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Vibration performance of a one-way simply supported timber-concrete composite (TCC) floor section has been studied using analytical as well as numerical methods. Focal points have been verification and validation of results from analytical and numerical calculations of vibration response based on experimental data. For the analytical calculations, floor bending stiffness and vibrational response are determined from methods proposed in the current and revised versions of Eurocode 5. The numerical calculations based on the finite element (FE) method are done using 3D solid elements with orthotropic material parameters. When comparing the results of the FE analysis, better agreement with the experimental data is reached for the fundamental frequency when 3D solid elements are used rather than 3D beam elements. Furthermore, better agreement with the experimental data is reached for RMS acceleration by FE analysis rather than the method based on Eurocode 5. For detailed analysis, the authors suggest performing dynamic FE analysis and calculating vibration response from the TCC floor's modal responses as eigenmodes and natural eigenfrequencies below 40 Hz. For future studies, it is recommended that the verification of vibration response may be accomplished by applying standard EN 16929.

The use of composite beams made with traditional concrete and bio-based materials (such as timber and bamboo) is a valuable solution to reduce the environmental impact of the building sector. Timber-Concrete Composite (TCC) beams have been used for decades in structural applications such as new buildings, refurbishment of old timber structures, and bridges. Recently, different researchers suggested composite beams based on engineered bamboo, commonly named Bamboo-Concrete Composite (BCC) beams. This study presents a systematic comparison of structural performances and connection behavior of TCC and BCC beams under short-term static load. TCCs beams are compared to BCC ones using similar shear connectors. The most important aspects of the two composite systems are compared: mechanical behavior of connectors and structural behaviors of full-scale composite beams (e.g., failure modes, connection stiffness, connection shear strength, ultimate load-carrying capacity, maximum deflection and composite efficiency). This comprehensive review indicates that BCC beams have similar or even better structural performances compared with TCC.

Publisher Copyright: © 2022 The Authors Design of modern timber floors is often governed by the vibration serviceability requirements. One way to improve vibration serviceability is through the design of two-way floor systems. In this paper, the behaviour of two-way LVL–concrete composite plates and a plate strip is investigated experimentally, with an emphasis on the performance of proposed dovetail joint for connecting the adjacent LVL panels. The investigations consist of the experimental modal analysis and static load deformation tests, performed under multiple support conditions. The results show a significant two-way action, indicated by about 45% higher fundamental natural frequency when four edges are supported instead of two. The point load deflection in the centre of the plate was reduced of about 9%. Furthermore, a numerical model for two-way TCC plates was developed and results show a wide agreement with the experimental behaviour, except for discrepancies related to deflections on the plate edge. The results from the experimental and numerical investigations indicate that the dovetail joint can produce a stiff connection, such that the LVL layer could be regarded as continuous in the connected direction.

This study aims to present a multi-criteria decision analysis (MCDA) for comprehensive performance evaluation of the alternative design of timber–concrete composite (TCC) floor system. Considered objectives are serviceability and sustainability performance with associated criterion as (1) comfort class regarding springiness and vibrations, (2) architectural quality with associated criterion as open spaces, (3) environmental aspect with associated criterion as CO2 emissions and (4) cost aspect with associated criterion as the total costs. Analytical Hierarchy Process (AHP) and Complex Proportional Assessment (COPRAS) as the methods in the multi-criteria analysis have been combined for (1) determining the weighting of criteria based on the survey results, (2) verifying the consistency ratio of decision matrix made by experts and (3) for ranking and selecting the optimal concept design among design candidates. According to the results, the TCC floor with the span length of 7.3 m belonging to comfort class A has got the highest ranking. However, sensitivity analysis indicates that the TCC floor with a 9.0 m span length belonging to comfort class A shall be selected as the optimal concept design. The study contributes by developing a complete concept design tool for TCC floor systems using AHP combined COPRAS methods to handle both beneficial and non-beneficial criteria.

