Advanced Steel Construction

Vol. 10, No. 4, pp. 385-403 (2014)



Fu Zhongqiu, Ji Bohai* , Maeno Hirofumi, Eizien A. and Chen Jiashu

College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, China

*(Corresponding author: E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.)


Received: 28 September 2012; Revised: 24 March 2013; Accepted: 18 October 2013




To study the flexural behaviour of lightweight aggregate concrete filled steel tubes (LACFST), 21 LACFST specimens and 8 steel tubes without filling concrete were tested under pure bending load. The parameters considered are: steel tube diameter and thickness, lightweight aggregate concrete (LAC) strength and shear span ratio. According to the test results, the failure mode, deflect ion and failure process were studied and their influence on the flexural behaviour of LACFST was analyzed. Several codes were used to calculate the stiffness and moment capacity. Based on the mechanical equilibrium and combined strength, two methods were provided to calculate the moment capacity in this paper. The calculated results were verified with the test ones. The constitutive model of confined LAC in compressive region was also proposed and used i n the FEM to analyze the flexural behaviour of LACFST. This study showed the strain distribution agreed with the Bernoulli-Euler’s theory. The deflection along the length distributed as half sine wave curve during the test. The moment capacity of LACFST increased as the steel ratio and LAC strength increased. But the shear span ratio had almost no influence on the flexural behaviour of LACFST. The comparison between the calculation and the test showed the results of AIJ (1997) for stiffness and DL/T5085 for moment capacity fitted with the test ones well. But the results using the two proposed methods had a better accuracy to calculate the moment capacity. The FEM analysis showed the constitutive model of confined LAC in compressive region was also proved having a good accuracy.


Keywords:Lightweight aggregate concrete filled steel tube, flexural behaviour, stiffness, moment capacity, calculation method 


Download PDF: