For a long time, frames have been built with traditional materials such as concrete and wood but there are newer, less tested alternatives. Posi-Joist is a new kind of hybrid beam which means that it consists of different materials that work together to form a stronger frame. Posi is a collective name for the different parts of the beam. Because Posi-Joist is a new beam, it hasn’t been tested as much as the more traditional materials. The purpose of this report is to investigate if Posi-Joist is an acceptable frame to use on larger constructions since it hasn't been investigated before. In order to investigate this, a hybrid frame consisting of Posi-Joist beams will be compared to a concrete and a wooden frame. When choosing a material there are different parameters that matter. The different materials will demand different spans, have different environmental impact, and have different costs. To investigate which frame is the optimal choice, different software will be used. Autodesk Revit will primarily be used to draw the frames’ different designs. Frame Analysis and FEM-Design will be used to perform calculations on the strength of the frames. One Click LCA will be used to obtain LCC and LCA. The wooden frame was the most expensive since the concrete frame’s price was just 40 % of the wooden frame's total cost. The hybrid frame’s price was 52,4 % of the wooden frame’s price and was therefore more expensive than the concrete frame but cheaper than the wooden frame. The wooden frame had less environmental impact since it emits 11,2 % of the concrete frame’s emissions. The hybrid frame emits 90 % of the concrete’s total emissions. The hybrid frame can manage the largest spans. The conclusion is that the concrete frame is the best option when it comes to design and price but has the most environmental impact. The wooden frame had the least environmental impact but could not manage compatible spans. The hybrid frame could manage the largest spans but was neither the worst nor the best in any of the other categories.

Due to time, cost, and environmental challenges, wood has become a more common building material even for more complex buildings. Implementing the concept of Level of Development (LOD) on timber structures could provide a tool for BIM collaboration that may save cost and time, and in the early stages mediate wood as an available building material. Studies explain that LOD enables a high level of content and clarity as well as improved control of the design process. As the concept of LOD heavily focuses on general BIM visualisation, existing research at the time of the study lacks descriptions of how to implement LOD for specific projects. The study aims to develop a framework that could provide the industry with a possible implementation concept that could be further developed on other building systems. The goal of the study is to present a framework of a possible LOD implementation on a timber building system with a detailed description focusing on the structural engineer’s role during the design process. From that the questions of how to apply LOD on different project types as well as what data characteristics vary between these project types will be answered. Stated in previous studies, Integrated Project Delivery (IPD)A  is required for a successful design process is gained by utilising Integrated Project Delivery (IPD) and is especiallyalso essential when working with LOD. LOD is defined as five stages: starting with 100, then 200, 300, 350, 400, and finally 500. For each level of a building system, element, or assembly, the vagueness of information decreases and is therefore visualised differently in a BIM model. The study is based on a qualitative analysis of current data and related work about the design process, LOD, and timber buildings. The framework is mainly built upon five theories, the IPD process, the MacLeamy curve, BIM use purposes, data vagueness determination, and data requirement for timber projects. An interview study was conducted where projects using Masonite Beam’s standardised I-joist system were studied and implemented usingg the framework. The resulting framework presents the percentage information vagueness of how mature the information for a given objects is for different data properties and of each LOD level. The analysis leads to the conclusion that if fulfilling three criteria, 1: Following the IPD process, 2: An effort process similar to MacLeamy, and 3: Utilising BIM, the timber system