Työn tavoitteena on laatia ohjeet CLT–betoni-liittorakenteisten laattojen rakennemitoitukseen sekä voimassa olevat että tulevat Eurokoodit huomioiden. Ohje on erityisesti tarkoitettu käytettäväksi vanhojen Eurokoodien voimassa ollessa, mutta sitä voi käyttää viitteellisenä ohjeena myös Eurokoodien päivittyessä. Tällöin suunnittelijan on kuitenkin varmistettava kaavojen ja ohjeiden pätevyys, sillä ne ovat saattaneet päivittyä. Myös CLT- ja liitostoimittajien tuotekohtaisten teknisten standardien voimassaolo pitää tarkastaa. Työssä on esitetty laatan kuormitukset ja kuormitusyhdistelmät nykyisten Eurokoodien EN 1990 ja EN 1991 mukaan. Kuormien ja yhdistelmien arvoissa ja kaavoissa on kerrottu Eurokoodin suositusarvot sekä Suomen kansallisten liitteiden arvot ja valinnat. Lisäksi on esitetty betonin ja CLT:n kutistumien ja lämpö- sekä kosteusliikkeiden kaavat sekä näistä aiheutuvien rasitusten laskentakaavat. Käytännössä usein ainoa huomioitava liike on betonin kuivumiskutistuma, joka aiheuttaa jopa 30–50 % lopputaipumasta. Viruman vaikutus jännityksiin ja taivutusjäykkyyteen on huomioitu käyttämällä pitkäaikaisten kuormien osuudelle jäykkyysominaisuuksien tehollisia arvoja. Betoni viruu puu–betoni-liittorakenteessa enemmän kuin normaalissa teräsbetonirakenteessa. Sen lopullisen kimmokertoimen arvo viruville kuormille saattaa olla vain 20 % alkuperäisestä. Betonin viruman ja kutistuman rajoittamisella olisi suuri merkitys poikkileikkaukselle varsinkin suurilla jänneväleillä. Poikkileikkauksen taivutusjäykkyyden laskennassa on huomioitava leikkausliitoksen ja poikittaislamellien leikkausmuodonmuutos. Tässä työssä se on tehty laajennetulla gamma-menetelmällä. Menetelmä osoittautui soveltuvan erinomaisesti monikerroksisille liittolaatoille. Työssä on esitelty CLT:n ja betonin välisten leikkausliitosten mitoitustapoja teknisten hyväksyntöjen sekä uusien Eurokoodien luonnosten mukaan. Nykyisen EN 1995 tai sen Suomen kansallisen liitteen mukaiset värähtelymitoitusohjeet eivät sovellu matalataajuuslattioille, jollaisia CLT–betoni-liittolaatat usein ovat, joten työssä on esitelty myös uuden EN 1995 luonnoksen mukainen värähtelymitoitus. Murtorajatilan mitoitus on esitetty tapauskohtaisesti nykyisen tai tulevan Eurokoodin luonnoksen mukaan. CLT:n palomitoitus on esitetty valmistajien sekä tulevan Eurokoodin luonnoksen mukaan huomioiden CLT:n lamellien mahdollinen delaminoituminen. Tyypillisesti laatan mitoittaa lopputaipuma. Tämän takia tutkittiin erityisesti liittolaatan sekä kimmoiseen että lopulliseen taivutusjäykkyyteen vaikuttavia tekijöitä. Tutkimuksessa havaittiin, että tyypillisesti selvästi jäykimpään liittopoikkileikkaukseen päästään CLT-levyllä, jonka alimmainen kantava kerros on paksu ja jossa on pinta-alaltaan paljon kantavaa lamellia. Tämä voidaan saavuttaa esim. liimaamalla samansuuntaisia lamelleja päällekkäin uloimpiin kerroksiin. Loviliitos on tyypillisesti jäykin tutkituista leikkausliitoksista. Myös erilaisten valutuentojen vaikutuksia tutkittiin. Tutkimuksen perusteella esitettiin eri jänneväleille esimerkkirakenteet. Liitteessä A on tutkitun esimerkkirakenteen laskelmaraportti, joka on toteutettu työn ohessa tehdyllä Excel-mitoituspohjalla. The purpose of this thesis is to establish a guideline for dimensioning CLT–concrete floors, while considering both the existing and upcoming Eurocodes. The guideline is specifically meant to be used with existing Eurocodes, but it can be used as a reference later. However, the designer must ensure that they follow the new Eurocodes, as the formulae and instructions may have been updated. Also, the latest technical documents and approvals must be used. The loads and load combinations have been presented according to existing Eurocodes EN 1990 and EN 1991. Both recommended and national Finnish values and choices are given. A method is presented to calculate the effects of inelastic strains, such as concrete shrinkage, which is usually the most significant by far, causing up to 50 % of the final deflection. The effects of creep are considered by using effective stiffness properties of timber, concrete and shear connectors for quasi-permanent loads. Concrete has higher creep in timber–concrete structures than in reinforced concrete structures. Its final effective modulus of elasticity may be as low as 20 % of its original value. The rolling shear deformation and the slip of shear connectors must be considered when calculating bending stiffness. This is done here with the extended Gamma method, which applies well with multi-layer composite slabs. This study presents different shear connectors and their dimensioning according to their European approvals or the upcoming Eurocodes. The current EN 1995 or its Finnish national annex’s vibration analysis don’t apply to low-frequency floors, which is often the case for CLT-concrete floors. This study suggests using the vibration analysis of the upcoming EN 1995 even before its passage. Calculation of the charring of CLT is presented according to existing guidelines from manufacturers and the upcoming Eurocode EN 1995-1-2, which takes possible delamination into account. Usually the final deflection was found to be the most demanding criterion for the slab. Therefore, the elastic and final bending stiffnesses and their factors were studied. It was found that CLT elements with thick bottom layers and small transverse layers were usually the stiffest choice by far. The notched connection was usually the stiffest out of the studied connections. The effects of propping were also studied. A list of example structures with different spans was made. A calculation report of an example structure that was studied is found in appendix A. The report was made with an Excel-based calculation tool that was developed during this thesis.

