applications to shaking table testing, as they allow the overcoming of most typical problems of traditional sensors, such as encumbrance, limitations in the number of devices, range restrictions and risk of damage of the instruments in case...

Steel Reinforced Polymer (SRP) systems, consisting of Ultra High Tensile Strength Steel cords and epoxy resin, are emerging as an effective and cost efficient solution for the externally bonded strengthening of structures. Their applications in civil engineering are more recent than those with Fibre Reinforced Polymers (FRP) employing carbon, glass...

Sono illustrate le caratteristiche di un sistema innovativo per il rinforzo strutturale delle volte in muratura mediante tessuti unidirezionali in trefoli di acciaio ad alta resistenza e malte di calce idraulica naturale – denominato Steel Reinforced Grout (SRG) – assieme ai risultati delle prove di durabilità dei tessuti, a seguito di invecchiamen...

Il lavoro illustra i risultati di prove di distacco condotte in un edificio del centro storico de L’Aquila su rinforzi applicati all’estradosso di volte in laterizi. Il sistema di rinforzo testato è costituito da un tessuto unidirezionale in trefoli di acciaio ad elevata resistenza, applicato con una malta di calce idraulica naturale. Le prove hann...

Steel Reinforced Grout (SRG) systems, comprising Ultra High Tensile Strength Steel cords embedded in mortar matrix, are increasingly used for the strengthening of existing structures. Their mechanical properties, however, still need to be fully investigated in order to provide reliable values of tensile and bond strength, strain and stiffness for d...

The paper presents a Round Robin Test (RRT) devoted to the characterization of the shear bond performance of fibre-reinforced strengthening systems bonded with epoxy resin to brick masonry. The research was carried out by six laboratories involved in the RILEM TC 250-CSM (Composites for the Sustainable strengthening of Masonry) as a continuation an...

The paper presents an experimental investigation on an innovative repair method, in which composite reinforcements, after debonding, are rebonded to the substrate using a highly deformable polymer. In order to assess the effectiveness of this solution, shear bond tests were carried out on brick and masonry substrates within two Round Robin Test ser...

The paper presents a brief overview of the experimental works carried out over the last eleven years on SRP systems, to provide an updated knowledge on the behaviour of SRP strengthened structures and identify areas of future research. First, the studies devoted to the mechanical characterization under tensile loading, to the durability of steel te...

Fibre Reinforced Cementitious Matrix (FRCM) composites are now widely used for repair and retrofitting existing structures. Guidelines for product qualification are needed to characterize the strengthening systems before they are made available in the market and installed. The paper proposes a procedure that combines the results of direct tensile a...

Masonry arch bridges are part of our cultural heritage and represent a significant proportion of the European road and rail infrastructure. Increasing traffic demand and exposure to seismic risk require a deep understanding of their structural behaviour and reliable assessment methods. This book contributes to the knowledge of the response of mason...

Textile reinforcements applied with inorganic matrices are currently receiving great attention for strengthening reinforced concrete and masonry structures, especially when preservation criteria need to be fulfilled for safeguarding cultural heritage. As the development of mortar-based reinforcements is still at an early stage, their mechanical pro...

Il Comitato Tecnico Rilem TC-250 CSM (Composites for the Sustainable Strengthening of Masonry) e Assocompositi stanno attualmente coordinando un ampio progetto di ricerca sulla caratterizzazione di materiali compositi a matrice inorganica (FRCM) per il rinforzo strutturale. E’ stato organizzato un Round Robin Test che coinvolge venti laboratori e u...

The paper presents the preliminary results of a shake table test carried out on a tuff masonry, natural scale, U-shaped assemblage (façade adjacent to transverse walls). The specimen has been subjected to scaled natural accelerograms with increasing intensity, inducing the detachment of the façade from the transverse walls and the activation of its...

This paper describes the results obtained by shaking table tests on unreinforced and reinforced full scale C-shaped masonry walls performed at the Qualification of Materials and Components Laboratory (UTTMAT-QUAL) at ENEA Casaccia research center. Firstly the experimental campaign was carried out on an unreinforced masonry macroelement made up of a...

SUMMARY The paper proposes the use of a fibre beam-based methodology to study the dynamic behaviour of masonry arches and arch bridges. The approach, previously used for load-carrying capacity assessment, allows for a detailed description of both the nonlinear material properties and the seismic action, with reasonable computational effort. As a fi...

Mortar-based composite materials are currently receiving great attention for strengthening masonry structures, especially when specific preservation criteria need to be fulfilled. Their mechanical properties and durability, however, still need to be fully investigated. An experimental campaign has been carried out to characterize the tensile behavi...

Mortar-based composite materials appear particularly promising for use as externally bonded reinforcement (EBR) systems for masonry structures. Nevertheless, their mechanical performance, which may significantly differ from that of Fibre Reinforced Polymers, is still far from being fully investigated. Furthermore, standardized and reliable testing...