Consider a rectangular slab system for an office building in the figure, which is supported by $400$ mm wide and $600$ mm deep beams. The office is located in Meckering, WA$.$ The concrete has a characteristic strength of $40$ MPa in all members. N$12$ D$500$ reinforcement bars are to be used in all slabs, and N$28$ D$500$ reinforcement bars in all beams. The live load is $3\mathrm{.}75$ kPa, and the suspended ceilings represent a $0\mathrm{.}15$ kPa permanent loading. The permanent load equivalent to partition walls and tiles can be considered as a superimposed dead load on the whole surface of the slabs of $2$ kPa. The density of reinforced concrete is $24$ kN$/$m$3.$

REFER TO SLAB PANEL C for the following questions

Question $1$

a$)$ Calculate the minimum cover and thickness to satisfy durability and fire requirements according to Australian Standards. Note: the design Fire Resistance Levels $($to satisfy the BCA$)$ are $180/120/60.$

b$)$ Determine the combination factors for short$-$term and long$-$term loading effects, as well as the loading for ultimate limit states, in accordance with AS$1170.$

Note: In the following questions, consider the minimum cover is $25$ mm$,$ and $\backslash$Psi s$=0\mathrm{.}7$ and $\backslash$Psi l$=0\mathrm{.}4$ whenever needed.

c$)$ Work out the minimum thickness for the selected slab panel using the deemed$-$to$-$comply approach in AS $3600.$

Note: In the following questions, assume the slab thickness is $150$ mm$.$

d$)$ Calculate the minimum longitudinal reinforcement required for the slab.

e$)$ Design the amount of longitudinal reinforcement in both directions and check for the ultimate limit state of flexure.

f$)$ Finalise the layout of reinforcements based on the deemed$-$to$-$comply approach in AS $3600.$ Sketch the details of the reinforcements in the plan and elevation.

Question $2$

a$)$ Based on the tributary areas, work out the load transferred from the slabs to the beam marked by orange dashed lines $($please refer to Fig. $1).$

b$)$ For the same beam, obtain an equivalent uniformly distributed load and develop a preliminary design for the layout of reinforcements for the cross$-$section located over the interior support.

Question $3$

Can you explain the load path developed in a flat slab and the need to design the slab to carry the full amount of applied load in each direction? Why is the same consideration not needed in a two$-$way slab?