A timber-concrete composite (TCC) combines timber and concrete, utilising the complementary properties of each material. The composite is designed in such a way that the timber resists combined tension and bending, whilst the concrete resists combined compression and bending. This construction technique can be used either in new build construction, or in refurbishment, for upgrading existing timber structures. Its use is most prolific in continental Europe, Australasia, and the United States of America but has yet to be widely used in the United Kingdom. To date, the topping upgrades used have been 40mm thick or greater. Depending on the choice of shear connection, this can lead to a four-fold increase in strength and stiffness of the floor. However, in many practical refurbishment situations, such a large increase in stiffness is not required, therefore a thinner topping can suffice. The overarching aim of this study has been to develop a thin (20mm) topping timber-concrete composite upgrade with a view to improving the serviceability performance of existing timber floors. Particular emphasis was given to developing an understanding of how the upgrade changes the stiffness and transient vibration response of a timber floor. Initially, an analytical study was carried out to define an appropriate topping thickness. An experimental testing programme was then completed to: characterise suitable shear connectors under static and cyclic loads, assess the benefit of the upgrade to the short-term bending performance of panels and floors, and evaluate the influence of the upgrade on the transient vibration response of a floor. For refurbishing timber floors, a 20mm thick topping sufficiently increased the bending stiffness and improved the transient vibration response. The stiffness of the screw connectors was influenced by the thickness of the topping and the inclination of the screws. During the short-term bending tests, the gamma method provided a non-conservative prediction of composite bending stiffness. In the majority of cases the modal frequencies of the floors tested increased after upgrade, whilst the damping ratios decreased. The upgrade system was shown to be robust as cracking of the topping did not influence the short-term bending performance of panels. Thin topping TCC upgrades offer a practical and effective solution to building practitioners, for improving the serviceability performance of existing timber floors.

In timber-concrete composite systems, timber and concrete are inherently brittle materials that behave linearly elastic in both tension and bending. However, the shear connection between the members can exhibit significant ductility. It is therefore possible to develop timber-concrete composite systems with ductile connection that behave in a ductile fashion. This study illustrates the use of an elastic-perfectly plastic analytical approach to this problem. In addition, the study proposes an incremental method for predicting the nonlinear load-deflection response of the composite system. The accuracy of the analytical model is confirmed with a computer model, and numerical solutions of the analytical model are compared to experimental results from the bending tests conducted by previous researchers. Reasonable agreement is found from the comparisons, which validates the capacity of the analytical model in predicting the structural behaviour of the timber-concrete composite systems in both elastic and post-elastic stages.

In timber-concrete composite systems, timber and concrete are inherently brittle materials that behave linearly elastic in both tension and bending. However, the shear connection between the members can exhibit significant ductility. It is therefore possible to develop timber-concrete composite systems with ductile connection that behave in a ductile fashion. This study illustrates the use of an elastic-perfectly plastic analytical approach to this problem. In addition, the study proposes an incremental method for predicting the nonlinear load-deflection response of the composite system. The accuracy of the analytical model is confirmed with a computer model, and numerical solutions of the analytical model are compared to experimental results from the bending tests conducted by previous researchers. Reasonable agreement is found from the comparisons, which validates the capacity of the analytical model in predicting the structural behaviour of the timber-concrete composite systems in both elastic and post-elastic stages.

