Dissertations / Theses on the topic 'Hollow concrete slab'

The most common prefabricated concrete slabs are hollow core slabs, which are usually pre-tensioned. How to design these parts is not compiled today in a manual where it is clear how this is done, this knowledge is generally classified as expert knowledge. The purpose was to bring forth how to design prefabricated pre-stressed hollow core slabs, HD/F, and then create a design aid that is compared by hand calculations with the PRE-Stress design program from StruSoft. Furthermore, to compare it with site-cast concrete slabs to see differences in the amount of material and the thickness of the structure under the same conditions.The design aid is not complete as some limitations had to be made. When it comes to results, the hand calculations in comparison with PRE-Stress have not resulted in identical answers but have proven to be on the safe side consistently through the design, which indicates that the design aid is fully functional. In the comparison with site-cast concrete slabs, it can be noted that prestressed hollow core slabs require less concrete volume, slimmer construction, and longer span widths but greater reinforcement volume.
Det vanligaste prefabricerade betongbjälklaget är håldäcksplattor som oftast är spännarmerade. Hur man dimensionerar dessa bärverksdelar finns idag inte samlat i en handbok där det står tydligt hur man gör, den kunskapen klassas generellt som expertiskunskap. Syftet var att ta fram hur man dimensionerar prefabricerade förspända håldäcksplattor, HD/F, och sedan skapa ett dimensioneringshjälpmedel som jämförs genom handberäkningar med PRE-Stress dimensioneringsprogram från StruSoft. Vidare genomfördes jämförande beräkningar för platsgjutet betongbjälklag för att se skillnader i materialmängd och konstruktionstjocklek under samma förutsättningar.Dimensioneringshjälpmedlet är inte komplett då vissa avgränsningar behövts göras. När det kommer till resultat har handberäkningar i jämförelse med PRE-Stress inte resulterat i identiska svar, men visat sig hamna på säkra sidan konsekvent genom dimensioneringen vilket tyder på att dimensioneringshjälpmedlet är fullt användbart. I jämförelsen med platsgjutet bjälklag kan man konstatera att förspända håldäcksplattor ger mindre betongvolym, slankare konstruktion och längre spännvidder men större armeringsmängd.

Byggnadstaktenav flerbostadshus i Sverige ligger på en hög nivå och ökar. Detta medför kravpå en snabb byggprocess. En lösning för att snabba på byggprocessen äranvändandet av prefabricerade delar. Författarnas uppgift, i samarbete med WSPSverige AB, är att utveckla ett hjälpmedel för konstruktörer som jämför fyraolika bjälklag, varav ett i korslimmat trä, två prefabricerade betongelementoch en platsgjuten konstruktion. Målet är att framställa en tabell som beaktarfaktorer som påverkar valet av stomsystem och som presenterar vilket avbjälklagen som är mest kostnadseffektivt. Rapporten sammanställdes under 10veckor och avgränsades till bjälklag i flerbostadshus upplagda på två stöd somuppfyller relevanta krav för dimensionering, beaktar torktid med fastaförutsättningar, leveranstid avseende produktionstid hos de prefabriceradeelementen och miljöpåverkan avseende CO2-ekvivalenta utsläpp iproduktionsskedet. Studiens resultat grundar sig på litteraturstudier ochintervjuer, kalkylhjälpmedel och beräkningsprogram som är vanliga i branschen.Resultatet visar att: · trä genererar lägst koldioxidutsläpp avbjälklagsalternativen · betong är, ur ett brand- och ljudperspektiv, detlämpligaste materialet · korslimmade träbjälklaget får den högsta byggnadshöjdenoch den högsta kostnaden per kvadratmeter · håldäcksbjälklag har den kortaste leveranstiden · det slakarmerade plattbärlag samt det platsgjutnabetongbjälklaget har längst torktid · den platsgjutna bjälklagskonstruktionen är detmest kostnadseffektiva bjälklaget av de fyra som har jämförts.
The building pace of multi apartment houses in Sweden is at a high leveland is increasing. This induces demands of a quick building process. Onesolution to quicken the building process is the use of prefabricated elements.The authors’ task, in collaboration with WSP Sverige AB, is to develop anaiding tool for engineers who compare different slabs, one cross laminatedwood, two precast concrete components and one construction cast in-place. Thegoal is to produce a table that considers factors that affects the choice ofstructure and presents which of the slabs that is most cost effective. Thepaper was compiled over a period of 10 weeks and limited to slabs inmulti-apartment buildings supported on two sides that meet relevantrequirements for dimensioning, consider hydration time with set conditions,delivery time regarding production time for the precast components andenvironmental effects considering CO2-equivalent emissions in the productionstage. The results of the study are founded on literature and interviews,calculation-aids and computational programs that are common in the industry.The outcome shows that: · woodgenerates the least amount of carbondioxide emissions of the slab alternatives · concrete is, from a fire- and acoustic perspective, the most suitable material · thecross laminated slab renders the highest cross-section and the highest cost persquare meter · hollow core slabs has the shortest delivery time · theconventionally reinforced precast slabs and the in-situ cast floor slabs havethe longest hydration times · thein situ slab is the most cost effective slab of the four that have beencompared.

Betyg 170707, H14.

A maioria dos edifícios de concreto pré-moldado, construídos no Brasil e no exterior, é constituída por lajes alveolares. Este trabalho considera o estudo da continuidade dessas lajes. No cálculo desses elementos, a prática comum é considerá-los como simplesmente apoiados. Para melhorar o desempenho, é possível promover a continuidade nos apoios intermediários. Isso pode ser feito colocando armadura na região tracionada da ligação, no interior da capa, ou através de barras concretadas dentro dos alvéolos. O objetivo deste trabalho é investigar o comportamento de pavimentos formados por lajes alveolares com continuidade, com armadura na capa. Para isso, foi realizado um estudo envolvendo análise teórica e experimental em três modelos. Esses modelos, em escala real, foram submetidos a um carregamento transversal, distribuído de forma linear. Os estudos teóricos consideraram uma simulação numérica com elementos de viga e a fórmula de Branson para descrever o comportamento não linear físico do material. Além disso, foram avaliadas as expressões dos principais códigos nacionais e internacionais, no que diz respeito à ruptura por cisalhamento da seção transversal e da interface laje-capa. Os resultados da análise experimental indicaram que o modelo 1 rompeu por cisalhamento da seção transversal, com o mecanismo de tração diagonal do concreto. O modelo 2 apresentou ruptura por cisalhamento da interface. No modelo 3, a ruptura foi por flexão. O comportamento dos modelos ensaiados foi governado pela fissuração da capa na região de momento negativo. A análise teórica com elementos de barra representou de forma satisfatória o comportamento dos modelos ensaiados. As únicas formulações que apresentaram resultados coerentes com os três ensaios foram: EUROCODE 2:2004, para o cálculo da resistência ao cisalhamento da interface, e FIB MODEL CODE 2010, para o cálculo da resistência ao cisalhamento da seção transversal. Conclui-se que a continuidade melhora o desempenho das lajes alveolares, uma vez que reduz os deslocamentos no meio do vão e aumenta a capacidade de carga.
Most buildings of precast concrete built in Brazil and abroad consist of hollow core slabs. This paper considers the study of the continuity of these slabs. In design of these elements the common practice is to consider them as simply supported. To improve the performance it is possible to promote the continuity in the intermediate supports. This can be done by placing reinforcement in the tensioned region of the connection, inside the topping, or by bars concreted inside the voids. The aim of this work is to investigate the behavior of hollow core floors with continuity, with reinforcement in the topping. For this, a study involving theoretical and experimental analysis was conducted in three models. The full-scale models were subjected to a transverse loading distributed linearly. The theoretical studies have considered a numerical simulation with beam elements and the Branson formula to describe the physical nonlinear behavior of the material. Furthermore, the specifications of the major Brazilian and international codes were evaluated, with respect to failure by shear of the cross section and the slab-topping interface. The results of the experimental analysis indicated that the model 1 failed by shear of the cross section with the mechanism of diagonal tension of the concrete. Model 2 presented shear failure of the interface. In model 3, the failure was by flexure. The behavior of the tested models was ruled by cracking of the topping in region of negative bending moment. Theoretical analysis with beam elements represented satisfactorily the behavior of the tested models. The only formulations that presented consistent results with the three tests were: EUROCODE 2:2004, to calculate the shear strength of the interface, and FIB MODEL CODE 2010, for calculating of the shear strength of the cross section. It is concluded that the continuity improves the performance of the hollow core slabs, as it reduces the displacements at mid-span and increases the bearing capacity.

Hollow-core flooring units are designed as simply supported members. However, frequently in construction, continuity is established between the units and supporting structure by the addition of insitu topping concrete and steel reinforcement. This change in structural form can result in negative bending moments and axial forces being induced in the floor by seismic and other structural actions. Significant negative moments are induced by load combinations that include the effects of seismic forces due to vertical ground motion. The focus of this research was two failure mechanisms possible under these loading conditions, a flexural failure and a shear failure. Both failure mechanisms were investigated analytically and experimentally. A brittle flexural failure was observed experimentally in a sub assembly test that contained starter bars and mesh reinforcement in the insitu topping concrete. The failure occurred at loads lower than those predicted using standard flexural theory. It appears that, due to the prestressing and low reinforcement ratio of the topping concrete, the assumption that plane sections remain plane is not appropriate for this situation. It is proposed that a strain concentration factor be introduced to account for the effects of tension stiffening. This factor improves the correlation between observed and predicted flexural strength. The second failure mode investigated was a flexure shear failure in a negative moment zone. Flexural cracks reduce the shear strength of a reinforced concrete member. Analytical predictions suggest that some hollow-core floor details could be prone to this type of brittle failure. A flexure shear failure was not observed experimentally; however, this does not eliminate the possibility of this failure mode. A summary of other failure mechanisms possible in hollow-core flooring is also presented. All failure modes should to be considered as part of establishing a hierarchy of failure in the design or retrofit of hollow-core floors.

