CONFINEMENT OF MASONRY WITH FRCM COMPOSITES: STRENGTH PREDICTIVE MODELS

Fabric reinforced cementitious matrix (FRCM) composites have emerged as an appealing alternative to fiber reinforced polymer (FRP) for the external confinement of masonry members; nevertheless, their use in practice is limited due to the lack of reliable formulas to estimate the compressive strength and ultimate strain of confined members. By following a recently published study, new formulas for the prediction of the compressive strength of the FRCM confined masonry are proposed here, which were obtained by considering an updated experimental database compiled from the literature. These formulas were developed by applying error minimization techniques to the collected experimental results; test data were treated in different ways, such as: (a) separating the members made of natural stones from those built with artificial blocks, and (b) treating separately the fiber types (basalt, carbon, glass, PBO and steel) of the FRCM system, or (c) considering the experimental data all together. Finally, to evaluate the reliability of the developed relationships, the strength predictions provided by the new proposals were compared with those obtained using the expressions reported in some international guidelines

Full Scale Reinforced Concrete Beam-Column Joints Strengthened with Steel Reinforced Polymer Systems

This paper presents the results of an experimental campaign performed at the Laboratory of Materials and Structural Testing of the University of Salerno (Italy) in order to investigate the seismic performance of reinforced concrete (RC) beam-column joints strengthened with steel reinforced polymer (SRP) systems. With the aim to represent typical façade frames' beam-column subassemblies found in existing RC buildings, specimens were provided with two short beam stubs orthogonal to the main beam and were designed with inadequate seismic details. Five members were strengthened by using two different SRP layouts while the remaining ones were used as benchmarks. Once damaged, two specimens were also repaired, retrofitted with SRP, and subjected to cyclic test again. The results of cyclic tests performed on SRP strengthened joints are examined through a comparison with the outcomes of the previous experimental program including companion specimens not provided with transverse beam stubs and strengthened by carbon fiber-reinforced polymer (CFRP) systems. In particular, both qualitative and quantitative considerations about the influence of the confining effect provided by the secondary beams on the joint response, the suitability of all the adopted strengthening solutions (SRP/CFRP systems), the performances and the failure modes experienced in the several cases studied are provided

Proceedings of the OpenSees Days - 2nd Italian Conference

Conference held at the University of Salerno (10-11 June 2015

Seismic retrofitting of RC columns with FRP systems: design relationships

"full paper" sul CD allegato agli Att

Reinforced concrete beams strengthened with SRP/SRG systems: Experimental investigation

Steel reinforced polymer (SRP) and steel reinforced grout (SRG) have emerged as promising and cost-effective technologies for the external strengthening of RC structures. Although the first studies date back to 2004, so far the literature related to the flexural strengthening of RC slabs/beams with steel tapes is rather limited. As a result, the application of such materials on a real structural member may be discouraged and, conversely, the use of carbon/glass FRP alternative systems may be preferred. The study presented in this paper contributes to filling this knowledge gap by presenting the results of 10 four-point bending tests performed on RC slabs strengthened with SRG/SRP systems. Test results have provided valuable information in terms of maximum forces, deformability and failure modes by varying number of layers and density of the steel tape. In particular, it has been shown that, disregarding the nature of the matrix (inorganic or polymeric), the presence of the external strengthening significantly increased the flexural strength of slabs, with percentage increases over the control (unstrengthened) member ranging from a minimum value of 27%, when using a single layer of low density tape, to a maximum of 106% in the case of SRP system with one layer of high density sheet. Preliminary analytical studies were also performed in order to investigate the possibility of extending to the SRP/SRG systems the applicability of formulations currently reported in some national and international guidelines for the flexural strengthening of RC members with FRP sheets

Concrete Confined by FRP Systems: Confinement Efficiency and Design Strength Models

Issue 4, Jun

Nuove proposte per il progetto degli interventi di confinamento con FRP

Lo studio presentato in questa memoria ha come oggetto la valutazione del comportamento a compressione di elementi in calcestruzzo confinati adoperando materiali polimerici fibro-rinforzati (FRP). A tal fine, gli autori hanno costruito un ampio database di risultati sperimentali derivanti da oltre 450 test eseguiti su provini cilindrici confinati mediante tessuti unidirezionali in fibra di vetro o di carbonio. I risultati sperimentali sono stati quindi utilizzati per la calibrazione di nuove relazioni per la stima della resistenza a compressione e della deformazione ultima del calcestruzzo confinato con FRP. L'affidabilità delle relazioni trovate è stata quindi confrontata con quella di alcune tra le più accreditate formulazioni presenti in letteratura