Nested Buildings: An Innovative Strategy for the Integrated Seismic and Energy Retrofit of Existing Masonry Buildings with CLT Panels

Abstract

The Italian building heritage is aged and inadequate to the high-performance levels required nowadays in terms of energy efficiency and seismic response. Innovative techniques are generating a strong interest, especially in terms of multi-level approaches and solution optimizations. Among these, Nested Buildings, an integrated intervention approach which preserves the external existing structure and provides a new structural system inside, aim at improving both energy and structural performances. The research presented hereinafter focuses on the strengthening of unreinforced masonry (URM) buildings with cross-laminated timber (CLT) panels, thanks to their lightweight, high stiffness, and good hygrothermal characteristics. The improvement of the hygrothermal performance was investigated through a 2D-model analyzed in the dynamic regime, which showed a general decreasing in the overall thermal transmittance for the retrofitted configurations. Then, to evaluate the seismic behavior of the coupled system, a parametric linear static analysis was implemented for both in-plane and out-of-plane directions, considering various masonry types and connector spacings. Results showed the efficiency of the intervention to improve the in-plane response of walls, thus validating possible applications to existing URM buildings, where local overturning mechanisms are prevented by either sufficient construction details or specific solutions.

Seismic Strengthening of Existing Urm Structures Through CLT Elements: Numerical Analysis of the Application of a Novel Intervention Technique

“…Figure 1: Approaches for CLT intervention on existing structures [6] Particular attention has to be paid to connection systems among the existing structure and CLT elements. Different approaches can be adopted, such as connection at floor levels, taking advantage of existing RC curbs [14], or distributed URM-to-CLT connections realized with screwed joints [16].…”

“…The intervention described in this paper is addressed to existing URM buildings which need an improvement in terms of structural-seismic capacity, functionality and energetic performances. Based on the effectiveness of URM-CLT coupling walls for shear capacity [4] [5] and energetic performances improvement [6], such as the benefits of stiffened timber diaphragms [7][8], an integrated intervention aimed at the insertion of a CLT endoskeleton within a URM structure was designed.…”

Timber Based Integrated Techniques to Improve Energy Efficiency and Seismic Behaviour of Existing Masonry Buildings

“…Most of the work in the literature focuses on evaluating the effectiveness of the solution in improving structural strength. The analysis of the state of the art highlighted a lack of investigation on the energetic aspects of the intervention, with very few works published on the topic (Valluzzi et al [22]).…”

The requalification of industrial buildings: a circular economy perspective

“…Nelle soluzioni in "inglobamento" si inquadra la metodologia denominata nested-building, o "scatola nella scatola" (Malighetti, 2016), ovvero l' operazione di inserimento di nuovi volumi all'interno fabbricato, garantendo la conservazione del linguaggio esterno dei manufatti. Le nested-cells, ovvero i singoli volumi inseriti nell' edificio, possono essere di tipo collaborante o non collaborante (Valluzzi et al, 2021). Entrambi permettono un miglioramento delle prestazioni energetiche e funzionali, tuttavia si rapportano in modo differente alla struttura esistente: la prima tipologia riprende con esattezza le volumetrie interne, sostenendo strutturalmente l' edificio originario, la cui funzione viene declassata a mero rivestimento (Malighetti, 2016); i secondi gravano sulle strutture esistenti operando il solo recupero funzionale, permettendo però allo stesso tempo una maggiore flessibilità di intervento poiché autoportanti e indipendenti da queste ultime (Grecchi and Malighetti, 2008).…”