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Long-span structures such as school gyms and sports centres are often used by the Italian Department of Civil Protection as post-catastrophe shelters or headquarters. The Emilia 2012 earthquake drew the attention of the department to this type of structure due to the damage that many of these buildings suffered. In this work, a dataset of 101 timber structures was analysed based on a simplified methodology that detects the major vulnerabilities in long-span timber roofs in order to help plan further investigations and retrofit interventions. Using fast and straightforward approaches, the elements most vulnerable to seismic action were analysed quantitatively and qualitatively. Quantitative evaluation of the vulnerabilities was achieved by applying the Italian Building Code. The aspects not considered in the quantitative evaluation were assessed through qualitative parameters inspired by damage identification forms (e.g. the AeDES form). The analysed structures are located near the epicentres of the last strong earthquakes that struck Italian territory: Abruzzo in 2009, Emilia in 2012 and central Italy in 2016. Damage and retrofits, identified by interviewing owners, designers and builders, showed a good correlation between the real behaviour shown by the surveyed structures and the vulnerabilities detected using the simplified methodology.

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.

Double-shear tests are reported on beech LVL-concrete composite connections based on coach screw connectors singly inclined at either 45° or 90°. On different specimens with the same screw orientation the longitudinal shear force was applied either in forward or reverse, because in practice concrete shrinkage, moisture-induced timber expansion and oscillatory (e.g. seismic) or moving loads can induce reversal of the force on the connection. The test data show that relative to the 90° screw connections, sloping the screws to 45° in tension only marginally affected longitudinal shear strength but led to a fivefold increase of slip modulus and to a significant drop in ductility, while sloping the screws the other way to 45° in compression only marginally affected slip modulus but led to an almost fourfold drop in longitudinal shear strength and to a substantial increase in ductility. The specimens tested within each group showed good consistency of shear strength and (except the 45° tension screw specimens, despite their consistent strengths) of failure mode, but high variability of slip modulus. Comparisons with previously tested timber-concrete composite (TCC) connections based on other screw types and layouts suggest good performance of the present connections. The gamma method applied to a given TCC T-section under load shows that the present alternate connections lead to quite different depths of uncracked concrete and so to significant variation of midspan deflection. In closing, it is recommended that both forward and reverse shear testing becomes a protocol for singly inclined coach screw-based TCC connections.

The assessment of the dynamic properties and vibration performance of two full-scale timber floor specimens is presented. The specimen set comprised a Timber-Concrete Composite floor and a Cross Laminated Timber floor. The floors, which are characterized by the same length and mass, are located in two separate five-storey timber buildings constructed in the urban area of Trento (Italy). The assessment was conducted by adopting analytical and numerical methods as well as by performing onsite experimental tests. Mock up samples of the floor specimens were also made and tested in laboratory. Multiple analytical methods that are available in literature were evaluated and compared. The Vibration Dose Value (VDV) method, as proposed by ISO 10137 and BS 6472, was used as reference method for the numerical modelling and the laboratory testing. To determine the VDV, loading associated to human walking was simulated. Dynamic identification tests, where the floors were excited by a modal hammer, were also performed in order to investigate the dynamic properties (i.e. natural frequencies, damping and mode shapes) of the floors. Discussion on the vibration performance of the timber floor typologies studied herein and on the effectiveness of the different assessment approaches (i.e. analytical, numerical and experimental) is provided.

This paper presents the results of an extensive experimental study on the short-term mechanical performance of timber screw connections comprising different types of fasteners (inserted at 45° and 90° to the grain) and different timber products (solid sawn timber, glued laminated timber, cross laminated timber and laminated veneer lumber) made from both softwood and hardwood species. Fifty-eight specimens laid out in fourteen arrangements were tested under quasi-static monotonic loading. The test configurations were meant to reproduce connections used in timber-to-timber hybrid composite structures for applications in both new constructions and retrofit interventions. Result comparisons regarding connection stiffness, strength, static ductility, residual strength and failure mode are presented and discussed. Additionally, the experimental data are used to check the extents of validity of existing analytical approaches (mainly developed for softwoods) to screw connections comprising hardwood elements. Practical aspects concerning screw insertion into hardwood elements are also addressed within the paper.

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.

