Ernesto Grande

Simple Model for Bond Behavior of Masonry Elements Strengthened with FRP

The aim of the present paper is the development of a simple procedure for the analysis of the bond behavior of fiber-reinforced polymer (FRP) sheets or plates externally applied to masonry supports for the strengthening or repair of masonry constructions. The procedure allows evaluation of the bond strength and the fracture energy developed during the debonding process through simple formulas based on a few parameters, evaluated either by standard tests performed on the materials making up the support and the strengthening system or by theoretical considerations. A brief discussion on the main experimental evidence and the theoretical models provided by the literature is also reported in this paper. The comparison between the theoretical results obtained by applying the proposed procedure and the experimental data deduced from literature is carried out.

Bond Behavior of Historical Clay Bricks Strengthened with Steel Reinforced Polymers (SRP)

In the strengthening interventions of past and historical masonry constructions, the non-standardized manufacture processes, the ageing and the damage of masonry units, could significantly affect the properties of the surfaces where strengthening materials are applied. This aspect requires particular care in evaluating the performance of externally bonded strengthening layers, especially with reference to the detachment mechanism. The bond response of old masonries could be very different from that occurring in new masonry units which are the ones generally considered in most of the bond tests available in technical literature. The aim of the present paper is the study of the bond behavior of historical clay bricks strengthened with steel reinforced polymers (SRP) materials. In particular, the results of an experimental study concerning new manufactured clay bricks and old bricks extracted from different historical masonry buildings are presented. The obtained results, particularly in terms of bond resistance, detachment mechanism and strain distributions, are discussed for the purpose of analyzing the peculiarities of the historical bricks in comparison with new manufactured ones. Some considerations on the efficacy of the theoretical formulations of the recent Italian code are also carried out.

The role of the adhesive on the bond behavior of SRPs applied on masonry supports: experimental and numerical study

Steel Reinforced Polymers (SRP) have been recently introduced and adopted as strengthening systems for existing constructions. Although the interest for this kind of strengthening materials is increasing also for masonry structures, in particular for historic constructions, only few studies specifically pertained to masonry elements strengthened with SRPs are available in the literature. In this context, a twofold purpose is at the basis of the present paper. The first one consists of experimentally investigating the bond behavior of masonry elements strengthened with SRPs using different types of adhesives and strips density. The second purpose aims at developing simple formulations for evaluating the bond resistance of masonry elements strengthened with SRPs applied with different types of adhesive systems.

FRP-strengthening of masonry structures: Effect of debonding phenomenon

The present paper shows and discusses some aspects concerning the delamination phenomenon of Fibre Reinforced Plastic (FRP) materials fixed on masonry support. With this aim, in the first part of the paper the results of an experimental campaign conducted by the authors concerning the effect of the bond length on the delamination phenomenon of CFRP glued on clay bricks are discussed. Moreover, in order to underline further aspects concerning the decohesion mechanism of FRP-reinforcements, in the second part some numerical analyses are also presented.

Experimental Response of RC Beams Strengthened in Shear by FRP Sheets

The paper discusses the results of an experimental investigation carried out on reinforced concrete (RC) beams strengthened in shear by externally bonded fiber reinforced plastic (FRP) sheets. The study is devoted to analyze the role that the transverse steel reinforcement and the beam slenderness ratio could play on the resistant mechanism of RC beams strengthened in shear by FRP composites. The results are summarized and analyzed in detail in the paper in terms of shear capacity, cracking pattern and shear resisting contribution of FRP.

FRP-Strengthening of Curved Masonry Structures: Local Bond Behavior and Global Response

The aim of the paper is to propose and assess the reliability of a modeling strategy which combines the homogenization of the masonry material and the use of zero-thickness interface elements. This strategy is specifically proposed for numerically investigating the structural response of FRP-reinforced curved masonry structures. Indeed, in order to consider the influence of the geometry curvature of the masonry substrate on the local bond behavior of the FRP-strengthening system, bond-slip laws which specifically account for the geometric curvature of the substrate are introduced at the FRP/substrate interface layer. Numerical analyses concerning masonry arches selected from the current literature are presented in the paper in order to assess the reliability of the proposed modelling approach.

Structural Optimization of Grid Shells: Design Parameters and Combined Strategies

AbstractThe optimization of structures is a tricky process that involves strategies and mathematical algorithms in which the design parameters—introduced in terms of variables, constraint condition...

Local Bond Behavior of FRCM Strengthening Systems: Some Considerations about Modeling and Response

The paper presents a study concerning the local bond behavior of FRCM strengthening systems externally applied to structural supports. The aim of the study is to analyze the main parameters influencing the interaction between the reinforcement and the mortar layer and their role. To this purpose, a theoretical approach is performed in order to analyze the main phases characterizing the bond behavior of FRCM-strengthening systems. In particular, the attention has been devoted to the upper mortar layer by analyzing its influence on the bond behavior of FRCM-strengthening systems.

A data fusion based approach for damage detection in linear systems

The aim of the present paper is to propose innovative approaches able to improve the capability of classical damage indicators in detecting the damage position in linear systems. In particular, starting from classical indicators based on the change of the flexibility matrix and on the change of the modal strain energy, the proposed approaches consider two data fusion procedures both based on the Dempster-Shafer theory. Numerical applications are reported in the paper in order to assess the reliability of the proposed approaches considering different damage scenarios, different sets of modes of vibration and the presence of errors affecting the accounted modes of vibrations.

A Frame Element Model for the Nonlinear Analysis of FRP-Strengthened Masonry Panels Subjected to In-Plane Loads

A frame element model for evaluating the nonlinear response of unstrengthened and FRP-strengthened masonry panels subjected to in-plane vertical and lateral loads is presented. The proposed model, based on some assumptions concerning the constitutive behaviour of masonry and FRP material, considers the panel discretized in frame elements with geometrical and mechanical properties derived on the basis of the different states characterizing the sectional behaviour. The reliability of the proposed model is assessed by considering some experimental cases deduced from the literature.