ASSIGNMENT (SILO)Q. A cement silo has an internal diameter of 10 m with the height of cylindrical portion being 30 m. The density of cement is 15.2 kN/m3. Coefficient of friction between concrete and material is 0.70. The angle of repose of the material is 17.50. Adopting M-20 grade concrete and Fe-415 HYSD bars, design the thickness and the reinforcement required at the bottom of the cylindrical portion of the silo using Jansens Theory.Data: Dia of silo= 10m; Depth of cylindrical portion= 30 m; Density of cement=15.2 kN/m3.Coefficient of friction between wall and material=m=0.70; Angle of repose of the material=f=17.50Ration of horizontal to vertical pressure intensity: n== = 0.54Characteristic strength:fck=20N/mm2, fy=415 N/mm2, Permissible tensile stress in conc= 2.8 N/mm2, modular ratio,m=13

Design of cylindrical walls:Using Jansens Theory, Horizontal pressure ph= [1- exp()]Where, R=D/4=10/4=2.5, n= 0.54,w=15.2 kN/m2, h=30 m, m=0.7.At the bottom of the cylindrical portion h= 30 m.The horizontal pressure, ph=[1- exp()]=54 kN/m2Hoop tension in cylindrical wall/m ht.= 0.5 paD=0.5 X 54 X 10= 270 kN.Ultimate hoop tension= 1.5 X 270= 405 kNArea of hoop reinforcement= Ast= =1122 mm210F hoop @ 100 c/c provided. Ast provided= 1256 mm2Using 200 thk. cylindrical walls , tensile stress developed in conc= sct= == 1.248 N/mm2< 2.8 N/mm2Vertical pressure intensity at a depth h =30 m,Pv= ==100 kN/mm2Equivalent depth of cement= 100/15.2= 6.57mEven though there is 30 m depth of cement, the effective vertical load is only due to 6.57 m of cement.30m depth of cement corresponds to a pressure= 15.2 X 30= 456 kN/m2Vertical pressure intensity at 30m depth= 100 kN/mm2