This paper discusses a seismic retrofit method that is intended for reinforced concrete (RC) frame structures and that sees the replacement of the existing masonry infills with timber structural panels. The intervention is aimed at enhancing the overall behaviour of the buildings without modifying the original concrete structural system. In the presented research over 200 finite-element models comprising bare, masonry-infilled and retrofitted single-storey single-bay frames were subjected to nonlinear static analyses. The response of the timber-infilled frames was then optimised, thus enabling the definition of a few simple design rules to guide the implementation of the retrofit system. Subsequently, the efficacy of the proposed solution was further investigated by applying the timber-based retrofit to an entire case-study building modelled via finite elements and subjected to nonlinear static pushover analysis. The comparison of the results obtained for the building in the original and retrofitted configurations indicates that the proposed system can favour the development of ductile behaviours and improve the seismic response of RC frame structures significantly.

The paper presents a new connection system for cross-laminated timber (CLT) structures, named X-RAD. This innovative connection system is characterised by the use of a single connector type that is positioned at the corners of the CLT panels. X-RAD is formed by a metal part surrounding a hardwood insert that is fixed to the panels by means of all-threaded screws introduced with double inclination. The peculiar geometry of the connector and the combination of different materials allow the full exploitation of the capacity of the CLT panels while ensuring a ductile response of the connection. Construction modularity, fast assembly/disassembly speed and prefabrication are some of the aspects that can be associated with X-RAD development. The outcomes of an extensive testing campaign on the new connector are also presented in the paper.

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.

Steel–timber hybrid construction systems, in particular structures with steel frames, composite steel–timber floors and shear walls with Cross-Laminated Timber (CLT) sheets, combine the industrialized construction technology typical of steel systems with the advantages offered by CLT panels, namely lightness and in-plane stability. The paper proposes some original engineered solutions for joining CLT panels with steel elements. Specifically, it examines connections which allow both prefabrication of the components in the factory and their quick assembly on site. Experimental tests performed on a number of different connections will be presented and discussed. The first Part of the paper addresses some fundamental aspects and potentialities of steel–timber hybrid prefabricated systems. Two innovative steel–timber hybrid components to build floors and shear walls will be described in detail in the companion paper (Part II).

This paper focuses on the possibility of using sound spectral analysis as a diagnostic technique for the assessment of existing timber structures. The basic idea is to perform a spectral analysis, through the Fast Fourier Transform (FFT) algorithm, of the sound (recorded by a smartphone microphone) that is produced by hitting the wood surface of the element with a hammer or an equivalent tool. The sound spectrum is compared to a reference spectrum obtained for sound wood in standard environmental conditions in order to detect the presence of damage or decay. Differently from “classic” stress wave propagation methods that are based on the determination of the time-of-flight of the stress wave, the proposed technique relies on the local acoustic properties of wood. A first insight on the method applicability was obtained by testing the technique on several timber specimens in different conditions, from sound to completely decayed. Registration of the signals was performed by using two different mid-market smartphone models. Moment analysis, by calculating the spectral and frequency energy centroid of the sound spectra, was used to evaluate and compare numerous experimental recordings. The parameters that have the most significant impact on the sound signal (e.g. impact tool, microphone distance, boundary conditions, etc.) and that can negatively influence the assessment were then identified and investigated. Finally, pros and cons of the presented method and future developments are examined and discussed.

Traditional un-reinforced masonry (URM) buildings often comprise flexible wooden floor diaphragms where a layer of floorboards is laid perpendicularly over the timber joists and fixed by means of nails. It is not rare that such floor structures need to be improved in order to satisfy serviceability and ultimate limit states criteria, as concerns their behavior both under out-of-plane and in-plane loading. A common retrofit technique, mainly aimed at improving out-of-plane floor performance, consists in the application of a layer of cross-laminated timber (CLT) panels laid over the existing floorboards and oriented parallel to the joists. Appropriate panel-to-joist shear connection determines a joist-slab composite behavior that results in a significant improvement of both the of out-of-plane strength and stiffness. In addition, if adequate connections between adjacent panels are provided, CLT elements can also increase the in-plane strength/stiffness, a key-aspect in defining the seismic response of URM buildings. Both force distribution among vertical resisting piers and out-of-plane deformation of masonry walls are in fact affected by the diaphragm in-plane behavior. Inadequate in-plane response from the diaphragms can lead to the out-of-plane collapse of large masonry portions (1st mode failures). Non-linear static and non-linear dynamic simulations proved that the above mentioned retrofit strategy can effectively increase diaphragm in-plane stiffness and limit the in-plane displacement demand of diaphragms subjected to seismic shaking.

