Abstract

Ferroconcrete pipes, used in drainage and water disposal systems of roads, works in conditions, in which the direction of the main tensile stresses is either unknown, or can change during exploitation. One of the ways of solving this problem is using of steel fibrous concrete, i.e. concrete on hydraulic tenacious substances with addition of reinforcing elements in the form of short lengths (fibers). Using of steel fibrous concrete allows to get the construction of low pressure centrifuged pipe for drainage and water disposal systems at places of automobile and railway transport heavy traffic with higher tensile and bending strength, crack resistance for the work under conditions when the direction of the main tensile stresses is unknown. © 2019 Published under licence by IOP Publishing Ltd.

Abstract

The adoption of effective strengthening techniques of historical constructions is one of the most widely debated aspects in structural engineering. Within this topic, the application of steel fiber reinforced mortar (SFRM) has been recently proposed as a low invasive and effective way to obtain a considerable structural benefit in the safety of existing masonry structure. To this purpose, in this paper the experimental results obtained on a circular masonry arches are presented. The considered specimens, subjected to a vertical increasing static load, is tested in the unstrengthened and strengthened configurations, and is part of a wider experimental campaign. After presenting and discussing the experimental results, they are compared with those relative to numerical simulations conducted by means of a discrete macro-element (DME) strategy, based on a simple mechanical scheme, able to model the nonlinear behavior of masonry structures with a limited computational effort. Such an approach is here extended to model the SFRM strengthening technique accounting for the main failure mechanisms associated to the combined presence existing masonry and the additional strengthening layer applied at the intrados of the arch. Numerical and experimental results demonstrate the efficacy of the proposed retrofitting strategy both in terms of bearing capacity and increase of ductility.

Abstract

Traditionally, reinforcement and consolidation of masonry structures has been done according to one of the following approaches, or a combination of them: By using materials with a very different nature and behaviour from the original ones in the reinforced structure or by increasing the section of those structures, increasing, therefore, their hardness. The first approach could unleash serious setbacks in the original structure. Using materials with high elastic modulus on more flexible elements might generate new tensions in the system, which previously did not exist, compromising the reinforcement intervention. The second approach implies increasing significantly the structural geometry and, therefore, its own global hardness. The modern approach, which reinforcement and consolidation of masonry structures pursue, is solving both, different nature of materials and sectional increasing. It is done by using compatible materials with the original structure, combining the elastic behavior of them and assuring the original breathability, and implementing low thickness interventions in order to do not modify the original hardness. The proposal of a reinforcement system compatible with the historic and architectonic nature of the structure, is based on a mineral matrix of hydraulic natural lime, GeoCalce F Antisismico, combined with basalt fiber fabrics (GeoSteel Grid) or galvanized steel unidirectional bands (GeoSteel HardwireTM). With this system typology, it is ensured an improvement in the mechanical resistances of the structure, based on a simple and low thickness application. The aim of the exposition is introducing a reinforcement and consolidation system for masonry structures developed by Kerakoll and showing several success cases, in Spain and Italy, reinforced with this system. Each case will be explained from the initial study phase to the execution of the intervention, including the calculations to determine the application to be done.