bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Laser Radar in Atmosphere Environment Monitoring
Authors: Li Jian Wei , Xu Nan , Li Jian , Zhang Zhi Xin , Yao He Jun
Published: September 2013

laser radar is a kind of modern active optical remote sensing device and is the outcome of the combination of the traditional radar technology and the modern laser technology. It takes laser as the light source and senses remotely the target through the radiation signal generated when the detecting laser and the target interact. This paper summarizes the structure and classification of the laser radar for the purpose of atmosphere composition detection, and also discusses the existing problems and development trends.
Research of College Classroom Intelligent Lighting Adjustment System Based on ARM
Authors: Xu Jin , Tian Jian Wei , Wang Qiao , Mei Zheng Mao
Published: September 2013

Research of college classroom intelligent Lighting control system is based on the point of view of intelligence and energy saving. Considering the phenomenon of lighting waste and poor system management, a design of high stability and low power consumption intelligent Light control system is proposed. Through the research of distribution method of light source and the application of CAN bus communications technologies, this paper mainly introduces a distributed light control system based on ARM. According to the demand of indoor illumination, the system can achieve real-time and accurate regulation of all classrooms lights. Compared with the traditional lighting control system, besides the characteristic of energy saving, the system also is characterized by strong anti-interference and intelligent management etc.
The Non-Constant Speed Bearing Fault Diagnosis Based on Speed Measuring Method
Authors: Wu Bin , Wang Shi Jun , Tang Ying , Luo Yue Gang
Published: September 2013

This paper compares the existing speed measurement methods, discusses a speed measurement based on microcontroller used in non-constant speed bearing fault diagnosis that has the wide measuring range, high precision, good real-time performance.
Design and Implementation of the Computer Monitoring and Management System for the Multi-Mode Combination Timer Device
Authors: Wu Peng Fei , Li Jian Xun , Wang Yu Jian , Li Jian Xun
Published: September 2013

The multi-mode combination timer device can receive the GPS\GLONASS, No.1 BeiDou and loran-C at the same time. Since the multiple external frequency sources are introduced for the system, it is necessary to manage and monitor it. The wavelet decomposition atomic time algorithm is used to weight average the external reference signals in the wavelet domain, and the integrated time scales are obtained. The disciplined clock technology is employed to the time scale for calibrating the clock; the results indicate that the system can achieve fast timing and the complementary advantages of all kinds of resources.
Influence of Groove Structure on the Performances of Water Lubricated Marine Stern Bearings
Authors: Wang Jian Ping , Zhou Jian Hui , Liu Yu
Published: September 2013

Groove structure has a great effect on the operational performance of the water lubricated marine stern bearings. This paper discusses that the effects of the number and the layout of the grooves on the carrying capacity and friction coefficient of the bearing based the application of numerical analysis with Software of MATLAB. The research results show that the wider the grooves are, the lower both carrying capacity and friction coefficient of the bearing are; the location of the grooves in the bearing is important factor to influence the performance of the bearing. When one groove is located just below the stern bearing, both friction coefficient and carrying capacity of the bearing will be decreased.
Mapping of Rescue Environment Based on NDT Scan Matching
Authors: Li Jin Liang , Sun You Xia
Published: September 2013

This paper studied the mapping problem for rescue robots based on laser scan matching and extend Kalman filtering (EKF). Because of the non-structural rescue environments, it is hard to extract typical features. Scan matching method based on normal distribution transform (NDT) can avoid the hard feature extraction problem by estimation of the probability distribution of laser scan data. By fusing NDT scan matching with EKF framework, the NDT-EKF SLAM algorithm was proposed, which can effectively and precisely build maps for rescue environment. Experiment results show that NDT-EKF SLAM algorithm is more precise than algorithms based solely on scan-matching.
Design and Implementation of Library Management System Based on .NET
Authors: WANG Xin Yu , Zhang Qing Song
Published: September 2013

All function modules of librarys portal website system are analyzed and .NET technology is utilized to process the key problems in this paper. The application of ASP.NET technology in library provides not only the more convenient, stable, efficient and safe operating environment for librarys digital resource construction and information service, but also the ways of thinking and methods for the development and implementation of similar system.
Detecting on Forward Error Correction Codes
Authors: Lai Zong Li , Xu Wen Tao
Published: September 2013

Under the development of society, the dissemination of information plays an increasingly significant role. How to achieve the goal of continually reducing the error rate and enhance the quality of communication and construct a highly reliable, efficient and high-speed Broadband Communication System is really a tough task. Here comes the FEC that is one particular type of error correction codes which is introduced to protect the process of data transmitting. In addition to a brief introduction to FEC, this article covers the categories of FEC and their applications along with comparisons and also describes the latest development of these error correction algorithms.
Dynamic Modeling and Simulation Studies of a Human-Rifle System Considering Bio-Characteristics of Human Body
Authors: Gong Peng Han , Zhou Ke Dong , He Lei , Shang Li Min
Published: September 2013