The research work presented herein deals with the analysis of light-frame wood (LFW) buildings under lateral seismic loading. The paper aim was to define the relationship between the global building ductility and the local ductility of the components via non-linear static analyses. Firstly, the different failure mechanisms were isolated and their influence over the building ductility was determined by focusing on single-storey buildings. Then, the study was extended to multi-storey buildings in order to evaluate how the number of storeys affects the ductility. In order to obtain results of general validity, the analyses were performed by varying the most relevant mechanical-geometrical parameters as well as the seismic input and the ductility of the base components.

In view of the development of heavy timber seismic resistant structures, in the context of modern seismic design approach based on the mechanical triad of strength, stiffness and ductility, the dissipative capabilities should be delegated to specific devices, considering that timber mechanical behavior is typically fragile. With reference to the structural type of Moment Resisting Frames (MRF), steel links located at the ends of the beams are very promising solutions. In this regards the paper focuses on a beam-column timber joint equipped with steel links for dissipative heavy timber seismic resistant MRF, inspired by a reference experimental campaign on timber beam-to column assemblages conducted at the University of Trento. A refined finite element numerical model of the joint is set-up through the Abaqus software (v. 6.14) and efficiently calibrated on the basis of the experimental evidences. A very good numerical simulation of monotonic tests carried out in Trento has been achieved. The FE model would be a powerful tool for carrying out parametrical analysis aiming at the characterization of the mechanical properties and the optimization of the system, for the application in seismic resistant timber MRF.

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.

This paper presents tests on beech LVL–concrete slab composite connections and externally indeterminate beams using connectors comprising fully threaded (FT), small-headed screws or partially threaded (PT), large-headed screws in X-formation. A test was devised to quantify connection characteristics in fully cracked concrete (applicable to hog zones of the beams). Relative to the FT-based connections, the PT-based connections were of greater strength, nonlinearity and flexibility in compression concrete, and weaker, less stiff but more ductile in tension concrete. One composite beam exhibited 22% redistribution of support reaction at 88% of the failure load. Failure occurred primarily at the connections, which then gradually led to fracture of the LVL as a secondary mode of failure.

This paper deals with the static and dynamic seismic analysis of light timber-frame buildings. Through the use of the UNITN-model proposed in a previous work, the study is here extended to full-scale buildings. An iterative procedure to properly distribute a horizontal load to the shear-walls, considering the coupled action of the vertical-load and the hold-downs state, is developed; three methods for the application of the response spectrum analysis are proposed as well. These methods may be used to predict the seismic-behaviour and to design non-regular timber shear-walls buildings. A numerical example illustrates the application of the procedures.

Methods and devices for in situ establishment of mechanical properties of wood have been recently developed in cooperation with European, US and Japanese researchers. The development of these new methods was motivated by requirements from engineers who need highly accurate data of mechanical properties of specific elements to plan renovations of historic buildings. Reliable data can replace overly conservative values (usually provided by visual strength grading) in structural analysis, which allows the retention of more original material as the behavior of specific elements is safely assessed. The recently developed methods, which are described in this chapter, are tensile strength of small samples, tensile Young’s modulus of mesospecimens, compression strength of cores, compression strength in a drilled hole, mechanical resistance to pin pushing, Young’s modulus derived by measuring the hardness and shear strength of screw withdrawals. Although in general the devices for the testing of mechanical properties by the mentioned methods provide more accurate results than the methods used so far, they are not yet mass produced, which should change soon.

In European seismic areas timber structures are found as building frames, in combination with masonry infills, in bridges, but most frequently in roof structures and floor slabs of traditional buildings. Seismic strengthening of existing structures should provide a well-defined and simple path to seismic forces, maintain timber members elastic, and develop as much as possible the post-elastic behaviour of joints. Provisions must be adopted to avoid sudden loss of capacity and brittle failure, and to foster ductility. Different criteria for seismic strengthening of floor slabs and of carpentry joints are presented.

This paper presents the results of the ongoing work on the revision of the provisions for the seismic design of timber buildings in Europe included within Chapter 8 of Eurocode 8. The most recent research results and technical developments regarding both wood-based materials and structural systems have been implemented into the proposed new version together with the application of the capacity design to each structural system. The main objectives are to update the few and incomplete provisions included in the current version to the current state-of-the-art and to correct some misleading rules. This manuscript represents the authors’ point of view on the basis of a scientific research background and the design common practice regarding different key aspects in the seismic design of timber structures.

In this paper the seismic low-cyclic fatigue strength for different typologies of dissipative timber connections is analysed by means of a novel methodology, which defines an interaction between the strength degradation and the ductility capacity. The results of more than 40 cyclic tests on panel-to-timber, timber-to-timber, steel-to-timber connections and mechanical anchors are reported and discussed, by defining an approximated linear relationship between the slip amplitude and the impairment of strength from the 1st to 3rd cycle. A proposal for considering the strength degradation as an additional condition in the determination of ultimate slip of dissipative connections subjected to low-cyclic load testing is presented. The seismic low-cycle fatigue strength in terms of ductility capacity and strength degradation is compared for all the tested connection. Four different categories of connections in terms of low-cycle fatigue strength are proposed.

Shake table tests were carried out on a 7 m × 5 m three-story, timber light-frame building (7.5 m height) at the TreesLab laboratory (Eucentre) in Pavia. The aim of the research was to evaluate the seismic behavior of a typical Italian prefabricated timber building and to study the interaction between the individual structural components tested in quasi-static manner in a previous experimental study. The 1979 Montenegro Earthquake ground motion, recorded at the Ulcinj-Hotel Albatros station, was selected as the ground motion for seismic tests. The maximum peak ground acceleration was scaled to 0.07 g, 0.27 g, 0.5 g. 0.7 g, and 1 g in order to evaluate the building’s performance at different levels of seismic input. More than 100 instruments were used to monitor the behavior of the building during seismic tests measuring acceleration, displacement, and forces. The visual inspection shows that the building did not show any damage during all seismic tests. However the data analysis (dynamic identification, c...

The strengthening and stiffening of traditional timber floors with the addition of timber planks and the use of dry connections falls into the category of “traditional” repair methods. Nevertheless, a high degree of innovation and scientific/industrial research is implicit in some modern applications of this type of intervention. If newly developed systems are to be satisfactorily adopted to repair ancient structures, their effectiveness and reliability need to be adequately evaluated. The study highlights the importance of investigation actions for the design, calibration, and control of intervention in the restoration of heritage structures. On the occasion of the adoption of an innovative timber-to-timber strengthening technique for the rehabilitation of a traditional timber floor in a mediaeval castle in Italy, a thorough investigation was carried out. Tests were performed in situ on the structural elements, in both the original and the repaired condition, and the results were compared with those obta...

This paper aims at applying a direct displacement-based method to assess the seismic vulnerability of existing multi-storey wooden buildings. This procedure is consistent with Priestley’s direct methodology firstly developed for reinforced concrete structures. The distinctive characteristic of the proposed method is that the system response is quantified through the use of displacements instead of equivalent elastic strengths, according to the traditional force-based approaches. Consequently, in comparison to common force-based procedures, this method cannot only be considered as a rational alternative but also as a new seismic philosophy to design or assess structures. A representative timber construction system commonly used in Italy was selected as case study. The construction system illustrated in this work was analysed in detail, with special attention given to the mechanical connections typically used. The typical failure mechanisms and the energy dissipation capacity of the structure or of its members were identified on the basis of the mechanical properties of structural parts and connections, as well as of their geometry. In the proposed direct displacement-based assessment approach, the seismic intensity that would cause the limit state to be exceeded can be calculated by means of simple formulas. Therefore, the capacity to demand ratio can be simply derived. The procedure could be used to gauge the likelihood of losses, by combining it with simple loss models to account for probabilistic aspects.

In refurbishment operation of existing timber floors could prove of some interest the possibility of hogging the existing timber beams, in case of the presence of excessive permanent midspan deflections. In the case of sagged timber floors which cannot be buttressed due to heritage issues, the possibility of cambering a timber beam by simply putting another wooden beam on the top of it and inserting screws inclined at 45° relative to the beam axis has been experimentally investigated, with some promising result. The cambering procedure has proved to be more effective when the fastener are inserting starting from the internal part of the beam, permitting to obtain significant values of upward deflection (it has been observed an upward deflection of about one three-hundredth of the total beam length): the values could possibly be increased by reducing the screw spacing or by using fasteners able to generate a greater pressure. The effectiveness of this method is based on the capability of self-tapping screws to induce internal stress in timber element during the drilling procedure: the horizontal component of the resultant pressure yielded by the inclined screws is directly related to the possibility to hog the composite system. The aim of the experimental campaign described in this paper was to investigate the values of the internal stress induced by different type of fasteners during the drilling procedure, studying the influence of different parameters such as screw angle with respect to the grain direction, initial pressure, head penetration length, threaded part length, connector typology, wood density, time-dependence.

The Italian wood packaging industry occupies a leading role in Europe and focuses its production on a collection of reference standards that describe the fundamental principles for designing industrial packaging made with lumber, plywood and OSB. The national standard framework, mainly based on UNI 9151 and UNI 10858, has been developed from the need for containers for the shipment of machines and equipment of any size, shape and weight in the global market. The main aim is to ensure maximum protection of goods and safety of operators in charge of the handling and transport of wooden packaging (boxes, crates, etc.). As for structural uses in building, the wood packaging industry adopted the concept of allowable stress design for approximately 50 years. Recently, the introduction of the limit states design according to the Eurocode 5 (EN 1995-1-1) and the availability of CE marked products have offered an opportunity to optimize the design not only of timber structures but also of some critical applications in the field of industrial packaging. In this context, a great effort has recently been dedicated to update the above mentioned national standards in order to implement them with the introduction of CE marked lumber and wood-based panels. The present paper describes the Italian standard framework for the industrial wood packaging and illustrates its evolution and new opportunities., Talijanska industrija drvene ambalaže ima vodeću ulogu u Europi i svoju proizvodnju temelji na zbirci referentnih normi kojima se uređuju temeljna načela projektiranja industrijske ambalaže izrađene od drva, furnirskih ploča i OSB-a. Nacionalni normativni okvir, uglavnom utemeljen na UNI 9151 i UNI 10858, razvijen je zbog potrebe za kontejnerima u kojima se strojevi i oprema različite veličine, oblika i težine otpremaju na svjetsko tržište. Glavni je cilj proizvođača ambalaže osigurati maksimalnu zaštitu robe i sigurnost osoba zaduženih za rukovanje drvenom ambalažom (kutijama, sanducima itd.) i za njezin transport. Kao i za konstrukcijsko drvo u graditeljstvu, tako je prije otprilike 50 godina industrija drvene ambalaže prihvatila koncept projektiranja ambalaže utemeljen na dopuštenom naprezanju. U novije se vrijeme uvodi model projektiranja prema graničnim stanjima, sukladno normi Eurocode 5 (EN 1995-1-1), i dostupnost proizvoda s oznakom CE, što je prilika ne samo za optimizaciju projektiranja drvenih konstrukcija već i za neke kritične primjene, posebice u području industrijske ambalaže. U tom kontekstu u proteklom je razdoblju uložen veliki napor da se navedene talijanske norme ažuriraju kako bi se implementirale istodobno s uvođenjem CE oznake za drvnu piljenu građu i ploče na bazi drva. U radu se opisuje talijanski normativni okvir za industrijsku drvenu ambalažu i prezentira njegov razvoj i nove mogućnosti.

An analytical model is proposed to estimate the seismic displacement capacity, at serviceability and ultimate limit states, of timber portal frame structures with dowelled joints. The predictions from the simplified formula are compared with the results of numerical analyses carried out on a sample of representative cases. These cases result from a simulated design procedure, consistent with Eurocode 8, and are generated via Monte Carlo sampling, with varying sizes, materials and load conditions and also uncertainties in these parameters. Based on the outcome of the analysis we propose a set of practical formulas which allow prediction of the displacement with a given percentile of overestimates. In addition, it is shown that these equations for displacement capacity can be used to generate fragility curves for performance-based earthquake engineering applications. Prescription of an overstrength factor in code provisions is recommended to avoid brittle failure.