Betong är idag ett av de material som vi använder mest i byggbranschen och det har sinaföljder. Mer än 50 % av energiutsläppen från byggplatsen kommer från cementtillverkningen.Voided biaxial slab eller VBS är en revolutionerande teknik där man gjuter in plastbollar ibetongen tillsammans med armeringen. Arbetstiden samt torktiden kortas ned samtidigt somvi bevarar hållfastheten och dess funktionalitet. I den här rapporten kommer vi titta närmarepå VBS teknik och jämföra det med konventionell betongplatta och se om tekniken är lämpligför att implementeras i Sverige.Vi har använt oss av en kvalitativ metod i form av källanalys från internet och tryckta källor.Även en komparativ metod i de fallen vi har hittat information från mer än en källa.Rapporten kommer enbart fokusera på betongplattor och våningsavskiljande bjälklag. VBSanvänds i horisontella plan endast. Tak och väggar är därför uteslutna. Tekniken kommerpresenteras i form av viktiga aspekter för dess överlevnad i den svenska marknaden såsomekonomi, strukturella fördelar och hållbarhet.Resultatet visar att VBS rent ekonomiskt nästan bara är positivt jämfört med denkonventionella betongplattan som endast består av armerad betong. Konstruktionsmässigt ärVBS ett konkurrenskraftigt alternativ till armerad betong. Böjhållfastheten är detsamma somarmerad betong. Andra bra positiva aspekter är miljövänligheten, arbetsmiljömässigt,energikonsumtion och värmeisolering.De mindre bra egenskaperna är sämre prestanda i skjuvmotstånd, brandmotstånd ochljudisolering.VBS kan implementeras i Sverige men för att plast ska introduceras i en så pass stor skala såbehövs en infrastruktur. Den bör tillgodose hållbart produktion av Bubbledeck och separeramaterialen vid rivning. Tekniken medför stora fördelar men trots det kan företagen få svårt attmotivera sig till att bygga med VBS när betong är så lättillgängligt och varit med så länge.
Concrete is today one of the materials we use most in the construction industry and it has itsconsequences. More than 50% of the energy emissions from the construction site come fromcement production. Voided biaxial slab or VBS is a revolutionary technique in which plasticballs are cast into the concrete together with the reinforcement. The working time and thedrying time are reduced while maintaining the strength and its functionality. In this report, wewill take a closer look at VBS technology and compare it with conventional concrete slab andsee if the technology is suitable for implementation in Sweden.We have used a qualitative method in the form of source analysis from the Internet andprinted sources. Also a comparative method in cases where we have found information frommore than one source.The report will focus solely on concrete slabs and floor separating flooring. VBS is used inhorizontal planes only. Roofs and walls are therefore excluded. The technology will bepresented in the form of important aspects for its survival in the Swedish market such aseconomy, structural benefits and sustainability.The result shows that VBS is financially almost only positive compared to the conventionalconcrete slab, which consists only of reinforced concrete. In terms of design, VBS is acompetitive alternative to reinforced concrete. The flexural strength is the same as reinforcedconcrete. Other good positive aspects are environmental friendliness, work environment,energy consumption and heat insulation.The less good features are poor performance in shear resistance, fire resistance and soundinsulation.VBS can be implemented in Sweden but for plastic to be introduced on such a large scale, aninfrastructure is needed. It should meet the sustainable production of Bubbledeck and separatethe materials during demolition. The technology brings great benefits, but despite this,companies can find it difficult to motivate them to build with VBS when concrete is so easilyaccessible and has been around for so long.

Cuenca Asensio, E. (2012). ON SHEAR BEHAVIOR OF STRUCTURAL ELEMENTS MADE OF STEEL FIBER REINFORCED CONCRETE [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/18326
Palancia

Ensaios não destrutivos são testes que não causam danos a estrutura ensaiada, o que os torna um excelente auxílio aos métodos de ensaios tradicionais quando estes apresentam alguma dificuldade de serem executados. Desta forma, este trabalho visa utilizar os ensaios de esclerometria e ultrassom, dando ênfase na transmissão indireta, para determinar a resistência à compressão nas primeiras idades do concreto e possibilitar um melhor controle tecnológico do material. Para se obter a relação entre os dados experimentais não destrutivos e a resistência à compressão, foram realizados ensaios em duas etapas. A primeira etapa foi desenvolvida em corpos de prova cilíndricos e prismáticos com três traços diferentes de concreto, onde foi variado o consumo de cimento. Na segunda etapa os ensaios foram realizados em uma laje alveolar produzida em laboratório. Com os dados coletados nos ensaios foi possível determinar a relação de crescimento da resistência, do índice esclerométrico e da velocidade do pulso ultrassônico ao longo do tempo, além das correlações velocidade x resistência, velocidade x índice esclerométrico; e a correlação múltipla entre os três fatores. Com base nisto, concluiu-se que é viável ter um bom controle tecnológico da resistência do concreto a partir dos ensaios não destrutivos. Este trabalho não obteve uma equação universal que correlacionasse os parâmetros para todos os tipos de traço de concreto, porém foram obtidas correlações satisfatórias para os traços ensaiados. Desta forma, é possível afirmar que o ensaio de ultrassom, especificamente posição indireta de 30 centímetros, e a esclerometria são ferramentas possíveis de serem aplicadas como auxílio à obtenção da resistência à compressão nas primeiras idades.
Non-destructive tests are tools that do not cause damage to the evaluated structure, which is an excellent support for traditional test methods. Therefore, this work used non-destructive tests such as rebound method and ultrasound, emphasizing the indirect transmission, to determine compression strength in the early age sand enable a better technological control of the material. Two-step tests were performed to see if there is a relationship between non-destructive test data and the compressive strength. The first one was performed in specimens with three different concrete compositions, where the cement ratio was varied, where as the second was carried out in a laboratory hollow core slab. With the experimental data was possible to determine the relationship of the compression strength, rebound number and ultrasonic pulse velocity over time; as the correlations strength x velocity, velocity x rebound number; and a multiple correlation between the three tests. Based on this, it was concluded that it is possible to have a good technological control of the concrete strength from non-destructive tests. A universal equation that correlates parameters for all types of concrete compositions was not found, but satisfactory correlations were obtained for the tested concretes. In this way, it is possible to affirm that the ultrasound test, specifically indirect position of 30 centimeters, and rebound method are possible tools to be applied as aid to obtain the compression strength in the early ages.

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The use of precast elements has become crescent in Brazil, due to the need of haste during production as well as while assembling the structures. Bearing in mind a quick assembly and the competitive price for this kind of frame, precast elements have been growing and spreading in this field throughout the country. There is something special about demanding hollow core slabs, in virtue of their own low weight, in face of the empty spaces generated by the hollows and a better use of materials because of pretension technique, making it economically feasible. The National Technical Code ABNT NBR 9062, which deals with precast concrete structures, shows no more specific criteria as far as hollow core slabs are concerned, but on the other hand the 2011 review in force to ABNT NBR 14861 which covers precast hollow core slabs brings about relevant aspects such as the method used to check the capacity of shear strength on precast hollow core slabs, both with and without concrete structural cover, and furthermore with and without hollow fillings. Considering the reduced amount of national research on this topic, this study aims to develop and perform techniques in different ways of filling the hollows and the slabs and how they behave when exposed to shear strength tests. As a consequence to the manufacturing process of such type of slab and the hollow- filling method, failure in the idealized filling, in virtue of each material own behavior and inappropriate technique are commonly found.
O emprego de elementos pré-fabricados tem se tornado crescente no Brasil, dado a necessidade de velocidade de produção e montagem de estruturas. Tendo em vista a rápida montagem e o preço competitivo deste tipo de estrutura, elementos prémoldados tem ganhado campo no mercado nacional. Há um destaque pela procura de lajes alveolares, devido ao seu baixo peso próprio, decorrente de vazios proporcionados pelos alvéolos e maior otimização dos materiais em virtude da aplicação da técnica de pré-tração, tornando-a economicamente viável. A Norma Técnica Nacional ABNT NBR 9062 que trata de estruturas pré-moldadas de concreto não apresenta critérios mais específicos para lajes alveolares, por outro lado a revisão em vigor de 2011 da ABNT NBR 14861 que aborda lajes alveolares préfabricadas traz aspectos relevantes tais como o método de verificação da resistência à força cortante de lajes alveolares com ou sem capeamento estrutural e com ou sem preenchimento de alvéolos. Tendo em vista o reduzido volume de pesquisas nacionais sobre o tema, esta pesquisa tem como objetivo fazer um estudo teórico-experimental das diferentes técnicas de preenchimento de alvéolos de lajes alveolares e o seu comportamento quando submetidas a ensaios de força cortante. Como consequência do processo de fabricação deste tipo de laje e do método de preenchimento dos alvéolos, falhas no preenchimento idealizado devido ao comportamento distinto dos materiais e técnicas inadequadas são comumente constatadas.

