FRP Confinement of Stone Samples after Real Fire Exposure.

Luis Estevan,Salvador Ivorra,F Javier Baeza,Francisco B Varona

doi:10.3390/polym12102367

Abstract

The mechanical properties of stone materials can be severely affected by exposure to high temperatures. The effect of fire on stone buildings could cause irreversible damage and make it necessary to retrofit the affected elements. Particularly, the strengthening of columns by confinement with composites has been widely improved during the last decades. Today, fiber reinforced polymer (FRP) confinement represents a very interesting alternative to traditional steel solutions. This work studied the behavior of cylindrical stone specimens subjected to real fire action and confined by means of CFRP or GFRP jackets, with the aim of assessing the effectiveness of these reinforcement systems applied to a material that has previously been seriously damaged by high temperature exposure. In general, the strengthened samples showed notable increases in strength and ductility. The response seemed to depend basically on the FRP properties and not on the degree of damage that the stone core may have suffered. Finally, the results obtained experimentally were compared with the confinement models proposed by the available design guides, in order to evaluate the accuracy that these models can offer under the different situations addressed in this research.

Highlights

Stone is generally considered as one of the most robust building materials in terms of fire resistance.recent episodes, such as the fires in Notre-Dame Cathedral in Paris or the National Museum of Brazil in Rio de Janeiro, showed that the action of fire in historic buildings can have catastrophic consequences and jeopardize the safety of people and the integrity of invaluable heritage
In other investigations published with different stone materials [3,4,5], similar results can be observed, and, in general terms, the mechanical properties of rocks were seriously affected by exposure to high temperatures
The results clearly showed a higher efficiency of the fiber reinforced polymer (FRP) confinement, doubling the ultimate strength with respect to the unreinforced samples and increasing the ultimate strain by more than 10 times in some series

Summary

Introduction

Stone is generally considered as one of the most robust building materials in terms of fire resistance.recent episodes, such as the fires in Notre-Dame Cathedral in Paris or the National Museum of Brazil in Rio de Janeiro, showed that the action of fire in historic buildings can have catastrophic consequences and jeopardize the safety of people and the integrity of invaluable heritage. The results showed significant drops in the compressive strength of the rock (up to 34% in the slowly cooled samples and 53% in the water cooled ones, for 600 ◦ C exposure) and, especially, in the modulus of elasticity, with reductions up to 85% (with both cooling systems). Kumari et al [2] proposed a similar experimental study with granite samples exposed to temperatures between 100 and 800 ◦ C, with slow and sudden cooling, obtaining strength decreases of up to 80% and drops in the modulus of elasticity of around 90%, somewhat greater in the series subjected to quick cooling. In other investigations published with different stone materials [3,4,5], similar results can be observed, and, in general terms, the mechanical properties of rocks were seriously affected by exposure to high temperatures

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