Effect of Thermal Distress on Residual Behavior of CFRP-Strengthened Steel Beams Including Periodic Unbonded Zones

Polymers

Isamu Yoshitake⁴  Hisatsugu Tsuda³  Yail J. Kim²  Nobuhiro Hisabe¹ 

[1] Mitsubishi Plastics Infratec Co., Ltd., 1-2-2 Nihonbashihongokucho, Chuo-ku, Tokyo 103-0021, Japan;Department of Civil Engineering, University of Colorado Denver, Denver, CO 80217, USA;IHI Infrastructure Systems Co., Ltd., 3 Ohama Nishimachi, Sakai, Osaka 590-0977, Japan;;Department of Civil and Environmental Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan

关键词: carbon fiber-reinforced polymer;    interfacial stress;    steel;    strengthening;    thermal coefficient;   

DOI  :  10.3390/polym7111517

来源: mdpi

【 摘 要 】

This paper presents the residual behavior of wide-flange steel beams strengthened with high-modulus carbon fiber-reinforced polymer (CFRP) laminates subjected to thermal loading. Because the coefficients of thermal expansion of the steel and the CFRP are different, temperature-induced distress may take place along their interface. Periodic unbonded zones are considered to represent local interfacial damage. Five test categories are designed depending on the size of the unbonded zones from 10 to 50 mm, and corresponding beams are loaded until failure occurs after exposing to a cyclic temperature range of ΔT = 25 °C (−10 to 15 °C) up to 84 days. The composite action between the CFRP and the steel substrate is preserved until yielding of the beams happens, regardless of the thermal cycling and periodic unbonded zones. The initiation and progression of CFRP debonding become apparent as the beams are further loaded, particularly at geometric discontinuities in the vicinity of the unbonded zones along the interface. A simple analytical model is employed to predict the interfacial stress of the strengthened beams. A threshold temperature difference of ΔT = 30 °C is estimated for the initiation and progression of CFRP debonding. Multiple debonding-progression stages in conjunction with the extent of thermal distress appear to exist. It is recommended that high-modulus CFRP be restrictively used for strengthening steel members potentially exposed to a wide temperature variation range.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.