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The floors consist of hollow core slabs are being increasingly used in Brazil, because it can overcome large spans, have a low self-weight, allow fast assembly, require no shoring in many situations and are more economical than other solutions. These floors are normally designed for ease of implementation, so that the slabs act as simply supported, without continuity. This work presents a roadmap of calculation and verification based on known theoretical models and tests already carried out considering that the hollow core slabs of pavement work as continuous. This continuity is made by adding passive reinforcement in the topping region. The calculation procedures are also detailed for the situations in which there are alternate accidental actions, as well as the situation in which there are concentrated mobile loads acting on the floor. Numerical examples comparative considering continuity with the situation simply supported show what can be achieved: the active reinforcement economy, increasing the value of accidental load and checks excessive deformation that is not checked on a system simply supported. Some situations are also pointed in which the consideration of continuity fails to bring great advantage. In all the examples developed are shown the details required to perform continuity. Every calculation methodology is based on Brazilian codes and should be noted that the calculations are done considering the simultaneous loss of prestressing. At the end of the work are proposed studies that may be performed to improve understanding of the behavior of pavements with continuous hollow core slabs.
Os pavimentos formados por laje alveolar estão sendo cada vez mais utilizados no Brasil, porque podem vencer grandes vãos, ter um baixo peso próprio, permitirem rapidez de montagem, não necessitam de escoramento e em diversas situações são mais econômicos do que outras soluções. Tais pavimentos são normalmente projetados, por facilidade de execução, para que as lajes funcionem como simplesmente apoiadas, sem continuidade. Apresenta-se neste trabalho um roteiro de cálculo e verificações baseados em modelos teóricos conhecidos e ensaios já realizados considerando que as lajes alveolares do pavimento funcionam como contínuas. Esta continuidade é feita através da adição de armadura passiva na capa das lajes. Detalham-se os procedimentos de cálculo também para as situações em que existem ações acidentais alternadas, assim como para a situação em que há cargas concentradas móveis atuantes no pavimento. Exemplos numéricos comparativos considerando a continuidade com a situação simplesmente apoiada mostram, que é possível alcançar: economia na armadura longitudinal ativa, aumento do valor de carga acidental atuante e atender verificações de deformação excessiva, não atendidas em um sistema simplesmente apoiado. Aponta-se também em quais situações a consideração da continuidade não chega a trazer grande vantagem. Em todos os exemplos desenvolvidos são mostrados os detalhes necessários para executar a continuidade. Toda a metodologia de cálculo é baseada nas instruções das normas Brasileiras e salienta-se que os cálculos são feitos considerando-se as perdas de protensão simultâneas. No final do trabalho são propostos estudos que podem ser realizados para melhorar o entendimento do comportamento de pavimentos contínuos com lajes alveolares.

Este trabalho apresenta dois tipos de ensaios não destrutivos para a correlação do módulo dinâmico com a resistência à compressão para elementos de concreto. Os métodos de ensaio são a ultrassonografia e o método de excitação por impulso utilizando o equipamento Sonelastic®. Neste trabalho estão descritos seus funcionamentos, aplicações e limitações. A ultrassonografia, através da propagação de ondas sonoras, fornece, indiretamente, o módulo de elasticidade dinâmico. Com o método de excitação por impulso obtêm-se as frequências naturais e os modos de vibração do elemento estudado, o que permite determinar seu módulo dinâmico. Primeiramente, estes ensaios foram utilizados em corpos-de-prova cilíndricos e lajes alveolares produzidas em laboratório para a obtenção das curvas de correlação e, em seguida, estes mesmos ensaios foram realizados na fábrica de concreto pré-moldado. Para elementos de geometria complexa, como é o caso das lajes alveolares, apresenta-se uma metodologia para a obtenção de uma equação analítica para o cálculo do módulo dinâmico no ensaio de excitação por impulso. Estes métodos tiveram o objetivo final de avaliar a resistência à compressão do concreto na pista de protensão da fábrica, e então determinar o melhor momento para a desforma e corte do cabo de protensão. Com ambos os métodos, obteve-se ótimas correlações do módulo dinâmico com a resistência à compressão dos elementos em laboratório. Na fábrica de concreto pré-moldado não foi possível obter uma curva de correlação representativa de toda a laje na pista de protensão, porém foi possível registrar um bom indicativo de que é possível obter boas correlações para futuras pesquisas no assunto
This work presents two types of non-destructive testing for the correlation of the dynamic elastic modulus with the compressive strength. The test methods are the ultrasonography and the impulse excitation using the Sonelastic® equipment. In this work the equipaments operations, applications and limitations are also described. The ultrasound test indirectly supplies the dynamic elastic modulus through the propagation of sound waves. The natural frequencies and the vibration modes of the studied elements are obtained through impulse excitation method allowing to determine its dynamic modulus. To start, these tests were used in cylindrical specimens and hollow core slabs produced in the laboratory to obtain the correlation curves, and then these same methods were performed in the pre-cast concrete plant. As for complex geometric elements, as in the case of hollow core slabs, a methodology is applied in order to obtain an analytic equation to calculate the dynamic modulus in the impulse excitation test. These methods had the final goal the evaluation of the strength of prestressed concrete lying on track of the plant, so as to determine the best moment to demold and cut the prestressed cable. Excellent correlations of the dynamic modulus with compressive strength of the elements made in laboratory were obtained using both methods. It was not possible to obtain in the precast concrete plant a representative correlation curve of the whole slab on the track, nevertheless, it was possible to record a good indication that it is possible to obtain good correlations for future research.

An investigation of prestressed concrete containing steel fibres as secondary reinforcement to improve performance in shear, flexure and bond is reported. Emphasis is placed on the use of steel fibres in prestresssed extruded hollow core slabs, since these common precast elements have intrinsic difficulty in incorporating traditional secondary reinforcement due to their unique shape and manufacturing method. Two separate studies were carried out. The first study involved laboratory investigations into the bond between fibre reinforced concrete (FRC) and the prestressing strand, and the shear behaviour of laboratory-cast prestressed fibre reinforced concrete (PFRC) beams. The second part involved the factory production of fibre reinforced hollow core slabs in co-operation with a local manufacturer. The fibre reinforced hollow core slabs were subjected to conventional full-width shear tests, concentrated load shear tests, and to transverse flexure. For all laboratory cast elements, cubes, cylinders and prisms were cast to investigate compressive, tensile and flexural properties, respectively. Two types of steel fibre were investigated: hooked-end steel fibres at fibre volume fractions (Vf) of 0.5%, 1.0% and 1.5%; and amorphous metal fibres at Vf‘s of 0.28% and 0.56%. The trial production of fibre reinforced hollow core slabs necessitated the investigation of the effect of steel fibres on the extrusion manufacturing process. It was shown that fibre reinforced hollow core slabs could be adequately compacted with only slight increases in mixing water. Fibres were found to distribute randomly throughout the cross-section. However, the rotation of the augers affected the orientation of fibres, with fibres tending to align vertically in the web. It was shown that the addition of steel fibres to prestressed concrete has a negative effect on the bond between matrix and tendon, leading to longer transfer lengths. The effect of the increase in transfer length was to reduce cracking shear strengths by 4%. Shear tests showed that the incorporation of steel fibres could increase shear strength by as much as 45% for Vf = 1.5%. This increase in shear strength, known as the fibre contribution, was shown to be due to fibres bridging across the crack and an increased compressive resistance due to fibres arresting the propagation of cracks into the compressive zone. A semi-empirical equation for shear strength of PFRC elements is developed. It is given in two forms, one compatible with the present equations for prestressed concrete given in BS 8110 and Eurocode 2, and a second form compatible with that advocated for fibres in reinforced concrete. The equation makes use of equivalent flexural strength which is recognised as the most useful material property for design of FRC. The equation was found to give good correlation with the shear strength of single web beams cast both in the laboratory and under factory conditions. However, a overall strength reduction factor is required for full-width hollow core slabs to account for uneven load distribution and inconsistent web widths. This is consistent with tests on plain hollow core slabs found in the literature.

The main aim of this thesis is to develop an insight into the behaviour of composite floors that utilise steel beams acting in combination with precast concrete hollow core floor slabs and to produce design recommendations for use by industry for this type of construction. Full scale bending tests of proprietary precast prestressed concrete hollow core unit floor slabs attached through 19mm diameter headed shear studs to steel Universal Beams (UB) have been carried out to determine the increased strength and stiffness when composite action is considered. The results show the bending strength of the composite beam to be twice that of the bare steel beam, and its flexural stiffness to be more than trebled. In addition to the beam tests, isolated push-off tests and horizontal eccentric compression tests were used to study the horizontal interface shear resistance of the headed studs and the strength of the slab, respectively. Maximum resistances were compared with the predictions of the Eurcode EC4, and a reduction formula for the precast effect derived. In addition to the experimental investigations, finite element (FE) studies were also conducted using the FE package ABAQUS to extend the scope of the experimental work. Results show a 2-dimensional plane stress analysis to be sufficiently accurate, providing the correct material input data obtained from isolated push-off and compression tests are used. The FE model for the composite beam was designed and validated using the full scale beam tests. A parametric study, involving 45 analyses, was carried out to cover the full range of UB sizes and floor depths used in practice. From the finite element work, design charts are formulated which may be used to simplify the design rules. Given the results of this work, a full interaction composite beam design may be carried out using the proposed design equations. The results show that precast slabs may be used compositely with steel UB's in order to increase both flexural strength and stiffness at virtually no extra cost, except for the headed shear studs. The failure mode is ductile, and may be controlled by the correct use of small quantities of transverse reinforcement and insitu infill concrete.

