Civil Engineering Reference
In-Depth Information
9
Equivalent wall for frameworks;
Buckling analysis of planar structures
The structural types covered in this chapter include frameworks on pinned and fixed
supports, with or without cross-bracing, in-filled frameworks, shear walls and coupled
shear walls. The simple procedures and closed-form solutions produced here make it
possible for the structural designer to carry out planar stability checks on multistorey,
multibay structures in minutes. In addition, a simple procedure is given for the
establishment of an equivalent wall for frameworks and coupled shear walls. In using
the equivalent wall, the frameworks and coupled shear walls can be included in the
bracing system, the equivalent column introduced in
Chapter 2
can be set up and the
3-dimensional global analyses presented in the previous chapters can be carried out.
9.1 INTRODUCTION
There are basically two ways to produce the critical load of frameworks and coupled
shear walls. Structural designers can rely on commercially available computer programs
based on the 'exact' method or they can use approximate methods. Both approaches
have their advantages and disadvantages.
Well-established methods have been developed for the calculation of stresses,
deformations and frequencies in frameworks and coupled shear walls and a number of
computer packages are available for the exact analysis. These computer procedures
are now standard items in design offices. The routine application of these programs
has also proved their reliability and accuracy.
Partly because of the large size of the structures and partly because of the sometimes
ill-conditioned stiffness matrixes, the situation regarding the stability analysis is
somewhat different. The stability analysis of multistorey, multibay frameworks and
