Master of Science / Department of Architectural Engineering and Construction Sciences / Kimberly Waggle Kramer / Bill Zhang / Cold-formed steel members quickly are becoming a popular material for both commercial and residential construction around the world. Their high strength to weight ratio makes them a viable alternative to timber framing. In most cases cold-formed steel is used as a repetitive member in floor, wall, or roof assemblies. Structural sheathing is used in conjunction with the framing members in order to transfer loads between individual members. This sheathing is connected mechanically to the cold-formed steel through a variety of methods. The most common method uses screws spaced at close intervals, usually between 6 to 12 inches on center. When such assemblies are constructed, load is transferred from the sheathing through the connectors into the cold-formed steel, forming a composite assembly in which load is transferred and shared between two materials, providing a higher strength and stiffness over individual members themselves. The amount of load that can be transferred is dependent on the amount of slip that occurs when the assembly is loaded. This slip value describes the amount of composite action that takes place in the assembly. The amount of slip can be described by a value called the slip modulus. The composite, or effective, bending stiffness can be calculated using the slip modulus. In current design of cold-formed steel composite assemblies this composite action is not being taken into account due to a lack of research and understanding of the composite stiffness present in these assemblies. Taking composite action into account can lead to decreased member sizes or increased spacing of members, thereby economizing design. Furthermore, improved understanding of the effective stiffness can lead to more accurate design for vibrations in floor systems. This thesis tests cold-formed steel plywood composite members in an effort to verify previously established slip modulus values for varying steel thicknesses and establishes new values for varying fastener spacings. The slip modulus values obtained are used to calculate effective bending stiffness values in an effort to prove that composite action should be utilized in design of cold-formed steel composite assemblies.

Master of Science / Civil Engineering / Hani G. Melhem / Bill Zhang / Composite action is the joint behavior of two elements connected or bonded together. It is a phenomenon that is utilized in several applications throughout engineering. Previous studies have shown that cold formed steel (CFS) sheathed with structural wood panels exhibits a degree of partial composite action behavior. However currently in the design process, CFS and wood sheathing systems are considered separately in a non-composite manner due to the absence of sufficient supporting data. These systems can include the floors, roofs, and walls of a building. In order to determine the level of composite action present, the slip modulus is needed. The slip modulus describes the relationship between the shear force and the displacement exhibited by two elements in a composite system. The scope of this research is to determine the influence of fastener spacing on the slip modulus and provide a foundation of information to fully define the composite action between CFS and wood sheathing.

Master of Science / Department of Architectural Engineering and Construction Science / Kimberly Waggle Kramer / Cold-formed steel framing sheathed with wood structural panels is a common method of construction for wall, roof and floor systems in cold-formed steel structures. Since wood structural panels are attached with screws at relatively close spacing, a certain amount of composite behavior will be present. However, the benefit of composite behavior of this system is currently not being taken advantage of in the design of these structural systems. While composite effects are present, they are not yet being accounted for in design due to a lack of statistical data. To determine the amount of composite action taking place in these systems, the slip modulus between steel and wood is required. The slip modulus reflects the amount of shear force able to be transferred through the screw connection, to either member of the composite system. This thesis presents the results of a study conducted to determine values of the slip modulus for varying thicknesses of cold-formed steel and plywood sheathing. Push tests were conducted and the slip moduli were determined based on ISO 6891 and ASTM D1761. Compared with data from a previous preliminary study performed by others, the values determined from these tests for the slip modulus were deemed reasonable. The determination of the slip modulus will lead to the ability to calculate a composite factor. Determination of a composite factor will allow cold-formed steel wood structural panel construction to become more economical due to the available increase in bending strength.

