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In the present paper, a simple model to reproduce the load-deflection response of corroded beams failing in flexure and shear is presented and discussed. Effects of diffused and pitting corrosion on steel bars, compressive concrete strength degradation and concrete bond strength degradation due to rust formation are included in the model. Engineering approach based on limit state theory was here adopted to predict the peak and the residual flexural and shear strength of corroded beams with corresponding deflections and ductility estimation. Calculation of deflection at cracking taking into account of rust formation and deflection at yielding and the ultimate state taking into account also of slippage of steel bars due to rust formation were made. The model was also widely verified against tests available in the literature referred to crack opening, pit depth, attach corrosion penetration, load-deflection curves.

In the present paper, a simplified model for hand verification of the flexural and shear strength of existing corroded T beams cast in place of lightened R.C. orthotropic slabs forming floors is presented and discussed. Diffused and pitting corrosion on steel bars, compressive concrete strength degradation and concrete bond strength degradation are included in the model. The original contribution of the paper is evaluation of the flexural and shear strength considering both the cases of strain compatibility and absence of compatibility and considering the main parameters governing the corrosion process. An arch-resistant model for the calculus of the flexural and shear strength of the beam was adopted in the absence of strain compatibility, while the plane section theory was adopted for the case of strain compatibility. No punching shear is considered. This approach is simple and can be applied on the basis of the experimental information available (carbonation test, chloride content, measurement of the pitting in the bar, gravimetric method for general corrosion) or by utilizing analytical expressions calibrated on the knowledge of the corrosion current intensity determined by linear polarization resistance measurement (LPR). The model was also verified against experimental results recently obtained by the authors.

In the present paper, a simplified model is used to determine the axial load-carrying capacity of compressed short reinforced concrete columns subjected to corrosion processes. The model considers members with circular and square cross-sections and accounts for—cover spalling, —concrete core confinement induced by transverse steel reinforcement, —buckling of longitudinal reinforcing bars. Strength reduction in concrete cover and core due to cracking induced by rust formation, reduction of steel area in longitudinal bars and transverse stirrups due to general and pitting corrosion and loss of confinement pressure are considered. The load-carrying capacity and load-axial strain curves here generated analytically fit well the existing experimental data.

This paper gives additional information on the use of new class of composites constituted by Basalt Fiber Reinforced Polymer (BFRP) bonded with epoxy resin to concrete specimens as an alternative confinement material for compressed concrete members with respect to carbon or glass fibers. From the experimental point of view, concrete cylinders are wrapped with continuous fibers, in the form of sheets, applying both full and partial discrete wrapping with BFRP straps, and then tested in compression. For comparison, few other concrete cylinders are wrapped with Carbon Fiber Reinforced Polymer (CFRP) sheets and tested in compression. The number and type of plies (full or partial wrapping), the type of loading (monotonic and cyclic actions) and the type of fiber (basalt and carbon) are the main variables investigated. The experimental results obtained from the compressive tests in terms of both stress–strain curves and failure modes show the possibility of reducing the brittleness of unconfined concrete, resulting significantly increased both the post-peak resistance and the axial strain of confined concrete corresponding to BFRP failure. Form the analytical standpoint, a review of the available models given in the literature is made and verified against the experimental data. Finally, a proposal for analytical expressions aimed at the calculation of the compressive strength and corresponding strain of confined concrete is provided also including the strain at BFRP failure.

The purpose of the work was the study of the structural safety of R.C. beams subjected to corrosion processes though the derivation of moment-curvature diagrams and moment-to-shear interaction diagrams. Normal-strength reinforced concrete beams with longitudinal bars in the presence of transverse stirrups and subjected to corrosion processed are considered. Experimental results available in the literature related to corrosion processes, for steel bars, crack openings and bond degradation due to rust formation are reviewed. Then analytical laws relating to crack opening, bond degradation with attack penetration depth, through a rearranged form of Faraday’s law, are presented. An analytical model for cross-section analysis and shear strength prediction including the main effect due to rust formation is developed and verified against experimental data. Finally, a case study is added giving moment-curvature diagrams and moment-to-shear interaction diagrams to show the effects of different scenarios of natural corrosion increasing with time on beam elements.

