Finite Element Modeling of Bond Behavior of FRP and Steel Plates

Strengthening systems for existing reinforced concrete (RC) structures are increasingly needed due to several problems such as degradation of materials over the time, underdesign, serviceability or seismic upgrading, or new code requirements. In the last decades, strengthening by fibers composite materials applied with various techniques (FRP, FRCM, NSM) were largely investigated and theoretical formulations have been introduced in national and international design guidelines. Although they are an excellent strengthening solution, steel plates may represent still a valid traditional alternative, due to low costs, ductile stress-strain behavior, simple and fast mounting with possibility of reusing the material. Guidelines for a correct design are still lack and, therefore, detailed models and design formulas are needed. In this paper, the bond behavior at the plate-concrete interface, which plays a key role for the effectiveness of the strengthening system, is analyzed by means of 3D finite element models calibrated on experimental results available in literature. Parametric analyses were carried out by changing some meaningful parameters

Experimental characterization of tensile strength of steel and fibre rovings also under environmental conditioning

Abstract The efficiency of the strengthening techniques by externally applied materials can be improved enhancing the debonding strength of the reinforcement from the support by the use of connectors (anchor spikes) consisting of unidirectional bundles of fibres embedded in concrete or masonry by means of organic or inorganic matrices. The use of connectors is suggested in various codes and guidelines of strengthening techniques by composite materials and provisions for their application are given, but currently there are no details for the qualification of the material. In order to investigate anchor spikes made of glass, basalt, aramid, carbon, PBO and steel, a large experimental campaign was carried out at the Materials and Structures Laboratory of the University of Sannio. The tests allowed to evaluate the mechanical characteristics (tensile strength, modulus of elasticity, deformation at the maximum load) of the anchor spikes constituted by only dry fibres, not impregnated, also as a result of environmental conditioning such as freezing and thawing, controlled humidity, alkaline and saline environment

Engineering properties of geopolymer concrete: a review

Geopolymer concrete (GPC) could be a solution that uses a cementless binder and recycled materials for producing concrete, while reducing the carbon dioxide emission and the demand for raw materials. In addition to the environmental aspect, previous studies on GPC showed that it can achieve mechanical characteristics higher than those of ordinary Portland concrete (OPC) such as greater strength a few days after casting, and it can be suitable for structural applications. In this paper, the state-of-the-art review of GPC is presented through an extensive literature analysis to determine the most recent information regarding the engineering properties of geopolymer concrete and the critical issues that prevent its widespread use and to put forward suggestions for future research. In particular, the physical properties in both fresh and hardened states and the mechanical characteristics are investigated; the structural performance of geopolymer concrete elements is also outlined

INFLUENZA DEL SOTTOSUOLO SUL COMPORTAMENTO DINAMICO DEL CAMPANILE DEL CARMINE A NAPOLI

La nota descrive l’identificazione dinamica del campanile del Carmine a Napoli, effettuata attraverso analisi dinamiche su un modello tridimensionale del sistema terreno - fondazione - struttura, tarato sui risultati di dettagliate indagini in situ. Sono stati riconosciuti fenomeni di risonanza tra la frequenza fondamentale del terreno e la seconda frequenza di vibrazione della struttura che ne condizionano il comportamento dinamico

Multidisciplinary Approach to Structural/Energy Diagnosis of Historical Buildings: A Case Study

Abstract A synergic approach for the investigations of the historical building performances - with reference to both the structural behavior and the energy performances for the space heating and cooling - is presented. The historical masonry building "Palazzo Bosco Lucarelli", located in Benevento, has been chosen as case study. The structural and energy analyses are carried out in parallel, especially during the identification of the building characteristics through tests and surveys in-situ. For the structural analysis - beyond examinations on materials - some dynamic tests have been used for better assessing a numerical Finite Element model necessary for the verification of the structure safety. Moreover, being necessary a structural refurbishment, also an energy retrofit could be realized. A rigorous evaluation procedure - aimed to guarantee the necessary reliability of numerical predictions - is performed in order to verify the technical and economical convenience of various energy retrofit solutions

Out-of-plane structural identification of a masonry infill wall inside beam-column RC frames

Field observations after seismic events have shown that out-of-plane collapses are one of the predominant modes of infill masonry wall failure leading to life-safety hazards. This type of mechanism depends on the geometrical and mechanical features of the structure, but it is substantially affected by the constraints along the structural frame. However, the actual boundary conditions are very difficult to define, especially in the case of an existing building, for which information is lacking, a visual screening can be inefficient, and deterioration may have occurred due to the design conditions. In this paper, a procedure for the structural identification of the out-of-plane behaviour of infill masonry walls using a simple and cost effective innovative procedure based on an in situ experimental dynamic test and a consequent process of updating is proposed. The procedure, composed of the in situ test and the updating of the numerical model, was implemented for a case study to confirm that it is effective in defining the mechanical characteristics of the masonry, the absence of collaboration between the two brick leaves of the infill wall, and the out-of-plane constraints along the perimeter