The deep understanding of human-rifle interaction is not only crucial to improve the rifle firing accuracy, but also important for rifle design. In this paper, the construction of a biological coupling human-rifle model for standing posture was created using MSC.ADAMS and BRG.LifeMOD. Firstly, the rifle model was built by virtual prototyping technology based on the software of MSC.ADAMS. Secondly, the human model was generated in BRG.LifeMOD on the database of Human dimensions of Chinese adults. Finally, the simulation of human-rifle system was performed by the model, in which the interface between the human model and the rifle model was modeled using corresponding constraints. The feasibility of the application of biology mechanics model of three-dimensional digital human body to the researches of human-rifle system was explored, and it can provide the basis for the researches of human-rifle interaction and dynamic response of human-rifle system.
A Comparison between Evaluation and Restoration Methods for Old Wooden Beam and Glued Laminated Timber
Authors: Cenci Giovanni , Cenci Sabrina
Published: September 2013

We illustrate the evolution of our systems for the restoration of old timber structures, devised to make up for the often operationally impractical purely theoretical concepts. These alternative systems are commonly accepted because they are effective and maintain the same readability as ancient knowledge did. We are using similar techniques to restore static conditions to damaged laminated timber structures, too.
Assessment, Reinforcement and Monitoring of Timber Structures – COST FP1101
Authors: Kasal Bo
Published: September 2013

This paper describes the goals, work plan, organization and results of the COST Action FP 1001 Assessment, Reinforcement and Monitoring of Timber Structures. 21 European countries with over 100 experts participate in the COST Action that started in 2012. The work of the COST FP 1101 is coordinated with the COST FP1004 "Enhance Mechanical properties of Timber, Engineered Wood Products and Timber Structures." This conference is one of the results of the COST action.
Recommendations for Design in Preserving Historical Buildings with Wooden Structures’ Roofs
Authors: do Valle Ângela , Biscaglia Pereira Natalia , Castello Branco Nappi Sergio
Published: September 2013

The wooden structures are most common on the roofs of historical buildings. The ancient building techniques that were employed such as the use of notched joints are no longer known today. This lack, affects the project and implementation of restoration of these structures, and demonstrates, therefore, the importance of its preservation as a legacy to future generations. As result, the decision to restore heritage structures is the key to safeguarding the cultural heritage. The designer should be aware of the consequences of choosing some intervention techniques on preserving the cultural value of the monument. The technique may harm or benefit such as the patrimonial as the technical issue, preserving its historical and cultural value, durability and safety. Although there are important technical manuals and books that refer to the restoration of ancient roof structures published by Brazilian governmental agencies, there are not references about the consequences of certain technique´s application on the patrimonial value. Thus, this work analysed, critically and reflectively, the technical solutions most commonly adopted by Brazilian designers on the restoration of the structural roofs in ancient wooden structures. This analysis will be based on principles and recommendations of the key documents and the charters of heritage preservation. After the evaluation of restoration techniques most commonly applied to restoration of roofs with wooden structures, general procedures are recommended in order to ensure the safeguarding of the heritage.
Timber Roof Structures in Extreme Weather Conditions
Authors: Pazlar Tomaž
Published: September 2013

Beside seismic activity climate changes, reflecting in extreme events such as heat and cold waves, storms and floods, presents the main natural hazards. Although predicting events perimeter is not trivial, the vulnerabilities of society emphasizing built environment should be at least critically estimated and re-estimated, especially after the occurrence of such event. Many strong thunderstorms causing huge damage to agriculture and to build environment occurred in recent summers. Meteorologists concluded that summer storms especially those ones in July and August 2008 were very intense and affected many Slovenian regions. Extensive damage to buildings rose up questions about possible causes: bad construction practice, use of inappropriate materials, deficient maintenance and inadequate building regulation relating to loads. Some experts also claimed that additional material and product characteristics should be tested /defined to prevent extensive damage, like hail resistance for example. Slovenian National Building and Civil Engineering Institute (ZAG) tried to answer to these questions in a special research project, financed by Slovenian Ministry for Environment and Spatial Planning (MOP).
Considering the Role of Wood and Timber Roof in Persepolis Architecture
Authors: Davoodi Alborz , Davoodi Alvand
Published: September 2013

Persepolis is one of the most important ancient monumental buildings in the world which unfortunately was burned by Macedonian Alexander arson in 330 B.C and its great and beautiful timber roof had been destroyed. In this article we tried to consider the role of wood and timber roof in Persepolis architecture and show a model to revitalize it.
Effects of Beetle Attack on the Bending and Compression Strength Properties of Pine Wood
Authors: Cruz Helena , Machado José S.
Published: September 2013

