The attachment of vibrators to bins can cause fatigue failure, usually at the welds of the vibrator mounting. Extended length ribs running in line with the radial surface of the cone offer a sound connection without interfering with the cones stiffness or circumferential oscillations of the cone’s vibration. The use of three vibrators seems a little ‘over the top’, as they may produce unpredictable cancelations or amplifications of deflection. In any case, vibration is a symptom of flow failure that can usually be countered by employing a suitable flow geometry of the hopper. The dimensions given indicates a conical slope angle of little more than 45 degrees, which virtually guarantees funnel flow and risk of ‘ratholing’. A short Mass Flow outlet section on the cone leading to the outlet provides a greatly improved discharge potential and gives gravity a much better chance for avoiding the capital, operating and maintenance cost and failure risk of mechanical flow aids. ■

Fatigue.

Do not exeed the endurance limit.

K-brace the legs etc.

What skin deflection are you anticipating with the design? Calculate the total skin distortion for empty and shaking to full and shaking. If you are inside the deflection allowed in IS then you will be OK. Have faith in IS, & AS. Lynn'e advice to stiffen locally will benefit greatly but remember to check the deflection at the limits of reinforcement unless you extend the stringers to the ring beam(s).

Concerns about the vibrations interfering are well mentioned. If the amplitudes cancel it doesn't mean the applied forces have also disappeared.

Further to what Lynn says: is there an ocasional flooding risk which disencourages mass flow design? ■