can be implemented on the framework. However, the closer the project meets the criteria the closer the vagueness values will relate to the framework. The project that utilises a highly standardised building system with predefined data presents even lower vagueness values than the framework. Due to varying scales of project complexities, the data properties that showed the most diverse results between the projects were material information, geometric shape, and element dimensions. The findings from the study could be of further use in another research whose authors defined detailed graphical LOD visualisation in a BIM collaborative environment. The concept is strongly dependent on defined vagueness values that the authors of the research did not focus on how to define, which this framework does. Finding theories that support the assumptions made during the analysis development of the framework is continuing work that could strengthen the framework and its reliability. / Med tid -, kostnad- och klimatutmaningar har trä blivit ett mer vanligt byggnadsmaterial även för komplexa byggnader. Implementering av konceptet Level of Devlopment (LOD) på träkonstruktioner kan förse byggnadsindustrin med verktyg för BIM- kollaboration som kan spara på både kostnader och tid, och i tidigt skede framhäva trä som ett möjligt byggnadsmaterial. Studier förklarar att LOD kan bidraförse med en hög klarhetsgrad för olika innehåll, men även förbättra kontrollen under designprocessen. Då LOD-konceptet är starkt fokuserad på generell BIM-visualisering förklarar inte funna studier LOD- implementering för specifika projekt. Studien avser att utveckla ett framework (struktur) som kan förse byggnadsindustrin med ett möjligt implementeringskoncept som vidare kan anpassas till andra byggnadssystem. Målet är att presentera ett framework av en möjlig LOD implementering för ett träbyggandssystem med en detaljerad förklaring utifrån byggnadskonstruktörens roll i designprocess. Från detta kan frågor om hur man kan använda LOD för olika projekttyper samt vilka olika typer av information som varierar mellan dessa projekttyper besvaras. Tidigare studier visar En lyckad designprocess erhålls vi nyttjandet av att Intergrated Project Delivery (IPD) är nödvändigt för att uppnå en lyckad designprocess, särskiltvilket även är essentiellt när man arbetar meddet kommer till LOD. LOD definieras av fem stadier som går: från 100, 200, 300, 350, 400 ochtill 500. För varje nivå minskas osäkerhetsvärdet för en viss information tillhörande ett byggnadssystem, element eller assmembly, och är därmed olika grafiskt visualiserad i en BIM- modell. Studien baseras på en kvalitativ analys av befintliga data and och relaterade studier inom designprocessen, LOD och träbyggnader. Frameworket är huvudsakligen uppbyggt på fem teorier: IPD- processen, MacLeamy- kurvan, användningssyften av BIM, informationsosäkerhetsbestämmelse samt data som behövs för träbyggnadsprojekt. En intervjustudie är utförd där projekt utförda med Masonite Beams standardiserade trä I-balkar av trä studerades och implementerades på frameworket. Det resulterande frameworket presenterar procentuella osäkerhetsvärden som beskriver i vilken grad informationen tillhörande ett objekt går att lita på för olika informationskategorier och för varje LOD- nivå. Analys leder till slutsatsen att om följande tre kriterium uppfylls; 1. Följer IPD- processen, 2. Liknande arbetskurva som MacLeamy, 3. Använder BIM, kan ett träsystem implementeras på frameworket användas för ett träsystem. Det visar sig att desto närmare ett projekt uppfyller kriterierna desto närmare visar sig osäkerhetsvärdena stämma överens med de värden som presenteras för enbart frameworket. Projektet med hög användning av standardiserat byggnadssystem och förbestämdt data påvisar till och med lägre osäkerhetsvärden än vad frameworket gör. På grund av varierade grad av projektkomplexitet visar datakategorierna; materialinformation, geometrisk form och elementdimensioner störst olikheter mellan projekten i resultatet. Resultatet skulle vidare kunna användas till en annan forskningsstudie vars författare definierat detaljerade grafiska LOD visualiseringar i en BIM-kollaborationsmiljö. Konceptet är starkt beroende av givna osäkerhetsvärden som författarna och studien inte fokuserade på att definiera, vilket detta framework gör. Vidare arbete som kan stärka frameworket är att hitta teorier som stödjer de antaganden som gjorts under frameworkets analytiska utvecklande.

