Concrete silos: Failures, design issues and repair/strengthening methods

Abstract

The review article investigated failure, design issues, repair and strengthening of reinforced concrete (RC) silos, primarily in agricultural set-ups. The durability of RC structures was influenced by the nature of the bulk solids, materials used in the reinforcement of the structures. Traditionally, high-grade steel has been used in silo wall reinforcement because it is affordable and readily available. However, it is susceptible to corrosion. In contrast, fiber-reinforced polymers (FRP) have better mechanical properties (tensile strength, elastic modulus, and Poisson's ratio) and are not corroded. Additionally, there are limited scalable and facile methods for commercial production. The low ductility elevates the risk of brittle fracture in external pre-stressing concrete repair/strengthening. Beyond the material factors, the existing silo design codes such as BS EN 1991-4:2006, Australian Standard AS 3774-1996, and American Society of Agricultural Engineers ANSI/ASAE EP433 DEC1988 (R2011), and American Concrete Institute ACI 313-97 are limited by simplified characterization of loading/unloading scenarios and exclusion of specific hopper geometries and configurations. The funnel and mass flow scenarios and accumulation of bulk materials contribute to silo failure. In brief, the present repair/strengthening strategies (external pre-stressing, insertion/removal of inserts, shear columns, and FRPs alternatives to steel) do not adequately address the diverse variables that elevate the risk of material failure.