The paper illustrates recent research on timber joints assembled with traditional and innovative dowel-type connectors. The experimental results are presented in terms of force–displacement relationships for specimens tested under a monotonic procedure and hysteretic diagrams for specimens tested under the cyclic procedure. The aim is to determine some quantitative values from the experimental data in order to characterise the ductility and dissipation capability of timber joints while taking account of design standards for earthquake-resistant structures. The paper presents and discusses procedures for the analysis of experimental data proposed in test standards and the scientific literature, the purpose being to evaluate the ability of current procedures to mechanically characterise a joint's behaviour as a function of different kinds of connector – traditional dowel-type systems or innovative self-tapping screws inserted with different inclinations with respect to the shear plane. For some cases, alternative more robust procedures are proposed, especially where a lack of consistency in the current standard procedures was noted.

We introduce a direct Displacement-Based Design methodology for glued laminated timber portal frames with moment-resisting doweled joints. We propose practical expressions to estimate ultimate target displacement and equivalent viscous damping, and we demonstrate that these expressions provide prior values that are close to those obtained a posteriori using a more refined model. Applied to case studies, the method yields base-shear forces lower than those obtained using the force-based approach of Eurocode 8. This is due to the high dissipation capacity of the specific connection technology, which apparently is conservatively accounted for in the q-factor of Eurocode 8.

Synthetic methods for the diagnosis of structures and particularly for their vulnerability assessment rely on simplified calculations and visual inspection. Their effectiveness strongly depends on an accurate calibration of the procedure by which data are collected. A recent methodology for the seismic vulnerability assessment of timber roofs in historical buildings has been applied to the Thun Castle during a study for its rehabilitation. The purpose was twofold: testing and calibrating the procedure on a heritage structure and estimating the capability of the roof structure to resist seismic action, as required in a zone of low but not negligible seismicity.

In this paper an investigation campaign, carried out in occasion of the restoration of a timber floor in the Belasi Castle (Trentino, Italy), is reported. In order to validate a testing procedure for the calibration and control of an innovative wood-wood strengthening technique, results of tests performed in situ on the structural elements, in both the original and the repaired condition, have been compared with those obtained in laboratory on some dismantled beams. For the characterization of the material decay, both local mechanical and global vibrational testing have been carried out. For the mechanical characterization of the beams, before and after repair, direct static bending tests have been performed, with distributed loads, on site, and according to standard four-points loading schemes, in laboratory.

The aim of this paper is to propose a method for calculating the load-bearing capacity and stiffness of screws placed in an inclined position with respect to the shear plane and subjected to shear–compression load, to shear–tension load or to a combination due to their crossed X-position. At the same time, the authors also wish to highlight how the current method indicated by Eurocode 5 is partially unsuitable for describing the experimental results of strength and stiffness for these particular configurations. To this regard, push-out tests were carried out and the analysis of the resulting load–displacement curves has led to the definition of the main parameters describing the mechanical behaviour of the connections: strength, stiffness, effective number, ductility. The experimental values of strength and stiffness were then compared with the theoretical ones obtained using the Eurocode 5 calculation method and the calculation method proposed in this paper.

Ductility is a fundamental component in the design of robust structures. For timber structures, the unfavorable material characteristics pose particular problems to its realization. Two approaches for improving the post-elastic behavior of glued-laminated timber beams have been investigated by testing and numerical analysis. The first is based on forming mixed beams with suitably assembled lamellae of different strength class; in the second, steel reinforcement is used. Satisfactory results have been obtained mixing laminations of different grade, whether from a single species or from different species, as long as the strengths of the lamellae are well differentiated. Steel-reinforced timber beams require taking special provisions in order to develop a ductile bending behavior, because material irregularities induce brittle failure of wood in tension before the steel bars may yield. Positive results were obtained, specifically preventing local failure modes, by releasing tension stresses in wood, by inser...