The dumping cost of wasted concrete including the rejected units in precast concrete plants is expected to keep rising as the production increases. The waste material from precast concrete hollow core floors (hcu) is high grade and uncontaminated material. This research work was carried out to investigate mainly the strength and other engineering properties of high strength concrete made with recycled concrete aggregate derived from rejected hcu. Three major categories (based on a questionnaire) were investigated: (i) Type of crushers and the crushing method, (ii) The properties of RCA output from these crushers, (iii) The performance of fresh and hardened concrete, including prestressed concrete, with these RCA. The input material for the crushers was from the same origin of disposed hcu's. The waste concrete was crushed to -14 mm using three different types of crushers - the cone, impact and jaw crushers. The recycled material was separated into fractions of 14 mm, 10 mm and - 5 mm, and tested for physical and mechanical properties relevant to use in concrete. Concrete was then made using zero (control mix), 20% and 50% replacement of recycled coarse (RCCA), recycled fine (RCFA) and mixed (RCCA+RCFA) aggregates. All three crushers produced acceptable shape and strength of RCCA. Some properties are competitive to that of natural limestone aggregate. RCFA was much coarser than river gravel and just complied with the British Standard coarse grading limits. The impact crusher performed best with regard to most aggregate properties, e. g. flakiness, strength and water absorption, but has a disadvantage in producing a large amount of fine-to-coarse RCA. Concerning shape and strength, RCA showed similar properties, and in some cases better, than the conventional limestone aggregate. The water absorption for RCA is 3 to 4 times greater than the natural aggregates. For that reason an extra amount of water (called free water) will be added to the mix to compensate the water absorptions for aggregates. Some proportions of this extra added water may not be absorbed by the aggregates and will float to interrupt the design W/C ratio and caused it to increase. The slump value of fresh concrete made with RCA varied widely depending on the percentage and type of replacement, and the type of crusher. The compaction factor of fresh concrete made with RCA was more consistent and logical. Compressive strength of concrete made with RCA were generally within ±5 N/mm2 of the control. For tensile strength, RCA showed similar performance to that of natural limestone. The SS density of concrete with RCA is lower than that of the control concrete and is lower if the replacement percentages increase. Using RCFA causes higher bleeding rate and considerably reduces density and strength, and the severity increases as the replacements of RCFA increases. Using natural limestone aggregates with RCFA will minimize this poor behaviour and maintain the strength to certain extent. However joining RCCA with RCFA will not limit the poor behaviour and is not recommended. For bonding reinforcing bars most methods indicated that high replacement (100%) of CA cause some reduction in bond strength. In pretensioning wires the RCA concrete had a better performance in bond but some reduction was still reported. Prestressed X-shape beams were used to assess the effects of using of RCA on the performance of hollow core slabs. For 20% RCCA replacements, the prestressing loss, deflection and X-beam flexure crack failure were similar to the standard X-beam, at least and within the design limit. However at higher replacements (50%) some deterioration starts to reveal and the effects are even greater when using a combination of RCCA and RCFA.

The aim of the diploma thesis is processing of the design documentation to execution newly-built multifunctional building in the city part Brno - Řečkovice. Multifunctional building is a detached house, which is located in a quiet area on the edge city. This is a five floor building with four floor, one basement and flat roof. Building is rectangular shape. At the object are twelve parking spaces for cars. Vertical load-bearing structure are made of masonry and reinforced frame system, reinforced concrete floor and prestressed hollow core slab Spiroll. External facade building is created by render scrape texture and flush facade in ground floor.

This diploma thesis solves the project of four-storey, partly cellared mountain pension situated in the plant number 645/2 in the cadastral area in Deštné in Orlické hory. The building has a capacity of 44 seats to accommodate 72 persons in the restaurant and 57 persons in the wellness center. There is a wellness center with fitness room and engine room of air-conditioning system in the basement. There is an entrance hall with hotel base, restaurant, sanitary facilities and utility room with boiler room on the first floor. The second and third floor is designed for accommodation. There is an outdoor terrace of restaurant. The building has a load-bearing wall system. The load-bearing walls and the partition walls are bricked up of the porous concrete YTONG bricks and sand-lime bricks SILKA. The walls are insulated of mineral wool thickeness 200 mm and EPS Perimeter thickeness 140 mm underground section and plinth area. The ceiling structure are made of the prestressed hollow core panels spiroll thickness 250 mm and wooden beamed ceiling. There is a saddle wooden roof. The windows and the doors are made by the company Progress. The part of facade of the building is ventilated. This project is designed by the computer software ArchiCAD.

The thesis presents results from a project dealing with ductility in high performance concrete structures. The main objectives were to investigate the material and structural ductility/brittleness of prestressed structural elements of High Performance Concrete (HPC). The aim was to get a better understanding of the fracture process and to study sudden and brittle failures formed by shear stresses. The project was split into three parts: (I) Torsion of cylindrical pole elements, (II) Shear, torsion and bending of hollow core slabs, and (III) Shear, torsion and bending of cylindrical pole elements. Laboratory investigations were performed and displacements were carefully studied. The test results were compared with different code models and especially with the Modified Compression Field Theory(MCFT) proposed by Collins & Mitchell (1991). A computer program based on MCFT was written to calculate the interaction between shear, torsion and bending. One conclusion is that structures made of HPC can be as ductile as structures made of normal strength concrete. Another conclusion is that the strain-based modified compression field theory can represent failure processes in a correct way with good results.
Godkänd; 1999; 20061117 (haneit)

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One of the main differences in the structures composed of prefabricated elements of the conventional structures (cast in situ) refers to the way of how structural elements are connected together. The operation of such links is essential to perform an accurate analysis of stability and removed from these buildings. A place where the connection is very important in verifying the structural behavior is among the cellular elements of the slab. In a conventional structure, usually made of solid slabs for floors, it is observed that the behavior of slabs have a great influence on the distribution of efforts arising from actions horizontal resistance between the porch and, consequently, the stability of the same. This phenomenon, defined as a rigid diaphragm, can also be found in precast buildings, with floors composed of hollow core slabs. In order to verify the necessity of including some details of connection between the slab elements (joints between the slabs and among other things) will be proposed in this paper the analysis of five structures with different characteristics, considering the different possibilities of bracing and disposal of prefabricated slabs in the floor. Consideration will be given the difference in the distribution efforts of the pavements, considering the application of shear walls and gateways, as well as the provision of slabs parallel and perpendicular to side action. The interference of the cover structure will also be analyzed in a number of examples. From a modeling specific to the floors of these buildings and different situations with different levels of horizontal actions, one can determine the stresses at specific points of the same, thus indicating the types of reinforcements to be willing to actually floors act as a diaphragm. Finally, we intend to discuss the organization of prefabricated elements interfere in the distribution of efforts on the pavement (joints between the slab elements), based on different amounts of reinforcing bars of each type of pavement structure will require.
Uma das principais diferenças das estruturas compostas por elementos pré-fabricados das estruturas convencionais (moldadas in loco) faz referência à maneira de como os elementos estruturais são ligados entre si. O modo de funcionamento de tais ligações é primordial para se realizar uma correta análise de estabilidade e deslocabilidade dessas edificações. Um local no qual a ligação se faz muito importante na verificação do comportamento estrutural é entre os elementos de laje alveolar. Em uma estrutura convencional, geralmente composta por pavimentos de lajes maciças, observa-se que as lajes têm um comportamento de grande influência na distribuição de esforços advindos de ações horizontais entre os pórticos resistentes e, conseqüentemente, na estabilidade da mesma. Esse fenômeno, definido como diafragma rígido, pode também estar presente em edificações pré-fabricadas, com pavimentos compostos por lajes alveolares. De modo a se verificar a necessidade de inserção de alguns detalhes de ligação entre os elementos de laje (juntas entre as lajes e entre outros elementos) serão propostos neste trabalho a análise de cinco estruturas com características distintas, considerando as diferentes possibilidades de elementos de contraventamento e disposição das lajes pré-fabricadas no piso. Será analisada a diferença na distribuição dos esforços nos pavimentos, considerando a aplicação de paredes de cisalhamento e pórticos, bem como a disposição de lajes paralelas e perpendicular a ação lateral. A interferência da capa estrutural também será analisada em um dos exemplos numéricos. A partir de uma modelagem específica para os pavimentos dessas diferentes edificações e situações, com diferentes níveis de ações horizontais, podem-se determinar os esforços em pontos específicos dos mesmos, indicando assim os tipos de reforços que deverão ser dispostos para que de fato os pavimentos funcionem como diafragma. Por fim, pretende-se discorrer sobre como a organização dos elementos pré-fabricados interfere na distribuição dos esforços no pavimento (juntas entre os elementos de laje), com base nas diferentes quantidades de armaduras de reforço do pavimento que cada tipo de estrutura exigirá.

