Fiber-Reinforced Polymer for Structural Strengthening: Post-Tensioning of Steel Silos

This paper illustrates a case study in which Fiber-Reinforced Polymer (FRP) pultruded laminates were used for strengthening circular steel silos. FRP laminate hoops were applied as external 'belts' resting on discrete supports on the perimeter of the silos. Using a simple mechanical device, the laminates were manually post-tensioned to the desired load level, measured indirectly using electric strain gages. Active strengthening allowed the laminates to compensate for part of the existing deformation of the walls, and to optimise the state of stress in the steel structure by tailoring the post-tensioning level. This paper examines in detail the design process, the experimental tests conducted for proper design of the construction details and the implementation of the strengthening system.