In the present paper the experimental results relative to flexural tests on out-of-plane loaded large scale panels made of laminated structural glass are presented and discussed. Glass panels are parts of the structural facade of the Fontanarossa International Airport of Catania (Italy). Panels are mounted on a rigid testing frame and loaded with an uniformly distributed lateral pressure. Two different kinds of tests were carried-out, cyclic and monotonic, able to reproduce the serviceability and the ultimate conditions of the glass panels when subjected to the coupled effects of dead load and horizontal forces, the latter reproducing the wind action. Results obtained focused the high performances of structural glasses for structural applications (structural facade) characterised by multiple and progressive failure that did not interest the bearing points neither the zone of the shell near the supports. From a theoretical point of view a simple model based on the structural behaviour of equivalent beams is proposed able to take into account of the flexural behaviour of glass panes including catenary action. The comparison between experimental, analytical and numerical results obtained with non-linear finite element analyses shows good agreement. Finally, the proposed model appears an useful tool for preliminary design of glass panels for practicing engineers.

In this paper, an experimental study referring to the flexural behavior of full-scale external beam-column joints externally strengthened with steel angles and strips and subjected to cyclic reversal loading is presented. One control specimen and five other specimens having the same characteristics as the control specimen but strengthened with steel angles and strips along beams and columns, and characterized by different configurations of strengthening in the critical regions, were tested. The control specimen was designed with a weak column and strong beam to reproduce the most common cases of old frame structures in the Mediterranean area, which were designed only for gravity loads and are in need of retrofitting to seismic standards. A detailed discussion of the strengthening technique used and of the mechanical properties of the specimens studied under cyclic loading is presented. It is highlighted that, referring to the case of external beam-column assemblages that are not yet extensively studied in the literature, the steel cage is an effective reinforcing technique to increase the flexural and shear strength of beams and columns, also increasing the energy capacity dissipation and reducing the stiffness degradation.

This work presents the results of an experimental investigation on the behavior of 42 solid clay brick masonry columns internally strengthened by fiber-reinforced polymer (FRP) fabrics or stainless steel grids placed in horizontal mortar joints. In some cases, every course, and in other cases, alternate courses were reinforced with steel grids, carbon, and basalt FRP fabrics. Monotonic compressive loading tests were carried out under concentric and eccentric loads. Eccentric tests were carried out by loading the specimens on a reduced area with respect to the entire cross section, producing a disturbed region (D-region). A detailed characterization of the constituent materials was made experimentally. The compression tests show the effectiveness of the proposed strengthening techniques to produce increases in strength and the energy required for collapse of brick columns under concentric loads. Under eccentric loads, the reduction in the load-carrying capacity owing to the reduced loaded area is attenuated by the presence of the transverse reinforcements. An analytical expression is proposed that gives the strength of clay brick masonry columns considering that the biaxial strength domain of the bricks is modified because of the tensile contribution provided by the presence of transverse reinforcements. Moreover, a strut-and-tie model was utilized to calculate the load-carrying capacity in the D-region and was verified against experimental data, with good agreement.

In this paper a comparison between the analytical expressions for the prediction of the load carrying capacity of strengthened reinforced concrete (RC) columns with steel angles and strips is made. Expressions examined consider: the strength contribution due to the confinement effects induced by transverse strips; the composite action due to steel angles and unconfined concrete core; the strength contribution due to the composite actions of angles and concrete core taking into account that steel angles are subjected to axial force and bending moment and concrete core is confined by transverse strips. Design rules given by recent codes for the design of the strengthened columns are given. Therefore, results here generated, in terms of load carrying capacity, were compared with good agreement with experimental data available in the literature and with those obtained by using the existing models.

In the present paper the experimental results relative to three-point bending tests on multilayer glass beams and on semi-rigid connections realised with stainless double web angles are presented and discussed. Small and medium size glass beams were tested and load–deflection curves and crack patterns at failure were recorded. The laminated glass specimens, of equal cross-section, were characterised by three different combinations of annealed float and fully thermally tempered glass plies and different interlayers. Steel joints constituted by double web angles to connect two glass beams were tested adopting several geometrical configurations and using stainless steel bolts preloaded with two different preloading values. The results obtained highlight the brittleness of glass beams with fail safe mechanism in the case of multilayer glasses with PVB. The joints tested were the semi-rigid type, which only make it possible to activate small percentages of the flexural capacity of beams. In all cases examined brittle failure in the glass beams was observed due to stress concentration near the hole, highlighting the importance of the choice of an adequate distance from the hole and the edges of the beams and of the study of an appropriate interface material for connections between glass panels and steel members in the case of both preloaded and non-preloaded bolts.

