bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Realization of the Multi-Function Tower CraneBlock Box Based on ZigBee
Authors: Lu Jian Feng , Zhang Ping , Li Shu Qi , Yan Xu , Wang Yong Tao
Published: September 2013

This paper introduces the design and realization of the Multi-function Tower Crane Black Box, completes the main hardware module design and type selection. With ZigBee, it constructing wireless sensor network to collect the communication among nodes and the communication between nodes and the gateway, the lower PC adopts the IAR to complete the chip CC2430 programming. The application development tool for the upper PC is C51RF - WSN - DA300, and it gives part of the source code. The system parameters acquisition is accurate, the operation is stable, and the actual application effect is good.
Researches on the Mechanism of Thermo-Mechanical Coupling and Boundary Effects in Thick Wall Cylinders
Authors: Lu Ye , Zhou Ke Dong , Wu Qi Jun , He Lei
Published: September 2013

The automatic weapons suffered the coupling load of in-bore pressure and temperature load during firing, which exerted a serious influence on the gun barrel life. Suppose the gun barrel was thick wall cylinders, the relations among the radial stress, tangential stress, longitudinal stress and equivalent stress in thick wall cylinders enduring interior pressure and temperature loads were analyzed by traditional analytic method, 2D finite element method (FEM) and 3D FEM respectively. Boundary effects of the stress field in thick wall cylinders were also analyzed. The obtained results showed that 3D FEM is suitable for the analysis on boundary effects, and the coupling stress could be designed and optimized by adjusting the interior pressure or temperature loads.
The World's Tallest Wooden Observatorion Tower. Design for Durability
Authors: Lackner Markus , Vodicka Michael
Published: September 2013

The new observation tower on the Pyramidenkogel (Keutschach, Austria) has a spatial frame structure, with three main components:
RILEM TC "Reinforcement of Timber Elements in Existing Structures"
Authors: Tannert Thomas , Branco Jorge M. , Riggio Mariapaola
Published: September 2013

The paper reports on the activities of the RILEM technical committee Reinforcement of Timber Elements in Existing Structures. The main objective of the committee is to coordinate the efforts to improve the reinforcement practice of timber structural elements. Recent developments related to structural reinforcements can be grouped into three categories: (i) addition of new structural systems to support the existing structure; (ii) configuration of a composite system; and (iii) incorporation of elements to increase strength and stiffness. The paper specifically deals with research carried out at the Bern University of Applied Sciences Switzerland (BFH), the University of Minho Portugal (UniMinho), and the University of Trento Italy (UNITN). Research at BFH was devoted to improve the structural performance of rounded dovetail joints by means of different reinforcement methods: i) self-tapping screws, ii) adhesive layer, and iii) a combination of self-tapping screws and adhesive layer. Research at UNITN targeted the use of dry connections for timber-to-timber composites, specifically reversible reinforcement techniques aimed at increasing the load-bearing capacity and the bending stiffness of existing timber floors. At UniMinho, double span continuous glulam slabs were strengthened with fibre-reinforced-polymers. All three examples demonstrate the improved structural performance of timber elements after reinforcing them.
Developing an Understanding for Grading Timber in Existing Buildings
Authors: Anthony Ron W.
Published: September 2013

Structural engineers and architects must make decisions about the ability of lumber and structural timber (wood members) to resist the design loads in existing or historic buildings. Unfortunately, they do so often without the necessary knowledge to properly assess the ability of the timber to provide reliable, long-term, safe performance. Due to uncertainties about the allowable design stresses that can be assigned to structural timbers, very conservative decisions to replace or reinforce these members are often made, even though the timbers are working, i.e. they have and will continue to safely carry the loads imposed upon them. Too many decisions result in the replacement of historic material that could, in fact, remain in service without compromising structural integrity. This paper presents engineers and architects with the justification to retain more structural timber in existing buildings through a better understanding of visual grading.
Structural Reliability of Spanish Softwoods. A New Answer for an Old Problem
Authors: Nevado Miguel
Published: September 2013

A group of databases making a total of ca. 9.000 beams from coniferous trees from Spain, tested according EN 384 and visually graded according Spanish standards were analyzed. The main goal was to reach a detailed comprehension about the true state of nature of the three reference structural material properties (density, MOR and MOE), in the conditions it reaches the real market. Provided the existing beams (reasonably) came from the same populations, the use of reliability updating technics is a meaningful approach to the problem of conjecturing its resistant behavior. Distribution parameters for the target species have been proposed. Spanish softwood (with the exception of p. radiata) has proved to be extremely dense and quite stiff related to its resistance, compared with usual North American, Central or North European coniferous trees. Hence, the basic information of these last species should not be used when dealing with Spanish historical timbers, as it leads to rather uneconomical conjectures (as deformation and joints use to be design governing factors). Also therere significant differences related to the current Probabilistic Model Code suggestion on the topic (as the Code itself warns of).
Seismic Vulnerability of Timber Roof Structures: Classification Criteria
Authors: Parisi Maria A. , Chesi Claudio , Tardini Chiara
Published: September 2013

