Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/35874
This thesis examines two methods of seismic design of structures. The methods are Force-Based design (FBD) according to Eurocode 8, and Direct Displacement-Based design (DDBD). These methods approach seismic design of structures from different directions. In FBD, the design is based on estimated strength of structures, while DDBD relies more on the target displacement of the structure.The aim of this work is to apply these procedures to better understand their finer details. A simple structural model of a bridge is chosen to compare these methods.
The DDBD method is much faster to use than the FBD method. No iterations are required in the DDBD for the simple structure selected here, while few iterations are required in the FBD. According to Eurocode 8, the behaviour factor used in FBD was chosen as 3.5 which is used to reduce the elastic response spectra. A similar effect is achieved in the DDBD by using the displacement ductility factor. This factor is used to calculate the additional damping provided by hysteretic energy dissipation. The numerical results highly depend on the value of the behaviour factor q and the displacement ductility factor. Since DDBD uses the estimated effective stiffness of the cross-section while FBD uses the elastic stiffness of the cross-section, for the same target displacement, the base moment, base shear and amount of reinforcement is higher evaluated with FBD than DDBD.
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