In the present paper a mechanical model to predict the compressive response of high strength short concrete columns with square cross-section confined by transverse steel is presented. The model allows one to estimate the equivalent confinement pressures exercised by transverse steel during the loading process taking into account of the interaction of the stirrups with the inner core both in the plane of the stirrups and in the space between two successive stirrups. The lateral pressure distributions at hoop levels are obtained by using a simple model of elastic beam on elastic medium simulating the interaction between stirrups and concrete core, including yielding of steel stirrups and damage of concrete core by means of the variation in the elastic modulus and in the Poisson?s coefficient. Complete stress-strain curves in compression of confined concrete core are obtained considering the variation of the axial forces in the leg of the stirrup during the loading process. The model was compared with some others presented in the literature and it was validated on the basis of the existing experimental data. Finally, it was shown that the model allows one to include the main parameters governing the confinement problems of high strength concrete members such as: - the strength of plain concrete and its brittleness; - the diameter, the pitch and the yielding stress of the stirrups; - the diameter and the yielding stress of longitudinal bars; - the side of the member, etc.

A softened strut-and-tie macro model able to reproduce the flexural behaviour of external beam-column joint is presented. The model is specific for concrete with hooked steel fibres (FRC) and it is designed to calculate the flexural response, as load-deflection curve, of a beam-column sub-assemblages. The model considers the presence of a constant vertical load acting on the column and of a monotonically increasing lateral force applied at the tip of the beam.

This paper presents an analytical model to determine the compressive response of concrete members, having a square transverse cross section and reinforced with steel angles at the corners and steel strips connecting the steel angles. The model evaluates the effects of transverse strips and steel angles on confinement pressures, including strength and buckling phenomena. Compressive response was evaluated in cases of directly and indirectly loaded elements. The data produced correlate well with available experimental data.

The flexural behavior of plain and fibrous reinforced concrete (FRC) beams under monotonic and cyclic actions was analysed. Twelve beams were reinforced with top and bottom longitudinal deformed steel bars and transverse steel stirrups. Concrete, having 30 MPa cylindrical strength, was reinforced with hooked steel fibres at a volume percentage of 1%. Beams, 600 mm in length and with a square side cross-section of 150 mm, were tested in flexure using a three point bending test, adopting three different cover thicknesses of 5, 15 and 25 mm, respectively. The results obtained show that the addition of fibers increases the bearing capacity of the beams and ensures more ductile behaviour, at the same time reducing degradation effects under cyclic reversal loads. Moreover, the presence of fibers reduces the cover spalling process, also in the presence of high cover thicknesses. Shear strength of the beams was calculated using an analytical expression given in literature for plain concrete beams and here extended to the case of fibrous concrete beams of hooked steel fibers on the subject, while the analytical results in terms of load–deflection curves, under monotonic actions, were generated using a non-linear finite element program (DRAIN-2DX). This program was calibrated on the basis of constitutive laws in compression and in tension capable of taking FRC properties into account, and verified against experimental data. Finally, practical considerations regarding the choice of the optimum geometrical ratio of longitudinal and transverse steel bars for the ductile behaviour of single reinforced cross-sections. Moreover shear strength are given and compared with European and International code prescriptions.

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 comparison is made between the predictions obtained using the constitutive models and simple expressions given in recent codes. Parametric analyses carried out highlight the importance of a definition of the limits of validity of expressions given in the literature for estimation of ductility increases in order to avoid nonconservative assessment.

An experimental and theoretical research referred to the flexural behavior of external R.C. joints strengthened with steel cages constituted by steel angles and battens is presented. The subassemblage (beam, column and joint) was subjected to a constant vertical load acting on the column and to a monotonically increasing lateral force applied at the tip of the beam. The control specimen is without strengthening system and it was designed with weak column and strong beam and overstrength in the joint region. Strengthening cases here studied refer to steel caging in the column and both in the beam and in the column. Cyclic response in term of load–displacement curves, crack patterns and observation of failure mode types were the main results of the experimental results. Results highlight the effectiveness of the external steel cages as strengthening system, which increases the flexural strength and allows one to move the failure mode from the column to the beam. A simplified analytical model is proposed that can be used for pushover analysis and is able to reproduce the flexural behavior of external beam–column joints under monotonic loading. The model includes shear-to-moment interaction for beams and columns and confinement effects induced by external steel cages. The model is based on the determination of elastic–plastic behavior of the beam and of the columns, the latter being obtained from knowledge of the ultimate moment associated with the design axial force and deduced through a simplified moment–axial force domain. The joint was modeled with a strut and tie model in which concrete crushing and yielding of stirrups are the only limit states considered. Finally, a comparison between experimental load–deflection curves and analytical prediction is made showing good agreement.