Criteria for assigning class values to different vulnerability indicators in a procedure for assessing the seismic vulnerability of timber roof structures are discussed here. The main issues concern grading the structural typology, the quality of the carpentry joints, the effectiveness of supports, the effect of strengthening interventions, if present, and the resulting global behavior.
XVIII Century Wooden Stretchers Structure Designed for Large Canvas and an Example of the Assessment Method
Authors: Górecka Katarzyna , Sklodowski Marek , Pawłowski Piotr , Szpor Joanna , Arendarski Henryk
Published: September 2013

Paper discusses large size canvas paintings stretching methods and deformations and damages specific for large canvas resulting from an incorrect stretching. Analysis of the preservation state of a wooden stretcher construction and its functionality was an important step in development of the program of conservation work. The case study of M. H Loders painting "Adoration of the Magi" (XVIII c.) from the cathedral Saint - Aubain in Namur (Belgium) is presented. The painting is exhibited 5,5 m above the floor and has a unique shape, as the wooden stretcher frame is adjusted to the round apse walls. Thus usual direct inspection was difficult due to poor access to the reverse side of the painting. Preliminary conclusions on the construction and preservation state of the stretcher frame were drawn on the basis of a thorough inspection of the painting surface. Actual shape of the painting and precise stretchers dimensions were measured with a laser scanner. More information concerning the stretcher frame construction was obtained from a simple micro-camera system combined with LED lighting introduced from the canvas reverse side.
In Situ Evaluation of the Reference Properties of Structural Timber Members. Use of Available Tools and Information
Authors: Machado José S.
Published: September 2013

Survey of existing timber structures often includes the need to allocate mechanical properties to structural timber members. This task has to take into account the huge variability of timbers properties (within and between species), characteristic that differentiates this material from other structural materials (e.g. concrete and steel). For many decades, and still now, the application of visual strength standards is the main or only procedure used for this task. Despite the large number of other non and semi-destructive technique developed their regular application to in situ assessment of timbers mechanical properties is still almost non-existent. The present paper discusses possible ways to use and combine information from visual grading standards and non and semi-destructive techniques to predict the reference properties of timber members in service. The discussion has in mind studies conducted over the last years and the information provided by different guidelines, standards or papers recently published.
Non-Destructive Tests and Bending Tests on Chestnut Structural Timber
Authors: Faggiano Beatrice , Grippa Maria Rosaria , Calderoni Bruno
Published: September 2013

In the context of a more wide research study for in situ mechanical identification of ancient timber structures by non-destructive techniques, the paper illustrates the experimental activity developed on structural elements made of old chestnut timber, 4x4x76 cm size: 24 squared specimens were extracted by six elements in actual dimensions, already used in a previous tests campaign. Non-destructive (ND: hygrometric, sclerometric and resistographic) and destructive (D: bending) tests were performed, the latter according to UNI EN 408 (2004) standard, in order to assess the mechanical properties and the collapse mechanisms of chestnut timber. Data gathered are presented in detail and, NDT-DT correlations, obtained through a linear regression approach, are provided to predict wood density, strength and modulus of elasticity of the tested members.
The Penetration Test to Evaluate Wood Decay after 20 Years Timber Structure Assessment Experience
Authors: Giuriani Ezio , Marini Alessandra , Cominelli Stefania , Gubana Alessandra
Published: September 2013

The Wood Penetration Test described in the present paper was set up almost 20 years ago to evaluate the timber vaulted roof decay of Palazzo della Loggia in Brescia (Italy). The test can be regarded as an extension to timber structures of the dynamic soil penetration test, as it is based on the insertion into timber structural members of a steel graduated rod, which advances by means of repeated constant energy blows transmitted by a rebound hammer. The test makes possible to distinguish between different degrees of decay as a function of the number of blows necessary for each centimetre layer penetration. This technique proved to be effective and reliable for investigating the extent and depth of wood decay and thanks to the assessment campaign the possibility of restoring the ancient vault gained strength. The test was then frequently proposed and adopted by the Structural Engineering Laboratory of Brescia University and several ancient building timber structures were checked by means of this methodology. Some significative examples will be briefly described. A recent investigation has been done on the rim beams at the basis of the Palazzo della Loggia timber vault by using the penetration test and the Resistograph and the comparison of the results is also illustrated.
The test is easy to perform and the output data can be interpreted very clearly by structural engineers: it is possible to determine the depth of the decayed layers and consequently the reliable dimensions of the resisting timber sections.
Investigation of Timber Members at the Marasyk Station in Prague by Non-Destructive Methods
Authors: Hasnikova Hana , Kuklík Petr
Published: September 2013

