Neste trabalho analisa-se a resistência à punção e a ductilidade das ligações laje-pilar em doze modelos de lajes-cogumelo de concreto armado, nas quais se efetuam combinações de emprego de concreto de alta resistência, diferentes volumes de fibras de aço e uso de armadura transversal na forma de conectores de aço tipo pino. Todas as lajes são quadradas com 1160 mm de lado e 100 mm de espessura. A armadura de flexão foi composta de barras de aço de 10 mm espaçadas de tal forma a resistir a um momento fletor único em ambas direções. Os conectores, quando utilizados, foram dispostos radialmente e compostos de barras de aço de 6.6 mm soldadas a segmentos de ferro chato nas duas extremidades. Para avaliar a capacidade resistente dos modelos de ligação laje-pilar e observar o ganho de ductilidade que as fibras proporcionam, foram ensaiados segmentos-de-laje, os quais representam uma faixa destes modelos de ligação laje-pilar. Foi utilizado um sistema de ensaio dotado de atuador hidráulico servo-controlado, programado para ensaio com deformação controlada e aquisição contínua dos dados, o que permitiu a avaliação do comportamento pós-pico de resistência e a realização de medições de resistência residual. Várias hipóteses de cálculo foram utilizadas para avaliar a resistência última das ligações laje-pilar. Empregou-se um critério de classificação para caracterizar o tipo de ruptura em: punção ou flexão predominante ou uma combinação de punção-flexão. Constatou-se que o emprego de concreto de alta resistência, juntamente com armadura transversal, aumenta substancialmente a resistência da ligação laje-pilar, e quando combinado com fibras de aço, consegue-se um considerável aumento da ductilidade. / This work analyses the punching shear resistance and ductility of slab-column connections on twelve concrete flat slab models. The model characteristics resulted from combinations of the application of high or ordinary strength concrete, different steel fiber volume fractions and use or not of shear reinforcement. All the slabs are square with 1,160 mm of side and 100 mm of thickness. The main flexural reinforcement was composed of 10 mm steel bars spaced in such a way to resist to the same bending moment in both directions. When used, the shear reinforcement of steel studs were disposed in radial directions and consisted of 6.6 mm steel bars welded to flat steel segments in their ends. To evaluate the resistant capacity of slab-column connection models and to observe the ductility that the fibers provide, they were rehearsed segments-of-slab, which represents a strip of these slab-column connection models. A testing system with a servo-controlled hydraulic jack was used and it was programmed for a controlled deformation test and continuous data acquisition. This method allowed the evaluation of the post-peak strength behavior and the measurement of residual resistance forces. Several calculations hypotheses were used to evaluate the ultimate strength of the slab-column connections. A classification criterium was applied to characterize the failure type as: predominant punching or flexure or a combination of punching-flexure. It was verified that the application of high strength concrete, together with shear reinforcement, increases substantially the slab-column connection strength, and, when combined with steel fibers, a considerable ductility increase is achieved.

