Development of Bonded/Riveted Steel Anchorages of Prestressed CFRP Strips for Concrete Strengthening.

Bartosz Piątek,Jerzy Michałowski,Tomasz Siwowski,Stanisław Błażewicz

doi:10.3390/ma13102217

Abstract

CFRP (carbon fiber reinforced polymer) strips are currently often used to strengthen reinforced concrete structures in flexure. In order to ensure effective strengthening, proper connection between FRP material and concrete structure is needed. CFRP strips can be applied passively (only by bonding to the concrete surface) or actively (by prestressing before bonding). In the case of passive strengthening, CFRP strips connecting by bonding to the surface along the strengthened element are usually sufficient. However, active (prestressing) CFRP strips should be additionally anchored at their ends. Anchoring of unidirectional CFRP strips to the reinforced concrete is difficult because of their weak properties in transverse directions. The paper presents a development of mechanical steel anchorages used in an active CFRP flexural strengthening system for reinforced concrete structures. The anchorages were made of steel plates connected to CFRP strips with steel rivets and epoxy adhesive. They were developed within series of tests on specimens from small-scale to full-scale tested in an axial tensile scheme. The paper describes successive modifications of the anchorages as well as the results of full-scale tests. The final version of the anchorage developed during the research had a tensile failure force of 185 kN, which is sufficient value for CFRP strengthening purposes.

Highlights

The carbon fiber reinforced polymer (CFRP) materials are a viable alternative to structural strengthening and offer several advantages such as high strength-to-weight ratio, ease of transport and installation, excellent fatigue characteristics, and are noncorrosive highly durable
Since the beginning of the new millennium, hundreds of research papers on flexural strengthening of reinforced concrete (RC) structures with the CFRP materials have been published in scientific journals and conference proceedings
100 inatmospheres, which, calculated per tensile the rivet cross-section, All thegauge anchorage specimens each series were subjected to the axial tests in the Instron corresponded to upsetting force force value full in the the corresponded to the the machine upsetting(Instron, force of ofNorwood, 28 kN

Summary

Introduction

The carbon fiber reinforced polymer (CFRP) materials are a viable alternative to structural strengthening and offer several advantages such as high strength-to-weight ratio, ease of transport and installation, excellent fatigue characteristics, and are noncorrosive highly durable. Since the beginning of the new millennium, hundreds of research papers on flexural strengthening of reinforced concrete (RC) structures with the CFRP materials have been published in scientific journals and conference proceedings. The most important research findings were reviewed and summarized in the following books [1,2,3,4] and state-of-the-art reports [5,6,7,8]. These reviews showed that the load-carrying capacity of the CFRP-strengthened beams can be significantly increased. On the basis of these and many more studies, it was concluded that using bonded CFRP materials as a flexural strengthening system can be effective

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Conclusion