The Masaryk Railway Station is the oldest still working terminal railway station in Europe. It was built in 1845 and the buildings belonged to the most splendid railway stations in that time. During the long life the part of Masaryk Station burned, it was also damaged while World Wars and finally large reconstruction started last year. The buildings have a high historical value, so the specialists from National Heritage Institute wanted all the original structural members to be preserved. The structure was constructed from two wooden species spruce and fir. Selected timber elements were tested by various non-destructive methods to assess their health. Pilodyn, a device with iron stick can assess a material quality using correlation between depth of stick indentation and material strength. Sylvatest device operates with ultrasonic waves and can determine dynamic modulus of elasticity as one of the mechanical characteristics. Dynamoe device uses an acoustic wave to assess the material quality. The aim of the paper is to present the procedure of timber testing and to discuss measured results.
Nondestructive Evaluation of Timber Columns of a Capela Bridge in the State of São Paulo, Brazil
Authors: Ferro Fabiane Salles , Pigozzo Julio César , de Almeida Diego Henrique , Icimoto Felipe Hideyoshi , Borges de Macedo Laurenn , Calil Junior Carlito , Rocco Lahr Francisco Antonio
Published: September 2013

After years of exposure in environmental conditions, the wood is subject to decay by chemical, mechanical, physical and biological agents. Consequently its physical and mechanical properties can be reduced, affecting their use. Timber used in bridge sustention columns is subject to intense decay process, mainly in outcrop area (area in contact to the ground), the most critical situation, because of the best combination of humidity e oxygen, factors that provide wood decay organisms. Decay process can be minimized with preventive maintenance, as wood impregnation with preservatives, before installation of the timber. After wood is installed, a periodical maintenance is necessary to conserve and prolong its life time. Thus, the aim of this study is to evaluate degradation occurred in timber columns used in Capela Bridge sustention, built with mixed system of wood and concrete, after 10-years-old of use. Located in Piracicaba - SP, Brazil, the bridge was made with Corymbia citriodora CCA-treated. The columns strength and degradation conditions were evaluated in 2 points with isntrumented driller. Point A was approximately 1,5 m of the ground and point B was in outcrop area. Instrumented driller results showed that all the columns, in both points, presented good strength and had no degradation level.
Experimental Investigations of Material Properties of Timber Utility Poles Using Various Material Testing Approaches
Authors: Elsener Roman , Dackermann Ulrike , Li Jian Chun , Samali Bijan , Crews Keith
Published: September 2013

This paper presents an investigation of using different material testing approaches to determine material properties of timber utility poles from two hardwood tree species, i.e. Spotted Gum and Tallowwood. The material properties investigated are the Modulus of Electricity (MOE), the Modulus of Rupture (MOR) and the compression strength (CS) in longitudinal direction as well as radial and tangential directions of the cross section of the poles. These material properties are needed for the accurate modelling of timber poles using Finite Element Method (FEM) for the study of stress wave propagation and damage detection in timber utility poles. In open literatures, for most timber species such comprehensive material property data are scarce to find. Typically, material properties available are only in the longitudinal direction. Furthermore, most international standards cover only details on material testing in longitudinal direction and no coherent nor comprehensive guidelines are given for the testing of the full orthotropic material properties of timber. Hence, an extensive study is deemed necessary to investigate a suitable approach to determine full material properties of timber. Two hardwood timber species, namely Spotted Gum and Tallowwood are selected for this investigation. Beside full material properties, the investigation is extended to examine different material testing approaches (bending, compression and tension testing) for the determination of the same material properties. The presented material testing is conducted on numerous small clear specimens as well as on four full scale 5 m long timber pole specimens of the two mentioned hardwood tree species.
Correlating Visual Grading with NTD Methods for Assessing Timber Condition in Historic Buildings
Authors: Anagnostopoulou Vasiliki , Pournou Anastasia
Published: September 2013

