Question

The value of ordinate at point E in influence line diagram for $M_A$ when unit load moves over the portion BD is_____m.

• A. 5

Answer 1

The correct option is A 5
When unit load moves on BE span (from B)
$So,V_C=0$
$V_A=1unit$

$M_A=5-(2-x)=3+x$
$Atx=0,M_A=3unit-m$
$Atx=2m,M_A=5unit-m$
When loads moves on ED span $\left(xfromB\right)$
$V_C=\frac{x-2}{3}and\frac{5-x}{3}$
$M_A=3+x-8V_C=3+x-8\left(\frac{x-2}{3}\right)=\frac{25-5x}{3}$
$Atx=2m,M_A=5unit-m$
$Atx-7m,M_A=-\frac{10}{3}unit-m$