Approximate Uniaxial Interaction Diagram For Slender Column Using Second Order Formula From Ebcs2, 1995
No Thumbnail Available
Date
2012-04
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
In concrete buildings, recently the design of column is increasingly determined by architectural,
aesthetic, and economic criteria leading to slender cross-sections of columns. However, slender
column design requires rigorous analysis to account second order effect due to deflection of the
column. Because the deflection provides additional eccentricity to axial load that induces
additional second order moment. If second order effect is not considered adequately, it can cause
stability failure, which is catastrophic. Since exact rigorous analysis demands more
computational effort, simplified methods have been proposed in building codes such as EBCS_2,
1995, CEB_FIP1990 and ACI code still that involves iterative procedure. Moreover, even
recently developed commercial computer programmes such as ETABS and SAP2000 do not
consider second order effects due to the deflection of the column between its ends adequately as
compared to relative deflection between ends of columns.
In this thesis, approximate uniaxial P_M interaction diagram for non-sway slender RC
rectangular column is presented based on the simplified method of EBCS_2, 1995-second order
eccentricity formula (deflection between two ends of a column) which is rather simple and
unsophisticated for design of slender column. For the preparation of the interaction diagram,
cross section interaction diagram and column slenderness is used. Since the slender column
capacity is smaller than short column capacity, the cross section interaction diagram is modified
so that it would have a room for the slenderness effect. This is made by deducting additional
moment due to second order and geometric imperfection eccentricity from cross section
interaction diagram.
Finally, the approximate interaction diagram is checked for its validity and satisfactory result is
obtained. Therefore, the interaction diagram can be used as a design aid as well as preliminary
cross section capacity estimation since it is very easy and quick method. Moreover, it can be used
for checking of computer output
Description
Keywords
Formula; from ;Ebcs2