Experimental and analytical evaluation of the in-plane behaviour of as-built and strengthened traditional wooden floors

Comparing In-Plane Equivalent Shear Stiffness of Timber Diaphragms Retrofitted with Light and Reversible Wood-Based Techniques

“…1 provides an overview of the selected reference research studies on the in-plane response of diaphragms, and reports static schemes, dimensions, and names of the samples, loading directions and adopted strengthening techniques: from this first summary, the variety of configurations is already evident. The order in which the samples are presented is according to the adopted strengthening techniques: superposition of an additional layer of planks arranged at an angle of 45° (Valluzzi et al 2008(Valluzzi et al , 2010 or at 90° (Corradi et al 2006;Branco et al 2015) with respect to the original sheathing; overlay of oriented strand board (OSB) panels (Gubana and Melotto 2018); and overlay of plywood panels (Peralta et al 2004;Brignola et al 2012;Giongo et al 2013;Wilson et al 2014;Mirra et al 2020). In the following sections, this same distinction among strengthening methods is adopted in presenting the configurations of the floors.…”

“…Depending on the specific contexts, the variety of construction methods and configurations of diaphragms led to a number of research studies focusing on the assessment of the seismic response of the floors and the development of retrofitting methods. Several authors (Peralta et al 2004;Corradi et al 2006;Parisi and Piazza 2007;Piazza et al 2008;Valluzzi et al 2008;Baldessari 2010;Valluzzi et al 2010;Brignola et al 2012;Giongo et al 2013;Wilson et al 2014;Branco et al 2015;Gubana and Melotto 2018;Mirra et al 2020) have emphasized the often poor characteristics in terms of in-plane strength and stiffness of as-built diaphragms, and have proposed different refurbishment techniques. Among innovative options such as use of fiber-reinforced polymers (FRPs) (Corradi et al 2006;Piazza et al 2008) or cross-laminated timber (CLT) (Branco et al 2015;Gubana and Melotto 2018), all research studies also focused on light and reversible strengthening systems, due to their wide versatility and applicability in existing buildings, from houses to monumental constructions.…”

“…The floor sheathing is usually realized with continuous planks, having a thickness from 15 to 24 mm. Besides, roofs of detached houses are normally composed of main and secondary beams, connected with one nail at every intersection, and often poorly fastened to the walls (Mirra et al 2020).…”

“…A literature survey was thus performed to evaluate possible reversible and effective retrofitting methods, and the opportunity to investigate simple and general criteria for comparing available results opened up when arranging an experimental campaign on the in-plane response of timber diaphragms with Dutch features at Delft University of Technology (Mirra et al 2020). The criteria were formulated to more homogeneously compare the obtained test results with those present in literature, in order to better evaluate the performance and improvement of the applied refurbishment, given the high seismic vulnerability of existing Dutch floors.…”

“…The criteria were formulated to more homogeneously compare the obtained test results with those present in literature, in order to better evaluate the performance and improvement of the applied refurbishment, given the high seismic vulnerability of existing Dutch floors. Because the adopted strengthening technique consisted of a plywood panels overlay (Mirra et al 2020), only light, timber-based and reversible refurbishment methods for timber diaphragms were considered in the comparison.…”