Papers by Author: Lucio Nobile

Abstract: Assessment of concrete strength in existing structures is a very fundamental task today, because the mechanical characteristics are strictly connected to seismic protection and performance estimation of the material. To this aim, several compression tests has been carried out on drilled core samples in conjunction with different NDT methods. The activity presented in the paper is still under development and is intended as a reference in the choice of the methods and correlations for structural survey of existing buildings.

Abstract: The Clemente Bridge is a multi-span masonry arch bridge built during the 18th century on Savio River in Cesena. The aim of this paper is to assess its static capacity under live loads prescribed by Italian Standards in force. The analysis is performed employing RING 3.0, a computational tool based on Limit State Analysis. This method allows to individuate the minimum adequacy factor, that is the multiplier on vehicle loads required to cause collapse. In this way, a first assessment on the bridge safety can be obtained.

Abstract: Several masonry panels are studied by means of destructive tests such as compressive, diagonal compression and shear-compression tests. The experimental research allows to characterize the mechanical properties of masonry walls in order to assess the masonry performance. Moreover, a brief recall of the most important experimental progress is presented in order to understand the state of the art of the research in the field of destructive tests.

Abstract: The present paper describes one of the most important slightly destructive technique used in the masonry survey: the flat-jack test. The test method is described in a critical way, emphasizing advantages and drawbacks. Besides, the relation between the flat-jack test and a numerical modelling is explored.

Abstract: To carry out maintenance and assessment of reinforced concrete (RC) structures, a good understanding of the effect of the change in bond behaviour of reinforcement during service life is essential. Steel reinforcement is subjected to corrosion due to carbonation and chloride attack. The former ordinarily induces uniform corrosion, the latter induces generally localised corrosion at cracks level. The existence of cracks and the crack width affect the starting points of corrosion, as indicated by the results of the exposure test carried out by Shiessl et al.[1]. Corresponding techniques, such as non-destructive in-situ testing for concrete cover thickness, permeability and the positions of the reinforcing bars, are helpful to model the real behaviour. Cracked portion around the tensile reinforcement in a flexural member can be considered to be equivalent to a concrete member having a single reinforcement subjected to pull-out force at both ends. In this paper a damage process model is proposed based on slip crack propagation in order to evaluate the effective load capacity.

Abstract: This paper deals with a simple and reliable method for the probabilistic characterization of the linear elastic response of frame structures with edge cracks of uncertain depth and location in the three-dimensional setting. A numerical test evidences the performance of the approach.

Abstract: Carbon fiber reinforced polymer (CFRP) sheets have been extensively used for strengthening deteriorated concrete structures. The effectiveness of such strengthening depends upon the load transfer from concrete to the FRP composite. Shear debonding is usually caused by a crack that forms and then propagates at the interface between the adherents. The influence of the geometric parameters of the adherents on the fracture propagation is still a subject of research. This paper presents an experimental investigation performed on direct shear specimens to study the influence of the relative width of FRP and concrete on the load carrying capacity of the bond and the stress transfer between the adherents.

Abstract: In this paper, the problem of torsional buckling of a thin-walled edge cracked column, under pure bending, is studied. To the authors’ knowledge, this subject has not been widely investigated in the literature. A cracked member can buckle in the plane orthogonal to the crack and out of plane triggering the Mode-III crack opening. Analytical expressions for the characteristic equation are derived for an I-beam. The influence of the crack length and position on the buckling load is investigated.

Abstract: This work is focussed on the numerical prediction of the fracture resistance of a flat fullscale aluminium alloy 2024 T3 stiffened panel under monotonic traction loading condition. The numerical simulations are based on the micromechanical Gurson-Tvergaard (GT) model for ductile damage. The applicability of the GT model to this kind of structural problem has been studied and assessed by comparing numerical results, obtained by using the WARP 3D finite element code, with experimental data provided from literature.