Abstract | The typical view of seismic performance of structure-content systems is one of segregation: Contents are assumed to be of low mass relative to the supporting structure, leading to a separate treatment of the two, whereby one first analyzes the structure and then subjects any contents to the resulting peak floor acceleration responses. Racking structures are of the exact opposite persuasion, having massive “palletized” contents that can slide on top of light cold-formed steel frames, with Content-Structure-Sliding Interaction (CSSI) governing global and local response. In support of assessment and design, three approaches are investigated to capture CSSI: (i) introducing friction sliders per pallet and running nonlinear response-history analysis, (ii) increasing the model viscous damping and using elastic response-history analysis, and (iii) reducing the horizontal seismic loads in tandem with modal response spectrum analysis. Each comes with its own challenges and modelling/analysis needs, offering different levels of accuracy (or no appreciable capability at all) when assessing the actual sliding displacement of contents. Three case studies are employed to calibrate empirical relationships for damping amplification and seismic load reduction, largely removing the bias of simpler alternatives (ii) and (iii), respectively, to level the ground for future code applications.

Abstract | A methodology is introduced for applying the FUSEIS beam-link steel lateral-load-resisting system for strengthening existing reinforced-concrete buildings. The purpose is to take advantage of the easy replaceability and architectural versatility of the FUSEIS systems to strengthen a deficient structure, while minimizing the economic impact of the rehabilitation works due to suspension of the operation of the building. Additionally, a case study is presented, where an existing building is upgraded by introducing FUSEIS beam-link systems, first by performing response spectra analysis using an initial behaviour factor, then refining the results via the INNOSEIS performance-based methodology. This necessitates the use of nonlinear dynamic analyses to quantify a risk-consistent behaviour factor that incorporates the effect of aleatory and epistemic uncertainty on the actual systems’ performance. Finally, a pre-normative assessment for the q-factor of FUSEIS-beam link systems is achieved, for use in existing reinforced concrete buildings within Eurocode 8.