Search results for " reinforced"
showing 10 items of 90 documents
A Mechanical Approach for Evaluating the Distribution of Confinement Pressure in FRP-Wrapped Rectangular Columns
2019
In recent decades, fiber reinforced polymer (FRP) wrapping has become a common technique to retrofit reinforced concrete (RC) columns. Numerous research works have sought to verify analytically and experimentally its effectiveness in terms of enhancement of axial load bearing capacity and ductility. These studies highlighted that in the case of sharp-cornered sections, the maximum allowable confinement pressure is limited by premature failure at corners and, consequently, stress in the FRP, as well as the distribution of the confinement pressure, is not uniform. The prediction of this phenomenon is not straightforward, and existing theoretical studies propose complex numerical simulations, …
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…
TENACITÀ ALLA FRATTURA INTERLAMINARE DI COMPOSITI CFRP SOTTOPOSTI A PROCESSI DI INVECCHIAMENTO IDROTERMICO
2011
In questo lavoro si è condotto uno studio degli effetti dell’invecchiamento idrotermico sulla tenacità alla frattura interlaminare in Modo I di laminati in composito CFRP con lay-up unidirezionale. I pannelli realizzati impiegano una resina epossidica DGEBA. Provini DCB sono stati ricavati in accordo con la norma ASTM D5528. Prove dinamico meccaniche DMTA sono state condotte per analizzare l’influenza dell’invecchiamento sulla temperatura di transizione vetrosa, e quindi sul grado di fragilità della matrice. Il lavoro descrive il set-up sperimentale per la determinazione delle Curve R, evidenziando l’influenza della morfologia del tessuto in carbonio. I valori di GIC di innesco e di propaga…
Analysis of the mechanical performance of hybrid (SPR/bonded) single-lap joints between CFRP panels and aluminum blanks
2013
Abstract The increasing use of innovative materials in manufacturing of modern mechanical components has led to the development of reliable joints between innovative (composite materials etc.) and traditional materials (steel, aluminum etc.). In the last few years, hybrid joints, combining the advantages of the adhesive joints and traditional mechanical joints as bolted or riveted joints, have been shown an increasing industrial interest especially in automotive and aerospace sectors. In the present paper a systematic experimental study of hybrid lap joints was carried out with the aim to detect the optimal joint configuration. Tensile tests on hybrid joints made by combining adhesive bondi…
Experimental investigation on the compressive behavior of short-term preloaded carbon fiber reinforced polymer-confined concrete columns
2017
Strengthening of concrete columns with fiber reinforced polymer sheets provides a good improvement to the existing structural members in terms of load and strain capacity due to the properties of the composite jacket. A proper knowledge of the load–strain response of the composite members is necessary to design retrofitting intervention of existing structures; however, so far the available design methods do not allow to take into account the effect of the possible presence of service loads on the compressive behavior of the reinforced columns. An experimental investigation on the compressive behavior of preloaded circular concrete columns reinforced with carbon fiber reinforced polymer was …
Experimental results of RC columns strengthnened with Fiber Reinforced Cementitious Mortars
2012
The structural behaviour of reinforced concrete columns strengthened with a system made up of fibre nets embedded in an inorganic stabilized cementitious matrix was investigated. Specimens with circular and square cross-section were cast and subjected to monotonic uniaxial compression to investigate the efficiency of a Polypara-phenylene-benzo-bisthiazole (PBO) Fibre Reinforced Cementitious Mortars (FRCM) system in increasing both carrying capacity and ductility. The experimental results show that confinement with PBO fibre produced a noticeable increment in strength and ductility, though the low mechanical ratios of fibre considered were not always able to ensure hardening behaviour up to …
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.
Experimental investigation on the effectiveness of basalt-fibre strengthening systems for confining masonry elements
L’impiego di materiali compositi per il rinforzo di colonne in muratura è diventato una pratica ampiamente diffusa nel corso degli ultimi decenni. Questa tecnica, che consiste generalmente nell’applicazione di materiali polimerici fibrorinforzati (Fibre Reinforced Polymer-FRP), ha mostrato buone potenzialità, essendo in grado di garantire notevoli incrementi di resistenza e duttilità dell’elemento rinforzato, grazie ad un’azione di confinamento passivo. Tuttavia, l’impiego di compositi a matrice polimerica presenta alcuni limiti legati soprattutto alle prestazioni delle resine epossidiche, che a causa della loro natura sintetica danno luogo a problemi di compatibilità con il supporto murari…