Experimental results of a national technical assessment procedure on commercial FRP for structural strengthening: wet-lay-up systems

A Occhiuzzi,A Bonati,P Salzano,F Ceroni,A Franco

doi:10.1617/s11527-020-1439-5

Abstract

The paper shows the results of a large experimental activity for the qualification of wet-lay-up FRP products for structural repair and/or strengthening, required by the Italian national approval authority. The qualification procedure and the correspondent design rules are described in national guidelines. The analysis of the experimental results of a large number of qualification tests allows to highlight some aspects in the national procedure that could be addressed in a future revision of the guidelines. In particular, statistical analyses were carried out in order to assess the most suitable probabilistic models able to describe the experimental distribution of the tensile strength and the Young’s modulus of FRP wet-lay-up materials falling in the same class. The analyses were developed with reference to both ordinary and artificial environmental conditions. Nevertheless the paper is focussed on the case of wet-lay-up FRP materials, it can be considered exemplary of a problem common to other products.

Highlights

Due to the huge retrofitting activity following the seismic events that struck Italy in the last decades and especially after L’Aquila earthquake of 2009, Fibre Reinforced Polymers (FRP), in the form of externally bonded systems, have been extensively adopted in Italy for strengthening and repairing damaged structures
It is interesting to note that the qualification process prescribes tests under artificial ageing too in order to check the durability of FRP materials
A description of the experimental results obtained from the product qualification of many different FRP products yields a global perspective of mechanical parameters of the most common FRP systems adopted for structural repair and/or strengthening in the Italian national market

Summary

Introduction

Due to the huge retrofitting activity following the seismic events that struck Italy in the last decades and especially after L’Aquila earthquake of 2009, Fibre Reinforced Polymers (FRP), in the form of externally bonded systems, have been extensively adopted in Italy for strengthening and repairing damaged structures. Guidelines for the design of strengthening interventions on concrete and masonry elements with FRP materials are available since several years in Italy [1–3] and are based on the wide experimental, theoretical and analytical studies carried out by several researchers in the last decades [4–9] focussed on several aspects governing the design (i.e., bond behaviour, flexural and shear strength, confinement, strengthening of beams-columns joints, serviceability conditions). It is interesting to note that the qualification process prescribes tests under artificial ageing too in order to check the durability of FRP materials. Such an aspect is worth of investigation in order to assess the real strength capacity for FRP applications on both concrete and masonry elements under environmental conditions different from the standard ones [11–14]. The experimental results examined highlight some aspects in the national procedure that could be addressed in a further revision of the current guidelines [10]

Methods

Results

Discussion

Conclusion