Search results for " Reinforced concrete"
showing 10 items of 42 documents
Convolution-based ensemble learning algorithms to estimate the bond strength of the corroded reinforced concrete
2022
Reinforced concrete bond strength deterioration is one of the most serious problems in the construction industry. It is one of the most common factors impacting structural deterioration and the major cause of premature decadence of reinforced concrete structures. Therefore, developing an accurate model with the lowest variance and high reliability for the bond strength of corroded reinforced concrete is very important. The current work evaluates the efficiency of convolution-based ensemble learning algorithms. To address these issues, convolution-based ensemble learning models are developed using a database collected from the previous experimental studies of relative bond strength for corro…
Case-studies of corroded reinforced concrete bridges in Southern Italy
2020
On Italian roads, a lot of reinforced concrete bridges were built in the 1950’s and 1960’s for short spans, before the advent of prefabricated structures. Many of these bridges, sited on principal or secondary roadways, show the effects of corrosion of reinforcements and high levels of damage, leading to the likelihood of achievement of the Ultimate Limit State, below the required performances of serviceability, especially in the case of Gerber saddles having strongly corroded reinforcements. Different case studies of bridges sited in Southern Italy (Sicily) are shown, allowing engineers to classify the main effects of damage in corroded structures with the Gerber static scheme (cantilever …
Simplified technique for constitutive analysis of SFRC
2014
Steel fibre reinforced concrete (SFRC) has become widespread material in areas such as underground shotcrete structures and industrial floors. However, due to the absence of material models of SFRC reliable for numerical analysis, application fields of this material are still limited. Due to interaction of concrete with fibres, a cracked section is able to carry a significant portion of tensile stresses, called the residual stresses. In present practices, residual stresses used for strength, deflection and crack width analysis are quantified by means of standard tests. However, interpretation of these test results is based on approximation using empirically deduced relationships, adequacy o…
The façade-tower of Santa Maria delle Stelle Church in Comiso. Historical events, vulnerability and conservation strategy
2020
Dopo avere richiamato l’estesa vicenda storica della costruzione della chiesa Madre di Santa Maria delle Stelle a Comiso, iniziata nel 1736 e terminata due secoli dopo, il contributo è focalizzato sul tema del completamento della sua facciata con l’uso della struttura intelaia di calcestruzzo di cemento armato, progettata dall’ingegnere Santoro Secolo. In tempi più recenti, alcuni dissesti improvvisi hanno posto in evidenza il tema del rischio e la necessità di interventi per risanare la struttura architettonica. L’importanza del monitoraggio e della manutenzione, intesi come fondamentali strategie di conservazione, concludono l’articolo.
Prediction of the out-of-plane response of infilled frames under seismic loads by a new fiber-section macro-model
2016
This chapter suggests that an extension of the capability of the traditional inplane macro-models to capture the simultaneous in-plane and Out-Of-Plane (OOP) response of infills. A new simplified macro-model for the assessment of both in plane and out-of-plane responses of infilled frames was developed and validated. The possibility to simulate the arching action is achieved by using distributed plasticity fiber-section elements, able to directly account for the coupling between axial load and bending moment. The arching action is explicitly introduced by the use of fiber-section beam-column elements, which can model the coupling between axial-load and bending moment. The model presented is…
Biaxial deformation and ductility domains for engineered rectangular RC cross-sections: A parametric study highlighting the positive roles of axial l…
2016
Abstract Axial load and biaxial bending strongly influence the deformation capacity of column cross-sections, in most cases causing a non-negligible loss of curvature and ductility with respect to the case of pure bending along principal axes, commonly assumed as the basic condition to assess the inelastic capacity. In consideration of this the paper investigates the biaxial deformation performance of RC rectangular cross-sections belonging to one-dimensional elements, focusing on the influence of some parameters as the cross-section aspect ratio and the distribution of the rebars, as well as the mechanical characteristics of concrete and steel and the impact of biaxial/axial stresses. In t…
Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets
2017
This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly adva…
Ductility of Reinforced Concrete Members Externally Wrapped with Fiber-Reinforced Polymer Sheets
2007
The effectiveness of external wrapping with fiber-reinforced polymer for enhancing the curvature ductility of lightly reinforced concrete members is investigated. Referring to members with circular transverse cross sections, the performances in terms of both strength and ductility capacities are analyzed, and the predictive reliability of two different recent constitutive models, available in the literature and able to take into account the softening behavior of confined concrete, is checked. A parameter characterizing the effectiveness of the confining wrapping is proposed, and characteristic values are suggested. Moreover, referring to ductility increases due to confinement effects, a com…
Incremental dynamic based fragility assessment of reinforced concrete structures: Stationary vs. non-stationary artificial ground motions
2017
Abstract Artificial and natural records are commonly employed by researches and practitioners to perform refined seismic assessments of structures. The techniques for the generation of artificial records and their effectiveness in producing signals which are significantly representative of real earthquakes are still debated as well as results of the consequent seismic assessment to expect from their application. The paper presents an in-depth comparative study highlighting the effect of employing different typologies of artificial ground motion records on seismic assessment results, especially addressing seismic fragility curves. Three sets of 50 stationary, nonstationary evenly modulated a…
Seismic Performance of Masonry Infilled RC Structures via N2 Pushover Assessment Procedures: Outcomes under Different Modeling Hypotheses of a Case S…
2016
The assessment of the capacity of RC masonry infilled RC structures constitutes nowadays a still debated issue. Pushover based procedures for the evaluation of seismic performance, such as N2 method, are largely used in practice and in force in several technical codes. The latter has proved to be reliable for a large number of structural typologies, however in the case of infilled frames, the choices made on the modelling strategy may radically modify the outcomes observable from the capacity curves and the consequent performance levels achievable. In the paper, the extent of different modelling choices on the results of the application of N2 procedure is investigated by the deep analysis o…