Este trabalho analisa, por meio de método experimental, a viabilidade de apropriar a produção de painel alveolar de concreto armado para aplicação em habitações de interesse social. Compara os processos industriais praticados para a produção deste elemento com alternativas inovadoras proporcionadas pela incorporação de fôrma interna, ou núcleo alveolar, que permite apropriar a tecnologia para aplicação em diferentes escalas conforme as características de cada empreendimento. Avalia a execução, a conectividade e o desempenho mecânico em relação à resistência à compressão do painel alveolar. Contribui com contexto de construção sustentável e o aproveitamento de resíduos industriais e conclui que o núcleo alveolar incorporado configura inovação tecnicamente viável no processo de produção do painel alveolar que pode ser utilizado em sistemas de fechamento e superestruturas (paredes portantes e lajes) em habitações.
This work analyzes the viability of appropriate the hollow core slab production for social housing construction, by means of an experimental method procedure. It compares the industrial process with innovated alternatives proportionate by internal hollow nuclear mould incorporate which provides technology appropriation for several production scales according to construction portage. Evaluate the execution, connectivity (with hydraulic and electric systems) and compressive strength of hollow core slabs. The researchs contributions is relate with the context of sustainable construction and the use of industrial waste as construction raw materials and it concludes that internal hollow nuclear mould incorporate is technically viable in hollow core slabs production´s process and this precast element could be applied in wall´s and slabs for housing construction.

Este trabalho trata da otimização de painéis alveolares e vigotas protendidas utilizando Algoritmos Genéticos (AGs). A proposta de tal algoritmo foi inspirada no princípio da seleção natural de indivíduos, onde o mais ‘apto’ tende a permanecer na população e se reproduzir, passando seu código genético para a próxima geração. Em alguns casos, esse método pode alcançar melhores soluções se comparados aos métodos tradicionais de otimização. O principal objetivo do trabalho é investigar o uso de AG como uma técnica para a minimização da função custo da aplicação de painéis alveolares e vigotas protendidas. Na análise estão incluídas as verificações dos elementos nas etapas transitórias referentes à produção, transporte e montagem. A função custo é avaliada considerando valores da realidade brasileira. O trabalho de pesquisa compara os resultados obtidos utilizando AGs com aqueles obtidos utilizando o método de otimização convencional conhecido como método do Lagrangiano Aumentado. Os resultados obtidos por ambos os métodos evidenciam a eficácia dos AGs com relação ao método convencional. Foram propostas e analisadas três famílias do AG simples, buscando identificar, dentre seus elementos, quais variantes mais adequados na busca da solução dos problemas.
This work aims to optimize the production cost of hollow core panels and prestressed joists using Genetic Algorithms (GAs). The proposal of such an algorithm was inspired by the principle of natural selection of individuals, where the most ‘capable’ tends to remain in the population and reproduce, passing its genetic code onto the next generation. In some cases, this method can achieve good solutions when compared with conventional methods of optimization. The main goal of the work is to investigate AG as a technique for the minimization of the function cost of hollow core panel and prestressed joist applications. The analysis takes account of the verifications of the precast elements in the transitory stages as production,transportation and erection. The function cost is evaluated within the Brazilian context. The research compares the results using GAs with those using a conventional method, the Augmented Lagrangian. The results provide evidence the effectiveness of the GAs with relation to a conventional method. The research considers three families of the simple GA, searching to identify, among them, the adjusted variant in the search of the solution of the problems.

The final thesis is focused on reworking hospital pavilion from cast-in-place structure to precast concrete frame. Calculation of internal forces is made by software system SCIA Engineer. Main load-bearing elements are inner beam, outside beam and all columns in axis 2-C. This thesis contains assembly report, structural design, calculations and drawings of the designed parts, joint details, assembly material drawing and hand calculation.

Utvecklingen av framtidens flerbostadshus ställer höga krav på en bjälklagslösnings tekniska egenskaper. Plattbärlagsbjälklaget som idag utgör det vanligaste förekommande bjälklagsvalet vid uppförandet av flerbostadshus kan ses som en lösning som kombinerar en god bärförmåga med stora möjligheter ur teknisk synpunkt. Målet med denna undersökning har varit att jämföra det traditionella plattbärlaget med en nyutvecklad bjälklagslösning baserad på produkten förspänt håldäcksbjälklag (HD/F). Jämförelsen har utgått från de aktuella kraven som enligt Boverkets byggregler (BBR) idag ställs på bjälklag och fokuserat på aspekter ur ljud, brand och fuktsynpunkt. Dessutom har jämförelsen beaktat de maximala spännvidder som respektive lösning kan dimensioneras för. Resultatet av de genomförda undersökningarna visade på att den nyutvecklade bjälklagslösningen är tillräckligt konkurrenskraftig för att i framtiden få ett större användande inom flerbostadshus. Medan plattbärlagets fördelar utmärker sig ur ljudsynpunkt möjliggör dock användandet av den nyutvecklade lösningen längre spännvidder och kortare torktider.
The development of apartment buildings puts high demands on the technical characteristics of floor systems. The lattice girder system which today represents the most commonly utilized floor system when building apartment buildings, is characterized by a good load-bearing ability along with great opportunities from a technical point of view. The aim of this analysis was to compare the traditional lattice girder system with a newly developed floor system based on hollow core slabs. The comparison is based on the current technical requirements set by Boverkets byggregler (BBR) and has its main focus on subjects related to sound, fire and moisture matters. The comparison has also accounted for the maximum spans which can be used for each solution respectively. The results of the investigation show that the newly developed floor system is competitive enough to be used in future apartment buildings. While the advantages of the lattice girder system are distinctive from a sound point of view, the utilization of the newly developed floor solution enables longer spans and shorter curing time.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This work presents the application of optimization techniques for the design of hollow core slabs and beams with precast and prestressed straight cable, considering the calculation of both the immediate losses as the time-dependent. For the slabs formulation allows the designer to obtain the optimal dimensions of the height of the panel, the diameters of the cables and the alveoli, and the number of cables. The beams are obtained beam height, diameter and the number of cables. Are still subject to the conditions of service for bending stresses, constructive limitations and failure conditions. Illustrative examples are presented using the Branch and Bound algorithm and Lingo (PLS), further comparison is made between the weight and the cost of the panel, and from the results of the algorithm and sizing Munte tables that follow Brazilian standards. We conclude that the optimal design has many advantages compared to conventional design, methods of discrete variation that best characterize the optimal variables of the problem, restrictions on the normal stresses ELS are crucial in obtaining the optimal dimensions of the structures and lower panels weight does not necessarily represent the lowest cost.
Este trabalho apresenta a aplicação de técnicas de otimização para o dimensionamento de lajes alveolares e vigas com cabo reto pré-moldadas e protendidas, considerando o cálculo tanto das perdas imediatas quanto das dependentes do tempo. Para as lajes, a formulação permite que o projetista obtenha as dimensões ótimas da altura do painel, dos diâmetros dos alvéolos e dos cabos, e do número de cabos. Nas vigas, são obtidas a altura da viga, o diâmetro e o número dos cabos. São, ainda, observadas as condições de serviço para esforços de flexão, limitações construtivas e condições de falha. Exemplos ilustrativos são apresentados usando o algoritmo de Branch and Bounde o Lingo(PLS). São feitos, ainda, comparativos entre o peso e o custo do painel e entre os resultados obtidos pelo algoritmo e tabelas de dimensionamento encontradas na literatura que seguem normas brasileiras. Conclui-se que o projeto ótimo apresenta inúmeras vantagens se comparado ao projeto convencional, que os métodos de variação discreta caracterizam melhor as variáveis ótimas do problema, que as restrições relativas às tensões normais do ELS são determinantes na obtenção das dimensões ótimas das estruturas e que painéis de menor peso não necessariamente representam o menor custo.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Industrialization in the Brazilian construction industry is a growing trend, while the need to fulfill tight deadlines increases as well as labor costs, being mandatory to keep quality standards and the competitiveness of enterprises. In this sense, the precast concrete is an increasingly valid solution.Among him, the floor in hollow core slabs of prestressed concrete, as part of a constructive system of open cycle. This kind of floor can be applied in various sectors and to the most varied typologies. The ABNT NBR 14861: 2011 is still quite new, and includes a set of quality control care for the implementation of hollow core slabs in prestressed concrete, although it is felt that the respective degree of detail could be improved.On the other hand, the standard has just focusing on such care specially concerning project and product approaches, and not so much with a process approach. There is also some difficulty in the flow of information and knowledge between the academy and industry in general. The dissertation provides a detailed analysis of production of hollow core slabs in prestressed concrete, according to the respective processes, since the inputs enter factories, until the structural cover is performed on site. The macro-production process is divided into several stages of lower complexity, and contains a detailed listing of quality control procedures required, in a simple and practical manner. Thus, can be established a kind of a guide to good quality control practices for the production of LACP, which is then systematized through a set of checklists. The establishment of guidelines for good quality control practices in the various LACP production stages is the main goal of this research. In order to accomplish this goal have been made extensive literature reviews on Quality and hollow core slabs, using theses, dissertations, monographs, papers, magazines and electronic sites. Were also made visits to a factory which produces equipment for production of hollow core slabs, and to a plant producing LACP, in the interior of the state of São Paulo, during which were made unstructured interviews with their maximum management responsables. Finally it was made an essentially qualitative comparative analysis of the data collected and the quality control procedures of the ABNT NBR 14861: 2011. It is intended, with the checklists contained in the dissertation, to ensure production, transportation to site, installation of LACP and execution of the respective structural wrapper, with the highest quality consistency that is possible, thereby minimizing to minimum the existence of possible non-compliances.
A industrialização no setor da construção civil brasileira é uma tendência crescente, ao mesmo tempo que a necessidade do cumprimento de prazos cada vez mais apertados vai aumentando, assim como os custos de mão de obra, sendo obrigatório manter-se os padrões de qualidade das obras e a competitividade das empresas. Nesse sentido, os pré-fabricados em concreto são uma solução cada vez mais válida e entre eles, os pisos em lajes alveolares de concreto protendido (LACP), como elemento de um sistema construtivo de ciclo aberto. Essas lajes podem ser aplicadas nos mais variados segmentos e nas mais variadas tipologias. A norma ABNT NBR 14861:2011 é ainda bastante recente, e contempla um conjunto de cuidados de controle de qualidade para a execução de lajes alveolares em concreto protendido, embora se julgue que o respetivo grau de detalhe poderia ser melhorado. Por outro lado, a norma acaba focando esses cuidados mais segundo abordagens de projeto e de produto, e não tanto numa abordagem por processos. Existe também alguma dificuldade no fluxo de informações e conhecimentos entre os meios acadêmicos e as empresas em geral. A dissertação faz uma análise detalhada da produção de lajes alveolares em concreto protendido, segundo os respetivos processos, desde que os insumos entram nas fábricas, até que a capa estrutural é executada em canteiro. O macro-processo de produção é dividido em várias etapas de complexidade menor, e é feita uma listagem detalhada dos procedimentos de controle de qualidade necessários, e de uma forma simples e prática. Desse modo, consegue-se estabelecer como que um guia de boas práticas de controle de qualidade para a produção de LACP, o qual é depois sistematizado através de um conjunto de listas de verificação (check-list ́s). O estabelecimento de diretrizes para boas práticas de controle de qualidade nas várias etapas de produção de LACP é o objetivo principal desta pesquisa. Para conseguir atingir esse objetivo foram feitas amplas revisões bibliográficas sobre Qualidade e Lajes Alveolares em Concreto Protendido, recorrendo a teses, dissertações, monografias, artigos científicos, revistas e sítios eletrônicos. Foram também realizadas visitas a uma fábrica de equipamentos para produção de LACP, e a uma unidade fabril produtora de LACP, no interior do estado de São Paulo, durante as quais foram feitas entrevistas não estruturadas com os respetivos responsáveis máximos. Finalmente fez-se uma análise comparativa essencialmente qualitativa entre os dados recolhidos e os procedimentos de controle de qualidade que constam da norma ABNT NBR 14861:2011. Pretende-se, com as listas de verificação que constam da dissertação, garantir uma produção, transporte a canteiro, montagem das LACP e execução da respetiva capa estrutural com a máxima coerência de qualidade possível, reduzindo assim ao mínimo a existência de possíveis não conformidades.

