a$)$ Select a suitable web and flange thickness, model the I$-$beam $($without opening$)$ using $3$D volume

method and determine the max deflection and max bending stress in the beam.

b$)$ Due to floor height constraint, the web openings are introduced $($in the opening zone shown

above$)$ in the I$-$beams to allow two $150mm$ diameter services pipes pass through it $($each

opening$).$ This enables the structural elements and service piping occupy in the same space.

Propose a suitable web opening $($shape and size$)$ within the opening zones by limiting the max

deflection increment within $20\%$ compared to Q$2$a$,$ at the same time not exceeding maximum

allowable deflection $\frac{L}{240}.$

c$)$ Compare and discuss the results of deformation and stress distribution between the two models.