Technological analysis of a prefabricated timber-based system for the integrated renovation of RC framed buildings

Abstract

Most of the building stock in European seismic countries is highly energy-intensive and earthquake-prone since it was built before the enforcement of effective energy and seismic codes. Renovation actions that synergically integrate both energy-efficient and anti-seismic interventions are strongly needed in these countries. However, the implementation of such interventions is currently limited by barriers that are mostly related to the high cost and invasiveness of traditional seismic retrofit techniques. A new holistic design approach to the building renovation is required to overcome these barriers. This should result in innovative and integrated retrofit interventions able to specifically meet the needs of cost-effectiveness, quick installation, reduced users’ disruption, and low environmental impact. In this framework, the use of cross-laminated timber (CLT) has been recently investigated for retrofit purposes in light of its good mechanical and physical performance. In this research context, this paper illustrates a novel timber-based retrofit technology for RC framed buildings developed within the e-SAFE H2020 project. This technology consists of cladding the external building envelope with a new prefabricated timber-based shell that acts as seismic-resistant and energy-efficient skin, also contributing to renovating the architectural image of the building. The new skin combines structural CLT-based panels – equipped with novel devices for seismic energy dissipation – with non-structural wooden-framed panels. Specifically, this paper presents a construction analysis of the proposed retrofit technology, investigating its technical feasibility, versatility, and potentialities, as well as possible application limits.

The Challenge of Integrating Seismic and Energy Retrofitting of Buildings: An Opportunity for Sustainable Materials?

“…In [46], an integrated retrofitting strategy was examined employing CLT boards for structural reinforcement together with insulating timber panels to improve the thermal performance of the original envelope (see Figure 3a). In terms of seismic capacity, CLT can limit the occurrence of brittle mechanisms in RC elements (e.g., short columns or soft storeys' failures), which are a typical failure in the presence of poorly detailed masonry infill walls [17], and enhance protection against the out-of-plane collapse of façades.…”

“…Figure 3. CLT panels for integrated retrofitting: (a) a conceptual representation of the solution proposed by Tardo and Margani[46]; (b) a schematization of work phases according to the "nested building" approach[48].…”