Calculator for Beam-column Design

The calculation of interaction equations in beam-column design is always tedious and time consuming. The author has designed a special calculator, as shown in Fig. 1, for calculating the interaction equations. By using this special calculator, the divisions, multiplications and summations of all terms appearing in the interaction equations can be performed without any longhand operations. The author has found it very handy and especially time saving during the trial-and-error operations in the selection of a proper section. As shown in Fig. 1, the calculator consists of four parts: a stationary graph, a movable graph, a rotary cursor and a slide cursor. The movable graph and slide cursor can be slid along the inside and outside, respectively, of the stationary graph. The rotary cursor is attached to and can be rotated about the origin of the horizontal Km scale on movable graph. The horizontal Ks scale on the stationary graph is identical to the horizontal Km scale on the movable graph. Both scales are dimensionless, and indicate the percentages of actual stresses to allowable stresses, axial or bending. The vertical Am scale on the movable graph, in kips per square inch, indicates the allowable stresses, axial or bending. On the slide cursor there are two scales. One is the As scale, in kips per square inch, which is identical to the Am scale on the movable graph, but indicates the actual stresses, axial or bending.