CIVIL ENGINEERING FORMULAS

64 CHAPTER TWO

Figure 2.19 shows the condition when two equal loads are equally distant on

opposite sides of the center of the beam. The moment is then equal under the

two loads.

If two moving loads are of unequal weight, the condition for maximum

moment is the maximum moment occurring under the heavier wheel when the

center of the beam bisects the distance between the resultant of the loads and

the heavier wheel. Figure 2.20 shows this position and the shear and moment

diagrams.

FIGURE 2.18 Two equal concentrated moving

loads.

l 2

P P

R 1 l a R 2

x

1

Moment

Shear

M 1 M 2

2

FIGURE 2.19 Two equal moving loads equally

distant on opposite sides of the center.

P P

R 1 =P R 2 =P

l

2

a

2

l

2

Moment

Shear

a

2