Linear Time-History Analysis for EC8 design of CBF structures

Increased availability of strong motions, improved computational capabilities and availability of open-source software for Eurocode 8-compliant record selection make Linear Time History Analysis (LTHA) a potential more rigorous analysis approach for the design of structures. This methodology is not explicitly codified in the Eurocode and it requires some "code-friendly" recommendations for its implementation in practice. Herein, LTHA is employed for the first time as design method for a five-storey archetype high ductility class concentric brace frame (CBF). A new-optimized design method for braces is presented for the smooth implementation of both Response Spectrum Analysis (RSA) and LTHA. In fact, the tension-only design approach for CBF in Eurocode 8 has some criticalities arising even when a routine RSA is employed. The design process is rather smooth only in the case of linear static approach classically implemented for regular, mid-rise structures. Results of this study provide insights for validation of LTHA as design method for CBFs, and for its code implementation as routine design method in EC8, valuable in near source conditions or for irregular structural configurations

Design of steel CBF structures through Linear Time-History Analysis

This thesis points out the problems related to the design of Steel Concentrically Braced Frame structures in seismic areas. The European seismic code (EC8) defines the limits in design of CBFs, which are very difficult to comply with by using steel profiles available on market. Moreover, the linear dynamic analyses of CBF structures have several difficulties in implementation. In this work, a five storeys steel structure, located in a seismic area, has been selected for design and analysed through RSA and LTHA. The Response Spectrum Analysis has the problem of the loss of the sign for axial loads in concentric braces. For this reason, Linear Time History Analysis (LTHA) as alternative linear methodology for seismic design according to Eurocode8 becomes an appealing alternative for CBFs