HYSTERETIC MASS-DAMPING EFFECTS OF LIGHT TIMBER FRAME VERTICAL ADDITIONS ON EXISTING RC BUILDINGS UNDER SEISMIC LOADING
Abstract
This study presents a framework for the seismic design optimisation of Light Timber Frame (LTF) Vertical Additions (VAs) constructed on low-code reinforced concrete (RC) buildings. The approach exploits the dynamic interaction between the existing structure and the added storeys to reduce seismic demand on the existing building, activating a mass-damping mechanism through the hysteretic behaviour of the addition. A novel analytical formulation is developed to capture the nonlinear response of LTF walls, enabling the parametrization of the nonlinear properties of the VA from design variables. This model is integrated with simplified single-degree-of-freedom and multi-degree-of-freedom representations of the existing structure, calibrated against detailed finite element analyses. The optimisation procedure is carried out through nonlinear time-history analyses over a wide range of design configurations and is applied to three archetype RC buildings representative of the Italian building stock of the 1970s. The results identify an optimal range of frequency ratios, within which the nonlinear interaction between the VA and the host structure leads to a significant reduction in seismic demand. Optimised configurations achieved reductions in peak inter-storey drift of up to 20%. Further analyses highlighted how the performance of the mechanism is influenced by the mass ratio between the addition and the existing structure. The results also indicate that LTF vertical additions do not inherently degrade seismic performance, even considering non-optimised configurations. The findings are validated through nonlinear time-history analyses on detailed finite element models using independent sets of ground motions, confirming both the effectiveness and robustness of the proposed methodology.
Reference
Andrea Bartolotti; Simone Piarulli; Ivan Giongo. (2026). HYSTERETIC MASS-DAMPING EFFECTS OF LIGHT TIMBER FRAME VERTICAL ADDITIONS ON EXISTING RC BUILDINGS UNDER SEISMIC LOADING. Elsevier BV. https://doi.org/10.2139/ssrn.6982108
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