Strengthening of masonry rings with composite materials

Jerzy Jasieńko,Piotr Frąckiewicz,Kajetan Kleszcz,Krzysztof Raszczuk,Łukasz Bednarz

doi:10.1186/s40494-021-00485-5

Jerzy Jasieńko, Piotr Frąckiewicz + Show 3 more

Open Access

https://doi.org/10.1186/s40494-021-00485-5

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Abstract

The paper presents the results of experimental testing of six masonry rings built to technical scale and strengthened with CFRP strips and sheets and also with an FRCM system with PBO, glass, basalt and carbon fibers. The rings were subjected to tensile loads induced by four hydraulic jacks. The assumption is that the masonry rings are a representative simplification of domes, especially their structural support. Both single layered domes and ribbed domes are exposed to tensile stress in up to one third of their height.During the tests, the following information was collected: loads, displacements, strains of composites and failure modes. In some cases, an initial prestressing of reinforcements was carried out. Recommendations and limitations related to the use of the materials tested for reinforcing round, masonry structures under tensile stresses are discussed. The criterion for choosing the best solution was not only based on comparing the tensile strength of the reinforcement but also its stiffness. A strengthening efficiency index is proposed. The assessment of strengthening effectiveness was carried out, taking into account also heritage building conservation standards. Adopting the EF indicator as the criterion for assessing the effectiveness of reinforcement, it can be concluded that the application of the following methods should be considered in the structural maintenance of historical buildings: PBO mesh reinforcement in the PBO-FRCM system, carbon mesh reinforcement in the C-FRCM system and also basalt reinforcement in the B-FRCM system.

Highlights

Dome structures are to be found all over the world, and their symbolism has inspired many cultures
Adopting the Effective Factor for strengthening technique (EF) indicator as the criterion for assessing the effectiveness of reinforcement, it can be concluded that the application of the following methods should be considered in the structural maintenance of historical buildings: PBO mesh reinforcement in the PBO-Fiber Reinforced Cementitious Matrix (FRCM) system, carbon mesh reinforcement in the C-FRCM system and basalt reinforcement in the B-FRCM system
Strengthening methods The following systems were used to strengthen the rings: R1: Single Carbon Fiber Reinforced Polymer B (CFRP) strip attached to the masonry by a two-component epoxy composition; R5: Single-layered carbon fiber wrap on epoxy resin; R6: Two layers of glass fiber mesh embedded in a mineral matrix; R7: Four layers of B-FRCM system based on basalt fiber mesh embedded in a mineral matrix; R8: Three layers of carbon fiber mesh embedded in a mineral matrix; R9: Three layers of P.B.O. fiber mesh embedded in a mineral matrix

Summary

Introduction

Dome structures are to be found all over the world, and their symbolism has inspired many cultures. For straightforward cases of spherical and polygonal domes, there are formal analytical solutions that, are easy to interpret when a membrane state of stress is assumed. This assumption is only valid when the stress state is torque-free, the thickness of the shell is small in relation to the other dimensions, and the central surface is continuously curved. The normal stresses from axial forces and stresses tangential to the central surface occur At this point, it can be stated unequivocally that in most domes, the static solution indicates the presence of tensile stress in the lower latitudinal bands regardless of their specific geometry. A comprehensive summary of the static work of domes, with particular emphasis on the crack patterns on their behavior, can be found in [1]

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