Abstract: “Stream flow in mobile river beds gives rise to scour phenomena around river piers that may jeopardize the stability of the bridge. As scour is dependent on pier shape (among other factors), estimating equations generally introduce shape coefficients. In the present study experimental tests concerning scour phenomena have been carried out on a particular shape of the already effective circular piers in order to determine if any improvement is verified in their shape coefficient (with a corresponding decrease in scour). In particular, the circular pier foundation has been shaped as a truncated cone, partially or totally sunk into the mobile bed. In the experimental tests a preliminary comparison has been effected between scour at uniform circular pier and non uniform piers with two different values of bevel angle for the truncated cone foundation. Experimental results have showed that, for both values, the scour depth has been lower than that identified in experimental tests conducted on”

Keywords: scour phenomena, mobile bed, river piers, bridge stability.