The subject of the article is to monitor the changes of moisture on the contact surface concrete and timber part of the composite timber-concrete beam. The moisture directly affects the properties of timber and causes its volume changes and degradation processes. These effects reduce of durability and load capacity of the structures. The beam was placed at the exterior. The observed contacts of the beam are often critical on real structures, as it is difficult to repair and maintenance in the case of increasing moisture or intrusion of dirt. The experiment was used to monitor and evaluate the dependence of changing moisture in contacts depending on ambient environmental conditions. Web of Science 65 6 924 917

Publisher Copyright: © 2021 The Author(s) This paper presents a two-dimensional interface model for timber-concrete contacts, that has been developed based on the empirical observations from a set of friction tests and additional micromechanical assumptions. In tangential direction, the interface model accounts initial bonding and debonding between the surfaces, different static and kinetic friction as well as smooth transition between them, effects of load reversal, pressure-dependence in friction and sticking stiffness and slip softening over increasing cumulative slip. In normal direction, simple linear cohesive and pressure-overclosure behaviour is assumed. The model has been formulated in cohesive-frictional interface framework, coupling damage-based cohesive behaviour with elastoplasticity-based frictional behaviour. The model has been tested in various cases and verified by comparison on a set of 27 tests on timber-concrete contact pairs under cyclic loading with varying normal pressure and multiple different material pairs. The interface model is able to capture relevant parts of the experimentally observed tangential behaviour, indicating suitability to present timber-concrete interface behaviour under cyclic loading. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

