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.
Highlights
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)
Finite‐Element Modelling To be able to simulate the response of the RC beams after fire, a sequential Thermal–Mechanical Coupling approach is implemented in ABAQUS modelling
This paper propose a new calculation model based on the finite-element analysis (FEA) results and the improved section method to calculate the residual flexural capacity of the post-fire RC beams aiming at refining the flexural capacity calculation with the accurate inclusion of defects of strength reduction of the components caused by fire
Summary
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 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. Di Capua and Mari (2007) proposed two models, the thermal model and the mechanical model, for calculating the RC beams exposed to fire, which were in good agreement with test results. In theory, Xiang et al (2010) studied the calculation method of flexural capacity for fire-damaged RC bending members, Yu et al (2005a, b) studied the effects of different factors on the mechanical properties of concrete exposed to high temperature and proposed the equations of stress–strain relation for various concrete after high temperature. In theory, Xiang et al (2010) studied the calculation method of flexural capacity for fire-damaged RC bending members, Yu et al (2005a, b) studied the effects of different factors on the mechanical properties of concrete exposed to high temperature and proposed the equations of stress–strain relation for various concrete after high temperature. Hu et al (2006) established estimation methods for the flexural capacity of slabs subjected to fire and axially loaded concrete square columns subjected to fire on four surfaces. Lie and Irwin (1993) described a method for the calculation of the fire resistance of RC columns with rectangular cross sections. Jiang et al (2008) discussed the rectangle beam with single reinforcement, and proposed a method to calculate the residual capacity of the RC member
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