Search results for "concrete"

RC Columns Strengthened with Steel Angles and Battens: Experimental Results and Design Procedure

2013

In this paper, an analytical model for the design of axially loaded strengthened RC columns with steel angles and battens is presented. Cases of directly loaded and not directly loaded steel angles are considered. The model considers the contribution in confinement pressures caused by transverse battens and steel angles and the contribution in terms of the load-carrying capacity of steel angles subjected to axial force and the bending moment. An experimental investigation on the compressive behavior of eight short, confined, RC columns externally strengthened with steel angles and steel battens with various pitches was carried out, and has been utilized as support for the analytical model. …

Increasing the flexural capacity of RC beams using steel angles and pre-tensioned stainless steel ribbons

2016

This article presents an experimental programme on reinforced concrete beams retrofitted with steel angles and pre-stressed stainless steel ribbons to increase their flexural strength and ductility. Two different configurations of the steel ribbon were designed, and two companion specimens for each type considered were subjected to a four-point bending test to facilitate a direct comparison in the analysis of the effectiveness of the retrofitting technique. The influence of longitudinal steel angles and transverse stainless steel ribbons is analysed, and the concrete confinement due to stainless steel ribbons examined. The strengthened beams show remarkable increments in flexural strength a…

Validation of a Shear Model for RC and Hybrid Beams with Two Different Inclinations of Transversal Reinforcement

2016

The validation of an analytical model recently proposed for evaluation of the shear capacity in Reinforced Concrete (RC) beams containing multiple inclination of transverse stirrups is presented. The model is a suitable extension of that currently proposed in Eurocode 2 for the evaluation of the shear resistance, and it is derived by means of the the variable-inclination stressfield theory based on Nielsen’s plastic approach. Experimental and numerical data available in the literature on Hybrid Steel-Trussed Concrete Beams (HSTCBs) are used for model validation and result discussion. Finally, also the comparison with a different analytical approach for the assessment of the shear resistance…

The use of pumice lightweight concrete for masonry applications

2011

In the last two decades, the use of pumice as lightweight aggregate for concrete in structural applications has been the object of different studies. The aim was to find out if pumice can be an alternative to ordinary lightweight aggregate. The present paper is framed in this context. Here, a study is presented showing the use of pumice for making lightweight concrete units for masonry members. Through the paper, the formulation of a mix design for lightweight concrete is proposed. Then the obtained mechanical characteristics of the masonry units are discussed and compared to the code requirements. Reinforced bearing masonry walls, made with the concrete masonry units in question, were made…

Durabilità, in ambiente fortemente basico, delle fibre di PET provenienti dalla raccolta differenziata

2012

La sperimentazione esposta nella presente pubblicazione tratta dell’impiego di fibre di PET, ricavate dal semplice taglio di contenitori per bevande secondo un procedimento brevettato, nel rinforzo di calcestruzzi destinati anche a impieghi strutturali. Descrive le caratteristiche geometriche delle fibre e ne indaga la durabilità in condizioni severe che potrebbero presentarsi in un’applicazione pratica quale una pavimentazione esterna. A tal fine campioni costituiti da gruppi di fibre sono stati immersi per tredici giorni a 65°C in soluzioni a differente concentrazione di NaOH (0,103 M e 1,75 M). In particolare la soluzione a concentrazione 0,103 M di NaOH (pH=13) simula la basicità della …

Flexural Behavior of Steel Fibrous Reinforced Concrete Deep Beams

2012

Experimental research was carried out regarding the flexural behavior of deep beams cast with plain and fibrous concrete with hooked steel fibers, and subjected to monotonic vertical loads. Four deep fiber-reinforced concrete beams were cast. Two of them were made of plain concrete with main and web steel reinforcements (RC), and two were made of hooked steel fiber-reinforced concrete (SFRC) with main steel reinforcements. The experimental results show the brittle behavior of reinforced deep RC members characterized by crushing of concrete struts and fracture of web steel bars. SFRC deep beams exhibit higher strength and, above all, ductility with respect to RC members due to the bridging a…

Numerical modelling of bond behaviour in Fabric Reinforced Cementitious Matrix strengthened reinforced concrete members

2022

Fabric Reinforced Cementitious Matrix (FRCM) composites are widely seen as offering advantages in structural retrofitting of existing buildings. In spite of their reputed effectiveness, FRCM systems typically suffers from several drawbacks related to the mechanical characterization due to complex stress transfer mechanicisms that can develop at fiber-matrix and FRCM-substrate interface. Numerous experimental studies focus on this topic, but few numerical studies are addressed to better understand the variables involved in the problem. This paper aims to propose a simple 1D numerical model to predict the shear bond behaviour of FRCM applied on concrete substrate, providing support to deduce …

Experimental analysis, numerical and analytical modeling of shear strength mechanisms in Hybrid Steel Trussed Concrete Beams

2014

Procedure for Safety Assessment and BIM Modelling of an Historical Complex Structure through a Macroelement Approach: The Building “Molino-Pastificio…

2022

The structural assessment of existing historical structures is a complex task due to the inner main difficulty in making up reliable models for structural analysis, able to include mechanical and geometrical nonlinearities, existing damage, complex configurations and arrangements of materials. This task becomes more difficult in mixed RC-masonry structures, which structural modelling can be particularly tough due to the different connections and interactions between structural members and materials. This paper presents the case study of a multi-storey mixed Reinforced Concrete (RC)- masonry historical structure, namely the former mill “Molino-Pastificio Soresi” building, located in Partinic…

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical mode…