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This work describes the procedures used in the manufacture and assembly of prestressed concrete hollow core slab systems, along with recommendations for presentation and implementation of projects in order to optimize the use of such elements and also its functionality, trying to keep the same quality and durability. So, it is briefly shown that the theory applied to the development of calculations and verifications in the ultimate and service states, considering the bending behavior of the panels, the shear and the excessive deformation, and prestress losses that are of great importance for the final results. Therefore, it creates a scheme to solve two numerical examples which come from a cross-section preestablished on the basis of tables published that are related to overload and long spans which the slab can achieve. Then compare the results obtained in the examples with the values that the tables showed and then do relevant comments. Finally, the conclusions are provided and comments for improvements in the sector of design and production of hollow core slabs, followed by suggestions for future work.
O presente trabalho descreve os procedimentos de fabricação e montagem utilizados no sistema de lajes alveolares em concreto protendido, juntamente com recomendações para apresentação e execução dos projetos a fim de otimizar o uso desses elementos quanto a sua funcionalidade, prezando manter a qualidade e a durabilidade dos mesmos. Para isso, mostrase sucintamente a teoria aplicada para o desenvolvimento dos cálculos e verificações nos estados limites último e de serviço, levando-se em conta o comportamento dos elementos à flexão, ao cisalhamento, assim como as deformações excessivas, além de tratar das perdas de protensão, que se mostram de grande importância para o resultado final. Com isso, cria-se um roteiro para resolver dois exemplos numéricos, os quais partem de uma seção préestabelecida, com base em tabelas publicadas, em que relacionam a sobrecarga e o vão máximo que a laje pode atingir. Em seguida, são comparados os resultados obtidos nos exemplos com os valores que as tabelas apresentam e feitos os comentários pertinentes. Finalmente, são fornecidas as conclusões e comentários para melhorias no setor de projeto e produção de lajes alveolares, seguidos de sugestões para trabalhos futuros.

The final thesis is focused on the design and elaboration of the project documentation of the sports and relaxation center. The proposed building is located in the south-eastern part of the town of Hradec Králové, in a location supposed for buildings and areas of sports and relaxation use. It is a three-storey building with a flat roof and partial basement. The construction system is wall-mounted with a combination of skeleton. The building is based on plain concrete and reinforced concrete foundation footing. The peripheral, supporting and partition walls are designed from ceramic blocks POROTHERM. The inner load-bearing elements consist mainly of reinforced concrete columns. The ceiling structure is designed from reinforced concrete slabs supported locally. The perimeter walls of the first overground floor and part of the perimeter walls of the basement are insulated by an external contact thermal insulation system. The thermal insulation of the perimeter walls of the second floor is designed by means of a ventilated facade with facade tiles except the squash courts and the relaxation area. The building is functionally divided into three main parts, where the central part forms an entrance hall with comunication spaces of all floors. In this part a basement with technical facilities is designed. The right part of the ground floor consists of a restaurant with a bowling alley and a kitchen with storage and hygienic facilities. As part of this section, a gym and exercise rooms for fitness exercises, spinning and TRX are designed on the second floor. The left part consists of two squash courts with the appropriate facilities and massage areas. There is also a relaxing facilities with a north-facing terrace on the second floor. There are also dressing rooms and hygienic facilities. The designed object is accessible for disabled people. There is a parking lot for 40 cars, 3 motorcycles, one bus and three barracks for cars.

This thesis deals with the design and elaboration process of a project documentation of a sports centre. The designed sports centre building is situated in the southern part of the town of Polička, in the area determined for sports and free time activities complexes and areas. It is a two-floor, non-cellar, flat-roof building. It is based on plain concrete strip foundations and reinforced concrete foundation footing. The bearing, peripheral and partition walls are designed from POROTHERM hollow clay blocks. Reinforced concrete columns are designated in open disposition areas. The ceiling construction is made from SPIROLL pre-stressed concrete floor slabs and point-supported reinforced concrete slabs. The peripheral walls of the first aboveground floor are insulated with external thermal insulation system with a protective gabion facade. The peripheral wall thermal insulation in a bowling restaurant and gym halls extension is designed from a ventilated facade with CEMBRIT METRO facade cladding panels. The building is functionally divided into two main parts with a shared entrance. The sports centre with gyms and other sports facilities form the first part. Three squash courts, a mini-football piste, a special room for spinning and alpinning, a room for group exercising and cloakrooms with sanitary facilities are designed within one part of the sports centre. A restaurant with a bowling area and a kitchen with storerooms and other facilities for employees form the second part. The designed complex is barrier-free. There is aimed to be a car park for fifty cars, four motorbikes and a bus in front of the building. Three parking places are for disabled people.

No mercado mundial existe uma visível tendência de tornar as obras mais industrializadas e racionalizadas com o objetivo de reduzir os desperdícios, acelerar a velocidade de execução das obras e garantir maior qualidade às mesmas. A adoção de elementos estruturais com certo grau de industrialização pode trazer benefícios em relação aos custos, à mão de obra, ao tempo de execução e ao impacto ambiental. Neste contexto, as estruturas mistas de aço e concreto satisfazem essa necessidade, pois tanto os elementos de aço quanto os elementos de concreto podem ser pré-fabricados, ficando apenas as etapas de içamento e montagem a serem realizadas na obra, reduzindo o uso de fôrmas e escoramentos. Os pisos mistos de aço e concreto de pequena altura caracterizam-se pelo embutimento da laje de concreto na altura do perfil de aço, sendo a principal vantagem, em relação ao piso misto convencional, a redução da altura total do composto. Portanto, este trabalho tem como objetivo analisar o comportamento de pisos mistos de aço e concreto de pequena altura com laje alveolar em concreto protendido por meio de ensaios de cisalhamento direto (push-out test) e de flexão. Na solução proposta, a transferência de esforços entre o perfil de aço e a laje alveolar foi feita por meio de conectores tipo pino com cabeça e concreto moldado no local. Os resultados demonstraram-se promissores em termos de comportamento do piso misto de pequena altura, aumentando significativamente a rigidez do sistema em relação à viga de aço isolada. Em complemento, foi desenvolvida uma simulação numérica dos modelos físicos ensaiados utilizando o pacote computacional DIANA®, fundamentado no método dos elementos finitos, na qual o modelo numérico representou adequadamente o comportamento dos pisos mistos de pequena altura, permitindo análises paramétricas.
On the world market, there is a visible tendency to turn buildings construction more industrialized and rationalized in order to reduce waste, accelerate the construction speed and ensure higher quality to them. The adoption of structural elements with a degree of industrialization can bring benefits regarding costs, labor, construction time and environmental impact. In this context, steel and concrete composite structures satisfy this need, since steel and concrete elements can be prefabricated, with only lifting and mounting steps to be performed on site, reducing use of formwork and shoring. A type of slim floor system consists in precast concrete hollow core slabs supported on the lower flange of steel beams. The major advantage of this solution, compared to conventional composite beam, is reducing the overall height of the floor. Therefore, this study aims to analyze the behavior of slim floor with prestressed concrete hollow core slabs through push-out and bending tests. In the proposed solution, the transfer of forces between steel beam and hollow core slabs was made by stud bolts and cast on site concrete. The obtained results proved to be promising in terms of slim floor behavior, significantly increasing the system stiffness regarding the isolated steel beam. In addition, a numerical modeling of the studied slim floor system was developed, using finite element based software DIANA®, in which the numerical model adequately represented the behavior of the composite beam, allowing parametric analysis.

