Explanation :
Direct shear load on each river = $\frac{400}4=100\;N$
Secondary shear load due to bending moment
additional force f_i =$f_i=\frac{F\cdot L}{\varepsilon\;l_i^2}\cdot l_{ik}$
$l_1^2=\left(0.2\right)^2+\left(0.2\right)^2$ =$\frac{F\cdot L}{l_1^2+l_2^2+l_3^2+l_4^2}\cdot l_1$
$=(2(0.2))^2$ = $\frac{400\times0.5\times\sqrt2\times0.2}{\left(0.02\times\sqrt2\right)^4\times4}$
$l_1=\sqrt2(0.2)$ = 1767.766953 N
Total load = Primary + Secondary
=100 + 1767.766953
= 1893.837 N .