The use of cold-formed steel (CFS) structures has become increasingly popular in different fields of building technology. For example, small housing systems using cold-formed steel for wall structures, framing systems and roof structures, including trusses and shielding materials, have been developed during recent years. The reasons behind the growing popularity of these products include their ease of fabrication, high strength/weight ratio and suitability for a wide range of applications. These advantages can result in more cost-effective designs, as compared with hot-rolled steel, especially in short-span applications. It has been common practice in cold-formed steel construction to cut openings in the web of beams for the passage of service ducts and piping. The provision of such openings reduces the story heights and consequently can result in saving of considerable amount of construction materials. On the other hand, the presence of a large web opening causes localized redistribution of stress around the opening region. The large opening causes loss of strength and changes the buckling characteristics of an entire member. It also affects the flexural stiffness, resulting in poor performance of member under serviceability. It is common practice to reinforce the opening of hot-rolled steel members, but proper reinforcement schemes for CFS perforated members has not been established yet. Various reinforcement schemes for cold-formed steel sections were investigated during this study. Two types of reinforcement schemes (for flexural zones and shear zones) were developed. Fifty-four flexural tests and 33 shear tests were conducted. Two types of sections (lipped channel joists with h/t ratio 180 and 118) were tested in flexure and one type of section (lipped channel joists with h/t ratio 180) was tested in shear. The study also included a finite element based numerical investigation, consisting of parametric studies on the size (web depth and thickness) of joists, size and shape of web openings, reinforcement and associated fastening schemes. It was observed that a 75 percent of opening in the web of CFS channel joist causes up to 25 percent reduction in flexural strength and up to 60 percent reduction in shear strength. Such reduced flexural and shear strengths were re-captured by providing proper reinforcement schemes. The flexural reinforcement schemes recommended by the current AISI Standard were found to be ineffective for the sections having low w /t ratios. Bridging channel reinforcement scheme was also considered in this study. Bridging channel reinforcement scheme was capable of restoring the flexural strength of cold formed steel joist having w /t ratios 118 and 180. Similarly, the reinforcement schemes recommended in AISI Standard were not adequate to restore the shear strength of joist sections. A newly developed Virendeel type reinforcement system was capable of restoring the original shear strength of a cold-formed steel joist section. / Thesis / Doctor of Philosophy (PhD)

The research summarized the experimental analysis and finite element modeling of the lateral and rotational response of unbraced wood composite I-joists to worker loads. All experimentation and modeling was conducted on simply supported I-joists varying from 11-7/8 inches to 14 inches in depth and 20 feet to 24 feet in length. I-joists were subjected to static and dynamic loads. The deflections of the top and bottom flanges, as well as the rotation, were measured or calculated at both one-half and one-quarter the span length. The overall goal of this project is to accurately model the lateral and rotational displacements caused by human load effects. I-joists were first tested statically by subjecting each joist to a three point bending test, free from all lateral restraints. This test was necessary to prove that the performance of the joists was repeatable. Lateral and rotational stiffness of the joist were calculated at one-half and one-quarter of the span length. The static experimental tests results were statistically analyzed using an analysis of variance (ANOVA) test. The results from this analysis indicated no difference between repetitions of the same joist; however, the test did indicate that there was a significant difference between joists of the same manufacture and size. Dynamic testing was then conducted. Dynamic loads were induced by having test subjects traverse each I-joist. The resulting loads induced at the top and bottom flanges were recorded for use in the finite element model. The lateral deflections and induced loads were compared to the static weight of the test subject and analyzed with an ANOVA test. The results indicated an increase in both the induced load and