One major difficulty one has to face in the assessment of old timber structures concerns the assessment of the effective strength of timber cross sections with biological damage.Its effects may generally be considered, either by assuming a reduced cross section or by assuming reduced mechanical properties for the apparent cross section.Where beetles attack produce a “diffuse” damage, i.e. their tunnels spread in most of the cross section surrounded by a significant amount of undamaged wood, the assumption of a reduced cross section may not be the best approach.To assess the effect of diffuse damage by beetles to pine timber, damaged timber was collected from an old structure and tested in bending and compression in small “clear” wood specimens (cross sections of 2cm x 2cm). The varied degrees of biological damage were assessed in terms of the “holes” area measured in the cross section surface with the help of image processing analysis. Bending and compression strength were correlated with biological damage. Test results suggest that, although very high levels of insect destruction have an impact on the timber strength, timber density still is the governing factor.
Prediction of Strength and Elasticity in Oak Beams on the Basis of External Wood Characteristics
Authors: Riesco Muñoz Guillermo , Remacha Gete Andrés
Published: September 2013

The purpose of the study was to search external features of timber useful for predicting modulus of rupture (MOR) and modulus of elasticity (MOE), both in axial direction bending, valid for a wide range of beam qualities. For the study, 23 European oaks (Quercus robur L.) were felled in northwestern Spain, where most of the oak stands in the country are located. The trees were sawn and a sample of quarter-sawn planks was selected. Planed and edged specimens (5×10×200 cm) were tested to obtain MOR, MOE, apparent density, wood moisture content, percentage of sapwood, ring width, slope of grain and size and position (faces, upper and lower edge, heads) of external defects. The MOR was correlated with the maximum face and edge knot diameter. However, the correlations were not high enough to justify construction of a predictive model of mechanical behavior on the basis of maximum knot size in the piece. The MOE was correlated with the size of knots and wane. Presence of sapwood did not exhibit significant influence on strength performance. Homogeneity in ring width was negatively related to MOR and mainly to MOE.
Subject headings: Bending; Mechanical properties; Stiffness; Wood beams; Wood structures.
Effectiveness and Subjectivity of Visual Inspection as a Method to Assess Bending Stiffness and Strength of Chestnut Elements
Authors: Sousa Hélder S. , Branco Jorge M. , Lourenço Paulo B.
Published: September 2013

Besides the difficulty of assessing an existing timber structure on site, the efficiency and accuracy of visual inspection is often compromised by its subjective nature inherited by the level of expertise of the inspector. This often leads to conservative predictions of the mechanical properties, even with the use of specific visual grading norms. The main objectives of this work are to assess the effectiveness of visual inspection as a method to define different classes of strength and stiffness and to provide a statistical analysis on its subjectivity. For that aim, visual inspection using Italian standard UNI 11119:2004 and bending tests of 20 old chestnut beams (Castanea sativa Mill.) at different scale element, were carried out. Comparisons and effectiveness of visual inspection is analyzed within and between different scales of the timber members, and also regarding different level of expertise of inspectors. The results evidence similar percentages of segments classified with higher and lower visual inspections classes and proved to be a good qualitative indicator of bending strength between sawn beams. An overall 42% accuracy of the most experienced inspectors was found with better differentiation between visual classes, whereas lower level inspectors scored approximately less 5%. Lower level inspectors also evidenced higher concentration of values around a higher mean for each class denoting a more conservative approach. Regardless of the inspector level, knot size was considered the main limiting visual parameter with higher influence in small scales of the timber elements. When studying the characterization of a single knot, coefficients of variation of 15.7% and 21.8% were found for measuring the minimum and maximum diameter. Bayesian probability networks were considered as to individually assess the accuracy in stiffness prediction of different level of inspectors, and by combination of their information, evidencing that parallel combination for prior information may allow the increase in visual inspection accuracy.
Juniper Structures in Western Mediterranean Vernacular Architecture: Ongoing Research
Authors: Ruiz-Checa José Ramón , Cristini Valentina
Published: September 2013

This research highlights the constructive features of Juniperus thurifera timber visible in the Western Mediterranean (from the island of Sardinia to Morocco). The use of this material is above all related to vernacular and traditional architecture, in the coastal areas as well as in the interior of the analyzed countries. An initial taxonomy of its use presents us with the issue of understanding the main structural performance of this type of timber, focusing in particular on its structural use and behavior. The results, visible throughout the research, are related to the resistance of the timber and its performance. On the other hand, this raw material is valued in vernacular architecture because of its strength when exposed to sea water or harsh weather conditions. Juniper beams and pillars are the most frequent solutions, but the use of branches and roots is also common, as the research demonstrates. In this framework, the text underlines the results of the research based on a geographical survey of juniper as a construction material, and on the first attempts to study its mechanical performance.
The Influence of Biological Factors on the Health of Timber Structures on 11th to 14th Century AD in Yazd
Authors: Moghaddam Sasha Riahi , Poormohamadi Sepideh , Saffar Marziyeh , Esfahanipour Faezeh
Published: September 2013