This study aimed to develop, apply and assess a visual grading system that could evaluate the preservation state of historic buildings structural timbers and correlate it with three NDT methods that are widely used during diagnostic surveys. Assessing timber condition is crucial not only for the structural analysis of buildings, but also for reinsuring that well preserved original material of Cultural Heritage will not be lost. However, assessment based only on NDT results may be biased as it depends on many parameters such as i) the natural variability of wood ii) the type and degree of deterioration iii) the experimental conditions e.t.c. Furthermore, results obtained are not always coinciding and they are often unrelated to the macrosopic condition of timbers. Therefore, this work investigates comparatively a grading system developed based on European with results obtained from ultrasounds application, resistograph profiling and X-ray radiation. The three NDT techniques were tested on samples coming from a post Byzantine mansion in Athens, which presented various types and degrees of decay. For comparison reasons techniques were applied on sound wood of the same species also. Prior to NTD implementation, samples were conditioned in two different RH in order to examine the role of wood moisture on NTD results.
Microwave Reflectometric Tool for Non-Destructive Assessment of Decay on Timber Structures
Authors: Macchioni Nicola , Mannucci Massimo , Olmi Roberto , Palanti Sabrina , Riminesi Cristiano
Published: September 2013

Timber structures can be degraded during their life both by structural problems and, mainly, by biological degradation factors like fungi, and insects (Coleoptera and termites). The occurrence of these biodegradation agents leads, in the absence of appropriate maintenance interventions, to the loss of their structural integrity. Furthermore, if these biological agents decay old buildings, the loss of mechanical resistance of timber structures can be added to loss of cultural heritages. Just in these contexts an early evaluation of decay is crucial to design remedial treatments and a less invasive restoration intervention. This work presents a new microwave diagnostic system for the in situ evaluation of timber structures based on microwave reflectometry, i.e on the measurement of the microwave reflection coefficient as a function of frequency. The continuous-wave (CW) microwave signal is launched by a double-ridged antenna, which also measures the wave reflected by the material under investigation. The measurement system allows diagnosing the effects of biodegradation during a first quick survey in a non-destructive and non-invasive manner. Measurements on laboratory models demonstrated the feasibility of the method. Results obtained on timber beam sections, compared with the findings of traditional investigation methodologies, demonstrate the potentiality of microwave reflectometry, suggesting its usefulness for decay detection and as a support to invasive diagnostic tools.
Non Destructive Characterization of Wooden Members Using near Infrared Spectroscopy
Authors: Sandak Anna , Riggio Mariapaola , Sandak Jakub
Published: September 2013

On site characterization of wood members is a very challenging task, after considering all the variables affecting the whole structure itself and material used for construction. The up-to-data procedures are limited to few characterizations, and in general based on visual assessment supported by local drilling resistance analysis, stress-wave time of flight measurement and/or moisture content estimation. The goal of this work was to promote near infrared (NIR) spectroscopy as a supplementary tool providing additional information for the expert assessing timber structures. The paper presents several examples of successful NIR application in species recognition, physical properties prediction, evaluation of wood weathering and/or fungal degradation level. However, it must be stated that implementation of NIR in routine assessment protocols requires prior preparation of a dedicated databases of high precision reference values to build reliable, flexible and sufficiently generalized models.
A Symbolic Wooden Building in Istanbul: The Amcazade Hüseyin Pasha Reception Hall/Divanhane
Authors: Erdem Ayten , Gürsel Özcan
Published: September 2013

The Amcazade Hüseyin Paşa or Köprülü Reception Room / Divanhane is one of the old, important examples of Ottoman house architecture. This building on the shore of the Bosphorus in Istanbul was constructed to house the Austrian ambassador after the Treaty of Karlowitz (1699). Divanhane is the only surviving part of the summer palace complex built by Grand Vizier Amcazade Hüseyin Paşa. It was repaired in 1870, 1947, 1954, 1971 and 1978 to strengthen. However, because of these repairs the building lost some of its characteristics and was partially changed. Today, Divanhane is became a symbol both of Istanbul and the traditional buildings faced with the danger of being destroyed. In this study, the special details of this building that is faced with the danger of rotting because of its age will be researched and documented.
Estimation of Load-Bearing Capacity and Stiffness of Timber Beams with Through-Thickness Cracks
Authors: Naychuk Anatoly Yakovlevich
Published: September 2013

The results of experimental and theoretical study of the load-bearing capacity and stiffness of wooden beams with through-thickness cracks depending on their length and location throughout the height of cross-section are given. The analysis of the regularity of change of stress-strain state, stress intensity factors (SIF) and at crack tips, deflections and timber beams load-bearing capacity depending on beam span length versus cross-section height, crack length versus span length, crack location throughout beam height was made. It has been established that load-bearing capacity and stiffness of timber beams with through-thickness cracks depends not only on the crack length, but its location throughout cross-section height as well. Procedure of assessing load-bearing capacity and stiffness of timber beams with through-thickness cracks based on fracture mechanics methods is given.
Non-Destructive and Semi-Destructive Test Methods for Strength Determination of Aged Wood
Authors: Kraler Anton , Beikircher Wilfried
Published: September 2013