resulting deflection with an increase in weight. The analysis also indicated an increase in load and deflection with a decrease in lateral and rotational joist stiffness. The recorded load values from the dynamic test were used as inputs into a finite element model. The resulting lateral deflections of the midpoint and quarter point were generated. The rotation of the beam was calculated from the difference between the top and bottom flange. Experimental results and finite element model results were compared by calculating a running average of the error between the acquired data and the finite element model. The model was said to be valid until the average model error reached 10 percent of the maximum acquired test value. All six deflection readings were analyzed in this manner. The percent of beam at which the model no long represented the test data was determined for each data set. This point was averaged across all deflection readings of similar joists and across all data sets of the same joist type. The model predicted the 20 foot long 11-7/8 and 14 inch deep joists until 54.5 percent and 51.2 percent, respectively, of the beam completed by the test subject. However, the 24 foot long 11-7/8 inch deep joist was only accurate to 31.2 percent of the beam completed by the test subject. Differences in peak values, and the time at which the peak values occurred were also analyzed using an ANOVA test. There was a significant difference between the peak values of the acquired test data and the deflections generated with the finite element model. However, there was no significance within the time that the peak values occurred between the model and experimental results. A simplified pseudo dynamic analysis was conducted using a constant percentage of the test subject's static weight applied to the top and bottom flange. This approximation proved adequate for the lateral displacement and rotation of the 11-7/8 inch and 14 inch deep and 20 foot long I-joists. However, the model became un-conservative for the 11-7/8 inch deep and 24 foot I-joists. / Master of Science

The research summarized in this thesis is comprised of an experimental analysis of the mechanical behavior of a wood composite I-joist with different bracing configurations exposed dynamic walking loads. Three 16 in. deep GPI® 65 I-joists were simply supported and laid parallel to each other, while the bracing was attached to the top flange. Five different brace stiffnesses were used: zero stiffness (control), 1.2 lb/in., 8.5 lb/in., 14.0 lb/in. and infinitely stiff. Two different brace configurations were used: one-quarter of the span length (60 in.) and one third the span length (80 in.). The dynamic walking loads consisted of human test subjects attached to a safety platform walking across the I-joist at a designated pace. Experimental results for this research consisted of the I-joist's lateral accelerations, lateral displacements and twist. An Analysis of Covariance (ANCOVA) was used for the statistical analysis of the results and was performed for each measurement. The statistical analysis determined the effects of different bracing configurations, stiffnesses, measurement locations as well as test subjects' weight and occupation. Test results and observed trends are provided for all test configurations. Lateral displacement and twist experienced the same trend throughout the experiment: as brace stiffness increased, lateral displacement and twist decreased. This correlated with basic beam theory and bracing fundamentals. It should be noted that as the stiffness increased, the effect on lateral displacement and twist response decreased. However, the trend for lateral displacement and twist was not observed for the lateral accelerations. The 1.2 lb/in. brace stiffness had much larger lateral accelerations for the 60 in. brace configuration throughout the span and were also larger at the bracing point for the 80 in. brace configuration. This could have been due to the energy applied from the springs or a natural frequency of the I-joist system could have been reached during testing. However, the other four brace stiffnesses followed the same trend as the lateral displacements and twist. In addition, this research demonstrates a method for the measurement of lateral buckling due to worker loads. The mitigation of lateral buckling can use appropriate bracing systems. The measurements of the change in lateral buckling behavior can be used to develop safety devices and ultimately ensure the protection of construction workers. / Master of Science