To achieve structural integrity in precast concrete systems, connections between elements must be capable to transfer both vertical and horizontal loads which puts high demands on single ties. Hollow-core slabs are often used to stabilize the structural system which puts high demands on the connections between the slab and the buildings stabilizing units. Because of this, the connections need to withstand high tensile and shear forces. The purpose of this report is to investigate the tensile capacity of tie-connections used between hollow-core slabs that are parallel with e.g. stabilizing walls and compare with current design methods. Current design methods suggest that tensile failure will occur in the roof and bottom of the cores which provides low design capacities. Two connections are investigated through full scale pull-out tests where the results are compared with the design methods. The results from testing the tensile capacity show that the failure module occurred as suggested. However, the tests show significantly higher capacity than proposed by the design methods. Eurocodes Design assisted by testing are applied to the test result and a new design method is proposed. Both provides design values that are approximately twice as large as the values suggested in previous design methods.

Within the frame of my master's thesis I processed a project documentation for a construction of an apartment house in Brno – Židenice. The building is unattached and has 7 floors. On the ground floor there are four individual garages, cellar cubicles and a utility room. There are apartments on all other floors. On the highest floor, there is situated a singular apartment with outdoor terrace and vegetation area. The building is founded on strips made of reinforced concrete, vertical load-bearing structure is made of cermic blocks, floor structure is made of hollow core slabs and staircase is also made of prefabricated elements. The house is insulated with contact thermal insulation made of mineral wool. During the process of creating the projet, I followed all the requirements of actual regulations and legal enactments, to provide sufficient mechanical endurance and stability, health safety of the inner space as well as safety of the natural environment.

Multifunctional buliding is designed as a alone standing new buliding in the cadastral area of Žilina on a private plot no. 4518, Alexandra Street Rudnaya. The buidling is situated in the older part of city build in the sixties with the dominanting residental houses. Type of the multipurpose building is dominant with a residental function. The building totaly contains four apartment units. In the ground floor are offices, spaces of surgeries and access to housing and accessories. Each function has a separate entrance, which is designed for handicapped. In the basemnt of the building are designed in a common garage, basement and substation for heating domestic hot water and heating all function in the building. Enterence in to garage is designed from the east side od street Juraja Sklenara. The building is covered wich flat, monotube roof. The building has got rectangular shape which one outlet on the southeast side. Attic roof is 10,75 meters above the ground.

The diploma thesis elaborates the project documentation for the construction of a new apartment of central fire station type C1 with the administrative part of the Territorial Department. The fire station is technologically linked to the second building SO.02 the technical and technological background of the fire station. The building is situated on the eastern edge of Svitavy. The building is non-cellular, it has three floors and a flat green roof. Three floors fulfilling matter with mainly administrative function is connected with two floors blocks fire station with an indoor gym. Above the floor containing garages for emergency vehicles facilities for the emergency unit are placed with a curtain that creates fading of the emergency door. The matter of the gym is optically separated from the station and highlighted with a volume narrow neck and height elevation. In the station there are training places and places for general physical preparation. The buildings are located in a sloping terrain. The ground fire station has a heliport. The establishment supporting columns of the building are for made of prefabricated calyx, and are concreted into monolithic foundation pads. Infill wall vertical bearing and non-bearing structures are designed from clay blocks type THERM. The bearing system is reinforced concrete prefabricated frame. Horizontally bearing structures are designed from prestressed hollow core slabs. The building envelope is made of a curtain wall in dark grey and red combined with a light contact thermal insulation system used on the indoor gym. The envelopes are in the administrative part and the part of the station divided by a glazed area. In the workshops and technology room the envelope is divided by lamellae. Usually there are 13 firemen during one shift, in three shifts there work 39 firemen all together. There are supposed to be 17 employees in the administrative department.

碩士
朝陽科技大學
營建工程系
103
Many major big buildings completed in the past 30 years in Taiwan have been designed with the concept of high-elevation and large span, which led to the use of heavy steel support frame during construction. The research was conducted to study the basic mechanism, assembling method and concrete pouring during the construction process in order to better understand the mechanical characteristics for the structures supported by the heavy steel supporting frame. The study also investigated the differences in design concept and influence of stability for structures using ordinary support system and the heavy steel frame. As part of the research results, advantage\disadvantage and tactics for improvements were identified to provide useful information for increasing the stability and safety of the studied supporting system during construction. In practical applications, the heavy steel frame can be used as the sole support system or combined with other traditional support systems to offset the lack of diversity using traditional door-type pipe support system. The studied heavy steel frame has been gradually become the most commonly used supporting system in the major construction projects in Taiwan. The conclusions of the studied are summarized as the following: 1.The layout of the heavy steel frame should be carefully examined and analyzed in accordance with the site conditions and design of the buildings. The experiences of field engineers in charge of supporting system should never overwrite the calculation and analysis prior to the beginning of the frame assembly. 2.The prototype and sample assembly of the heavy steel frame should be used for each individual construction project to identify problems and difficulties prior to the assembly, thus to avoid accidents that could impair the progress of the construction. 3.The procedure of concrete pouring, including the instructions for concrete crew members should be well planned to assure good and acceptable pouring results.

Prestressed hollow core slabs are essential components in structures such as bridges, parking garages, marine structures, and commercial and industrial buildings. Material degradation and altered functional requirements may seriously threaten the structural integrity of these reinforced concrete structures. Using FRP composites, the NSM strengthening technique presents a viable solution to these challenges. However, further investigation is required to establish comprehensive empirical design guidelines. The intent of this research project is to investigate the NSM technique in conjunction with common design concepts such as prestressed concrete, precast hollow core slabs, the complex behaviour of disturbed regions, and fiber-reinforced composite materials. An experimental program was developed, which included eleven full-scale slab specimens, subject to a four-point load configuration. The main parameters included the prestressing reinforcement ratio, CFRP strengthening ratio, and in-service opening location. Experimental results showed that prestressed concrete strengthened in flexure with NSM-CFRP is a viable technique for lower reinforcement ratios.

Precast concrete hollow core floor units are frequently used in multistorey steel- framed buildings where they bear on to the top flanges of universal beams. The steel beam is normally designed in bending in isolation from the concrete slab and no account is taken of the composite beam action available with the precast units. Although some commercial data are avail- able, there is no general design guidance to cover the wide range of material and geometric variables found in this form of construction. This paper summarizes research carried out at the University of Nottingham on this form of construction and presents the results of three full-scale bending tests of steel beams acting com- positely with proprietary precast hollow core slabs. The 150 mm deep units were attached to the universal beams through 19 mm diameter headed shear studs, and tested in four-point bending over a span of 6 m. For typical geometry and serial sizes the composite beams were found to be twice as strong and nearly three times as sti as the equivalent isolated steel beams. The failure mode was ductile, and may be controlled by the correct use of small quantities of tie steel and in situ infill concrete placed between the precast units. To generalize the findings, isolated push- off tests and eccentric compression tests were used to study the horizontal interface shear resistance of the headed studs and the strength of the slab, respectively.

The shear capacity of headed studs in precast concrete hollow-core slab construction has been determined experimentally in 12 full-scale push-off tests. The tests were used to study the effects of the size of the gap between the ends of the precast slabs, and the amount of tie steel placed transversely across the joint, and the strength of concrete infill. Under certain situations the capacity of the stud is reduced compared with that in a solid reinforced concrete slab. Maximum resistances are compared with the predictions of BS 5950 and EC4, and a reduction formula for the precast effect is derived.

This paper describes the finite element modelling of steel beams acting compositely with proprietary precast hollow core slabs. A companion paper (Lam D, Elliott KS, Nethercot DA. Experiments on composite steel beams with precast hollow core floor slabs. Proceedings of the Institution of Civil Engineers: Structures and Buildings 1999; in press [1]) reports results of full scale bending tests and compression slab tests. The finite element package ABAQUS was used to extend the scope of the experimental work, by first demonstrating that a 2-dimensional plane stress analysis is sufficiently accurate, providing that the correct material input data and shear stud characteristics obtained from isolated push-off tests are used. The FE results are within 5% of the experimental results. An extensive parametric study was carried out to investigate the flexural behaviour of composite beams with variations in transverse reinforcement ratio, stud spacing and steel UB section.

The horizontal shear strength of the interface between prestressed concrete hollow core slabs and cast-in-place concrete topping slabs was evaluated through a set of 24 push-off experiments. The push-off test specimens featured segments of dry-mix and wet-mix hollow core slabs with a variety of surface treatments including machine finished, sandblasted, broom roughened, rake roughened and grouted. A cast-in-place slab was poured on top of the hollow core specimens to form a 15 inch by 15 inch interface between the two materials. Results indicate the average horizontal shear strength of the push-off specimens was 227 psi. Higher shear strength and slip capacity was observed in specimens that were broom roughened in the direction transverse to the applied shear force and in grouted dry-mix specimens. Specimens with machine finished surfaces had lower average horizontal shear strength than those with intentionally roughened surfaces, but still exceeded the shear strength of 80 psi specified in the ACI 318-08 code. A method to comparatively quantify the surface roughness of the hollow core slabs with different surface treatments was adapted from an existing ASTM standard for pavements. This standard specifies the procedure to determine mean texture depth that can be correlated to horizontal shear strength of the push-off specimens. Analytical studies were also performed to estimate the maximum horizontal shear stresses that can be expected in composite hollow core slabs under normal construction conditions. A finite element model was developed to observe the behavior of the horizontal shear failure mode for composite hollow core slabs.