In der heutigen Zeit steigt das Bestreben nach ���nachhaltigem Bauen��� immer mehr. Durch diesen Trend r��cken zus��tzlich zu den ��konomischen auch die ��kologischen Faktoren immer weiter in den Fokus des sozialen Interesses, wodurch der Einsatz von heimischen H��lzern auch f��r tragende Komponenten im Hochhausbau in Ballungsr��umen verst��rkt wird. Diese Anwendung bringt zus��tzlich zu den statischen Kriterien auch eine Reihe hoher Anforderungen in den Bereichen Brandschutz, Schallschutz, Schwingungsreduzierung, etc. mit sich. Im Zuge dieser Diplomarbeit soll eine Holz-Beton-Verbund-Decke entwickelt werden, die zum Einsatz bei Holzhochh��usern f��r den B��robetrieb im urbanen Raum geeignet ist. Dabei sollen Spannweiten zwischen 8 und 12 Metern abgedeckt werden und als Holzkomponente der Hochleistungs-Holzwerkstoff Furnierschichtholz (LVL - Laminated Veneer Lumber) eingesetzt werden. Zu Beginn werden die hohen konstruktiven Anforderungen an tragende Bauteile im Holzhochhausbau aus den g��ltigen Richtlinien und Normen recherchiert und ��berlegungen zur bestm��glichen Umsetzung mit Hilfe der Holz-Beton-Verbund-Technologie angestellt. Anhand des definierten Anforderungsprofils wird eine Parameterstudie durchgef��hrt, mit dem Ziel eine ressourceneffiziente L��sung f��r die untersuchten Spannweiten zu finden. Dabei wird die Ressourceneffizienz im Sinne der Gesamtheit untersucht, d.h. die Konstruktion, die Konstellation der Materialen und die Bauweise werden betrachtet. Um die statische Bemessung im Zuge der Parameterstudie m��glichst realit��tsgetreu auszuf��hren, werden experimentelle Untersuchungen in Form von Kleinteile-Scherversuchen durchgef��hrt. Dabei werden Werte f��r die Tragf��higkeit und das Verschiebemodul f��r den nachgiebigen Verbund zwischen Furnierschichtholz und Beton mittels stiftf��rmigen Verbindungsmittel eruiert. Diese dienen als Eingangsparameter f��r die statische Bemessung der Holz-Beton-Verbund-Decke. Zum Schluss wird eine Vergleichsstudie zwischen den ermittelten L��sungsvarianten f��r die Spannweiten 8 bis 12 Meter durchgef��hrt und die im Zuge der Arbeit erlangten Erkenntnisse und Ergebnisse diskutiert und kritisch betrachtet., Nowadays the desire for "sustainable building" is increasing more and more. Besides economic factors, the environment is therefore becoming more relevant to the social conscience. Local wood is also increasingly being used in load-bearing components in high-rise buildings in urban areas. In addition to the static criteria, this practice brings with it a number of stringent requirements, such as fire protection, sound insulation, vibration reduction, etc. This thesis aims to develop timber-concrete composite floors for use in timber high-rise buildings for office purposes in urban areas. Spans between 8-12 meters will be covered and used as wooden components of the high-performance material laminated veneer lumber LVL. First, the high structural requirements for load-bearing components in timber high-rise buildings will be researched using the valid guidelines and standards. Thereafter, considerations will be made to find the best possible implementation with the help of timber-concrete composite technology. Based on the defined requirement profile, a parameter study will be done with the aim of finding a resource-efficient solution for the examined spans of the ceiling. This process will investigate the resource efficiency in terms of the construction of the cross-sectional dimensions, the constellation of the materials and the method of construction. In order to perform the static design as part of the parameter study, as realistically as possible, experimental investigations will be carried out in the form of shear tests. The idea is to get values for the load capacity and the module of displacement for the composite between laminated veneer lumber and concrete connected by bolt-shaped connecting means. These values are used as input parameters for the static design of the timber-concrete composite floors. Finally, a comparative study is done for the different solution variants of the investigated span-range from 8 to 12 meters. To conclude, the findings and results are discussed and considered critically.

