Performance assessment of seismic retrofitting measures on silo structures using innovative seismic protection systems

Abstract

This paper deals with a real-world silo structure and the assessment of its seismic performance and possible retrofitting measures by using seismic protection devices. Firstly, the silo structure is shortly described followed by a simplified numerical modelling approach with the aim to save computational effort as much as possible but still achieve a reliable response of demands and failure modes. A comparison between the complex and simplified model is done, showing a very good match in terms of its dynamic properties, which are Eigenfrequencies, modal shapes and effective modal masses. With this simplified model incremental dynamic analyses are conducted to assess the current performance of the structure as-built. Strengths and weaknesses are highlighted by the simulation outcomes. Following, two possible retrofitting strategies using torsion-based hysteretic dampers are discussed. Hereby it is shown, how the seismic device can be modelled in any finite element software by using rheological models. In one strategy of seismic retrofit an innovative torsional device is inserted at single bays of the structural frame. In the second strategy the steel torsional hysteretic damper is applied at the base of the steel columns, such that the structure is separated from the ground. The first retrofit approach proves to be effective in prohibiting a severe sides-way collapse which occurred for some earthquakes. The second shows to be greatly effective in preventing failure and also decreases deformation demands on the structure efficiently.