One of the main reasons for the decline and exhaustion of wood materials in old buildings is biological factors. In Yazd According to the position of buildings in hot and dry desert climate and the use of wood as an integral part of the building structure, This factors of damage to obvious and hidden that could threaten the stability of buildings. With respect to this, the several period laboratory and field research to identify the species and damage caused by biological agents work on timber structures Which mainly on 11 to 14 century AD buildings of Yazd damage has Was performed. In order to identify malicious insects, so far three type of Borer beetles the scientific name of the family Buprestidae Pseudocastalia aegyptiaca and Xylopertha reflexicauda and family Bostrichus capucinus Bostrychidae and three termite species with scientific names Anacanthotermes vagans (Hagen) family of Hodotermitidae, Amitermes sp. and Microcerotermes sp. The family Trmytyda has been identified in Yazd. The damage that these insects create many factors such as type of wood density, moisture content of wood depends on environmental conditions and location of the attack. According to climate of Yazd and construction technology, most of the structural damage, such as domes, arches and brick walls to show. These damages brought down the long-term structural strength and the instability in natural factors such as earthquakes, the structural imbalances and collapse of the buildings.Therefore the pathology of Integral component on timber structures brick in assessing the health and stability of structure in a desert climate of Yazd is very important and necessary. In this paper, by introducing the use of timber in 11th century to 14 century adobe structures in Yazd to review and evaluate the damage caused by the destruction timber structures Monuments By biological agents are paid.
Strength Class Prediction of Sardinia Grown Timber by Means of Non Destructive Parameters
Authors: Concu Giovanna , de Nicolo Barbara , Trulli Nicoletta , Valdés Monica , Fragiacomo Massimo
Published: September 2013

In Italy timber and wood products are becoming increasingly used for building constructions due to their excellent physics and mechanical properties. International Codes require the use of wood previously graded according to the current regulation. This paper reports the preliminary results of an experimental campaign aimed at verifying the reliability of the use of Sardinian timber as structural material. For this purpose Maritime Pine boards from two different Sardinian areas have been analyzed and visual strength graded. Physical and morphological properties (density, knots, clusters knot, resin pockets, deviation of the grain, annual ring width position of board respect to the pith, humidity, etc.) along with mechanical and non destructive properties (elastic modulus, tensile strength, ultrasonic pulse velocity) have been checked. Timber properties have been statistically evaluated in order to identify the performance of the base material. Regression analyses have been carried out by studying the correlation between non destructive parameters and mechanical properties in order to define a criterion for predicting the strength class of the base material.
In Situ Compression Stress-Deformation Measurements along the Timber Depth Profile
Authors: Drdácký Miloš , Kloiber Michal
Published: September 2013

The paper presents a novel concept and a prototype of a diagnostic tool for in-situ assessment of timber in existing structures and buildings. The device enables direct determination of conventional compressive strength and modulus of deformation in arbitrary depth along timber profile. The measurement of the stress-deformation relationship is performed in a prepared hole of a very small diameter by means of a special small size symmetrical loading jack. Testing and verification of the new device behaviour during loading of wood along the fibres has been carried out on fir which is the most frequent wood species in European buildings. The comparison of stress-strain diagrams acquired by means of the new device with those measured in compliance with the European standard for testing of wood shows a very good correlation including the determination of the compressive strength values. This semi-destructive method causes a very gentle damage and can be also used for the assessment of historic timber structures.
Experimental Values of Wood Strength in Bending between the 17th and the 18th Century
Authors: Tardini Chiara
Published: September 2013

Through the reading of some French engineering treatises published in the 18th century values of the ultimate normal stress of wood elements in bending have been derived. This has allowed to highlight the different purposes with which the tests were carried out in the course of time in that period: from the observation of the phenomenon, to derivation of a law of general behavior, and to the publication of load charts useful for building practice, for the verification of the theory, and finally for the determination of the values of various coefficients.
Effect of Elastic Modulus and Poisson's Ratio on Guided Wave Dispersion Using Transversely Isotropic Material Modelling
Authors: Subhani Mahbube , Li Jian Chun , Gravenkamp Hauke , Samali Bijan
Published: September 2013

