Abstract

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Title:: Bending capacity test of lightweight aggregate concrete filled steel tube spatial truss beam

Author(s):: FU Zhong-qiu; JI Bo-hai; LIU Hai-sheng; YU Zhen-peng; ZHOU Yu; School of Civil and Transportation Engineering, Hohai University, Nanjing 210098, Jiangsu, China

Keywords:: bridge engineering; lightweight aggregate concrete-filled steel tube; spatial truss beam; pure bending test; bearing capacity; serviceability limit state

Abstract:: In order to study the bearing capacity design method of lightweight aggregate concrete filled steel tube (CFST) spatial truss beam, a lightweight aggregate concrete filled steel tube (CFST) spatial truss beam specimen was made to be tested. The bending capacity of specimen was studied through the analysis of deflection and strain of steel surface. Based on the plane cross-section assumption and neglecting the effect of web members, the stress at mid-span section of specimen was studied and calculation method of bending capacity was proposed. The results show that the web members keep relatively small force in the loading process. The deflection of upper chord members has the same tendency with that of bottom ones. The longitudinal strain distribution of chords at mid-span section obeys the plane cross-section assumption. When the truss girder deflection exceeds L/50, there is no buckling phenomenon on surface of the chord and web members, which indicates that it is ductile failure. According to the serviceability limit state, bending capacity value of the truss beam was taken. And the test value agrees well with the test result which the deviation is less than 5%.