To what extent is there a change in the strength of wood over the course of centuries, when installed under a constant load? Are there non-destructive measurement methods for the determination of strength that are suitable for this investigation? These two questions were the starting point of this research project. Through experience we have learned that the strength of wood is dependent on the growth regions and climatic conditions in which it originates. For example, over centuries, in a northern Italian valley, there were commonly known and clearly defined areas which provided the wood for the construction of the local buildings. Another decisive factor for selecting this research region was that the buildings concerned had already been dated by means of dendrochronology. This created a unique situation in that the strength of the timber in these buildings, which cover about nine centuries (1250 to present), could be compared and analyzed. Local spruce and larch used in the construction typical of this region were selected for the investigations. Starting with 1250AD (the oldest dated wood construction) and in consecutive steps of 100 years, two projects (of the entire 18 projects) are selected and explored. Three non-destructive and respectively semi-destructive measurement methods were used for the strength testing. The measurement devices are: for drill resistance measuring IML-RESI F400S, for the fractometer tests (bending and compression tests) IML-Instrumenta Mechanik Labor Gmbh. For ultrasonic testing the device Sylvatest duo is used. So the validity of the measurement systems used could be brought into relation with the actual strength. Some small, flawless samples (without knots) from selected projects were removed and then tested in a laboratory with the universal testing machine Shimadzu 100KN.
Damage Assessment and Residual Service Life Estimation of Cracked Timber Beams
Authors: van de Kuilen Jan Willem G. , Gard Wolfgang
Published: September 2013

Service life modelling of cracked timber beams can be performed using modified damage accumulation models that describe the combined effect or long term loads (mechanical) and biological of physical wood degradation. The combined model allows for the estimation of residual service life and an analysis of crack development. The model can also be used to analyse safety factors that may need to be applied. Also, a sensitivity analysis can be performed for future risks. It is shown that the failure risk is very sensitive to the level of the applied loads, similar to time to failure analysis of non-degraded timber. Failure in timber structures occurs within a very short time frame. A practical case of cracked glulam beams is included in the paper.
Evaluation of the Load-Carrying Capacity in Bending of Large Cross Section “Pitch Pine” Beams in Standing Structures
Authors: Váquez Manuel C. Touza , Soilán Cañás Azahara , Lorenzo Fouz David
Published: September 2013

This paper deals with the procedure followed in order to define a visual grading protocol to determine the mechanical properties of existing old pitch pine timber beams with large sections. The commercial name pitch pine comprises several species in the group of southern yellow pines, being the Longleaf pine or Georgia pitch pine (Pinus palustris) the most important. Old growth Pinus palustris, was very much appreciated for its rigidity, density, strength properties and natural durability. In Spain, many of the buildings constructed with this timber (named as pino tea) are nowadays under rehabilitation processes which, in some cases, will change the previous use of the building. All these interventions require understanding the mechanical properties of the timber. The structural properties of the aged pitch pine timber are unknown and there is not any European stress grading standard to enable the classification of the existing elements. For this reason, a total of 45 large section pitch pine pieces were visually analyzed and graded according to Spanish standard UNE EN 56.544 [. After this, the beams were tested according to UNE EN 408 [ in order to determine their modulus of rupture and flobal modulus of elasticity. All beams were tested keeping their original positions in the building and a new classification system for old beams is proposed based on a reduced number of chief visual grading parameters and taking into account their position into the beam.
A Study on Timber Structural Elements of a Traditional Turkish House
Authors: Yilmaz Karaman Ozgul , Tanac Zeren Mine
Published: September 2013

Preservation of traditional settlements is an important issue of sustainable cultural heritage politics and this is an ongoing research to raise an argument on concept of restoration works going on in small scaled residential wooden structures in Turkey. Authors have had several analysis studies that identify the architectural and structural features as well as damage assessment of the house stock in Kula district. The main concept of the restoration work of selected cases is replacing the old timber structural elements with the new one, instead of treating them. In this study it is aimed to evaluate this renovation process by focusing the wooden elements. Destructive testing methods have been used on wooden elements that were obtained from Goldeliler House during the fieldwork to make a mutual evaluation for the quality of old and new samples.
An Evaluation of the Seismic Performance of a Traditional Timber Building in Istanbul, Based on the Material Deterioration, with the Finite Elements Method
Authors: Dışkaya Hülya , Ceylan Oğuz
Published: September 2013

This paper endeavors to identify the structural characteristics that render traditional timber buildings in Istanbul earthquake-resistant even ifthey are in a deteriorated state. A traditional timber building of approximately 110 years old located in the Historical Peninsula was selected as a subject for the finite elements model. According to the structural material analysis and the condition of the elements of the load-bearing system, three modelling criteria were chosen to classify the strength capacity of the building. These are: an undamaged (new) building, a 110 year-old building with material defects, and a building with structural decay and broken node points. Seismic data from the 1999 Adapazarı and Düzce earthquakes were used for the modelling. The relative floor displacements of the systems were investigated and theresults were evaluated by comparing the cross-sectional load-bearing capacities
Seismic Analysis of a 2-Storey Log House
Authors: Branco Jorge M. , Lourenço Paulo B. , Aranha Chrysl A.
Published: September 2013

