Study On Strength And Stability Behavior Of Steel Silo Strengthened With FRP

The steel silo is widely used for storage of bulk solid in industry and agriculture. Compared with reinforced concrete silo, it has a lot of advantages such as simple convenient construction, simplified structure and so on.As a typical cylindrical thin shell, the mechanical behavior of silo wall is very complicated. Silo wall is susceptible to buckle under vertical friction force. The geometrical imperfections and internal pressure play a great role in stability performance of silo wall. The internal pressure can reduce the sensitivity of imperfections to silo wall and increase buckling strength in some degree. If the internal pressure is too large, yielding of the wall near the base boundary leads to reductions in flexural stiffness and local amplifications of displacements. The circumferential membrane stress resultants are raised and elastic-plastic buckling occurs. This elastic-plastic instability failure near base boundary is know as elephant's foot buckling.To strengthen the silo wall against buckling, the tradition method is using a small ring stiffener. This paper presents a novel method of strengthening silo wall against buckling in which a small amount of fiber-reinforced polymer(FRP) composite, used at critical location, can effectively increase the buckling strength. FRP has been broadly used in strengthening structures, especially in concrete structure. It is bonded to surface of structures by adhesive to improve mechanical performance of structures. Many researchers start to use FRP to strengthen metallic structures such as steel structures. FRP composites have superior properties, including a high strength-to-density ratio and superior durability to many traditional materials. Bonding FRP to silo wall has many advantages compared with welding ring stiffener to it, such as no stress concentration, no residual stress, easy to construct and low maintenance.Numerical analyses including linear stress analyses, linear eigenvalue buckling analyses, geometrical nonlinear analyses, elastic-plastic analyses are carried out to investigate the stability behavior and strength of the ground-supported flat bottomed steel silo reinforced with CFRP. The results show that FRP jacketing can effectively improve structure mechanical behavior and increase buckling strength. In addition, the height and thickness of CFRP are main parameter that affect the buckling strength of the silo. The buckling strength of silo will continuously raise with the increase of the height and thickness of CFRP. Increasing the thickness is more effective than increasing the height of CFRP to enhance the stability of silo.