In the present paper, an integrated intervention system applicable to concrete-framed buildings is presented. The purpose of the intervention is to improve both the seismic and the energetic behaviour of such buildings using cross-laminated timber (CLT) panels. Two alternative intervention configurations with different levels of invasiveness are described. Considering a double-wythe masonry-infilled frame, the most invasive configuration consists in the replacement of the external masonry wythe with the CLT panel, while the least invasive configuration consists in the arrangement of the CLT panel from the outside without removing the wythes. The technical details and implementation procedures were studied, considering functionality and disturbance to occupants. An isolated one-storey-one-bay frame was used as a reference for the seismic and thermal analyses. Subsequently, the two intervention configurations were applied to a case-study building by identifying two alternative intervention strategies. The obtained results showed that the proposed integrated intervention approach can significantly reduce both the seismic vulnerability and the energy consumption of concrete buildings.
An in-situ experimental campaign investigating the in-plane behavior of retrofitted timber floor diaphragms was undertaken on full-scale specimens located in a two-story clay brick unreinforced masonry building constructed circa 1913. The diaphragm retrofit strategies included renailing of board-to-joist connections, use of a fire-rated ceiling, use of steel chords, and the application of a plywood sheet overlay. When compared with as-built single straight-sheathed diaphragms, all tested solutions provided significant stiffening of the in-plane diaphragm response, with the sole exception being the configuration incorporating steel chords, where the chord influence was observed to be negligible. The fire-rated ceiling showed noticeable strength degradation due to cyclic loading while the plywood sheet overlay exhibited no strength loss between cycles to the same deformation levels, demonstrating the ability of the plywood-overlaid diaphragm to resist multicyclic loading. The subsequent phase of the study included comprehensive numerical modeling of the adopted retrofit strategies and their validation against the attained experimental results. A detailed parametric study on retrofitted timber floor diaphragms was also undertaken and is reported herein. These numerical investigations allowed evaluation of the most efficient overlay pattern, and also allowed the influence of aspects such as the plywood thickness and connection properties to be considered.
Understanding and predicting the durability of timber structural components of buildings can lead to a more reliable and efficient use of this material in constructions. The work described herein presents a methodology to assess the life-expectancy of wall-foundation details in timber buildings based on the estimation of the durability of the timber structural element. Risk classes were defined starting from the inputs from the most relevant standards addressing the durability of timber available in Europe. The attribution of a risk class to the wall-foundation detail requires decision trees that consider the key aspects that affect the durability of this construction detail in the case of fungal attack. The methodology was then applied to three case studies and the results were compared to the observations from onsite inspections carried out on the decayed structural timber elements. The present work represents the first step towards the development of a tool capable of predicting the durability of timber components within the building structure. The work reported herein was carried out within the framework of the TSafe project.
Mechanical and dynamic in-plane properties of timber diaphragms are known to be key parameters when determining both the local and global seismic response of unreinforced masonry (URM) buildings. However, few data pertaining to experimental campaigns on this issue are available in the literature, especially regarding existing floors. In this work, the outcomes of a field testing campaign on full-scale old timber diaphragms are presented. Two specimens, whose size was 5.6 x 9.6 m 2 and 4.7 x 9.6 m 2 were obtained from a 17 x 9.6 m 2 floor and were subjected to a series of both cyclic and snap back tests in the direction orthogonal to the joists. Since the original anchoring system was deficient, new epoxy-grouted anchors were installed before starting the testing procedure. So as to reproduce the inertial load distribution, an ad hoc loading system was developed by means of wire ropes and steel pulleys. After testing the diaphragms in the as-built condition, the effect of different refurbishment techniques was also investigated. From the results, it seems that even simple and cost-effective solutions such as the re-nailing of the flooring are sufficient to achieve a significant increase in the equivalent shear stiffness.
This article studies the use of sound spectral analysis as a possible diagnostic technique for the assessment of existing timber structures. The idea is to analyze the spectrum of the sound that is generated by hitting a wood surface with a hammer (or an equivalent tool) and is recorded by a microphone. The sound spectrum and its relevant indicators are compared to reference data obtained for sound wood, in order to detect the presence of damage/decay. A first insight on the method applicability was obtained by testing the technique on 10 timber specimens in different conditions, from sound to completely decayed. The study was then expanded on 20 more beams (10 with a 2 m span and 10 with a 4 m span) that were tested in sound conditions and after an induced damage. Recording of the signals was obtained by using different mid-market smartphone microphones and a professional microphone. Moment analysis was used to evaluate and compare the experimental data. The parameters that were expected to have the most significant impact on the sound signal (e.g., impact location, boundary conditions, etc.) and that can negatively influence the assessment were then identified and investigated.
