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.

A madeira foi largamente utilizada em edificações no período colonial brasileiro por sua abundância em variadas espécies e a facilidade de obtenção e adaptação aos fins previstos. Muitos destes imóveis ainda existem e abrangem a maior parte do patrimônio histórico e cultural de nossas cidades. Devido à degradação causada pelo tempo e a falta de manutenção adequada destes elementos estruturais, as edificações estão expostas ao risco de colapso. O objetivo deste trabalho foi sugerir um método de reabilitação parcial de vigas estruturais de madeira, pois se notou um problema recorrente nestes elementos em construções antigas pelo fato de acumularem umidade, serem alvos de patologias principalmente na parte superior. Para reabilitação empregamos madeiras de baixa densidade pela facilidade de compra desse material, baixo custo e principalmente por aderir muito bem a tratamento preservativo com CCB, o que garante que a estrutura estará protegida de novos ataques. Além das madeiras de baixa densidade tratadas, parafusos auto atarraxantes foram escolhidos para fazer a união entre as madeiras. Para os ensaios de flexão estática de 3 pontos foram adotados 4 diferentes tipos de parafusos variando o diâmetro e comprimento além disso, o número de parafusos inseridos nos corpos de prova também variou. Este estudo contém a análise de relação entre a quantidade de parafusos auto atarraxantes (que fazem a união das peças) e o produto de rigidez de peças mistas compostas de madeira referência (que simula a viga em estado de degradação) e madeira tratada (substituindo a porção degradada). Para a madeira referencia adotou-se Eucalipto (classe C30 de resistência) e Roxinho (classe C60) e, para madeira tratada adotou-se Pinus e Caxeta (de baixa densidade, ambas da classe C20). Análises estatísticas foram utilizadas para interpretação dos resultados obtidos em laboratório. Estas análises apontaram o crescimento do produto de rigidez das vigas mistas conforme a inserção de parafusos e a partir dai foi possível expressar em formulas a correlação dos dados. Utilizou-se o teste de Tukey para apontar o melhor tratamento para cada tipo de viga mista (Pinus e Eucalipto, Roxinho e Caxeta) além do melhor parafuso a se utilizar. / Wood was widely used in buildings in the Brazilian colonial period because of it is abundant in varied species and the ease of obtaining and adapting to intended purposes. Many of these properties still exist and cover most of historical and cultural heritage of Brazilian cities. Due to the degradation caused by the weather and lack of adequate maintenance of these structural elements, buildings are exposed to risk of collapse. The objective of this work was to suggest a method of partial rehabilitation of structural timber beams, since a recurrent problem was observed in these elements in old constructions due to accumulation of humidity, being targets of pathologies mainly in their upper part. For rehabilitation we use low density wood because of ease to purchasing this material, low cost and mainly for adhering very well to condom treatment with CCB, which ensures that the structure will be protected from further attacks. In addition to the treated low density woods, self-tapping screws were chosen to make union between woods. For tests, 4 different types of screws were used, varying diameter and length, and number of screws inserted in the specimens also varied. This study contains an analysis of relationship between the number of self-tapping screws (which make the joining of pieces) and the rigidity product of composite pieces of reference wood (which simulates beam in degraded state) and treated wood (replacing degraded portion). Eucalyptus (class C30 of resistance) and Roxinho (class C60) were used for reference wood, and Pinus and Caxeta (low density, both of class C20) were used for treated wood. Statistical analyzes were used to interpret results obtained in laboratory. These analyzes indicated growth of product of flexural stiffness according to insertion of screws and from this it was possible to express in formulas a correlation of data. Tukey test was used to indicate the best treatment for each type of mixed beam (Pinus and Eucalyptus, Roxinho and Caxeta) as well as the best screw to be used.

Intresset för flervåningshus i trä ökar stadigt. Trä är ett lätt och mjukt material vilket är problematiskt med avseende på stomstabilisering och horisontella deformationer. Syftet har varit att undersöka förbandstyper för KL-trä och huvudfrågan var hur stommens horisontella deformationer påverkas av infästningstyperna och deras styvhet. En jämförande studie av självborrande skruvar och beräkning av deras förskjutningsmodul har utförts. En modell på 22 våningar med en stomme av KL-trä modellerades i RFEM. Analyser genomfördes för olika värden på förskjutningsmodul för att kunna jämföra de horisontella deformationerna. Resultatet visade på att deformationerna blev små och att skillnaden mellan olika förskjutningsmoduler gav en knappt märkbar skillnad i horisontell deformation, trots att variationen av värdet på förskjutningsmodulerna var stor. Detta kan förklaras av att modellen i sig är väldigt stabil, vilket främst skulle kunna bero på fasadelementens vertikala förskjutning och höjd. Andra bidragande orsaker var att modellen saknade urtag för dörrar och fönster, KL-elementens tjocklek samt att pågjutning av betong applicerades på varje våning. / The interest for multi storey buildings with timber is growing. Timber is a material that is light and ductile, characteristics that make timber a challenging material in terms of horizontal stabilization and horizontal displacements. The purpose was to examine connectors for CLT and the main question was how the horizontal displacement of the frame is affected by the connectors and their stiffness. A parametric study for self-tapping screws and calculation of their slip modulus was carried out. A model of a 22-storey building with a CLT frame was modelled in RFEM. Analyses were run for different values of the slip modulus for comparison of the horizontal displacements connected to each slip modulus. The results show that the deformations were small and that the differences in slip modulus only caused small differences in horizontal deformations even though the variation in slip modulus was wide. The reason for this could be due to the modelling; the model in itself is very stiff, possibly as a result of the façade panels’ vertical adjustment and height. Other factors contributing were the lack of openings for doors and windows in the model, the thickness of the CLT panels as well as the concrete decks on all floors.

Im Projekt wurden lösbare Verbindungstechniken für hochgefüllte Holz-Polymer-Werkstoffe für das statisch-dynamische Belastungskollektiv des Maschinenbaus erarbeitet. Im Fokus der Untersuchungen standen vorgespannte Schraubverbindungen in den konstruktiven Ausführungen als Durchsteckschraubverbindung und Einschraubverbindungen. Die Direktverschraubung und die Quergewindebolzen-Steckschraubverbindung wurden aus technisch-wirtschaftlicher Sicht für den Werkstoff als Sonderverfahren der Einschraubverbindung favorisiert. Für die benannten Verschraubungsarten wurden Montageempfehlungen, Grenzlastbereiche und Einflussfaktoren der Verbindungen unter Berücksichtigung des Werkstoffes erarbeitet. Abschließend wurden die erarbeiteten Kenntnisse zu lösbaren Verbindungstechniken auf einen Demonstrator in der Fördertechnik übertragen. / In the project removable connection methods for high filled wood polymer composites for static and dynamic loads were worked out. The focuses of studies were pre-stressed screw connections in a constructive style as push-through screw connection and screw in connection. On the basis of the material and the technical-economic reasons the 'direct-screw-connection' and 'cross-threaded bolt plug-in screw connection' were favored as a special method of the screw-in connection. Installation recommendations, limit load ranges and influencing factors of the connections based on the material were compiled for the named types of bolting. Finally the compiled knowledges of the removable connections were transferred into demonstrator for conveying systems.