Out-Plane Buckling Of Eccentrcally Tensile Members And Tapered Beam-Columns

This paper is composed of two parts. In the first part, the elastic-plastic flexural-torsional bucking of members in combined bending and axial tension is investigated. In the second part, the elastic-plastic flexural-torsional buckling of doubly-symmetrical tapered I-beam is studied after a summarization of previous studies.Firstly, using the similarity in flexural-torsional buckling of the members with combined bending and axial compression and the members with combined bending and axial tension, an analytical and numerical analysis on flexural-torsional bucking of members in combined bending and axial tension is carried out, interactive relations of axial force and bending moment are established for members with different cross-sections, and confirmed by Finite element analysis. Interactive equation of axial load and bending load is proposed for practical design. Comparison is made between the proposed formulae and those of Eurocode 3.Secondly, the members with combined bending and axial tension is investigated under biaxial bending moments. A FEA program is compiled on the basis of incremental variation principle for elastic-plastic flexural-torsional buckling analysis, two different modes of collapse are identified, design formulae are presented according to the interactive curve of axial tension and moment.Finally, the elastic-plastic flexural-torsional buckling of doubly-symmetrical tapered I-beam under axial compression and bending is studied respectively. Using the conception of equivalent cross-section, the formula of elastic carrying capacity at the larger end of the tapered member is suggested. P - M curves are available according to the result of elastic-plastic ultimate carrying capacity analysis of simply supported web tapered I-section under different eccentricities. Interactive equation of axial load and bending load is proposed for practical design referring to ECCS and GBJ50017-2003 respectively.