Experimental testing on the flexural capacity of hybrid-reinforced concrete beams after fire

TIAN Jingbo1 ZHU Peng1 QU Wenjun1 YAN Bing1

(1.Department of Structural Engineering, Tongji University, Shanghai, China 200092)

【Abstract】After fire tests of six reinforced concrete beams, one unbroken concrete beam reinforced with steel bars and two unbroken hybrid-reinforced concrete beams were subjected to static load tests according to the fire resistance time and their condition after fire. In this study, the flexural capacity of the concrete beams reinforced with steel bars and hybrid-reinforced concrete beams after fire were investigated. The influence of the ratio of the steel bars to GFRP bars and the load on the hybrid-reinforced concrete beams was discussed. As a result, firstly, the strength of the GFRP bars was basically wiped out, but the strength of the steel bars can restore to a certain degree after fire. The restoring of the flexural capacity of the concrete beams reinforced with steel bars was better than that of the hybrid-reinforced concrete beams. Secondly, the residual flexural capacity of the hybrid-reinforced concrete beams was significantly influenced by the ratio of the steel bars to the GFRP bars. The higher the ratio was, the better the restoring of the flexural capacity after fire. Based on experiments and the theoretical analysis, a method for calculating the residual flexural capacity of hybrid-reinforced concrete beams was proposed. The results of calculation and experiment showed a good agreement, for which the method can be used for future engineering applications.

【Keywords】 hybrid-reinforced concrete beams; static load tests after fire; ratio of steel bars to GFRP bars; residual flexural capacity;

【DOI】

【Funds】 National Natural Science Foundation of China (51678430) National Key R&D Program of China (2017YFC0703003)

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(Translated by LIU T)

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This Article

ISSN:1004-4574

CN: 23-1324/X

Vol 28, No. 04, Pages 22-31

August 2019

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Article Outline

Abstract

  • 1 Fire test
  • 2 Data arrangement and analysis of static load tests after fire
  • 3 Calculation of cross-sectional flexural capacity after fire
  • 4 Conclusions
  • References