Timber poles are commonly used for telecommunication and power distribution networks, wharves or jetties, piling or as a substructure of short span bridges. Most of the available techniques currently used for non-destructive testing (NDT) of timber structures are based on one-dimensional wave theory. If it is essential to detect small sized damage, it becomes necessary to consider guided wave (GW) propagation as the behaviour of different propagating modes cannot be represented by one-dimensional approximations. However, due to the orthotropic material properties of timber, the modelling of guided waves can be complex. No analytical solution can be found for plotting dispersion curves for orthotropic thick cylindrical waveguides even though very few literatures can be found on the theory of GW for anisotropic cylindrical waveguide. In addition, purely numerical approaches are available for solving these curves. In this paper, dispersion curves for orthotropic cylinders are computed using the scaled boundary finite element method (SBFEM) and compared with an isotropic material model to indicate the importance of considering timber as an anisotropic material. Moreover, some simplification is made on orthotropic behaviour of timber to make it transversely isotropic due to the fact that, analytical approaches for transversely isotropic cylinder are widely available in the literature. Also, the applicability of considering timber as a transversely isotropic material is discussed. As an orthotropic material, most material testing results of timber found in the literature include 9 elastic constants (three elastic moduli and six Poisson's ratios), hence it is essential to select the appropriate material properties for transversely isotropic material which includes only 5 elastic constants. Therefore, comparison between orthotropic and transversely isotropic material model is also presented in this article to reveal the effect of elastic moduli and Poisson's ratios on dispersion curves. Based on this study, some suggestions are proposed on selecting the parameters from an orthotropic model to transversely isotropic condition.
Ultrasonic Imaging of Defects in Building Elements Made from Timber
Authors: Krause Martin , Mayer Klaus , Chinta Prashant Kumar , Effner Ute
Published: September 2013

There is a great demand for non-destructive testing methods for quality assurance and to assess the safety and durability of wooden structures. Ultrasonic echo technique with shear waves in the frequency range of 50 kHz is one of those promising methods and is already frequently applied for usual and glued laminated timber. The article describes the development and first results for an imaging method for this purpose. The highly anisotropic properties of the ultrasonic velocity have to be considered. A 3D-SAFT (Synthetic Aperture Focusing Technique) imaging scheme is developed initially for synthetic data resulting from modelling the elastic wave propagation. The main part of the paper describes the experimental validation of this evaluation technique by experimental studies applying automated ultrasonic scanning techniques. 3D ultrasonic imaging results are described for test specimens made from pine and spruce wood. Another object of investigation was a pedestrian bridge made from siberian larch.
Approaches to the Moisture Content Monitoring Intimber Elements: Development of a Resistive Method
Authors: N'Guyen Tuan Anh , Angellier Nicolas , Caré Sabine , Ulmet Laurent , Dubois Frédéric
Published: September 2013

The scope of this work is based on the use of resistive method to quantify the water content in timber elements. For an in-depth mapping, we adapted a multiplexed technique derived from geophysics based on a maximum crossing of current lines to obtain topography of measures sweeping the space boundary conditions being defined by the sample. The calibration of these measures is completed by a gammadensimetry laboratory method which allows access to water profiles along a preferred direction. Nevertheless, the resistive method is penalized by logarithmic laws linking moisture and resistivity. So, we develop a hybrid method for coupling the data obtained to diffusion models: it will provide complementary information where resistivity and gammadensimetry are no longer effective. The developed experimental protocol allows employing the selected method and optimizing the diffusion properties (diffusion coefficient and convective exchange coefficient) injected into a characterization algorithm (Nelder-Mead’s simplex inversion method) based on a finite difference method for the Fick’s diffusion law determination integrating orthotropic and non- linear properties. Overlap between electric field and density measurements and the numerical simulation tool are possible.
Terrestrial Laser Scanning and Settled Techniques: A Support to Detect Pathologies and Safety Conditions of Timber Structures
Authors: Bertolini-Cestari Clara , Chiabrando Filiberto , Invernizzi Stefano , Marzi Tanja , Spanò Antonia
Published: September 2013