IBK Bericht, 371

This paper presents results of the laboratory tests of timber-concrete structural connectors applicable (but not limited to) road/pedestrian bridges. The tested elements are discrete circular hollow section connectors installed in the pre-drilled slots of a glulam. Symmetrical push-out tests are conducted for two groups of connectors: 1) with wood core not removed; no interlayer between wood and concrete; 2) concrete in-fill core instead of the wood core; waterproofing membrane interlayer between concrete and timber elements. Main structural parameters of the connectors are established including ultimate shear capacity and slip modulus. Relationship between the connector’s stiffness and ultimate shear capacity is established and failure mechanisms are briefly discussed.

The paper reports the results of a comprehensive experimental test performed on a 6 m span timber-concrete composite beam with glued re-bar connection. The beam had first been subjected to sustained load in unsheltered outdoor conditions for 5 years. Eventually a ramp loading test up to failure was performed. The long-term test showed an increase in deflection mainly during the first two years, while the slip rose during the whole testing period. Thermo-hygrometric variations of environment caused an important fluctuation of all quantities on both yearly and daily scale. By comparing experimental and analytical results, it is highlighted that composite beams in outdoor conditions should be assigned to the 3rd service class according to the Eurocode 5 (EC5). Analytical predictions based on approximate formulae suggested by such regulation are found to be not conservative for the long-term behaviour and fairly accurate for the collapse behaviour. Since the simplified formulae proposed by the latest versions of the EC5-Parts 1.1 and 2 largely underestimate the actual connection stiffness and strength, it is recommended that realistic values of these properties, such as those obtained through push-out tests, be used when designing timber-concrete composite beams.

