cross sectional capacity of the column materials and the lateral stability of the column. Figure 9-6 illustrates

this relationship between capacity and stability. In very short columns crushing failure occurs as the result

of the load exceeding the ultimate material strength and stability does not become a design consideration. For

most columns, inelastic deformation of the materials occurs on some portion of the column cross section

before general column buckling occurs. Nonetheless, the allowable compressive stresses used during for

design of the cross section are reduced to account for potential instability of the column. For long slender

columns, elastic buckling failure will occur before any material reaches the yield state.

member. The slenderness is expressed as the ratio of the effective height, h*, to the radius of gyration, r. h*

is the product of the clear height of the column, h, and the factor, K, which considers the effects of column

end restraint and whether or not lateral deflection (sidesway) occurs at the top of the column. Values of K

are provided in table 9-1. Since pilasters act as stiffening elements within a wall, they can be considered

laterally supported in the direction parallel to the plane of the wall. However, slenderness effects must be

considered in the direction perpendicular to the plane of the wall, and the design for that direction will be

based on the effective wall height.

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