Nowadays, there is an increasing demand for detailed geometrical representation of the existing cultural heritage, in particular to improve the comprehension of interactions between different phenomena and to allow a better decisional and planning process. The LiDAR technology (Light Detection and Ranging) can be adopted in different fields, ranging from aerial applications to mobile and terrestrial mapping systems.
One of the main target of this study is to propose an integration of innovative and settled inquiring techniques, ranging from the reading of the technological system, to non-destructive tools for diagnosis and 3D metric modeling of buildings heritage. Many inquiring techniques, including Terrestrial Laser Scanner (TLS) method, have been exploited to study the main room of the Valentino Castle in Torino. The so-called “Salone delle Feste”, conceived in the XVIIth century under the guidance of Carlo di Castellamonte, has been selected as a test area. The beautiful frescos and stuccoes of the domical vault are sustained by a typical Delorme carpentry, whose span is among the largest of their kind. The dome suffered from degradation during the years, and a series of interventions were put into place.
A survey has revealed that the suspender cables above the vault in the region close to the abutments have lost their tension. This may indicate an increase of the vault deformation; therefore a structural assessment of the dome is mandatory.
The high detailed metric survey, carried out with integrated laser scanning and digital close range photogrammetry, reinforced the structural hypothesis of damages and revealed the deformation effects. In addition, the correlation between the survey-model of the intrados and of the extrados allowed a non-destructive and extensive determination of the dome thickness. The photogram-metrical survey of frescos, with the re-projection of images on vault surface model (texture mapping), is purposed to exactly localize formers restoration and their signs on frescos continuity.
The present paper illustrates the generation of the 3D high-resolution model and its relations with the results of the structural survey; both of them support the Finite Element numerical simulation of the dome.
Modulus of Elasticity and Bending Strength of Squared Timber with Wane of Spruce and Larch
Authors: Schrentewein Thomas
Published: September 2013

Historical wooden structures are made of round timber or frequently of squared timber with wane, in southern European countries also known as Uso Fiume and Uso Trieste. Knowledge of the mechanical properties of these load-bearing structures is very important in their assessment and maintenance.
In two research projects undertaken in cooperation with IVALSA/CNR, TIS Techno Innovation South Tyrol, Microtec and Lignaconsult, more than 750 spruce and larch beams were subjected to bending fracture tests to determine their mechanical properties. Using existing datasets, a method was developed to determine the modulus of elasticity of an irregular cross section which varies along the length of the beam. If the effective cross-section geometry of a wooden structure made from squared timber with wane is known, the elasticity behaviour and the load-bearing capacity can be defined using the calculated mechanical properties.
The Influence of Routed Grooves on the Bending Behavior of Old Timber Beams
Authors: Cavalli Alberto , Togni Marco
Published: September 2013

Old timber structures represent an important portion of the World cultural heritage: wooden buildings materials and building techniques are part of our history and their conservation is an essential contribution to cultural diversity and global cultural wealth. In recent times, the methods and approaches used to assess and to maintain timber in historic buildings have evolved considerably and various techniques for timber repair and strengthening were developed and deeply investigated. A very common and widely used technique for the timber strengthening-repair is realized by inserting reinforcement materials in grooves cut in the original sound wood. The proposed reinforcement materials are various (fiber reinforced plastic materials, steel bar/s or plate/s, wood and wood products) and the grooves number and depth are variable. Several researches were conducted to determine the Modulus of Elasticity (MOE) of old timber members strengthened with the described technics. A common approach is to consider the strengthened timber beam as a composite one and the MOE of the wooden part correspondent to the original. In practice, the timber members work together with strengthened materials, and the strengthening intervention is planned taking into account both original timber and strengthening material MOEs. The basic assumption of this approach is that the slots executed along the timber length have no effect on the timber MOE. The aim of this research is to investigate the effects of the routed grooves cut along the wooden beams, on the bending MOE of old timber members, to provide important information for the strengthening interventions plan.
A Vibration-Based Approach for the Estimation of the Loss of Composite Action in Timber Composite Systems
Authors: Dackermann Ulrike , Li Jian Chun , Rijal Rajendra , Samali Bijan
Published: September 2013

This paper presents a novel approach for the determination of the loss of composite action for timber composite systems using only measurements from non-destructive vibration testing. Traditionally, the composite action of a system is evaluated from static load testing using deflection measurements. However, static load testing is expensive, time consuming and inappropriate for existing flooring systems. The method proposed in this paper is based on the Damage Index (DI) method, which uses changes in modal strain energies, to detect locations and severities of damage. In the proposed method, a new Loss of Composite Action Index (LCAI), which is derived from direct mode shape measurements obtained from dynamic testing, is introduced to evaluate the loss of composite action. The proposed method is tested and validated on numerical and experimental models of a timber composite beam structure, which consists of two timber components that are connected with different numbers of screws to simulate various degrees of partial composite states. The results obtained from the new method are very encouraging and show a clear trend of the proposed dynamic-based LCAI in indicating the loss of composite action in the investigated timber composite structure.
Assessment of the Realistic Stiffness and Capacity of the Connections in Quincha Frames to Develop Numerical Models
Authors: Quinn Natalie , D’Ayala Dina
Published: September 2013

