The experimental results of three and four point loading tests on reinforced concrete beams stren... more The experimental results of three and four point loading tests on reinforced concrete beams strengthened by angles and/or pre-stressed stainless steel ribbons (CAM system) are presented. The stainless steel prestressed ribbons play the role of adjunctive transversal reinforcement as well as confine the structural element. Six flexural critical beams and nine shear critical beams were tested. In the first group four beams were retrofitted with bottom stainless steel angles and transversal ribbons, with two different spacing. In the second group three specimens were retrofitted by wrapping the beam with the ribbons, while three specimens were strengthned by perforation of the beam beneath the slab height, and by partially wrapping the beam by inserting the ribbons through the hole, in order to simulate a strengthening performed without drilling of the slab. The test results prove the effectiveness of the retrofitting system for both the flexural and shear critical beams.
In the last decades a great effort has been made to obtain accurate evaluation of the resistance ... more In the last decades a great effort has been made to obtain accurate evaluation of the resistance of reinforced concrete elements subjected to pure shear or combined internal forces including shear. In regard to this latter subject, continuum models characterized by simplified stress fields have recently been applied by some of the Authors for the evaluation of the ultimate capacity interaction diagram of rectangular reinforced concrete cross-sections undergoing combined axial force, bending moment and shear force. The present paper constitutes the natural progress of these studies and describes an analytical tool for the calculation of the ultimate capacity interaction diagram of reinforced concrete columns with circular cross-section. The proposed method is based on the application of the static theorem of limit analysis and requires the definition of equilibrium equations and boundary conditions for geometrical and mechanical parameters. In order to validate the method, the relati...
A clear distinction can be made between brittle shear failure, occurring before the flexural stre... more A clear distinction can be made between brittle shear failure, occurring before the flexural strength of the column has been attained, ductile shear failure that occurs after that a flexural plastic hinges has been activated, and plastic rotations increased. The shear strength reduction is due to degrading of several resisting mechanism:aggregate interlock due to reduction of the roughness of the crack surface by the smoothing action of the cyclic load, and bond slippage; dowel action due to cover rupture, hoops and longitudinal rebar plastic strain, and eventually buckling of the latter; strength of chord and web concrete due to compression softening and development of cracking for cyclic load. Several studies addressed the shear strength reduction due to ductility demand on the basis of smeared cracking non-linear models, such as the Modified Compression Field Theory (MCFT). However, despite their success in modeling several structural type behaviors, they do not appear suitable t...
A Model for the Analysis at ULS of Corroded RC Beams
Lecture Notes in Civil Engineering
The proposed model is able to consider the interaction between bending, shear and normal forces. ... more The proposed model is able to consider the interaction between bending, shear and normal forces. Some experimental tests present in the literature, where the structural behaviour of reinforced concrete beams in presence of corrosion of longitudinal and transversal rebar was investigated, were used in the present study in order to validate the proposed model. The numerical results seem to be in good agreement with the experimental ones.
It is well known that adding steel fibres to concrete enhances the shear strength and ductility o... more It is well known that adding steel fibres to concrete enhances the shear strength and ductility of reinforced concrete beams. Despite the numerous experimental studies made, current design formulations are empirically based and present large scatter when comparing their predictions with tests results. One of the reasons is the uncertainty of the SFRC behaviour associated to the type, amount, distribution and orientation of the fibres. Due to this, parameters characterizing the SFRC are obtained by means of flexural tests, even though the residual stresses obtained cannot be directly considered as the stresses transferred across the critical shear crack. Furthermore, such tests results are not provided by most of the available shear tests on SFRC. There is, therefore, the need for a mechanically-based shear strength model, capable to reproduce the effects of fibres on the shear strength, using as input data the usual design parameters of SFRC members. For this purpose, the previously...
In the last decades a great effort has been made to obtain accurate evaluation of the resistance ... more In the last decades a great effort has been made to obtain accurate evaluation of the resistance of reinforced concrete elements subjected to pure shear or combined internal forces including shear. In regard to this latter subject, continuum models characterized by simplified stress fields have recently been applied by some of the Authors for the evaluation of the ultimate capacity interaction diagram of rectangular reinforced concrete cross-sections undergoing combined axial force, bending moment and shear force. The present paper constitutes the natural progress of these studies and describes an analytical tool for the calculation of the ultimate capacity interaction diagram of reinforced concrete columns with circular cross-section. The proposed method is based on the application of the static theorem of limit analysis and requires the definition of equilibrium equations and boundary conditions for geometrical and mechanical parameters. In order to validate the method, the relations developed are applied with reference to many laboratory models tested in the past and the theoretical results are compared to the experimental ones.
N-M-V Interaction Domains for Box and I-Shaped Reinforced Concrete Members
ACI Structural Journal, 2003
ABSTRACT This paper proposes an approximate physical model to evaluate the N-M-V interaction resi... more ABSTRACT This paper proposes an approximate physical model to evaluate the N-M-V interaction resistance domains for box and I-shaped concrete cross sections. The model subdivides the concrete beam in layers, with nearly constant stress fields, and determines the internal forces satisfying equilibrium of the cross section, applying the static theorem of plasticity (lower bound theorem). The resisting contribution of the web longitudinal reinforcements is also considered by including stress fields of variable inclination on the longitudinal element direction. The proposed model leads to a conservative evaluation of bearing capacity and permits to numerically obtain the N-M-V interaction resistance domains of the indicated cross sections. The obtained N-M-V failure surfaces are in good agreement with the experimental evidences of tests performed by P. Regan and H. Rezai-Jorabi and by J. R. Robinson and J. M. Demorieux.