Results of an experimental investigation on the compressive behavior of concrete prisms with square cross-section, externally wrapped with carbon fiber reinforced plastic (CFRP) sheets are presented. The effects of the following parameters were analyzed: local reinforcement at the corners and continuous layers; horizontal and vertical discontinuous strips; number of continuous layers—length of specimens. An analytical model is proposed to determine the maximum bearing capacity of compressed concrete members with square cross-section and externally wrapped with FRP for the different configurations examined, and also able to consider the strength reduction with the length increase of concrete members. Analytical results are then compared with the experimental data available in the literature, showing good agreement.

In the present paper an analytical and experimental investigation referring to the flexural behaviour of reinforced concrete corbels subjected to vertical forces is presented. For fixed shape and dimensions of the corbels the experimental investigation analyses the effects of the following: longitudinal and transverse steel reinforcements; fiber reinforced concrete (FRC) with hooked steel fibers; external wrapping retrofitting technique with a thin layer of carbon fiber sheet (CFRP). The analytical model based on equivalent truss structures, allows one to determine the bearing capacity of corbels, distinguishing the different ultimate states reached. The analytical results are then compared with experimental values, showing good agreement. 1359-5997 © 2004 RILEM. All rights reserved.

The compressive behavior up to failure of short concrete members reinforced with fiber reinforced plastic (FRP) is investigated. Rectangular cross-sections are analysed by means of a simplified elastic model, able also to explain stress-concentration. The model allows one to evaluate the equivalent uniform confining pressure in ultimate conditions referred to the effective confined cross-section and to the effective stresses in FRP along the sides of section; consequently, it makes it possible to determine ultimate strain and the related bearing capacity of the confined member corresponding to FRP failure. The effect of local reinforcements constitute by single strips applied at corners before the continuous wrapping and the effect of round corners are also considered. Analytical results are compared to experimental values available in the literature.

In this paper the behaviour in compression of RC columns externally strengthened with concrete jacketing is analysed and a cross-section analysis of the jacketed member under axial load and bending moment is developed. The focus was to study the effect of confinement of concrete jacket on concrete core and the behaviour of compressed bars with buckling effects. Some other important aspects such as shrinkage, creep, old to new concrete surfaces and bond split effects were not included in the model because: the use of thick non-shrink grout jacket and a well-roughened surface of old-to-new concrete was supposed; long term effects were included though corrective coefficients for monolithic behaviour proposed in the literature. A preliminary validation of the model adopted was made referring to the short-term experimental data available in the literature on the compressive behaviour of RC columns strengthened with concrete jacketing. Good agreement was obtained with the available data in terms of moment-axial force domains and moment–curvature diagrams. The analysis showed the effectiveness of this reinforcing technique in improving both the strength and the ductility of RC cross-sections of columns, highlighting the importance of an accurate choice of strengthened materials (concrete grade, thickness of jacket, space and diameter of stirrups, etc.).

In the present paper the focus is on the compressive response of short high strength reinforced concrete members having circular transverse cross-sections and reinforced with longitudinal steel bars and transverse spirals or hoops. An analytical model is proposed which allows one to estimate the confinement pressures exerted by transverse steel and by longitudinal bars during the loading process, taking into account the interaction of the hoops or spirals with the inner core both in the plane of the transverse steel and in the space between two successive hoops. Yielding of steel spirals or hoops and longitudinal bars including buckling phenomena and damage to the concrete core are also considered by means of variation in the elastic modulus and in the Poisson’s coefficient. The proposed mechanical model is able to reproduce the load-shortening curves of compressed members; it gives good agreement with several experimental data and with analytical results obtained by using other recent models available in the literature.

In this paper the behaviour of R.C. members externally strengthened with steel angles and battens subjected to axial force and bending moment is analysed. A fibre model was utilised to predict the moment–curvature diagrams of the strengthened members on the basis of stress–strain curves of the constituent materials (confined concrete, steel bars and angles) recently derived by the author. The stress–strain curves utilised for compressed concrete were able to take into account the confinement effects induced by longitudinal (bars and steel angles) and transverse (stirrups and battens) steel reinforcements. Constitutive laws in compression for confined concrete and steel bars and angles were utilised for a preliminary calibration of the compressive response of axially loaded columns strengthened with steel cages. Therefore axial force and bending moment diagrams and moment curvature diagrams were derived and verified against experimental data available in the literature. Finally, a parametric analysis showing the influence of the main parameters governing the problems (angle and strip geometry and mechanical properties of constituent material) was carried out, mainly referring to moment axial force domains, moment curvature diagrams. The analysis showed the effectiveness of this reinforcing technique in improving both the strength and the ductility of R.C. columns.

