Xiao-Ling Zhao

A theoretical analysis of the plastic-moment capacity of an inclined yield line under axial force

Abstract Existing formulae for the reduced plastic-moment capacity of an inclined yield line under axial force are reviewed. Lower-bound solutions, which are based on the Tresca yield criterion and the von Mises yield criterion, are derived to determine the reduced plastic-moment capacity of an inclined yield line under axial force. The effect of the twisting moment on the reduction of the plastic-moment capacity is considered.

Research into the strength of cold-formed tubular sections

Abstract Over a period of eight years, an extensive test programme researching the strength of cold-formed square hollow sections (SHS) and rectangular hollow sections (RHS) has been performed at the University of Sydney. The main purpose of the research programme has been to determine design rules for cold-formed SHS and RHS which can be used in the Australian Limit States Steel Structures Standard AS 4100-1990. The research to date has been concentrated on columns and beams. For columns, stub columns of both C350 (350 MPa) and C450 (450 MPa) grades have been performed to determine the limiting plate slenderness beyond which the sections are not fully effective. Long column tests have been performed on C350 SHS sections to determine an appropriate column design curve for cold-formed tubular sections. For beams, plastic bending tests on sections of both C350 and C450 grades have been performed to determine their plastic bending capacity and the plate slenderness limit below which the sections can be used for plastic design. Further testing under the action of concentrated force and combined bending and concentrated force has been performed to determine design rules for localised failure at loading points.

Welded connections in thin cold-formed rectangular hollow sections

Publisher Summary This chapter describes welded connection tests, which were performed on C450L0 Rectangular Hollow Sections (RHS). The thickness of the RHS sections varied from 1.6 mm to 3.0 mm. Butt welds, transverse fillet welds and longitudinal fillet welds were tested, and the test results are compared with existing Australian and American design formulae. The test results are also compared with the proposed design rules for welds in RHS members derived from the previous research project on C350L0 RHS members. The reliability analysis method is used to calibrate the existing and proposed design rules. Tests are performed on welds in C350L0 RHS members and proposed design rules are given for butt welds, transverse fillet welds and longitudinal fillet welds. The cold-formed Square Hollow Sections (SHS) and RHS sections used in the tests were supplied by Tube makers of Australia Limited. These sections were manufactured by a unique cold forming process, including in-line galvanizing so that the complete penetration butt weld of C350L0 tubes may be designed in accordance with the tension member rule in AISI- 1991 (AISI, 1991) with a capacity (resistance) factor of 0.95 or the tension member rule in AS4100-1990 with a capacity (resistance) factor of 0.90.