Peru is one of the most seismically active countries in the world, this fact highlighted by several destructive earthquakes in recent years. The centre of Lima has a large number of historic structures with a ground floor in adobe, and their upper storeys in quincha, a traditional technique consisting of a timber frame with an infill of canes and mud. Despite the existence of a large number of buildings containing this technique, very little is known about its seismic performance. In order to investigate this, a series of experimental tests on quincha frames, with and without the infill, have been carried out previously, with the aim of quantifying the lateral behaviour and identifying vulnerable areas. The present paper details work carried out to develop a finite element model of the test frames without infill. This model of the timber frame will enable an accurate representation of the frame behaviour to be developed before adding the infill of canes and mud to the model. As the behaviour of the infill material and its connection to the frame is difficult to determine, characterising the timber frame with a high degree of accuracy ensures that the contribution of the infill can be globally quantified from the overall experimental results. The beams and posts are connected by cylindrical mortice and tenon joints, with a diagonal bracing member providing some lateral restraint. The connections have been modelled semi-rigid springs, with the stiffness calculated using variations of the component method. This was found to give very similar results to those obtained experimentally.
Moisture and Temperature Influence on Biocomposites-to-Timber Bonding
Authors: Valluzzi Maria Rosa , Nardon Fabiola , Garbin Enrico , Panizza Matteo
Published: September 2013

Compatibility and durability are fundamental aspects to take into account when dealing with strengthening and repair of structural components in existing buildings. In particular, timber elements in floors and roofs, like beams and joists, can be improved in their load-bearing capacity by the use of composite (fiber-reinforced) materials. Applied as textiles or laminates, those materials can provide additional tensile strength without weight increase, and are easily applied in situ. Recently, an increasing interest towards the biocomposites (flax, hemp) opened new perspectives: the advantages in comparison with traditional FRPs includes the higher mechanical compatibility and sustainability, especially if glues suitable for wood (e.g., vinyl) are used as matrix, instead of epoxy resins.In the paper, the results of an experimental campaign carried out at the University of Padua, aimed at investigating the influence of humidity and temperature on the adhesion of composite materials (carbon or glass FRP) and biocomposites (flax) reinforcing spruce timber elements are presented. Epoxy resins were used as matrix for all composites; flax was also applied with vinyl glue and considering a protective treatment (alkaline-based). Effectiveness of bond at the interface timber-reinforcement was measured by pull-off tests, and analyzed at micro-structural level by optical microscopy and infrared spectroscopy.
Reinforcement of Timber Beams with Prestressed Wires
Authors: de Oliveira Negrão João Henrique Jorge
Published: September 2013

This paper presents and discusses the possibility of improving the bending strength of timber beams through the use of prestress. The emphasis is put on various methods of imposing the prestress force and transferring it into the wood part: i) through post-tension, with the force being mechanically anchored on the ends of the wood elements; ii) through pre-tension, with the anchorages being either mechanical, as in the previous system, or glued, with the force being gradually transferred through shear stresses along a certain length of the wire/wood interface. Although the risk of failure due to tension perpendicular to the grain in the anchorage regions exists, it is not specifically studied in here, due to the limited scope of the study. The main conclusion is that any of the procedures may be advantageously used with either small (mass-production) or large-span glued-laminated timber beams and, though they are mostly suited to the production of new elements, they may also be adapted to the strengthening of existing beams.
Reinforcement of Timber Floors-Transversal Load Distribution on Timber-Concrete Systems
Authors: Dias Alfredo M.P.G. , Monteiro Sandra R.S. , Martins Carlos E.J.
Published: September 2013

In this paper the transversal load distribution in timber-concrete systems is analysed and discussed. The analysis is based on experimental and numerical results obtained for real scale timber-concrete systems. Two situations are considered: a timber-concrete floor for a multi-storey building with dimensions of 3.39mx3.48m in plan view and a road bridge deck with dimensions of 5mx14m also in plan view. In both situations the systems were designed to the loads required by the European codes. The effect of the transversal load distribution was experimentally assessed by imposing concentrated loads in various locations, eccentric to both transverse and/or longitudinal direction. Additionally, FEM models were developed to describe the mechanical behaviour of the two composite timber-concrete systems. The results obtained with both methodologies are presented and discussed. Based on this discussion conclusions are drawn regarding the amount of transversal distribution that can be expected in this type of reinforcement solution.
Experimental Characterization of Timber Floors Strengthened by in-Plane Improvement Techniques
Authors: Valluzzi Maria Rosa , Garbin Enrico , dalla Benetta Massimo , Modena Claudio
Published: September 2013