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridge, as well as in the building construction for the design of wood-concrete floor systems. The Navier laboratory has been working for many years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors (metal connectors), this assembling technique does ensure an almost perfect connection between wood and concrete. Previous work has already shown good performances of glued wood-concrete composite structures in terms of mechanical fatigue. However, the bonding connection requires additional research on the long-term behaviour of glued wood-concrete composites, especially when this structure is subjected to variable hygrometric conditions. The work undertaken during this thesis aims at determining the factors which induce damages on these glued wood-concrete assemblies under hygrometric loading; the research is divided into 3 parts:-Two experimental parts:(1)"Push-Out" shear tests conducted in collaboration with the Departmental Laboratory of Autun, were used to assess the effect of the elastic properties of the resin on the shear strength of the assembly. This experimental study aims at validating the adhesive of choice for this kind of connection, taking into account ageing under variable hygrometric conditions. Analysis is based on maximum shear capacity and on the failure mode of the assembly. (2)In addition to shear tests, the effect of hygrometric loading on the durability of glued wood concrete assemblies was examined. The analysis of the hydric behaviour of the structure was carried out by the digital image correlation (DIC) technique on small-sized glued wood-concrete assemblies. The measurements of the local deformations allowed us to locate areas of damage, particularly due to the hydric deformations of the wood prevented by the glued connection The effects of the elastic properties of the resin, the microstructure of the wood (including its structure and the direction of the annual rings) as well as the mechanical behaviour of the concrete material were examined.- A numerical part:(3) A numerical finite element model was validated by comparing the numerical results to the deformation maps experimentally obtained. Numerical analysis was used to quantify the stresses induced to the structure, in relation to hydric deformations prevented by glued connection. Moreover investigations at the full scale were conducted to evaluate the long-term behaviour under variable hygrometric conditions. These investigations were conducted in order to offer solutions aiming at optimizing this type of connection, and to define conditions for use of these glued assemblies; La mixité bois-béton est une solution intéressante dans le domaine des ouvrages d'art pour la réalisation de ponts, et dans le domaine du bâtiment dans la confection de planchers mixtes bois-béton. Le laboratoire Navier travaille depuis plusieurs années au développement du procédé par collage appliqué aux structures mixtes bois-béton. En effet, cette technique d'assemblage permet d'assurer une connexion quasi-parfaite entre le bois et le béton, contrairement aux techniques d'assemblage usuelles (connecteurs métalliques). Des travaux antérieurs ont montré la bonne performance de structures mixtes collées bois-béton du point de vue de leur tenue mécanique en fatigue. Cependant la connexion par collage nécessite une étude complémentaire concernant la durabilité de l'assemblage collé bois-béton, en particulier lorsque la structure mixte est soumise à des conditions hygrométriques variables. Les travaux menés pendant la thèse ont pour objectifs de déterminer les facteurs qui influent sur la tenue de ces assemblages collés sous chargement hydrique ; ils se divisent en 3 parties :-Deux parties expérimentales :(1)Des tests de cisaillement « Push-Out », en collaboration avec le Laboratoire Départemental d'Autun, ont permis d'évaluer l'effet des propriétés élastiques de l'adhésif sur la tenue en cisaillement de l'assemblage. L'objet de cette étude expérimentale est de valider un choix de colle pour ce type d'assemblage, prenant en compte un vieillissement hydrique, en se basant sur la capacité maximale atteinte en cisaillement, et le mode de rupture de l'assemblage. (2)Parallèlement aux tests de cisaillement, l'effet de chargements hydriques sur la tenue d'assemblages collés bois-béton a été étudié. L'analyse du comportement hydrique de la structure a été réalisée par la technique de corrélation d'image (DIC) sur des assemblages bois-béton collé de petite taille. Ces mesures de déformations locales ont permis de localiser des zones d'endommagement liées notamment aux déformations hydriques du bois empêchées par l'interface collée. Les effets des propriétés élastiques de l'adhésif, de la géométrie du bois (notamment sa structure et le sens des cernes par rapport au plan de collage) ainsi que du comportement mécanique du matériau cimentaire ont été étudiés.-Une partie numérique :(3) Un modèle numérique par éléments finis a été validé en comparant les résultats numériques aux cartes de déformation obtenues expérimentalement. L'analyse numérique a permis de quantifier les contraintes induites au niveau de l'interface en relation avec les déformations hydriques empêchées par l'interface collée et de prévoir le comportement à l'échelle 1 de structures mixtes. Ces différentes investigations ont permis de proposer des solutions optimisant ce type de connexion et de définir des conditions de mise en œuvre et d'utilisation de ces assemblages

Made available in DSpace on 2014-06-11T19:25:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-11Bitstream added on 2014-06-13T18:53:17Z : No. of bitstreams: 1 moraes_vm_me_ilha_prot.pdf: 4456756 bytes, checksum: 70a028ea28db2cfaed1abecec234c525 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) As pontes mistas com vigas de madeira e tabuleiro de concreto, que constituem uma técnica já bastante estudada pelo meio acadêmico brasileiro, vêm ganhando cada vez mais espaço entre os projetistas e construtores de pontes em estradas vicinais do interior do Brasil. Entretanto, o vão dessas pontes é limitado pelo comprimento das peças de madeira, cujos valores máximos, em geral, ficam em torno de 6 metros para vigas serradas e 12 metros para vigas roliças. Neste contexto, a presente pesquisa propõe um novo sistema estrutural de pontes mistas para vencer vãos da ordem de 15 a 20 metros, constituído por vigas treliçadas de madeira que suportam a laje de concreto armado. O tabuleiro do sistema proposto pode ser executado utilizando, como pré-laje, painéis treliçados pré-moldados auto-portantes, evitando-se escoramentos e, conseqüentemente, reduzindo o tempo e os custos de construção. A laje final é solidarizada às treliças de madeira por intermédio de pinos metálicos de cisalhamento, que fazem com que ambos os materiais trabalhem solidariamente na resistência aos esforços solicitantes, buscando, portanto, a otimização do uso estrutural desses materiais. A principal abordagem desta pesquisa é experimental, com a construção e análise de um modelo físico reduzido na escala 1:4... Timber-concrete composite structures - TCCS - constitute a technique well studied by the Brazilian academy and have been each time more present among the designers and constructors of bridges in secondary roads in the interior of Brazil. However, the span of these bridges is limited by the length of the timber beams, whose maximum values, in general, are around 6 meters for sawed beams and 12 meters for round beams. In this context, the present research suggests a new structural system of composite bridges, to overcome spans from 15 to 20 meters, built by trussed timber beams that support a reinforced concrete deck. The deck of the system can be executed using precast self-supported trussed panels, preventing props and, consequently, reducing time and costs of construction. The final slab is connected to the trussed beams by metallic shear bolts, which make that both the materials (timber and concrete) work together in the resistance to the requesting efforts, aiming the optimization of the structural use of these materials. This research was based on an experimental approach, with the construction and analysis of a reduced physical model in the scale 1:4, based on a bridge design classified as 30t with a free span of 16 meters. The model was instrumented with strain gauges and... (Complete abstract click electronic access below)

