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Closed-form expressions for the cross-section strength of steel-concrete composite beam-columns according to the plastic stress distribution method are tabulated in the AiSC Seismic Design Manual and the AISC Design Examples. Approximations have been used in the derivation of these formulas, most of which do not significantly affect the accuracy of the results. However, an approximation in the equation for the axial strength of circular, concrete-filled steel tubes that are simultaneously subjected to flexure at one of the key points on the interaction curve (designated as Point E) leads to results that are unconservative. The derivation of the equation is reviewed and a more accurate expression is proposed. [ABSTRACT FROM AUTHOR]

The article presents the background on the step-by-step procedures available in the 2005 American Institute of Steel Construction (AISC) Specification for Structural Steel Buildings for computing composite column and beam-column strength, including accounting for stability effects on members subjected to biaxial flexure plus axial compression. The new processes highlighted in the AISC Specification are discussed, including the use of a plastic stress distribution method that accounts for the beneficial effects of the concrete to the strength of the cross-section. Several examples are provided for calculating the design strength of encased composite sections as well as filled composite sections, both rectangular and circular.

The article summarizes the background information for composite columns and beam-columns relevant to new provisions in the 2005 American Institute of Steel Construction Inc. (AISC) Specification (AISC, 2005b). The columns include steel reinforced concrete (SRC) and concrete-filled steel tube (CFT) members. According to the authors, AISC, 2005b include provisions for composite column axial compressive strength, local buckling strength of concrete-filled tubes, and shear strength of composite members.

The article discusses the behavior of steel joist girder structures with PR column bases. The section reports on a combined analytical/experimental investigation aimed at: assessing the frame behavior of joist girder frames with different column base fixities; evaluating the stiffness and strength of column bases by means of both experimental and analytical approaches; and developing seismic design procedures that account for the real column base conditions. It also reflects on a companion paper, discussing in detail other design aspects and provides an example design for type of structure.

The article examines the seismic design of steel joist girder structures. The paper aims to develop a safe and efficient seismic design methodology for steel joist girder structures, including a set of step-by-step seismic design guidelines for use in the design office. Experimental and analytical studies aimed at verifying the procedure are also described within the study. It illustrates the main steps of the design procedure with design examples for two different seismic areas. It also describes the adoption of a weak column-strong beam philosophy as a possible solution for the seismic design of one-story steel joist girder frames.

The article focuses on the comments regarding the derivation of the plastic section modulus ZS of circular high speed steel (HSS). It states the assumptions made in Equation 16, in which the wall of the HSS is estimated to be thin. It mentions that Equation 8 can replace both the original equation for ZS. An appendix of equations used in the plastic section modulus of a circular HSS thin tube is presented.