The goal of this study is to experimentally and analytically evaluate the influence of circular openings in reinforced concrete deep beams with low shear span-to-depth ratio. Twenty reinforced concrete small-scale deep beams with or without openings were tested in flexure under four-point loading. The beams had a small shear span-to-depth ratio in order to stress the shear behavior. The specimens had different reinforcement arrangements and opening positions. The load was transmitted to the specimen with bearing plates having the same side length as the beam. Two LVDT’s were arranged to record the transverse and axial strain of the theoretical struts forming in the beam. Additionally another device was mounted to measure the middle deflection of the beam. Comparative analysis of the experimental results shows that: the effect of the hole depends on its position in the beam; the benefit of the presence of reinforcement depends on its arrangement. An analytical model is proposed to predict the shear strength and corresponding deflection of deep beams with openings and the results are also compared with a non-linear finite element analysis showing good agreement.

Several experimental investigations in the past few years have highlighted the fact that the compressive strength of glass was significantly higher than its tensile strength, allowing new applications of glass in compression members. However, due to the high slenderness of structural glass elements made of thin glass panels, they tend to fail in a brittle manner. A substantial amount of fundamental research has been carried out in the past few years to investigate the stability behaviour of structural glass elements. However, although buckling of glass panels has been quite well studied, a very poor amount of research has been addressed to glass columns, which by contrast represent the most interesting case due to their direct application in buildings. In this paper, the results of ten compressive tests on glass panels and columns are presented and discussed. The main variables considered were slenderness of panels and the shape of the cross-section for columns. The results of six bending tests on monolithic and laminated glass panels are also shown, and the level of connection between the glass sheets was evaluated. A review of the theoretical background is provided and the results achievable with existing analytical models are compared.

An experimental investigation into the behavior of 16 short, confined, reinforced concrete columns with and without steel fibers was carried out. The columns with square sections had a concrete core 165 x 165 mm (6.49 x 6.49 in.) at the midsection and were hunched at the ends to apply eccentric loading and prevent boundary effects. The specimens were tested to failure at different strain rates under two loading schemes: concentric compression and eccentric compression with a constant eccentricity. The axial load and axial strains were obtained to evaluate the effects of the presence of steel fibers, the thickness of the cover concrete, and the eccentricity of the applied axial load. The comparative analysis of the experimental results showed that the presence of steel fibers delayed the spalling of concrete cover and increased the strain capacity and ductility; the eccentricity of the applied axial load caused substantial variation in the peak load, ultimate strength, and failure modes. Finally, the structural response of cross sections of normal concrete (NC) and steel fiberreinforced concrete (SFRC) columns subjected to compressive concentric and eccentric loading was numerically modeled to compare the experimental results. A suitable choice of constitutive laws for concrete and reinforcing steel bars and a reasonable calibration criterion of the model allowed for the reproduction of the experimental results with a good approximation level in terms of load-axial strain and the moment-curvature curves. Copyright © 2010, American Concrete Institute. All rights reserved.

In the present paper, an analytical model is proposed that is able to determine the flexural response of supported beams under four-point bending tests. Cases of normal strength reinforced concrete beams with longitudinal bars in the presence of reinforcing hooked steel fibers and transverse stirrups are considered. A simplified analytical model is presented that is able to calculate the load-deflection curves and the maximum and ultimate deflections occurring in the case of shear or flexure failures. In the case of shear failure, the maximum shear strength of the beams is evaluated by using a recent analytical expression proposed by the author able to account for the shear-to-moment interaction, which covers a large range of shear span-to-depth ratios. This expression is based on the evaluation of shear strength contribution due to beam and arch actions including their interaction with the fibers. In the case of flexural failure, the hypothesis of perfect bond of steel bars and concrete and limiting the range of shear-to-depth ratios to between two and four was considered to determine the ultimate moment. No tension stiffening and size effects were considered. A nonlinear finite element analysis program (ATENA) was utilized to verify the simplified model. The program was utilized by assigning the constitutive laws in compression and in tension for fibrous concrete available in the literature. Finally, on the basis of test data obtained by the author and of that available in the literature, a comparison was made to show the ability of the simplified proposed model to also predict the flexural response of beams when shear failure is attained.