The paper presents the structural solution to the joisted floor when the timber joist of composite cross‐section and the concrete slab are interconnected via a special semi‐rigid connection and form a timber‐concrete joisted floor composite element. Tensioned bottom flange is formed of a solid timber joist, the web is of oriented strand boards (OSB) and the compressive top flange is of a concrete slab into which a part of the web is let in. Studies were carried out on the “sleeved” connector in this part of the web between OSB and concrete slabs that should increase the stiffness of this connection. Theoretical and experimental researches on inter‐behaviour of connection of the sub‐components of composite timber I beam‐concrete were carried out, the obtained results are presented and evaluated. Kompozitinių medinių-betoninių perdangų „įvorinių“ jungių laikysenos tyrimas Santrauka.Aptariamas sijinės perdangos konstrukcinis sprendimas, kai sudėtinio skerspjūvio medinė sija ir betono plokštė tarpusavyje sujungiamos per specialią iš dalies standžią jungtį ir sudaro kompozitinį medinės‐betoninės sijinės perdangos elementą. Šio elemento tempiamoji apatinė juosta padaryta iš vientisos medienos lentų, sienelė – iš orientuotųjų skiedrų plokštės (OSB), gniuždomoji viršutinė juosta – iš betono plokštės, į kurią įleista sienelės dalis. Tirta šioje sienelės dalyje tarp OSB ir betono plokščių esanti “įvorinė” jungtis, skirta šios jungties standumui padidinti. Atlikti kompozitinės medinės‐betoninės sijinės perdangos sudėtinių dalių tarpusavio jungčių laikysenos teoriniai ir eksperimentiniai tyrimai, pateikti ir įvertinti gauti rezultatai. Reikšminiai žodžiai:kompozitinė medinė‐betoninė konstrukcija,medinė plonasienė sija,slinktis,iš dalies standi jungtis,slankumo modulis,šlyties jungė,išstumiamasis bandymas. First Published Online: 14 Oct 2010

In the framework of the ongoing research project &laquo ; Investigation of elastic and mechanical properties of timber and timber-concrete composite structures&raquo ; at the Faculty of Civil Engineering in Osijek properties of timber-concrete composite structures are studied. The study focuses on timber-concrete composite structures joined by serially produced special type dowels. One-side dowels of Type C (according to DIN 1052 T2 Dowel Type C) have been selected. The research includes investigation of an actual-size specimen under ultimate static loading. Girder deformability caused by programmed loading is evident in the midspan deflection and slipping in the fastener area. In this paper the results of experimental research into bearing capacity and deformability of a specimen subjected to static tests of ultimate loading are presented.

Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are a simple and practical solution, they are not widely adopted. One of the reasons for this is the lack of uniform design mies. In this research programme shear tests on four different fastener types were performed as well as bending tests on tcc beams, manufactured with these fasteners. A simulation model was built that is able to perform a Monte Carlo simulation on single tcc beams and tcc floor s-ystems. The model was succesfullv verified with the bending tests before other simulations were performed. Several geometries were simulated resulting in a statistical distribution of the load-carrying capacity of each geometry. The 5-percéntile characteristic load-carrying capacity of each geometrv was determined and it was found that the 5-percentile load-carrying capacity can also be calculated using a linear model. To do so the mean values for MoE and fastener stiffness and the 5-percentile bending strength of the timber beam should be used.

At the Faculty of civil engineering, University of Josip Juraj Strossmayer in Osijek within a scientific project experimental researches of TIMBER-CONCRETE composite structures have been performed lately. Especially a bond by means of dowels which are produced in series have been researched. One-side dowels of the Bulldog firm were chosen. The focus of the research is on the rheological behaviour of TIMBER-CONCRETE composite structures by means of Bulldog type dowels. The research program encompasses testing of real dimensions model at long term continuous loading. Behaviour of midspan deflection and dowels sliding on the ends of the carrier have been investigated at programmed loading. For the sake of long term usage of space and equipment for the testing, only one model research has been done so far and its results will be displayed in this paper.

Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are a simple and practical solution, they are not widely adopted. One of the reasons for this is the lack of uniform design mies. In this research programme shear tests on four different fastener types were performed as well as bending tests on tcc beams, manufactured with these fasteners. A simulation model was built that is able to perform a Monte Carlo simulation on single tcc beams and tcc floor s-ystems. The model was succesfullv verified with the bending tests before other simulations were performed. Several geometries were simulated resulting in a statistical distribution of the load-carrying capacity of each geometry. The 5-percéntile characteristic load-carrying capacity of each geometrv was determined and it was found that the 5-percentile load-carrying capacity can also be calculated using a linear model. To do so the mean values for MoE and fastener stiffness and the 5-percentile bending strength of the timber beam should be used.

In the field of timber bridges progressive static structural solution is if the timber bearing members of the bridge deck are combined with concrete layer applying a shear connection to receive their composite action. The composite timber-concrete bridge deck comparing to the standard timber bridge deck has a higher rigidity, is more resistant to dynamic effects and has protected wooden part from external mechanical actions. The behavior of timber–concrete bridge deck is significantly influenced by the conditions of surrounding environment. In the presented paper, results of theoretical and experimental investigation of the effect of temperature and humidity changes of environment on the timber-concrete composite bridge deck will be presented. The applied analytical calculation model developed for analysis of long term behavior of timber-concrete elements influenced by the environment temperature and humidity will be introduced. In the experimental program, timber–concrete members with different timber structural parts and various composite connections under short and long term loading were investigated. The environmental conditions, temperature and humidity, during the 5 year long test were continually registered. Comparison of theoretical and experimental results and some practical conclusions for design of timber–concrete bridge deck will be finally presented.

Wood and concrete are materials with different time dependent behaviour and both have different reactions to thermal and humidity environmental changes. In timber-concrete composite beams, it results in generation of inelastic strains and redistribution of stress in cross-section. It is possible to determine load carrying capacity of composite wood-concrete elements according to Additions B of EN 1995-1-1, Design of Timber Structures. This calculation technique, however, does not consider the influence of the rheological properties of composite materials such as shrinkage, the eventual bulking of materials, the influence of composite on creep coefficient, and the influence of environmental changes. In this paper, the analytical calculation model of long term behavior of the timber-concrete composite beams is presented, which considers the most significant rheological phenomena such as: viscous-elastic creep of concrete and wood, mechano-sorptive creep of wood, creep of shear connection, concrete shrinkage, and strains due to thermal and relative humidity changes of environment. This model is applicable for simple beams with linear material properties and allows determining the final deflection in the middle span and stressing distribution in the middle cross-section of the composite beams affected by long term loading. Applying the presented calculation model and results of experimental tests, the analysis of rheological behavior influence on long term load carrying capacity of timber-concrete beams is described as well.