Francesco Porco

The influence of infilled panels in retrofitting interventions of existing reinforced concrete buildings: a case study

During the seismic events occurred in the last decades, the existing reinforced concrete (RC) building stock has often exhibited a significant brittle collapse of joints and secondary elements such as infill walls. A quite common strategy, in the attempt of mitigating this vulnerability, is the generalised implementation of strengthening interventions on the structural elements, even in the absence of a complete seismic assessment procedure. This paper presents some considerations about the effects induced by strengthening interventions involving the tying of the infill panels to the RC frame. Within this context, an appraisal of the actual displacement capacity and the possible alteration induced on the global collapse mechanism is provided. The analyses and discussion of results are presented with reference to an actual case study concerning a school building, which was part of a wide vulnerability assessment investigation performed in the Province of Foggia, Italy. In particular, seismic analyses performed using nonlinear static analysis procedures on the strengthened configuration and on the original structure are critically compared and discussed.

Simplified vulnerability assessment of reinforced concrete circular piers in multi-span simply supported bridges

This paper proposes a simplified procedure for the seismic vulnerability analysis of multi-span simply supported bridges, in the case of single piers with solid circular sections. The proposed method can be applied whenever the seismic response of the whole bridge depends on the most critical pier. For an assigned limit state, the procedure determines the capacity curve of the critical pier as a function of three parameters (elastic stiffness, displacement at yielding, displacement at collapse), starting from the behaviour under combined axial stress and bending, and then taking into account the different possible collapse modes (shear failure; lap splice failure of the longitudinal bars; buckling) and the geometric nonlinearity. A significant numerical example is presented in which the traditional FEM solution is compared with the proposed simplified procedure.

The assessment of structural concretes during construction phases

Purpose – The purpose of this paper is to collect the numerical elaboration of resistances measured on cubes made during the concrete casting and on cores extracted after the completion of the structure, for the concrete used in the construction of the “Esaro” Dam facilities (Cosenza, Italy). In addition to the statistical treatment of the sample, aimed at assessing the analytical congruence with the homogeneous classes provided in the design, the influence of compaction degree on in place strength value was qualitatively evaluated. Design/methodology/approach – The reliability of the concrete during the construction phases was evaluated by two analytical control types according to Italian and European technical rules: “production controls” based on statistical processing of resistance values; “laying controls” that serve to assess the compaction degree with a statistical approach. Findings – Results highlighted in the assessing of compliance checks of the mixture, the fundamental relation between statist...

The SonReb Method: Critical Review and Practical Aspects

Current regulations require surveys on materials in order to identify one or more representative values of the in-situ concrete strength. In this context, the SonReb method is widespread. It correlates the in-situ concrete strength with the ultrasonic pulse velocity and rebound-hammer index. The method improves the reliability of both non-destructive methodologies that are less reliable if considered separately. However, the method neglects the numerical dispersion of the acquired resistances, making uncertain the reliability of every representative value identified. Uncertainty is inherent not only in the variability of the parameters that determine the values, but also in the use of literature formulations calibrated on “recurring concretes”, i.e. concretes characterized by properties evenly variables (age, w/c ratio, …) that don’t allow wider use. In this work, a critical review of the SonReb method is proposed, through a purely statistical approach with the aid of surveys on some school buildings in the province of Foggia built in the 60s and 80s.