a reinforced concrete bunker is 4m in internal diameter. the circular wall is 4.5m high. it has a 45 degree conical hopper bottom. the hopper has a concentric circular opening of diameter 0.5m. the bunker is supported by four columns. the bunker is used for storing material weighing 8.5kN/m3. angle of friction is 30 degrees. using limit state design, design the circular walls of the bunker and the conical hopper bottom. adopt concrete with fcu = 20N/mm2 steel with fy = 450N/mm2. adopt a 160mm wall thickness. assume a partial factor of safety of 1.4 and 1.6 for dead and live loads respectively. similarly, adopt 1.5 and 1.15 partial safety factor for concrete and steel respectively.