Syfte: Miljömedvetet och prisvärt byggande har länge varit två uttryck som använts ibyggbranschen. Betong har använts och är väl beprövat. Trä och framförallt KL-trä ärdäremot ett material som växt fram det senaste decenniet. Frågan är, när är det bäst attbygga med de olika materialen och vad är materialens respektive klimatavtryck? Målet med denna rapport är att jämföra två bjälklagssystem, ett i KL-trä och ett i betong, utifrån ett sammanvägt kostnads-, dimensions- och miljöperspektiv och hur de förhåller sig mellan spännvidderna fyra, sex och åtta meter. ▪ Hur stor är den procentuella kostnadsskillnaden mellan dessa bjälklagssystem? ▪ Hur stor är den procentuella skillnaden i koldioxidutsläpp under produktionen avdessa bjälklagssystem ▪ Hur stor är den procentuella dimensionsskillnaden mellan dessa bjälklagssystem? ▪ Vilket bjälklagssystem är det bästa valet utifrån en multikriterieanalys? Metod: Studien består av flera experiment för att få ut empiri till en kvotmätning.Denna metod användes för att få fram primärdata till arbetet.Sekundärdata samlades in via dokumentstudier av lagar och krav för byggnation inombrand, ljud och dimensionering. Resultat: Studien visar resultaten av en jämförelse mellan bjälklagssystem med olikamaterial och spännvidder. En multikriterieanalys används för att rangordna resultatenför att visa det mest fördelaktiga alternativet. Konsekvenser: Vid användning av KL-trä bör dimensionering tas i beaktande dådimensionerna blir relativt stora jämfört med betong. Kostnaden av materialen skiljersig markant. Detta speglar dock inte totalkostnad då produktion, leveranser, montering,etcetera ej är medräknat. Att använda en multikriterieanalys vid jämförelser ger entydlig bild på fördelaktigt alternativ samt hur stor skillnad det är mellan alternativen. Begränsningar: Då det endast är en del i totalkostnaden som berörs speglar interesultatet rättvis kostnadsbild och kan därför inte användas som referenspunkt. Resultatfungerar endast som ett hjälpmedel vid delberäkning av totalkostnad. Nyckelord: Betong, KL-trä, Plattbärlag, Plattbjälklag, Kassettbjälklag,Multikriterieanalys, Dimensionering, Kostnad, Koldioxidutsläpp / Purpose: Environmental and affordable construction has long been two terms used in theconstruction industry. Concrete has been used and is well proven. Wood and especiallyCLT wood, on the other hand, is a material that has emerged in the last decade. The questionis, when is it best to build with the different materials and what are their respective climatefootprints? The aim of this report is to compare two structural floor systems, one in CLT wood and onein concrete, based on a balanced cost, dimension and environmental perspective and howthey relate between the spans of four, six and eight meters. ▪ What is the percentage cost difference between these structural floor systems? ▪ What is the percentage difference in carbon dioxide emissions during theproduction of these structural floor systems? ▪ What is the percentage dimensional difference between these structural floorsystems? ▪ Which structural floor system is the best choice based on a multi-criteria decisionanalysis? Method: The study consists of several experiments to obtain empirical data for a quotameasurement. This method was used to obtain primary data for the work. To obtain secondary data consisting of standards, calculation models and requirements, adocument study was used. Secondary data were collected via document studies of laws and requirements forconstruction in fire, acoustics and dimensioning. Findings: The study shows the results of a comparison between structural floor systemswith different materials and spans. A multi-criteria decision analysis is used to rank theresults to show the most advantageous alternative. Implications: When using CLT-wood, dimensioning should be taken into account as thedimensions will be relatively large compared to concrete. The cost of the materials differsmarkedly. However, this does not reflect the total cost as production, deliveries, assembly,etcetera are not included. Using a multi-criteria decision analysis in comparisons gives aclear picture of a favorable alternative and how large a difference there is between thealternatives. Limitations: As only a part of the total cost is affected, the result does not reflect a faircost picture and can therefore not be used as a reference point. The results only serve as anaid in the partial calculation of total cost. Keywords: Concrete, CLT-wood, Prefabricated Concrete Slab Joist, CLT Flat Joist,Rib Elements, Multi-Criteria Decision Analysis, Cost, Carbon Dioxide Emissions