Timber-concrete composite (TCC) floor systems consist of a bottom layer of wood that is connected to a top layer of concrete using shear connectors. The shear connectors resist slip between the layers, thus allowing wood and concrete develop composite action when subjected to flexure. The objective of this study is to determine the flexural strength and behavior of TCC floor systems that consist of a cross laminated timber wood layer connected to a concrete top layer using hexagonally headed self-tapping screw shear connectors. To accomplish the objective, coupon specimens and full-scale TCC floor panels were tested, and a finite element modelling approach was developed. The coupon tests were used to determine the stiffness of the shear connection and to determine the effect of the screw configuration. The results from the coupon tests indicated that the inclined screw configuration provided the largest shear strength compared to the normal, crossed, and nested screw configurations. Based on the results from the coupon tests, bending and vibration (heel drop) tests were conducted on full-scale panel specimens with an inclined screw configuration and with a strong-axis panel orientation. The results from the full-scale panel tests showed that the flexural stiffness and strength of the TCC floor system was consistent and that the composite floor panels have adequate stiffness to minimize transient floor vibrations that are caused by walking for typical span lengths and typical loading. A finite element model of TCC floor systems was developed to simulate TCC floor systems and calibrated with the test data. The simulated response matched the test response fairly well for partially composite single-span and double-span panels. Additional refinement of the model is needed to better match fully composite panels. The research demonstrated that hexagonal-headed self-tapping screws may be effectively used to connect wood and concrete layers in TCC floor systems.

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)

Orientador: José Antônio Matthiesen / Banca: José Luiz Pinheiro Melges / Banca: Antonio Alves Dias / Resumo: 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... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: 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) / Mestre

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 / 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

This diploma thesis deals with the problems of revitalization of historical objects. The theoretical part describes the technologies for static reinforcing and rehabilitation of vertical and horizontal bearing structures for a purpose of increasing the general stiffness of the object. As the practical part a static design project is made for reinforcing of the bearing walls and also for the general reconstruction of the slab. The slab is designed as the composite timber-concrete structure. The design project of the slab is economically compared with other variants. The designs are made for an existing object of the old restaurant in the village Velichovky.

This Ph.D. thesis represents a summative report detailing research processes and outcomes from investigating the ultimate and serviceability limit state short- and long-term behaviour and design of timber-concrete composite floors. The project enables the realization of a semi-prefabricated LVL-concrete composite floor system of up to 15 m long using 3 types of connection. Design span tables which satisfy the ultimate and serviceability limit state short- and long-term verifications for this system form the novel contribution of this thesis. In quantifying the behaviour of timber-concrete composite floors, 5 different experimental phases have been carried. 9 major achievements in meeting 9 sub-objectives have been concluded: 1) Three best types of connection system for timber-concrete composite floors have been identified; 2) The characteristic strength and secant slip moduli for these connections have been determined; 3) The short-term behaviour of the selected connections defined by their pre- and post-peak responses under collapse load has been established; 4) An analytical model for the strength evaluation of the selected connections based on the different possible modes of failure has been derived; 5) Easy and fast erected semi-prefabricated timber-concrete composite floor has been proposed; 6) The short-term ultimate and serviceability limit state behaviour of timber-concrete composite floor beams under collapse load has been investigated; 7) The long-term behaviour of chosen connections defined by their creep coefficient has been determined; 8) The long-term behaviour of timber-concrete composite floor beams under sustained load at serviceability limit state condition has been investigated; and 9) Design example and span tables for semi-prefabricated timber-concrete composite floors that satisfy both the ultimate and serviceability limit state in the short- and long-term using the gamma-method have been developed.

Recently more and more buildings of light structures have been built in Lithuania as well as in other European and world countries. Nevertheless, timber products are not widely used for floors in this share of construction market. Traditional light timber frame floors are characterized by vibrations, acoustic transmission and low fire resistance. The above-mentioned problems can be rationally solved by using timber-concrete composite (hereinafter TCC) floors. In comparison with entirely timber floors such type of floors are characterised not only by increased strength and stiffness but also by increased fire resistance and better sound insulation. In comparison with reinforced concrete floors manufactured of non-regenerative sources TCC floors are lighter and more economic. These characteristics stimulate usage of TCC floors in newly built buildings. It should also be noted that usage of timber in building structures instead of concrete or steel could substantially decrease energy demand and emission of carbon dioxide during production. In this work author presents TCC structural solution when thin-webbed beams (I-joists) used for timber floor beams instead of solid or glued rectangular beams. Thin-webbed beams are without upper flange of structural timber. Embedding in concrete a part of web of oriented strand board (hereinafter OSB) connects the OSB web and the concrete slab. This concept allows to save structural materials and production costs. Nevertheless, not so many... [to full text]