Publications

Evaluation of the displacement ductility for the seismic design of light-frame wood buildings

Mechanical characterization of a pre-fabricated connection system for cross laminated timber structures in seismic regions

On-site testing of masonry shear walls strengthened with timber panels

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.

Cross‐laminated timber for seismic retrofitting of RC buildings: Substructured pseudodynamic tests on a full‐scale prototype

Abstract This paper presents an experimental study on an innovative timber‐based retrofit solution for reinforced concrete (RC) framed buildings, with or without masonry infills. The intervention aims to enhance seismic resistance through a light, cost‐effective, sustainable, and reversible approach integrating energy efficiency upgrades. The method employs cross‐laminated timber (CLT) panels as infills or external retrofitting elements, mechanically connected to the RC frame through steel fasteners. The system is combined with thermal insulation for improved energy efficiency. The seismic performance of the proposed retrofit technique was assessed experimentally on a full‐scale building model at the European Laboratory for Structural Assessment (ELSA). The experiments included tests on two five‐story building configurations: a masonry‐infilled RC building as a reference and the same structure strengthened with CLT panels. Each building was subjected to unidirectional earthquake simulations of increasing intensity using the pseudodynamic (PsD) testing method with substructuring. The physical substructure of the hybrid model consisted of the first story of a two‐story mockup built and retrofitted in the laboratory, while stories two to five were simulated numerically. The paper discusses major observations from the tests, comparing the damage evolution and hysteretic responses of the two configurations. The experiments yielded promising results, showing that the suggested retrofit solution significantly increased displacement and energy dissipation capacity. The retrofitted building survived earthquake intensities up to 50% higher than the non‐retrofitted counterpart, exhibiting only slight structural damage. These pioneering experiments provide compelling data on the high effectiveness of the proposed CLT‐based retrofit system in enhancing the seismic performance of full‐scale RC buildings.

Experimental testing of pre-stressed timber-to-timber composite (TTC) floors

Analysis of timber log-house construction system via experimental testing and analytical modelling

TIMBER BALCONY MONITORING PLAN: REVIEW AND STEP-BY-STEP PROCEDURE

The aim of this paper is to present a step-by-step procedure for defining an accurate and revised monitoring plan for timber balconies. This methodology was defined and tested on 58 balconies with a timber beam structure but can be adapted to a CLT structure. The primary goal is to evaluate and control fungal decay of the various components, enabling preventive and planned interventions before significant damage occurs. Inspection intervals are determined through a prediction model of the progression of decay. The procedure is divided into three phases: a preliminary study and coding stage; an inspection stage, in which conditions are also assessed through non-destructive testing (NTD); and a post-elaboration stage, which is useful for defining interventions and the monitoring plan. These phases have been updated, standardised, and summarised in a procedural flowchart, with new supporting forms developed. The paper concludes with the application of this procedure to a real case study.

An aggregated non-destructive testing (NDT) framework for the assessment of mechanical properties of unreinforced masonry Italian medieval churches

Seismic risk assessment and intervention prioritization for Italian medieval churches

Use of timber panels to reduce the seismic vulnerability of concrete frame structures

Editorial

Editorial

A Risk-Based Approach for Quantifying Durability and Life-Expectancy of the Wall-Foundation Construction Detail in Timber Buildings

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.

Acoustic Testing for the Preliminary Assessment of Timber Beams — A Pilot Study

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.

Detailed seismic assessment and improvement procedure for vintage flexible timber diaphragms

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.

A risk-based approach for timber building decay prediction

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.

Experimental shear testing of timber-masonry dry connections for the seismic retrofit of unreinforced masonry shear walls

Experimental assessment of wall thermal properties using an integrated response factor approach

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.

Predicted Versus Experimental Out-of-plane Force-displacement Behaviour of Unreinforced Masonry Walls