The use of roof bracing is one of the solutions that are required to prevent or reduce the side sway of the columns in halls and single story buildings. Indeed, design of columns in state of no-sway buckling needs to a large amount of the area of bracing and Codes of the design do not limit the necessary in-plane stiffness of the roof bracing for such case of design. Thus, the present study provides assistance in determining the required in-plane stiffness of roof bracing to enhance the buckling capacity of the columns of halls, under the case of no-sway buckling mode. The in-plane stiffness of the roof bracing is obtained for different buckling loads of hinged- and fixed-base columns supporting roof girders and roof trusses. The effect of rotational restraints at the top of columns as well as the effect of depth of the roof truss on the stiffness of bracing is investigated. Also, slope of the roof is considered in the analysis. The upper levels of buckling load of columns are recommended in the study to satisfy the material economy requirements.
The study is extended to derive two mathematical formulae for evaluating the equivalent stiffness of two common configurations of roof bracing. Flexibility of the end gables and shear deformations of the bracing are considered. An excellent agreement is observed between the exact and the predicted values of bracing stiffness.
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