The current paper deals with the analysis of the results yielded by a series of tests performed to evaluate the seismic behaviour of a model log construction. The study was based on an experimental investigation performed to improve the existing knowledge on log houses subject to seismic events. The main part of the experimental work is based on a full scale shaking table test, conducted on a two-storey log house designed by the Portuguese company Rusticasa® in compliance with design rules for timber buildings. The test was performed by the University of Minho within the framework of the SERIES Project Multi-storey timber buildings and was coordinated by the University of Trento, at LNEC, Lisbon, Portugal. The geometry of the specimen, the design of the test, the setup and the instrumentation layout are first presented in this paper. The test procedure was conducted in stages with maximum accelerations (bi-directional) of 0.07g, 0.28g and 0.5g. During this incremental test procedure, whenever damage occurred, identification tests were performed to assess any variation in the fundamental period of the house. The experimental results of each test have been analyzed and the resultant values of inter-storey drift, wall slippage and uplift measurements, shear deformations and hold-down forces measured are presented. Most importantly, the dynamic properties (fundamental period and mode shapes) of the system have been determined.
Traditional Seismic Construction Technology of the Turkish House 'Konak', Concentration of the Case Study 'Saraçlar Şehir House' in Safranbolu
Authors: Kerimcan Apak
Published: September 2013

In this study, the construction analysis of Turkish House Konak, was researched according to its traditional construction technology against seismic actions. Case study building was chosen from Safranbolu and construction datas were getting from different bibliography for receiving more informational data about their traditional construction technology. The traditional Turkish house construction technology against the seismicity was researched by concentrating the timber skeleton and its relation to the seismic forces that affect the structural behavior.The aim of this study was to understand the seismic precautions and seismic weakness of the traditional Turkish house structures that were done in the previous times.
Bamboo Reinforced Glulam Beams: An Alternative to CFRP Reinforced Glulam Beams
Authors: Echavarria Cesar , Echavarría Beatriz , Cañola Hernán
Published: September 2013

A research study was undertaken to investigate the mechanical performance of glulam beams reinforced by CFRP or bamboo. Local reinforcement is proposed in order to improve the flexural strength of glulam beams. The glulam beam is strengthened in tension and along its sides with the carbon fiber-reinforced polymer CFRP or bamboo. A series of CFRP reinforced glulam beams and bamboo reinforced glulam beams were tested to determine their load-deformation characteristics. Experimental work for evaluating the reinforcing technique is reported here. According to experiment results, the CFRP and bamboo reinforcements led to a higher glulam beam performance. The results show a considerably improved stiffness of the reinforced over the non-reinforced specimens. By using CFRP and bamboo reinforcements several improvements in strength may be obtained.
Analysis of Wood Laminated Beams Reinforced by Natural Fibres
Authors: Mascia Nilson Tadeu , Mayer Raul Martini
Published: September 2013

This paper presents an analysis on the viability of the use of natural fibres, in particular sisal fibres, as a reinforcing material in wood laminate structures. The use of natural fibres associated to the manufacturing of beams, with wood from reforestation, is in accordance with the current economic interest and ecological appeal. Sisal fibres have attracted attention for presenting adequate mechanical characteristics for such application. The laminated beams used in this research were constituted byPinus spand were reinforced by sisal strips with a thickness of 2 mm glued by Epoxi adhesive on bottom of the beam on the tensile region. Each lamina had the following dimensions: width of 50 mm, height of 20 mm and the length of the beam is 1.5 m. For the theoretical analysis of wood laminate beams three models: stress functions, classical lamination theory and section transformed method are carried out. It was noted that the average differences between the theoretical results and experimental data are given by: 11% and 2 % for normal and shear stresses respectively, and around 8%, for displacements. As a conclusion, the strengthening of wood laminate beams with sisal fibres is effective in wood structural elements, in which the elastic modulus is at maximum equal to these fibres and also prevents fragile failure on critical tensile region.
Wood Glass-Fiber Reinforced Polyester (GFRP) Hybrid Cross-Section Used to Improve the Structural Behavior of Timber Beams
Authors: Lanivschi Cristina E. , Decher Emanuela
Published: September 2013