<p>U ovom radu ispitano je dinamičko ponašanje spregnutih međuspratnih&nbsp; konstrukcija tipa drvo-laki&nbsp; beton&nbsp; usled&nbsp; svakodnevnih&nbsp; ljudskih&nbsp; aktivnosti.&nbsp; Pri&nbsp; sanaciji,&nbsp; nadogradnji&nbsp; i seizmičkom ojačanju objekata na postojeće drvene međuspratne konstrukcije najčešće se izlivaju betonske ploče koje se sprežu sa postojećom konstrukcijom. Beton u gornjoj ploči<br />međuspratne konstrukcije povećava njenu krutost i time smanjuje&nbsp; setljivost na dinamičku pobudu.&nbsp; Potreba&nbsp; da&nbsp; se&nbsp; smanji&nbsp; dodatno&nbsp; opterećenje&nbsp; na&nbsp; postojeće&nbsp; temelje&nbsp; konstrukcije, dovodi do sve češće upotrebe lakog betona pri sanaciji i rekonstrukciji objekata. NJegovom primenom povoljni efekti sprezanja ostaju očuvani, a prednosti u vidu smanjenja dodatne težine dolaze do izražaja.<br />Međutim,&nbsp; u&nbsp; dostupnoj&nbsp; literaturi,&nbsp; podataka&nbsp; o&nbsp; dinamičkom&nbsp; ponašanju&nbsp; spregnutih međuspratnih konstrukcija izvedenih sa lakim betonima&nbsp; malih zapreminskih masa nema, pa je cilj ovog rada bio da se ispitaju osnovne dinamičke&nbsp; karakteristike drvenih međuspratnih konstrukcija saniranih lakim betonom raznih zapreminskih težina. Analizirano je&nbsp; dinamičko<br />ponašanje,&nbsp; odnosno&nbsp; sračunate&nbsp; su&nbsp; prve&nbsp; tri&nbsp; sopstvene&nbsp; frekvencije&nbsp; oscilovanja&nbsp; četiri međuspratne&nbsp; spregnute&nbsp; konstrukcije&nbsp; sa&nbsp; identičnim&nbsp; poprečnim&nbsp; presecima&nbsp; i&nbsp; spojnim sredstvima,&nbsp; ali&nbsp; sa&nbsp; različitom&nbsp; klasom&nbsp; zapreminske&nbsp; mase&nbsp; lakog&nbsp; betona&nbsp; u&nbsp; gornjoj&nbsp; betonskoj ploči.&nbsp; Preliminarnim&nbsp; laboratorijskim&nbsp; ispitivanjem&nbsp; relevantnih&nbsp; svojstava&nbsp; četiri&nbsp; vrste&nbsp; lakog<br />betona,&nbsp; monolitnog&nbsp; drveta&nbsp; i&nbsp; spojnih&nbsp; sredstava,&nbsp; koja&nbsp; su&nbsp; se&nbsp; koristila&nbsp; pri&nbsp; sprezanju&nbsp; drveta&nbsp; i lakog betona, dobijeni su potrebni ulazni podaci za numerička istraživanja. Za&nbsp; potrebe&nbsp; analitičkog&nbsp; istraživanja&nbsp; predložena&nbsp; je&nbsp; jednostavna&nbsp; metoda&nbsp; dinamičkog proračuna&nbsp; sopstvenih&nbsp; frekvencija&nbsp; oscilovanja&nbsp; elastično&nbsp; spregnutih&nbsp; konstrukcija.&nbsp; Tačnost rezultata predloženog dinamičkog proračuna potvđena je&nbsp; eksperimentalno, i poređenjem<br />sa rezultatima programskog paketa Ansys.</p> / <p>This&nbsp; work&nbsp; has&nbsp; examines&nbsp; dynamic&nbsp; behavior&nbsp; of&nbsp; composite&nbsp; wood-lightweight&nbsp; concrete&nbsp; floor structures&nbsp; exposed&nbsp; to&nbsp; normal&nbsp; everyday&nbsp; human&nbsp; activities.&nbsp; In&nbsp; a&nbsp; case&nbsp; of&nbsp; restoration, renovation or seismic reinforcement, the most common approach is to pour concrete slabs onto&nbsp; existing&nbsp; wooden&nbsp; floor&nbsp; structures.&nbsp; Concrete&nbsp; in&nbsp; the&nbsp; upper&nbsp; zone&nbsp; of&nbsp; floor&nbsp; structure&nbsp; is increasing its stiffness and thus reducing the dynamic excitation. In the attempt to reduce the&nbsp; weight&nbsp; on&nbsp; the&nbsp; existing&nbsp; foundations,&nbsp; lightweight&nbsp; concrete&nbsp; is&nbsp; used&nbsp; for&nbsp; restoration&nbsp; and renovation. Coupling effect remains undisturbed but added weight is&nbsp;&nbsp; significantly reduced when lightweight concrete is used.<br />However,&nbsp; the&nbsp; available&nbsp; literature&nbsp; does&nbsp; not&nbsp; provide&nbsp; data&nbsp; about&nbsp; dynamic&nbsp; behavior&nbsp; of&nbsp; the composite wood-lightweight concrete floor structures; therefore the goal of this research work&nbsp; is&nbsp; to&nbsp; examine&nbsp; the&nbsp; characteristics&nbsp; of&nbsp; the&nbsp; restored&nbsp; wooden&nbsp; structures&nbsp; coupled&nbsp; with lightweight concrete of the different specific weights. This research work analyzes dynamic behavior&nbsp; that&nbsp; included&nbsp; first&nbsp; three&nbsp; frequencies&nbsp; of&nbsp; four&nbsp; composite&nbsp; floor&nbsp; structures&nbsp; with identical cross&nbsp; sections and&nbsp; connections,&nbsp; but different specific weights&nbsp; of the lightweight concrete&nbsp; in&nbsp; the&nbsp; upper&nbsp; layer&nbsp; of&nbsp; the&nbsp; concrete&nbsp; slab.&nbsp; Preliminary&nbsp; laboratory&nbsp; testing&nbsp; of&nbsp; four different types of the lightweight concrete, wood and connections, yielded necessary data for the further numeric analysis.<br />Simple&nbsp; calculation&nbsp; method&nbsp; for&nbsp; obtaining&nbsp; mode&nbsp; frequencies&nbsp; of&nbsp; the&nbsp; partial&nbsp; composite structures has been proposed, for the purpose of this analytical research. The accuracy of the&nbsp; proposed&nbsp; dynamic&nbsp; model&nbsp; has&nbsp; been&nbsp; confirmed&nbsp; through&nbsp; experimental&nbsp; research&nbsp; and compared up against the results from the Ansys</p>

