ABSTRACT
As C' is located on the circle which has AC as diameter, the greatest value of AC' is obtained when C' coincides with C, i.e. when the yield lines are perpendicular to the short diagonal AC of the parallelogram. It will be seen from this that, when the angle between a and the short diagonal d is obtuse, we have to use the short diagonal instead of the span b sin cu. For a point load, formula (1.14) applies without alteration, as the derivation shows that only the number of restrained sides, and not the shape of the slab, is of importance. In the main, the interpolation formulae (1.146-8) would apply if the wheel loads were distributed over parallelograms with the sides k and 1 parallel with a and b (Fig. 2.113). However, no significant change in m can be expected if these parallelo grams are replaced by rectangles, the sides of
which are 1' = 1 sin to and k, as shown in the Figure. In other words, formulae (1.146-8) are used with 1 = l '/s in co. In the limiting case,k = 1' = 0 ,formu la (1.146) gives m = P/6, which differs less than 5% from the correct value, P/27r. In the limiting case, k = 1 = a = b, we get m = P/24, whilst the correct value is
pa2 sin2 to P / 2 m = k -----------------= — sin to 1*75 sin to
24 24 V 3 = ^ (1 ± 0-08)
for to > 45°, in which the corner levers are taken into account.
