Finite Element Analysis and Calculation Method of Residual Flexural Capacity of Post-fire RC Beams
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International Journal of Concrete Structures and Materials Open Access
RESEARCH
Finite Element Analysis and Calculation Method of Residual Flexural Capacity of Post‑fire RC Beams Bin Cai1,2, Bo Li1 and Feng Fu2*
Abstract Fire tests and subsequent bending tests of four reinforced concrete (RC) beams were performed. Based on these tests, the post-fire performance of RC beams was further studied using finite-element simulation through reasonable selection of suitable thermal and thermodynamic parameters of steel and concrete materials. A thermodynamic model of RC beams with three sides under fire was built using finite-element analysis (FEA) software ABAQUS. The FEA model was validated with the results of fire tests. Different factors were taken into account for further parametric studies in fire using the propsed FE model. The results show that the main factors affecting the fire resistance of the beams are the thickness of the concrete cover, reinforcement ratio of longitudinal steel, the fire exposure time and the fire exposure sides. Based on the strength reduction formula at high temperature of steel and concrete and four test results, an improved section method was proposed to develop a calculation formula to calculate the flexural capacity of RC beams after fire. The theoretical calculation method proposed in this paper shows good agreement with FEA results, which can be used to calculate the flexural capacity of RC beams after fire. Keywords: Post-fire, reinforced concrete beams, finite element, ABAQUS, theoretical calculation 1 Introduction Reinforced concrete (RC), as one of the major building materials of modern architectural structures, will form nonuniform temperature fields after exposure to fire (Shao et al. 2003; Cheng 2007). The thermal stress and expansion (Zhao 2014) due to fire will lead to stress redistribution of overall structures and reduction of structural flexural capacity or even the local structural destabilization, which further induce the collapse of overall structures and bring about massive losses to the possessions and life of humans (Ban 2008). Thus, the temperature fields should be determined first for subsequent analysis of RC structures to understand the degradation in the mechanical properties and flexural capacity after exposure to fire, which are the keys to evaluate *Correspondence: [email protected] 2 School of Mathematics, Computer Science and Engineering, City, University of London, London, UK Full list of author information is available at the end of the article Journal information: ISSN 1976-0485 / eISSN 2234-1315
whether the RC structures can be used anymore (Tian 2002; Zeng 2006). So far, there is considerable research in the aspect of test and finite-element analysis (FEA). Fu et al. (2015) studied how the fire surfaces of RC beams affected the temperature fields. Liao et al. (2013) designed the shear tests and a FEA method was proposed to calculate the shear flexural capacity among one room temperature and seven post-fire RC beams, which has the accepted accur
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