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The recently published report on Rethinking Construction in the UK has highlighted the need to reduce on-site activities as part of its drive for greater efficiency, improved quality and greater certainty in the delivery of construction projects. For multi-storey buildings, the use of precast slabs in the floors - particularly if this can be done without the need for in-situ screeds - drastically reduces the volume of on-site concreting required. Although the use of precast hollow core slabs in steel framed buildings are common, their use in composite design with steel beams is relatively new. By designing the steel beams and precast hollow core slabs compositely, a reduction in beam size and overall floor depth can be achieved, which would lead to an overall reduction in construction cost. This paper summarises the recent developments and on-going research on composite construction with precast hollow core slabs.

This paper is concerned with the behaviour of beam ¿ column connections of steel ¿ concrete composite beams with precast hollow core slabs. Experiments were carried out to investigate the joint rotation characteristics and ultimate moment capacity of these connections. Details of the test specimens, instrumentation, test set-up and test procedures are described. Results obtained for the connection moment capacity, rotation capacity and failure modes are presented. It is found that through proper design and detailing, these simple steel connections display the characteristics of a semi-rigid connection with very little extra cost.

[EN] Several efforts have been made in experimental and theoretical research about shear to understand all the variables that influence the phenomenon. Nowadays, however, due to its complexity, the shear performance of structural concrete elements, especially those without any traditional transversal reinforcement, continue with no clear explanation of the problem. Uncertainty about the problem grows when new variables like fibres are incorporated into the shear study. Research works have demonstrated the effectiveness of steel fibre in improving the mechanical properties of concrete elements. Experimental results reveal that steel fibres have proven effective in improving shear resistance, and they confer some concrete elements more ductility. In adequate amounts, steel fibres can completely or partially substitute traditional shear reinforcements. This is why international codes have included some requirements to take into account the action of fibres on the shear response of concrete elements. However, most recommendations and requirements for steel fibre-reinforced concrete (SFRC) were originally created. New fibres with different materials properties and shapes, such as macrosynthetic fibres, are now available on the market. These fibres, some of which are made of polypropylene, are an alternative in the construction industry given their properties and final cost. Initially, polypropylene fibres were used to control shrinkage cracking. Nevertheless, in the last decade the chemical industry has created larger fibres with better surface shapes, which allows polypropylene fibres to meet the requirements of international codes so they can be used in structural elements. Within this framework, the present PhD thesis aims to contribute to knowledge about fibre reinforced concrete (FRC), especially to study the effectiveness of polypropylene fibres when used as shear reinforcement. For this purpose, a literature review of the material, polypropylene fibre-reinforced concrete (PFRC) and its structural applications is first carried out. This study also discusses the parameters that affect the shear behaviour of traditional concrete and FRC. In order to evaluate the effectiveness of polypropylene fibres in shear, three experimental campaigns are presented. Each campaign represents a different level of study. The first corresponds to the material level, where the shear behaviour of PFRC is evaluated by push-off specimens. The second level involves studying shear in real scale elements. For this purpose, shear critical slender beams were manufactured and tested. The last level corresponds to real application of polypropylene fibres to act as shear reinforcement. In this campaign, deep hollow core slabs, with real sections and supports conditions, were tested. At each level, the shear behaviour of PFRC was evaluated against control reinforced concrete specimens, which were also tested during each campaign.
[ES] Varias investigaciones experimentales y teóricas han sido realizadas para entender el comportamiento a cortante de elementos de hormigón y sus variables. Sin embargo, hoy en día debido a la complejidad del tema, el comportamiento a cortante de elementos de hormigón armado y en especial aquellos que no tienen refuerzo transversal, continúan sin tener una explicación clara. Por otro lado, esta complejidad del cortante aumenta cuando nuevas variables, como las fibras, se incorporan al estudio. Investigaciones han demostrado la efectividad de las fibras de acero para mejorar las propiedades mecánicas de hormigón. Según resultados experimentales, la fibra de acero mejora la resistencia cortante y ductilidad de ciertos elementos. Y en cantidades adecuadas, la fibra puede sustituir total o parcialmente los refuerzos tradicionales de cortante. Es así que varios códigos internacionales han incluido requisitos para tener a las fibras en la respuesta estructural de elementos de hormigón. Sin embargo, estos requerimientos se han creado originalmente para el hormigón reforzado con fibra de acero (Steel fibre-reinforced concrete -SFRC). Nuevas fibras con diferentes materiales y formas, como las fibras macro-sintéticas, han sido introducidas en el mercado. Estas fibras, también llamadas fibras de polipropileno o poliolefina, son una alternativa en la construcción debido a su propiedades y costo final. Inicialmente, las fibras de polipropileno eran usadas únicamente en el hormigón para controlar la fisuración por retracción. Sin embargo, en la última década la industria química ha desarrollado fibras más grandes y con mejores prestaciones de adherencia, que permiten a estas fibras cumplir con requisitos para ser utilizadas estructuralmente. En este contexto, la presente tesis pretende ser una contribución al conocimiento sobre el hormigón reforzado con fibras (Fibre-reinforced concrete - FRC), especialmente en la efectividad de las fibras de polipropileno como refuerzo a cortante. Para esto, primero se realiza un estudio bibliográfico del hormigón reforzado con fibra de polipropileno (PFRC) como material y sus aplicaciones estructurales. Este estudio también tratará sobre los parámetros que afectan el comportamiento a cortante del hormigón tradicional y hormigón reforzado con fibras. Para evaluar la efectividad de las fibras de polipropileno en el cortante, se realizarán tres campañas experimentales. Cada campaña representa un nivel de estudio diferente. El primero es a nivel material en donde se evalúa el comportamiento a cortante a través de especímenes tipo Push-off. El segundo nivel, corresponde al estudio del cortante en elementos a escala real. Para esto se fabrican y ensayan vigas esbeltas críticas a cortante. El último nivel corresponde a una aplicación real de fibras de polipropileno actuando como refuerzo cortante. En esta campaña, se fabrican y ensayan placas alveolares de gran canto con secciones y condiciones de apoyos reales.
[CA] Diverses investigacions experimentals i teòriques han estat realitzades per entendre el comportament a tallant d'elements de formigó i les seues variables. No obstant això, hui en dia a causa de la complexitat del tema, el comportament a tallant d'elements de formigó armat i especialment aquells que no tenen reforç transversal, continuen sense tindre una explicació clara. D'altra banda, aquesta complexitat del tallant augmenta quan noves variables, com les fibres, s'incorporen a l'estudi. Investigacions han demostrat l'efectivitat de les fibres d'acer per a millorar les propietats mecàniques del formigó. Segons resultats experimentals, les fibres d'acer milloren la resistència a tallant i la ductilitat de certs elements. A més, en quantitats adequades, les fibres poden substituir total o parcialment els reforços tradicionals de tallant. És així que diversos codis internacionals han inclòs requisits per a tindre amb compte la resposta estructural de les fibres en els elements de formigó. No obstant això, aquests requeriments s'han creat originalment per al formigó reforçat amb fibres d'acer (Steel fibre-reinforced concrete -SFRC). Noves fibres amb diferents materials i formes, com les fibres macro-sintètiques, han estat introduïdes al mercat. Aquestes fibres, també anomenades fibres de polipropilè o poliolefina, són una alternativa a la construcció a causa de les seues propietats i cost final. Inicialment, les fibres de polipropilè eren usades únicament en el formigó per controlar la fissuració per retracció. No obstant això, en l'última dècada, la industria química ha desenvolupat fibres més grans i amb millors prestacions d'adherència, que permeten a aquestes fibres complir amb requisits per a ser utilitzades estructuralment. En aquest context, la present tesi pretén ser una contribució al coneixement sobre el formigó reforçat amb fibres (Fibre-reinforced concrete - FRC), especialment en l'efectivitat de les fibres de polipropilè com a reforç a tallant. Per això, primer es realitza un estudi bibliogràfic del formigó reforçat amb fibres de polipropilè (PFRC) com a material i les seues plicacions estructurals. Aquest estudi també tractarà sobre els paràmetres que afecten el comportament a tallant del formigó tradicional i del formigó reforçat amb fibres. Per avaluar l'efectivitat de les fibres de polipropilè en el tallant, es realitzaran tres campanyes experimentals. Cada campanya representa un nivell d'estudi diferent. El primer és a nivell material on s'avalua el comportament a tallant a través d'espècimens tipus Push-off. El segon nivell, correspon a l'estudi del tallant en elements a escala real. Per això es fabriquen i assagen bigues esveltes crítiques a tallant. L'últim nivell correspon a una aplicació real de fibres de polipropilè actuant com a reforç a tallant. En aquesta campanya, es fabriquen i assagen plaques alveolars de gran cantell amb seccions i condicions de suports reals.
Ortiz Navas, FR. (2020). Effectiveness of polypropylene fibres as shear reinforcement in structural elements [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/153147
TESIS