The effectiveness of a method to strengthen/repair unreinforced masonry (URM) by using timber-based products was investigated through experimental in situ testing. The strategy consists of timber-based panels connected to the masonry by means of screw fasteners. URM piers obtained from a century-old building were subjected to in-plane semi-cyclic quasi-static loading in as-built, repaired and retrofitted configurations. The application of the reinforcement on previously damaged piers led to a notable increase in the in-plane capacity while the initial stiffness of the repaired specimens was found to be consistent with that of the specimens tested as-built. When applied to undamaged masonry, the retrofit system allowed an in-plane force 40% higher than the capacity of the unreinforced walls, with the initial stiffness comparable with that of the repaired specimens. Both repaired and retrofitted specimens exhibited remarkable displacement capacity (drift levels > 2.0%) and energy dissipation.
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.
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.
Currently there is little guidance available on an experimentally-validated detailed seismic assessment procedure for vintage flexible timber diaphragms such as are routinely encountered in New Zealand unreinforced masonry buildings. The results from recent testing of full-scale diaphragms are presented and interpreted with particular attention given to the definition of shear stiffness and shear strength values, whilst acknowledging that the recommendations derive from a small data set. References are provided to information previously published elsewhere to justify the theoretical framework adopted, and the procedure is linked to ASCE 41-13 for guidance regarding diaphragm scenarios that have not been studied by the authors. A procedure is provided to account for the effects on diaphragm response of supplementary stiffness due to masonry end walls. The performance of several diaphragms that were improved with either overlays or underlays is reported as potential proof-tested standard solutions. The assessment procedure is demonstrated by providing a mock worked example of a detailed diaphragm assessment.
The durability of timber structures subjected to biotic attacks is becoming of increasing concern due to several recent examples of failures caused by early degradation. Therefore, the design process of a timber building cannot prescind from accounting for the possible degradation due to biotic attack, especially in light of the recent spread of high-rise timber buildings. Furthermore, it is of extreme importance that reliable models to foresee possible sources of degradation in existing buildings are made available so that retrofit interventions can be programmed before it is too late. In the work presented herein, the decay due to fungal attack was predicted through a risk-based approach where decision trees were created to address all the possible scenarios where water or moisture can intrude within the construction details that most affect the durability. These decision trees allow to assign a risk class, defined based on a thorough review of the major European standards addressing timber "use-classes". The trees also lead to the selection of a proper prediction function for estimating the decay depth, chosen among suitable functions available in the literature. The proposed methodology was applied to selected case studies where a good correlation was found between the decay level detected onsite and the results from the prediction model. To facilitate the application of the methodology to both the design of new durable timber buildings and the assessment of existing timber structures, an ad hoc software tool named TSafe was developed. In the present paper, due to the length limit, the focus is on the decision trees and the risk classes, while just a brief description of the case study used for the procedure validation is given.
Accurate determination of thermal parameters in building envelope components is crucial for evaluating energy performance. While response factor theory has been applied to accelerate the experimental characterization of steady-state thermal properties such as the U-value, periodic thermal properties remain underexplored despite their growing relevance due to global warming. This study presents a novel model based on response factor theory to characterize the unitary heat flux on the opposite side of a pulse solicitation as a function of time and four key parameters. A unified testing methodology is proposed, enabling simultaneous characterization of stationary and periodic thermal properties through a single hot box experiment. Key aspects of the setup, testing protocol, and data processing are detailed. The method was first validated via numerical simulations. Simulations, performed using a Finite Element Method, demonstrate the high accuracy of the proposed method in estimating both stationary and periodic thermal parameters with deviations under 5 %. The method also showed resilience to boundary condition noise (mainly below ± 10 %). Following on from this point, experimental validation on an insulated wall confirmed the approach’s effectiveness, with deviations under 10 % compared to traditional decoupled methods. This approach offers a streamlined pathway for standardized thermal characterization assessment.