This work intends to assess the accuracy of the methodology proposed in the Eurocode 5 for laterally loaded nailed timber-to-concrete connections. First, the adequacy of the methodology proposed by Eurocode 5 for the dowel-type fasteners is analyzed and discussed, using timber elements from Pinus pinaster Ait. Square and round smooth nails have been used, initially on push-out tests of single and double shear dowel-type connections. Later, a similar investigation is carried out on timber-concrete connections, using the same kind of fasteners (nails), in single shear, wood species and experimental procedure. The use and the influence of permanent formwork are also investigated. As a result, comparisons between the values obtained for the load-carrying capacity and the slip modulus using the analysis provided by the Eurocode 5, when existing, and the experimental results are presented.

In order to assess the safety of old timber structures and eventually to select appropriate strengthening strategies, the evaluation of mechanical properties of the material is of key importance. Visual strength-grading coupled with the use of nondestructive in situ testing allows these properties to be determined. Nowadays, the definition of both nondestructive testing (NDT) procedures and criteria for the results interpretation are almost exclusively in charge of the producer. In Italy, effort has been made to develop codes for grading timber on-site, and also by means of NDT. The aim of this paper is to highlight the difficulties and shortcomings that still occur in the assessment of traditional timber members following the criteria established by the legislation in force in Italy. The presented results can be helpful for the building surveyor who is in charge of the inspection of existing timber structures. Indeed, the paper gives some indications on the effectiveness of the grading criteria applied on historical timbers, as well as on the level of accuracy of some nondestructive methods.

This paper aims at the development of multi-storey prefabricated modular buildings. Particularly, this document deals with a novel versatile construction system in which the main structural members, made by combining timber with steel, are highly engineered and can be produced in the factory. The research demonstrates the potential of steel–timber hybrid structures in terms of sustainability, providing lightweight modern seismic-resistant constructions. This document presents the results of a comprehensive experimental campaign, including tests on several innovative connections, and of the numerical FEM analyses of the structural components. The paper also provides prototypes of new highly-industrialized steel–timber hybrid shear wall and floor components.

Conservative restoration principles developed for the protection of monuments are currently applied in the structural upgrading of traditional existing buildings in order to preserve their cultural heritage. Timber structures, typically, present in these buildings to support roofs and floors, had for long been substituted when buildings were upgraded, often using new and different materials, and sometimes yielding unsatisfactory results in terms of structural behavior. The current conservation trend requires developing criteria for interventions and implementing operative procedures complying with modern structural safety requirements and satisfying conservative restoration principles. Research progress is also being made in understanding the behavior of traditional timber joints and elements in service conditions and at the limit state under exceptional actions, as well as the effectiveness of different types of reinforcement. Actual cases of restoration of buildings that included conservation of the timber structures have proven to be economically competitive with the choice of substitution.

In case of exceptional or accidental destructive events (e.g., earthquakes, floods, fire), the advisability of completely reconstructing a vanished artifact may be questionable. Among the possible approaches for reconstruction, the so-called philological method allows the complete reading of the whole building. Analogous to the study of literary texts, this method is based on the analysis of the “architectural language” of a building that is its form and its technical characteristics as well as its structural behavior. This case study concerns reconstruction of the timber roof of the Church of the Pieve in Cavalese (Italy), destroyed during a fire on March 29, 2003, for which the philological approach has been chosen. The design process consisted of two important phases: first the determination of the precise form of the original roof, by considering different kinds of evidence, then the introduction of necessary modifications, to meet the present-day structural standards. Such design choice, far from bei...

This paper reports the results of an investigation on the behaviour of axially loaded joints utilising glued-in steel rods. A finite element model has been set up, in order to study the most influencing parameters for the shear stress distribution. Then, a series of tests have been carried out on joints made with Norway Spruce blocks and threaded steel bars, with different epoxy resin formulations and various ratios of hole/bar diameters. Different bar diameters have been used in experimental survey, ranging from 8 to 12 mm. Clearances of 1 or 2 millimetres have been left between bar and hole wall. The reported results are based on a sample of 240 specimens, which can be considered sufficient for statistical reliability. A statistical analysis has been performed, which confirms that: 1) the system proved to be highly efficient and reliable, with regard both to failure load and to joint stiffness; 2) with the epoxy-based adhesive used, the most important parameters affecting the strength and the stiffness of these joints seem to be the thickness of glue line and the viscosity property of the adhesive during the pouring phase; 3) these kinds of joints can be designed as ductile for specific purposes, choosing a suitable diameter of the bar.