Giuseppe Campione

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. The analytical results generated are compared with the experimental data available in the literature and with those obtained by using existing analytical models. The comparison shows the acceptable prediction of the experimental results in both cases of directly loaded and not directly loaded steel angles. Final...

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 actions of fibers across main and secondary cracks. From the analytical point of view, a softened strut-and-tie macromodel able to reproduce the flexural behavior (in terms of multilinear load-deflection curves) of deep beams in plain and fibrous concrete and with the presence of horizontal steel bars, including softenin...

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.

A softened strut-and-tie macromodel able to reproduce the flexural behavior of corbels in plain and fibrous concrete and with the presence of steel bars, including softening of compressed struts and yielding of main and secondary steel bars, is presented in this paper. The main focus of the proposed model is the determination of the load-deflection curves of corbels subjected to the coupled effects of vertical and horizontal forces bearing in mind the influence of the type of concrete (normal or high strength), of the fiber percentage and of the arrangement and percentage of the main and secondary (horizontal stirrup) steel bars. A validation of the proposed model is made therefore with reference to some of the experimental data available in the literature and also to numerical results obtained by using a nonlinear finite-element program (ATENA-2D) able to analyze the flexural behavior of deep members. Finally some design considerations on the use of fibrous reinforced concrete in RC corbels are given.

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 ...