Simple Plastic Model for Shear Critical SFRC Beams
Journal of structural …, 2009
A simple physical model, for prediction of ultimate shear strength of steel fiber-reinforced conc... more A simple physical model, for prediction of ultimate shear strength of steel fiber-reinforced concrete (SFRC) beams is developed on the basis of a plastic approach originally proposed for reinforced concrete beams without stirrups. It is founded on the hypothesis that cracks ...
Proceedings of SMSST'07, World Forum on Smart Materials and Smart Structures Technology (SMSST’07), China, 22-27 May, 2007, 2008
Structural Health Monitoring (SHM) aims to improve knowledge of the safety and maintainability of... more Structural Health Monitoring (SHM) aims to improve knowledge of the safety and maintainability of civil structures and infrastructures. Within the Italian research project RELUIS-DPC 2010-2013, funded by the Italian Department of Civil Protection, a specific task deals with the possibility of set up a fast procedure to determine the damage evolution on a large number of structures after seismic events. This paper presents an upgrade of a method for damage detection based on a statistical approach that uses the most significant data recorded on both the top floor and the bottom of a building, with the purpose of extracting the value of the maximum inter-story drift expected along the building height, adopted as damage indicator. Nonlinear interferometric analyses combined with the S-Transform are used to evaluate frequencies and damping variation of the monitored structure during an earthquake. The method has been tested on numerical reinforced concrete framed structures.
Abstract The purpose of this paper is to improve the performance of a twodimensional finite eleme... more Abstract The purpose of this paper is to improve the performance of a twodimensional finite element approach, called the Rotating Compression Field Model (RCFM). The RCFM capability for reproducing the non-linear behaviour of reinforced concrete (RC) beams, ...
Adeguamento Statico Mediante Precompressione Esterna Del Ponte Ferroviario Sul Terdoppio
dist.unina.it
... 1 Cav.To.Mi Consorzio Alta Velocità Torino Milano Via Case Sparse S. Antonio, 21 Novara... more ... 1 Cav.To.Mi Consorzio Alta Velocità Torino Milano Via Case Sparse S. Antonio, 21 Novara (NO) 2 Prometeo Engineering srl Corso XXIII Marzo, 168 Novara (NO) 3 Dipartimento di Ingegneria Civile, Università di Messina, C.da di Dio - Vill. ...
La reparación y el refuerzo de estructuras en hormigón armado con fibras o laminados de material ... more La reparación y el refuerzo de estructuras en hormigón armado con fibras o laminados de material compuesto (FRP y FRCM) ha adquirido, en la ultima década, mucho prestigio. Pero el estudio de un modelo de interacción, relativo al refuerzo por cortante-momento flector, no ha sido desarrollado lo suficiente y, por lo tanto, se requieren todavía muchas investigaciones numéricas y experimentales que permitan progresar en su conocimiento. En este trabajo se ha desarrollado un nuevo modelo resistente, basado en el mecanismo de los campos de tensiones (stress fields). Para la comprobación del modelo propuesto se han contrastado los resultados de algunas campañas experimentales con los resultados numéricos obtenidos. Por fin, se ha ilustrado un particular ejemplo de aplicación de refuerzo de algunas estructuras de hormigón armado, construidas en el año 1920, que presentaban fisuración por cortante y flexión. PALABRAS CLAVE: Esfuerzo cortante, diseño de refuerzo a cortante, material compuesto, FRP, FRCM, hormigón armado, interacción M-V, momento flector. V CONGRESO DE 2/10 Investigaciones y estudios
Shear Strength Prediction By Modified Plasticity Theory For SFRC Beams
AIP Conference Proceedings, 2008
the plastic Crack Sliding Model (CSM) is extended for derivation of a physical model for the pred... more the plastic Crack Sliding Model (CSM) is extended for derivation of a physical model for the prediction of ultimate shear strength of SFRC beams, by assuming that the critical cracks is modeled by a yield lines. To this aim, the CSM is improved in order to take into account ...
Rubble masonry strengthened by three-dimensional pre-tensioned stainless steel ribbons. In situ f... more Rubble masonry strengthened by three-dimensional pre-tensioned stainless steel ribbons. In situ full-scale tests on masonry panels and an arch-wall in Messina earthquake prone area. Discussion of the results that validate the retrofitting method. The retrofitting method produces a noticeable increment in strength and ductility of ancient masonry.
Experimental test results vs. analytical prediction of welded joint strength in hybrid steel trussed concrete beams (HSTCBs)
European Journal of Environmental and Civil Engineering, 2013
ABSTRACT The aim of the paper is to provide practical guidelines for the design of welded joints ... more ABSTRACT The aim of the paper is to provide practical guidelines for the design of welded joints of steel truss for encased composite steel–concrete beams. The results of experimental tests are presented and interpreted. The steel truss is made of a steel plate acting as the bottom chord, made of S355 structural steel, coupled with steel rebars which form the upper chord, and steel inclined web rebars (V-reverse) welded to the two chord elements, both of them made of steel B450C. Butt welded joints of web bar to bottom steel plate and fillet welding joints of inclined web bars to top chord bars were tested, as they are different from the ones which are normally used due to the coupling of different steel types and complex geometry. For the prediction of strength of fillet welding joints, two analytical expressions are derived: the first is based on a local failure criterion and the second on a limit domain of the welding section. Comparison with experimental data proves the equivalence and reliability of the proposed indications. Guidelines for choosing the effective dimensions of the fillet weld able to ensure a required strength are provided. For validation of the suggested guidelines, a high precision digital scanner is used to determine the geometrical characteristics of the fillet weld.
Uploads
Papers by A. Recupero