Composite systems used for increasing the load bearing capacity of timber structural elements are of special interest for engineers, basically because of their beneficial weight/strength ratio. By creating a hybrid cross section composed of wood and interposed GFRP lamellae, the improvement of wood limited elastic properties may be achieved, considering the compatibility between composite materials matrix, thermosetting unsaturated polyester resin, and wood.
The main objective of the paper is to carry out an experimental study on the technical solution represented by associating these two materials with similar structures, both pertaining to the class of composites reinforced with long fibres and bonded, for the case of wood by lignin and hemicelluloses and for the case of GFRP by unsaturated polyester resin. The experimental program consists in performing the bending test of timber beam type structural elements, considering two types of cross-sections, the first being composed by joining three timber boards of 25x100x1900 mm by aid of screws and the second, with wood/GFRP hybrid cross-section, having the same number of timber boards as specified above joined together by two 3...5x100x1900 mm GFRP interposed lamellae.
Determination of some physical and mechanical properties, in the laboratories of Faculty of Civil Engineering and Building Services, Iasi, Romania and the obtained results are comparatively presented for the two types of tested beams, the final step of the paper consisting in optimizing the technology involved for execution of the hybrid structural element.
Typical Failures, Seismic Behavior and Safety of the “Bourbon System” with Timber Framing
Authors: Ruggieri Nicola , Tampone Gennaro , Zinno Raffaele
Published: September 2013

All the research on the behavior and failure of specimens of the Bourbon System, masonry with timber framing, has been done on early 1900 C photographic records. The photos show some case baraccate damaged by the 1905 and 1908 seismic events. The damage is recorded also in the official documents of the technicians sent from Rome, just like Commissione del Genio Civile [, including Canevazzi and Panetti. More data come from Baratta punctual description [ who visited Calabrian towns damaged in the 1908 earthquake. Other news has been taken out from some old chronicles regarding timber frame buildings before 1783.
Mechanical Evaluation of Timber Conservation Processes by Bending Tests
Authors: Henriques Dulce Franco , Nunes Lina , de Brito Jorge
Published: September 2013

This paper presents the laboratory work performed with the purpose of understanding the mechanical performance of 340x20x20 mm maritime pine wood samples degraded by rot fungi when treated with a biocide product followed by consolidation through impregnation with a polymeric product.Four commercially available products were used: a water-based biocide, BC, a solvent-based biocide, X, an acrylic consolidant, PB (PB 72), and an epoxy-based consolidant, E.Seven sets of specimens each one having a varied range of fungal degradation were prepared. Then the product combinations were applied by brush to six sets of specimens (E, X-E, BC-E, PB, X-PB, BC-PB) of which one was left untreated for control, 0-0. Finally all sets were subjected to static bending strength test until rupture.Results showed that the acrylic and epoxy-based products lead to increased mechanical capacity of the consolidated wood up to 100% in some cases in specimens with 70% of MOE loss. The results presented the same order of magnitude for both wood consolidants. The previous application of biocide did not have a significant impact in the behavioral pattern of the consolidant: a marked improvement of the bending strength of the degraded specimens after treatment and consolidation. These results demonstrated the feasibility of combining biocide/consolidation products, and provide indications of interest to the application of this technique to extend the lifespan of wood elements moderately degraded by fungi in old buildings.
Lateral Resisting Experiment of Prestressed-Tube Bolted Connection for Post-and-Beam Timber Construction
Authors: He Min Juan , Zhao Yi , Ma Ren Le
Published: September 2013

Connections are key elements and the weak points for timber structures. The most commonly used bolted timber connections with slotted in steel plate have low lateral stiffness and poor ductility in post-and-beam construction. This paper introduces the prestressed-tube bolted connection to alleviate this problem. To evaluate its lateral resisting performance, the failure mode, strength, lateral stiffness, ductility, hysteresis curve and equivalent viscous damping ratio of the ordinary and improved connections, as determined by the monotonic and reversed cyclic loading test, are compared. The results demonstrate that the lateral stiffness of the prestressed-tube bolted connection has been significantly improved, and its ductility is also better than the normal bolted connection with no decrease in the ultimate moment resisting capacity. It is believed that the semi-rigid prestressed-tube bolted connection, as an alternative to current bolted solutions, may provide reasonable lateral stiffness and has good potential for use in post-beam timber construction.
Numerical Analysis of a Rigid Node of a Spatial Timber Frame Made of Structural Elements with Built-up Cross-Sections
Authors: Lanivschi Cristina E. , Secu Alexandru , Atanasiu Gabriela M.
Published: September 2013