The rehabilitation of existing timber floors in seismic area should take into account the possibility to use both traditional and more modern materials and techniques. An extensive experimental program carried out at the University of Padova concerned full-scale wooden floors segments strengthened through the application of several solutions, belonging to the following three main categories: planks overlapping, diagonals, and nets.In detail, the following techniques were considered: single and double planking with an orientation of ±45° having different thicknesses; steel, CFRP, SRP or wooden diagonals; natural fibre (hemp) composites applied as nets with resin or vinyl glue; wooden nets applied with hardwood pins and screws.The study is aimed at characterizing the behaviour of strengthened floors for the selection of the most suitable solutions applicable in existing buildings, which are able to provide a proper in-plane stiffness for seismic load distribution among bearing walls. The test set-up was designed and realized on purpose to simulate the in-plane shear behaviour of timber floors. The experimental results and the comparison between unreinforced and strengthened floors under monotonic shear load are presented in the paper.
Optimization of Mechanical and Acoustic Performance of Timber Floors
Authors: Valluzzi Maria Rosa , di Bella Antonino , Garbin Enrico
Published: September 2013

In the paper, the results of an experimental study aimed at evaluating the mutual influence among the intervention techniques normally employed to improve separately the acoustic or the mechanical performance of timber floors are provided. The superimposition of planks having different thickness and arrangement or connections is usually considered to improve the in-plane stiffness of floors, especially in case of interventions on existing buildings in seismic zone, to take into account, if possible, also preservation criteria. On the other hand, the improvement of acoustic comfort is addressed to the use of specific noise-abating materials, like insulating boards (OSB) or sheathings, whose contribution, in terms of mechanical stiffness/strength is often neglected. This work proposes a combined interpretation of the two abovementioned requirements, through the characterization of the main parameters governing the involved physical and mechanical phenomena. The first results obtained on simple unidirectional full-scale specimens of floors are presented; seven combinations among various solution of boards and noise-abating materials are compared, first from a structural and subsequently acoustic point of view. The results allow identifying the solution, which is able to optimize at best both the mechanical and acoustic requirements, to be proposed for the intervention on existing timber floors.
A Numerical Approach for the Hygro-Thermal Monitoring of Timber Structures under Environmental Conditions
Authors: Genoese Alessandra , Genoese Andrea , Fortino Stefania , Hradil Petr
Published: September 2013

The monitoring of timber structures exposed to natural climate fluctuations during their service life is an important topic for both their serviceability and safety. Numerical methods based on the recent advances in hygro-thermal modelling of wood can integrate the usual sensor-based monitoring techniques by reducing the maintenance costs for timber structures. In this paper, a 3D full coupled analysis based on the multi-Fickian theory with sorption hysteresis of wood is implemented in Abaqus FEM code by defining a new finite element in a user subroutine. To verify the method, the hygro-thermal behaviour of a glulam beam tested in laboratory under variable humidity within a previous research is analysed and the numerical values of moisture content are found to be in agreement with the experimental data. Furthermore, a numerical case-study of a glulam cross section under real climate variations is presented and the related results show the capability of the method to predict the moisture states in each points of the glulam member under continuously variable humidity and temperature.
The Hidden Gem
Authors: Andreescu Ioan , Gaivoronschi Vlad Alexandru , Mosoarca Marius
Published: September 2013

Timisoara is an important city situated in the westernmost corner of Romania. Its historic core was until late XIXth century a heavily defended citadel. The Great Synagogue in the Citadel, inaugurated by the Emperor Franz Josef I, is one of the most spectacular buildings of the city. A centrally shaped and domed building, enveloped in “moorish-andalusian” decorated façade, stands out for both the civic dignity of the newly emancipated Jewish community (1865), and its desire to integrate in the modern society.
The beautifully ornamented massive brick building, covered by a central skylighted dome and surrounded by vaulted aisles also contains two exceptional wooden structures: the interior balconies including the orgue balcony and the roof structure over the vaults. Both are functional as well as ornamental, structurally and geometrically sophisticated and displaying high levels of craftsmanship. The ongoing project for the restoration of the Synagogue and its conversion into an auditorium revealed the complexities of the wooden structures – the lightweight and delicate balconies were able to sustain hundreds of worshippers for more than a century: the complex roofing system, stretched between the exterior tympans, the skylight of the dome and the exterior profile of the vaults, display elegance and minimalism. Both structures withstood the test of time, neglect and constant seismic activities. Maintaining these structures according to contemporary safety and risk management standards proved to be both a challenging and a rewarding opportunity.
Reconstruction of the Technical Museum in Zagreb
Authors: Rajčić Vlatka , Čizmar Dean , Stepinac Mislav
Published: September 2013

Technical Museum is one of the most visited Museums in Zagreb (capital of Croatia). The museum presents scientific and educational centre in the field of technical sciences. The entire structure of the Museum is constructed as a timber structure and as such represents a rare existing example of the European engineering concept of expo-halls timber structures with large span (85m x 40 m) from the early 20 century. In this article overview of different NDTs that were performed in order to assess the structural performance of elements is given; moisture ratio and ultrasound investigations are carried out in situ in order to investigate timber condition. Based on the detected state of the structure reconstruction measures are presented.