The calculation process in Eurocode 2 that is showing how calculation of punching is to be done is long and some parts are not well explained. At the end of the calculation of punching, it is said that a check of the shear capacity without any reinforcement should be done outside the affected zone but the intent of the check is not justified. The purpose of the study was to find out why the check must be done and then examine whether it is possible to limit the use of the control. The results have been produced by doing literature studies on the field and calculations to understand how the control is affected. The program Excel have been used to compile and compare all the results in the calculation part. To gain a wider understanding of the area two other international standards have been compared with Eurocode 2. The standards used are American Concrete Institute 318 and Brittish Standard 8110. The maximum allowed distance of shear reinforcement without having to extend the area is 2d because the length of the base control section from the column surface in each direction has that distance. By testing how all the conditions affect the distance, is it possible to see which values are required to make the distance exceed 2d. After calculations have been made on several different prerequisites, it can be noted that on many occasions the distance is below 2d. Since so many conditions influenced the outcome, it was difficult to judge reasonable values on all of them which was making it more difficult to evaluate how often the control was needed. An uncomplicated way to limit the use of the control was by finding a prerequisite that is dominant, but it did not work in these cases so instead it was chosen to compare the shear capacitance without shear reinforcement with the transverse force loaded over the control perimeter. / När en pelarunderstödd platta belastats av en koncentrerad last från pelarna och utbredd last ovanifrån finns det risk för genomstansningsbrott eftersom pelarna som stabiliserar pressas mot plattans yta så att betongen runt pelarna stansas ut. Pelarunderstödda plattor är ett vanligt stomsätt som möjliggör att det går att ha balkfria konstruktioner som enbart stabiliseras utav innerväggar och pelare. Stomsättet kan användas i flera sorters konstruktioner t ex i kontorsfastigheter, parkeringshus och broar. Beräkningsgången i Eurokod 2 som visar hur beräkning av genomstansning i pelardäck ska göras är lång och avsikten med kontrollen är inte motiverat. I slutet av beräkningsgången av genomstansning anges att en kontroll av skjuvkapaciteten utan armering ska göras utanför den påverkade zonen men utan förklaring till varför. Eftersom det inte nämns varför kontrollen måste göras vet inte alla konstruktörer vad det är de kontrollerar och om den ens kommer till användning. Vid beräkning av pelardäck måste det göras beräkningar vid alla pelare som skiljer sig vilket kan resultera i att samma beräkning behöver göras många gånger och därför skulle det spara mycket tid om det gick att undvika sista kontrollen. Syftet med studien är att ta reda på varför kontrollen måste göras och sedan undersöka om det går att begränsa användandet av kontrollen. Resultaten har tagits fram genom att göra en litteraturstudie inom området och beräkningar för att förstå hur kontrollen påverkas. Vid beräkningsdelen har programmet Excel används för att sammanställa och jämföra alla resultat. Andra internationella normer har studerats för att kunna jämföras med Eurokod 2 samt för att få en större förståelse inom området. Normerna som används är American Concrete Institute 318 och Brittish Standard 8110. BS8110, ACI318 och Eurokod 2 skiljer sig i tillvägagångsätt en hel del och en av de största skillnaderna är att ACI318 använder en längre procentenhet av betongskapacitet när skjuvkapaciteten med armering dimensioneras. Det högst tillåtna avståndet på skjuvarmering utan att behöva förlänga området är 2d eftersom grundkontrollsnittets längd från pelarens yta i varje riktning har det avståndet. Genom att prova hur alla förutsättningar påverkar avståndet går det att se vilka värden som krävs för att avståndet ska överskrida 2d. Förutsättningen som gör störst påverkan är effektivhöjden vilket syns tydligt när de 3 faktorer som påverkar mest jämförs. Efter att beräkningar har gjorts på flera olika förutsättningsfall kan det konstateras att vid många tillfällen blir avståndet under 2d. På grund av att så många förutsättningar påverkar resultatet är det svårt att bedöma rimliga värden på alla vilket gör det svårare att värdera hur ofta kontrollen är viktig. Ett enkelt sätt att begränsa användandet av kontrollen är genom att hitta en förutsättning som är dominerande men det gick inte detta fall så därför valdes det istället att jämföra skjuvkapaciteten utan armering med tvärkraften belastad över grundkontrollområdet. Det här sättet att begränsa är bundet av vad som antas vara rimliga värden på förutsättningarna och därför kan användandet variera mycket.

The thesis deals with the topic of the punching shear of the reinforced concrete structures with a focus on an additional strengthening. The introduction of the thesis is devoted to the research of various types of strengthening against the punching and their efficiency on an increase of load-bearing capacity. Material nonlinear models are formed for strengthening by an additional concrete head, a slab concrete overlay and a column concrete jacketing. The results from the nonlinear analysis are compared with various standards, including the new generation of Eurocodes. Detailed analysis of an additional concrete head is performed regarding governing inputs, which influence load-bearing capacity. Theoretical assumptions were applied to the design of the additional concrete head, where long-term measurement has been performed for the comparison with the analytical assumptions and the material nonlinear model. The second part of the thesis deals with the strengthening of foundation structures, which are accessible only from one surface. There is presented newly developed technology for strengthening by the additional shear reinforcement with the combination of bonding and mechanical anchorage. The assessment of proposed technology is defined for the strengthening against punching shear based on tested samples. The detailed technological procedure is described, including the procedure for the application on the structures below ground water level. Long-term measurement of the shear reinforcement was carried out for the strengthened foundation slab.

The diploma thesis deals with the design of concrete structures reinforced by FRP according to ACI, fib, CSA and EC2 regulations, which are stressed by a shear force. The diferences between steel rebar and FRP reinforcement were described, in particular its mechanical degradation over time and a different stress-strain diagram. Furthermore, shear capacity calculations were performed according to the regulations and compared with the real tests. Then the parametric analysis of shear strength was performed. In the practical part, the design of concrete floor slab structure supported by the pillars and walls was performed. The upper reinforcement of this slab was designed with FRP and the lower with steel rebar. Double-headed studs were used as a punching shear reinforcement.

No description available.