I och med att klimatfrågan blir allt viktigare ökar även intresset för miljövänligt byggande. Förbyggnader av högre karaktär är förädlade träprodukter något som syns mer av på marknaden.Element av KL-trä, korslimmat trä, är en stabil träprodukt med stora användningsområden förhela byggnaden men dessa måste på något sätt förankras i varandra. För att få en djupareförståelse om hur förband i KL-trä verkar i en skarv utvärderar detta examensarbete totalt åtta(8) stycken olika skarvtyper teoretiskt, varav några mer ingående. De mekaniska- ochekonomiska egenskaperna jämförs för att bedöma bästa kapaciteten ochanvändningsområdet för olika bjälklag.De skarvar som beaktas är bland annat plywoodskarven där en plywoodremsa läggs ned i etturfräst spår i överkant längs KL-träskivans långsida. Halvt i halvt-skarven med urfräsning tillhalva djupet i över- och underkant för att passas ihop och rakskarv med skråskruvning. IRakskarv 2D skråskruvas skruven 45° i YZ-planet, Rakskarv 3D skruvas också i 45° men där vridsäven skruven 45° i XY-planet. Skarvarna behandlas för tillämpning i bjälklag för flerbostadshus,parkeringshus och tak. Genom att testa olika teoretiska beräkningsmetoder, från Eurokod ochvidare forskning inom ämnet, kontrollera hur dessa skiljer sig emot tidigare gjorda tester. Föratt jämföra skarvarnas kapacitet har en fem (5) meter lång skarv i en mindre konstruktion med200 mm tjocka KL-träskivor använts som referens. Fästdonen har begränsats till ett fåtal därvinkeln mot virkets yta varierar. Kostnaden för tillverkning, montage och fästdon sätts emotkapaciteten för att kunna jämföra vilken skarv som är mest kostnadseffektiv, då det alltid ären viktig fråga inom projekt.Kostnaden för Rakskarv 3D är 63 % av kostnaden för en Plywoodskarv 12 mm. För att klarapåfrestningen från tvärkraften behövs cirka 18 stycken SW-D-skruvar men upp emot 95stycken ankarspikar. Resultatet blev att den mest kostnadseffektiva skarven ur tillverkningochmontageperspektiv samt behovet av smide per löpmeter är Rakskarv 3D. För skarvtypermed SW-D skruv blir ofta den horisontella skjuvkraften dimensionerande då de vertikalakrafterna är lägre och utdragsbärförmågan är hög för dubbelgängad skruv. För bjälklag ibostäder är Rakskarv 2D att rekommendera, då den är en beprövad metod som har godkapacitet och är snabb att montera. Att också vrida skruvarna 0-45° i XY-planet, Rakskarv 3D,för att möta tvärkrafterna har positiv inverkan. Även för takbjälklag är rakskarven det bättrealternativet. Vad gäller parkeringsbjälklag rekommenderas också Rakskarv 3D även om Halvti halvt har likvärdiga mekaniska egenskaper på grund av pris och c/c-avstånd.Stora skillnader mellan beräkningsmetoder och tester framkommer för både kapacitet ochstyvhet. Vid horisontell skjuvning kan detta leda till att utfallet av brottmod, som normalt blir”f” enligt tester, blir fel. Högsta horisontella styvhet enligt beräkningarna har Halvt i halvt,däremot är enligt tester Rakskarv 3D den med högst styvhet. Utifrån detta kan man ifrågasättahur säkra beräkningsmetoderna verkligen är eller om variationen i träet för stora. Bortser manifrån att Rakskarv 3D får låga värden på kapaciteten enligt beräkningar och bara tittar tillutförda tester tillsammans med vetenskapliga publikationer är den allmänt ett bra val avskarvmetod. / As the climate issue becomes more important, the interest in environmentally friendlyconstruction also increases. For buildings of higher character, refined wood products aresomething that is more common at the market. Elements of cross-laminated timber (CLT) arestable wood products with large uses for the entire building, but these must in some way beanchored in each other. To gain a deeper understanding of how joints in CLT works, this thesisis evaluating a total of eight (8) different types of joints theoretically, some of which are moredetailed. The mechanical- and economical properties are compared to assess the best capacityand area of application for different slabs.The joints that are considered include the spline joint, where a plywood strip is laid down in amilled groove at the top along the long side of the CLT slab. Half-lap joint, with cut to halfdepth at top and bottom to fit together, and butt joint with screw in shear. In Butt joint 2D,the screw is screwed 45 ° in the YZ plane, Butt joint 3D is also screwed in 45 ° but the screw isalso turned 45 ° in the XY plane. The joints are treated for application in flooring for apartmentbuildings, parking garages and roofs. By testing different theoretical methods of calculation,from Eurocode and further research in the subject, check how these differ from previous tests.To compare the capacity of the joints, a five (5) meter long joint in a smaller structure with a200 mm thick CLT slab has been used as reference. The fasteners have been limited to a fewwhere the angle to the surface of the wood varies. The cost of production, assembly andfasteners is set against the capacity to be able to compare which joint is the most costeffective,as it is always an important issue within projects.The cost of a 3D joint is 63% of the cost of a 12 mm spline joint. In order to cope with the strainfrom the transverse force, about 18 SW-D screws are needed, but up to 95 anchor nails. Theresult was that the most cost-effective joint from the manufacturing- and assemblyperspective, as well as the need for fastener per meter was Butt joint 3D. For joint types withSW-D screws, the horizontal shear force is often dimensioned as the vertical forces are lowerand the withdrawal capacity is high for double threaded screws. For slab in homes, Butt joint2D is recommended, as it is a proven method that has good capacity and is quick to assemble.Also turning the screws 0-45 ° in the XY plane, like Butt joint 3D, to meet the transverse forceshas a positive effect. Even for roof joists, the butt joint is the better option. Regarding jointsin parking garages, Butt joint 3D is also recommended even though Half-lap joint has similarmechanical characteristics due to the price and c/c- distances.Differences between calculation methods and tests appear for both capacity and stiffness.Horizontal shear can result in wrong type of failure, which normally becomes "f" according totests. The highest horizontal stiffness according to the calculations has Half-lap joint, however,according to tests Butt joint 3D is the one with the highest stiffness. Based on this, one canquestion how accurate the calculation methods really are or whether the variation in wood istoo great. Apart from the fact that Butt joint 3D receives low values of capacity according tocalculations and only looks at tests carried out together with scientific publications, it isgenerally a good choice of joint method.

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.

Timber-concrete composite (TCC) structures are becoming more popular in several industrial applications as an efficient method for optimizing the structural performance and the cost of construction as well as lowering the emissions of carbon dioxide. TCC floors are more sustainable than pure concrete floors and more resistant to vibrations and excessive deflections than pure wooden floors. The effectiveness of a TCC floor is dependent on the connection between the materials. The stiffness and strength of the composite element increases by having a rigid connection. An example of a rigid connection is an adhesive-bonded connection, however obtaining a connection without slip is difficult considering there will always be certain amount of slippage in the connection. In this thesis adhesive connections are investigated with two different types of adhesive, one called Sikasil SG-500 and the other Sika PS. The application of the adhesives for the test specimen differ. Since Sika PS is a more fluid glue, a different approach was necessary than for the Sikasil SG-500. Five test specimen were tested of each adhesive by performing double shear push out tests and comparing the results to a numerical model, which was performed in ABAQUS. In the numerical model, the adhesive was created as a cohesive element. Furthermore the properties of the modeled adhesive was based on the experimental results for respective adhesive. The experimental results showed that both adhesives managed the estimated shear force in the serviceability limit state and the ultimate limit state and yet remained in the elastic region. Sikasil SG-500 turned out to be more flexible while Sika PS specimen resulted in higher shear strength. The short creep tests (30 minutes of a constant load) showed that the deformation increased more for Sika PS than for Sikasil SG-500. However both adhesives had large deformations after only 30 minutes. There was also a difference in the average longitudinal shear strength, where it resulted in 1.06 MPa for Sikasil SG-500 and 2.02 MPa for Sika PS. This study indicates that Sika PS is more preferable in TCC structures than Sikasil SG-500.