tailieunhanh - Aluminium Design and Construction - Chapter 9

Tài liệu tham khảo giáo trình nhôm trong thiết kế xây dựng bằng tiếng anh - Chương 9 Tension and compression members GENERAL APPROACH Modes of failure This chapter covers the static design of members subjected to axial force either in tension (‘ties’) or in compression (‘struts’). The basic requirement is that the factored resistance should not be less than the tensile or compressive force (action-effect) arising in the member under factored loading. | CHAPTER 9 Tension and compression members GENERAL APPROACH Modes of failure This chapter covers the static design of members subjected to axial force either in tension ties or in compression struts . The basic requirement is that the factored resistance should not be less than the tensile or compressive force action-effect arising in the member under factored loading. The factored resistance is found by dividing the calculated resistance by the factor Ym Section . There are four possible modes of failure to consider in checking such members 1. localized failure of the cross-section Section 2. general yielding along the length Section 3. overall column buckling Section 4. overall torsional buckling Section . Check 1 which applies to both ties and struts must be satisfied at any cross-section in the member. It is likely to become critical when a particular cross-section is weakened by HAZ softening or holes. Checks 2 3 and 4 relate to the overall performance of the entire member. Check 2 is made for tension members and checks 3 and 4 for compression members. Check 4 is not needed for hollow box or tubular sections. Most of the chapter is concerned with finding the calculated resistance Pc to each mode of failure when the force on the member acts concentrically . through the centroid of the cross-section. We then go on to consider the case of members which have to carry simultaneous axial load and bending moment Section one example of this being when an axial load is applied eccentrically not through the centroid . Copyright 1999 by Taylor Francis Group. All Rights Reserved. Classification of the cross-section compression members An early step in the checking of a compression member is to classify the section as compact or slender. If it is compact local buckling is not a factor and can be ignored. If it is slender local buckling will reduce the strength and must be allowed for. The classification procedure is first to .