Considering wood currently used in construction domain, it may be observed that it possesses good strengths, but reduced modules of elasticity. This drawback may be prevented by creating structures with rigid nodes or by using hybrid or composed cross-sections for the structural elements.The paper consists of numerical analysis of a timber frame with rigid nodes, assuming composed cross-sections for the structural elements, made of four props with cross-sectional dimensions of 0.1x0.1 m each - for columns and two chords of 0.1x0.1 m each - for beams.Analyzing this type of structures by considering equivalent cross sections` properties of the structural elements, the real phenomena may not be covered, since it doesn`t consider all elastic characteristics of wood, resulting in different stress` distribution in the structural elements.The analyze of this structure considering both real solid cross-sections and all elastic properties of wood by using specialized software, leads to a laborious work because of the high number of finite elements. Thereby, a two-step analysis is proposed: the first one consists in solving the spatial timber frame with bar type finite elements and the elastic properties parallel to the grain, as provided by design codes. In the second step, an intermediary node is detached and loaded with the internal forces obtained from the first step, considering all elastic parameters of wood and using solid type finite elements.Currently, in the design process, only the first step in performed. The two-step analysis aims to compare the results with those obtained using the strength of materials methods, relieving the necessary corrections in the case of one-step design process.
Novel Nail-Like Wood Connectors
Authors: Riggio Mariapaola , Pauliny Dusan , Sandak Jakub , Sandak Anna
Published: September 2013

In traditional timber structures, hardwood connectors such as a nails, wedges, dowels and pegs have been used as reinforcement of carpentry joints or to fix wooden ceiling matts or floor boards. In the study reported, the possibility to rely on enhanced mechanical and technological properties of densified wood, for the production of wooden nails to be used in the repair of traditional timber structures is discussed. The wood used for connectors were domestic wood species; ash, beech, black locust and poplar. Wooden blocks were exposed to densification procedure with the purpose of increasing the materials density, dimensional stability and possibly, improve durability and selected mechanical properties. The densification ratio varied between 50 and 67%. A dedicated research has been performed in order to determine the effect of densification on the compression behavior of wood in the form of nails. The progress of pushing force during insertion of the wooden nails into wood samples was also monitored and served for insertion process control. A preliminary series of push-out tests have been carried out on timber-to-timber joints assembled with the densified nails.The results obtained show potential for using the novel wooden nail connectors for substitution or integration repair works in traditional timber systems.
Ultra-Thin Topping Upgrades for Improved Serviceability Performance
Authors: Skinner Jonathan , Harris Richard , Paine Kevin , Walker Peter , Bregulla Julie
Published: September 2013

Timber floors can be refurbished by connecting a concrete topping to the timber joists; stiffening the floor and reducing serviceability problems, including vibration. Research to date has focused on upgrade solutions with relatively thick toppings (40mm or greater). This paper presents a novel, ultra-thin topping solution where the topping is placed at a thickness of 20mm or less. Advantages of the solution include: reducing the mass added to the existing structure and minimising the change in floor to ceiling height whilst delivering a significant increase in floor stiffness. This paper reports the findings from the serviceability testing of an upgraded, full scale timber floor. Measurements prior to and after the upgrade are compared, including: elastic testing under static loads, vibration testing and short-term bending tests. The paper also compares the results with simple analytical approaches and design limits prescribed in Eurocode 5 Part 1-1.
Seismic Behaviour and Retrofitting of Timber Frame Walls
Authors: Poletti Elisa , Vasconcelos Graca
Published: September 2013

Half-timbered buildings are well known as one of the most efficient seismic resistant structure in the world, but their popularity is not only due to their seismic performance, but also to their low cost and the strength they offer. These structures generally consist of exterior masonry walls with timber elements embedded which tie the walls together and internal walls which have a timber frame with masonry infill and act as shear walls. Generally, different types of infill could be applied to half-timbered walls depending on the country, namely brick masonry, rubble masonry, hay, mud, etc. The focus of this paper is to study the seismic behaviour of the walls when no infill is present, i.e. considering only the timber frame, and then compare the results with those of the infill walls.
Static cyclic tests have been performed on unreinforced timber frame walls and appropriate strengthening solutions have been applied in order to test the walls in a retrofitted condition, namely (1) steel plates with different configurations and (2) steel flat bars inserted with the NSM technique.
Development of Wood-Based Multi-Layer Systems in Existing Building Stock
Authors: Fadai Alireza , Winter Wolfgang , Stefanoudakis Dimitrios , Hollinsky Karlheinz
Published: September 2013

The possible significance of natural building materials and their application in the existing building stock is the question of overriding importance and was explored on two levels: 1) Developing wood-based building components and optimizing manufacturing processes;2) adapted design methods, structural analysis of historical wood-based structures and respectively of contemporary structural concepts especially according to fire and earthquake. This paper illustrates the development and application of wood-based multi-layer shear wall and floor systems in existing building stocks. Several cases of mixing different material elements use for shear walls and floor constructions are presented.