Este trabalho enfoca a análise estrutural de um dos tipos de laje que vem ganhando espaço no mercado brasileiro, que é a laje formada por vigotas de concreto protendido. O objetivo principal do trabalho é contribuir na avaliação do comportamento desse tipo de laje com relação aos momentos fletores negativos no apoio, mediante análise teórica. Esta análise foi realizada a partir da relação momento x curvatura proposta pelo CEB-90 em conjunto com a técnica do carregamento incremental para a consideração da não-linearidade física do concreto. Esse método foi avaliado através da comparação com resultados experimentais de painéis alveolares encontrados na literatura, verificando que o modelo teórico representa satisfatoriamente o comportamento estrutural de lajes formadas por elementos pré-moldados protendidos. A partir disto, fez-se análises em situações representativas de projeto de lajes formadas por vigotas protendidas, chegando-se as seguintes conclusões: a) a utilização da continuidade favorece fortemente a redução dos deslocamentos; b) os deslocamentos praticamente independem da taxa de armadura de continuidade; c) a evolução do momento fletor negativo no apoio e momento fletor positivo máximo no vão apresentou um comportamento padrão para os casos analisados; d) esse comportamento foi independente da taxa de armadura de continuidade e e) a taxa de armadura de continuidade afetou praticamente o valor da carga última. / This work aims the structural analysis in a type of slabs that is increasing its utilization in Brazil. These slabs are made by precast prestressed joists. The main objective of this work is the evaluation of the behavior of this type of slabs by theoretical analysis of the bending moments on the supports of continuous slabs. In the theoretical analysis was carried out the consideration of the non-linear of the concrete behavior through the moment x curvature relationship of Model Code CEB-90 add incremental load technique. This methodology was appraised with experimental results of panels of hollow core slabs and this methodology was able to represent satisfactorily the behavior of slabs made by precast prestressed elements. Analysis of representative cases of slabs with precast prestressed joists was carried out and the main conclusions were: a) the use of continuity aids highly to decrease the displacements; b) displacements were practically independent of reinforcement ratio on the support; c) the development profiles of the bending moments had a standard behavior to the analysed cases; d) this behavior was independent of reinforcement ratio on the support and e) the reinforcement ratio on the support affected practically the ultimate load value.

Made available in DSpace on 2014-06-11T19:25:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-28Bitstream added on 2014-06-13T19:53:01Z : No. of bitstreams: 1 trigo_apm_me_ilha.pdf: 2296077 bytes, checksum: aa464f95de9d5130225ee4ae495722db (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No Brasil, o concreto armado é bastante empregado na confecção de pilares, vigas e lajes das estruturas de edificações. As lajes são utilizadas como piso ou forro e, considerandose que a laje de forro não demanda ações elevadas, quando comparada à laje de piso, pensa-se na possibilidade de substituir parcialmente o agregado do concreto por outros materiais que sejam, ecológica e economicamente, viáveis. Desses materiais, o resíduo de borracha se mostra promissor, por ser gerado em abundância. Este trabalho objetiva mostrar uma alternativa de reaproveitamento para o resíduo proveniente do processo de recauchutagem de pneu, utilizando-o como parte do agregado de concreto para lajes de forro. São ensaiadas, à flexão, duas lajes unidirecionais, sendo uma delas constituída parcialmente por resíduo de borracha de pneu, e a outra sem, ambas formadas por vigotas pré-moldadas treliçadas. Através dos deslocamentos verticais, das deformações no concreto e na armadura, medidos com auxílio de relógios comparadores e extensômetros elétricos, e dos modos de ruptura da estrutura, obtidos nos ensaios, avalia-se o comportamento dessas lajes. / In Brazil, the reinforced concrete is used for pillars, beams and slabs. The slabs are used as floor or lining and, as the lining slab do not demand raised actions, when compared with the floor slab, it is possible to replace partially the concrete aggregate for ecologically and economically viable materials. From these materials, the rubber residue is promising and abundant. The aim of this work is to show a recycling alternative for tire rubber from retreading process, using it as part of the concrete aggregate in lining slabs. Two unidirectional slabs are assayed to the flexure, one partially with tire rubber residue and another one without, both formed by precast lattice joist. The slabs behavior is evaluated through the vertical displacements, concrete and reinforcement deformations, measured with comparing clocks and electric strain gages, and structure rupture ways.

