P$\mathrm{.}17\mathrm{.}12$A thin$-$walled closed section beam of $$constant wall thickness t $$has the

cross$-$section shown in $$Fig$.$ P$\mathrm{.}17\mathrm{.}12.$

Assuming that the direct stresses are distributed according to $$the basic theory of

bending, calculate and sketch the shear flow distribution for a vertical shear force Sy

applied tangentially$$to $$the curved part of $$the beam.

Ans.

qO$1=$Sy$1\mathrm{.}61$cos$-0\mathrm{.}80$r

q$12=$Syr$3(0\mathrm{.}57$s$2-1\mathrm{.}14$rs$+0\mathrm{.}33$r$2)$

Fig. P$\mathrm{.}17\mathrm{.}12$

Please could you solve it $$clearly step by $$step bu using eq$\mathrm{.}17\mathrm{.}28$ if its not, why qs$,0$could not calculated with eq$\mathrm{.}17\mathrm{.}28.$This is$$my $$point that $$do $$not understand $.$