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The Structural Engineer
The Structural Engineer

This paper explores a number of situations where columns with out-of-tolerance crookedness may still be designed and used without compromising the general levels of structural safety intended by common codes of practice. The case of a column whose crookedness is out-of-tolerance is first examined, and two design methods are suggested. In the first method, the column is treated in a similar way to that used for the basis of the BS 5950 column design method by allowing for the excess crookednesses. In the second method, the column is designed as a straight beam-column with design moments equal to those resulting from the first-order analysis of an imperfect structure whose geometry includes the excess crookednesses. Following this, the case is considered of a column damaged by unexpected bending which leaves an out-of-tolerance permanent set. It is concluded that the damaged column can be designed for its increased crookedness by using either of the methods proposed for columns with out-of-tolerance crookedness. The straightening of the damaged column is also considered. Finally, the case is analysed of a force-fitted column which has excessive crookedness locked in during its connection to other members of a structure. It is found that the force-fitting deflection can be regarded as an initial crookedness, so that the column can be designed as an out-of-tolerance column. N. S. Trahair, BSc, BE, MEngSc, PhD, DEng Emeritus Professor of Civil Engineering, The University of Sydney K. Kayvani, BSc, MEngSc, PhD Principal, Connell Mott MacDonald

The Structural Engineer
The Structural Engineer
The Structural Engineer
The Structural Engineer
The Structural Engineer
The Structural Engineer
The Structural Engineer
The Structural Engineer