Resumo: No Brasil, o concreto armado é bastante empregado na confecção de pilares, vigas e lajes das estruturas de edificações. As lajes são utilizadas como piso ou forro e, considerandose que a laje de forro não demanda ações elevadas, quando comparada à laje de piso, pensa-se na possibilidade de substituir parcialmente o agregado do concreto por outros materiais que sejam, ecológica e economicamente, viáveis. Desses materiais, o resíduo de borracha se mostra promissor, por ser gerado em abundância. Este trabalho objetiva mostrar uma alternativa de reaproveitamento para o resíduo proveniente do processo de recauchutagem de pneu, utilizando-o como parte do agregado de concreto para lajes de forro. São ensaiadas, à flexão, duas lajes unidirecionais, sendo uma delas constituída parcialmente por resíduo de borracha de pneu, e a outra sem, ambas formadas por vigotas pré-moldadas treliçadas. Através dos deslocamentos verticais, das deformações no concreto e na armadura, medidos com auxílio de relógios comparadores e extensômetros elétricos, e dos modos de ruptura da estrutura, obtidos nos ensaios, avalia-se o comportamento dessas lajes. / Abstract: In Brazil, the reinforced concrete is used for pillars, beams and slabs. The slabs are used as floor or lining and, as the lining slab do not demand raised actions, when compared with the floor slab, it is possible to replace partially the concrete aggregate for ecologically and economically viable materials. From these materials, the rubber residue is promising and abundant. The aim of this work is to show a recycling alternative for tire rubber from retreading process, using it as part of the concrete aggregate in lining slabs. Two unidirectional slabs are assayed to the flexure, one partially with tire rubber residue and another one without, both formed by precast lattice joist. The slabs behavior is evaluated through the vertical displacements, concrete and reinforcement deformations, measured with comparing clocks and electric strain gages, and structure rupture ways. / Orientador: Jorge Luís Akasaki / Coorientador: José Luiz Pinheiro Melges / Banca: Jefferson Sidney Camacho / Banca: Roberto Chust Carvalho / Mestre

Este trabalho enfoca a análise estrutural de um dos tipos de laje que vem ganhando espaço no mercado brasileiro, que é a laje formada por vigotas de concreto protendido. O objetivo principal do trabalho é contribuir na avaliação do comportamento desse tipo de laje com relação aos momentos fletores negativos no apoio, mediante análise teórica. Esta análise foi realizada a partir da relação momento x curvatura proposta pelo CEB-90 em conjunto com a técnica do carregamento incremental para a consideração da não-linearidade física do concreto. Esse método foi avaliado através da comparação com resultados experimentais de painéis alveolares encontrados na literatura, verificando que o modelo teórico representa satisfatoriamente o comportamento estrutural de lajes formadas por elementos pré-moldados protendidos. A partir disto, fez-se análises em situações representativas de projeto de lajes formadas por vigotas protendidas, chegando-se as seguintes conclusões: a) a utilização da continuidade favorece fortemente a redução dos deslocamentos; b) os deslocamentos praticamente independem da taxa de armadura de continuidade; c) a evolução do momento fletor negativo no apoio e momento fletor positivo máximo no vão apresentou um comportamento padrão para os casos analisados; d) esse comportamento foi independente da taxa de armadura de continuidade e e) a taxa de armadura de continuidade afetou praticamente o valor da carga última. / This work aims the structural analysis in a type of slabs that is increasing its utilization in Brazil. These slabs are made by precast prestressed joists. The main objective of this work is the evaluation of the behavior of this type of slabs by theoretical analysis of the bending moments on the supports of continuous slabs. In the theoretical analysis was carried out the consideration of the non-linear of the concrete behavior through the moment x curvature relationship of Model Code CEB-90 add incremental load technique. This methodology was appraised with experimental results of panels of hollow core slabs and this methodology was able to represent satisfactorily the behavior of slabs made by precast prestressed elements. Analysis of representative cases of slabs with precast prestressed joists was carried out and the main conclusions were: a) the use of continuity aids highly to decrease the displacements; b) displacements were practically independent of reinforcement ratio on the support; c) the development profiles of the bending moments had a standard behavior to the analysed cases; d) this behavior was independent of reinforcement ratio on the support and e) the reinforcement ratio on the support affected practically the ultimate load value.