Corbels are structural members often used in reinforced concrete structures to transfer vertical and horizontal forces to principal members. This paper presents experimental research regarding the flexural behavior of corbels in plain and fibrous concrete and in the presence of steel bars. The study considers the influence of the type of concrete grade (normal- and high-strength concretes), of the fiber percentage and of the arrangement and percentage of the steel bars on the flexural behavior of the corbels. The results in terms of load-deflection curves and crack patterns show the effectiveness in using fibrous reinforced concrete corbels as well as in the presence of stirrups ensuring adequate strength and deformation capacity in reinforced concrete corbels. A simplified analytical model is proposed to calculate the shear strength of fibrous reinforced concrete corbels as well as in the presence of stirrups. The expression proposed for the calculation of the shear strength is then compared with other expression from the literature. The experimental results generated in terms of bearing capacity and those available in the literature are compared with the results obtained through the proposed model and with existing analytical expression. They show a good level of approximation, highlighting the role of the individual contributions from bars, concrete and fibers in the resistant mechanisms.

The present paper proposes a semi-empirical analytical expression that is capable of determining the shear strength of reinforced concrete beams with longitudinal bars, in the presence of reinforcing fibers and transverse stirrups. The expression is based on an evaluation of the strength contribution of beam and arch actions and it makes it possible to take their interaction with the fibers into account. For the strength contribution of stirrups, the effective stress reached at beam failure was considered by introducing an effectiveness function. This function shows the share of beam action strength contribution on the global strength of the beam calculated including the effect of fibers. The expression is calibrated on the basis of experimental data available in literature referring to fibrous reinforced concrete beams with steel fibers and recently obtained by the authors. It can also include the following variables in the strength previsions: - geometrical ratio of longitudinal bars in tension; - shear span to depth ratio; - strength of materials and fiber characteristics; - size effects. Finally, some of the more recent analytical expressions that are capable of predicting the shear strength of fibrous concrete beams, also in the presence of stirrups, are mentioned and a comparison is made with experimental data and with the results obtained by the authors.

Experimental results of the local bond stress-slip relationship of reinforcing bars embedded in lightweight fiber reinforced concrete with expanded clay aggregates are presented. The effect of the following parameters were investigated: - dimension of specimens; - anchorage length; - percentages of hooked steel fibers; - geometrical ratio of transverse reinforcement; - confinement external transverse pressure. Prismatic specimens with deformed steel bars embedded for a fixed length equal to five and eight equivalent diameters were tested under both monotonic and cyclic reversal imposed displacements at the tip of the bars, in controlled displacement tests. The influence of the above mentioned parameters was investigated, and the effects in terms of strength and ductility of the confinement due to transverse steel, to the fibers or to the pressure applied externally are shown. © 2005 Elsevier Ltd. All rights reserved.

This paper presents basic information on the mechanical properties of steel fibre-reinforced light-weight concrete, manufactured using pumice stone or expanded clay aggregates. Results are presented for standard compressive tests and indirect tensile tests (splitting tests on cylinder specimens and flexure tests on prismatic beams using a three-point loading arrangement) under monotonically increasing or cyclically varying loads. The influence of steel fibres and aggregate types on modulus of elasticity, compressive and tensile strength and post-peak behaviour is evaluated. Test results show that compressive strength does not change for pumice stone aggregates, while an increase is observed for expanded clay; tensile strength and fracture toughness are significantly improved for both pumice stone and expanded clay. The results also show that with both expanded clay and pumice stone lightweight aggregates a suitable content of fibres allows one to obtain performances comparable with those expected from normal weight concrete, the important advantage of lower structural weight being maintained.

The goal of this investigation was the experimental verification of the dispersion of compression in bottle-shaped struts. Two typical bottle shapes were generated under load in compression concrete—both drilled and undrilled—and were reinforced concrete prismatic members with loading steel plate having a reduced area with respect to the entire cross section of the members. Axial load, and axial and lateral strains were recorded during the tests to evaluate the effects of key parameters. The comparative analysis of the experimental results showed that: 1) the presence of a hole produces a variation on the stress and strain distribution and a reduction in the load-carrying capacity; 2) the reduction in the dimension of the loading plate produces a reduction in the load-carrying capacity; and 3) the presence of transverse steel reduces this phenomenon, ensuring more ductile behavior. Finally, an analytical prediction of the load-carrying capacity was made and compared with the experimental results.