The construction industry is currently developing and evolving towards more automated and optimized processes in the project design phase. One reason for this development is that computational power is becoming a more precise and accessible tool and its applications are multiplying daily. Complex structural engineering problems are typically time-consuming with large scale calculations, resulting in a limited number of evaluated solutions. Quality solutions are based on engineering experience, assumptions and previous knowledge of the subject.The use of parametric design within a structural design problem is a way of coping with complex solutions. Its methodology strips down each problem to basic solvable parameters, allowing the structure to be controlled and recombined to achieve an optimal solution.This thesis introduces the concept of parametric design and optimization in structural engineering practice, explaining how the software application works and presenting a case study carried out to evaluate the result. In this thesis a parametric model was built using the Dynamo software to handle a design process involving a common structural engineering problem. The structural problem investigated is a reinforced concrete slab supported by a centre column that is exposed to punching shear failure. The results provided are used for comparisons and as indicators of whether a more effective and better design has been achieved. Such indicators included less materials and therefore less financial cost and/or fewer environmental impacts, while maintaining the structural strength. A parametric model allows the user to easily modify and adapt any type of structure modification, making it the perfect tool to apply to an optimization process.The purpose of this thesis was to find a more effective way to solve a complex problem and to increase the number of solutions and evaluations of the problem compared to a more conventional method. The focus was to develop a parametric model of a reinforced concrete slab subjected to punching shear, which would be able to implement optimization in terms of time spent on the project and therefore also the cost of the structure and environmental impact.The result of this case study suggests a great potential for cost savings. The created parametric model proved in its current state to be a useful and helpful tool for the designer of reinforced concrete slab subjected to punching shear. The result showed several solutions that meet both the economical and the punching shear failure goals and which were optimized using the parametrical model. Many solutions were provided and evaluated beyond what could have been done in a project using a conventional method. For a structure of this type, a parametric strategy will help the engineer to achieve more optimal solutions. / Just nu utvecklas Byggbranschen mot mer automatiserade och optimerade processer i projektdesignfasen. Denna utveckling beror till stor del på teknikutveckling i form av bättre datorprogram och tillgänglighet för dessa. Traditionellt sett löses komplexa konstruktionsproblem med hjälp av tidskrävande och storskaliga beräkningar, vilka sedan resulterar i ett begränsat antal utvärderade lösningar. Kvalitets lösningar bygger då på teknisk erfarenhet, antaganden och tidigare kunskaper inom ämnet.Användning av parametrisk design inom ett konstruktionsproblem är ett sätt att hantera komplexa lösningar. Dess metod avgränsar varje problem ner till ett antal lösbara parametrar, vilket gör att strukturen kan kontrolleras och rekombineras för att uppnå en optimal lösning.Denna avhandling introducerar begreppet parametrisk design och optimering i konstruktionsteknik, den förklarar hur programvaran fungerar och presenterar en fallstudie som genomförts för att utvärdera resultatet. I denna avhandling byggdes en parametrisk modell med hjälp av programvaran Dynamo för att hantera en designprocess av ett vanligt konstruktionsproblem. Det strukturella problemet som undersökts är en armerad betongplatta som stöds av en mittpelare, utsatt för genomstansning. Resultaten används för att utvärdera om en bättre design med avseende på materialanvändning har uppnåtts. Minimering av materialanvändning anses vara en bra parameter att undersöka eftersom det ger lägre kostnader och/eller lägre miljöpåverkan, detta undersöks under förutsättning att konstruktionens hållfasthet bibehålls. En parametrisk modell gör det möjligt för användaren att enkelt modifiera en konstruktionslösning med avseende på olika parametrar. Detta gör det till det perfekta verktyget att tillämpa en optimeringsprocess på.Syftet med denna avhandling var att hitta ett mer effektivt sätt att lösa ett komplext problem och att multiplicera antalet lösningar och utvärderingar av problemet jämfört med en mer konventionell metod. Fokus var att utveckla en parametrisk modell av en armerad betongplatta utsatt för genomstansning, som kommer att kunna genomföra optimering med avseende på tid som spenderas på projektet och därmed också kostnaden för konstruktionen och miljöpåverkan.Resultatet av denna fallstudie tyder på att det finns en stor möjlighet till kostnadsbesparingar och anses därför vara ett mycket hjälpsamt verktyg för en konstruktör. Resultatet visade flera lösningar som uppfyllde de konstruktionsmässiga kraven samtidigt som de gav en lägre materialanvändning tack vare optimeringen. Många lösningar tillhandahölls och utvärderades utöver vad som kunde ha gjorts i ett projekt med en konventionell metod. En parametrisk strategi kommer att hjälpa ingenjören att optimera lösningen för en konstruktion av denna typ.

This research aims to investigate the behaviour of glass fibre reinforced polymer bars (GFRP) reinforced continuous concrete deep beams. For this purpose, experimental, analytical and numerical studies were conducted. Nine continuous concrete deep beams reinforced with GFRP bars and one specimen reinforced with steel bars were experimentally tested to failure. The investigated parameters included shear span-to-overall depth ratio (𝑎/ℎ), size effect and web reinforcement ratio. Two 𝑎/ℎ ratios of 1.0 and 1.7 and three section heights of 300 mm, 600 mm and 800 mm as well as two web reinforcement ratios of 0% and 0.4% were used. The longitudinal reinforcement, compressive strength and beam width were kept constant at 1.2%, ≈55 MPa and 175 mm, respectively. The web reinforcement ratio achieved the minimum requirements of the CSA S806-12. The experimental results highlighted that the web reinforcement ratio improved the load capacities by about 10% and 18% for specimens having 𝑎/ℎ ratios of 1.0 and 1.7, respectively. For specimens with web reinforcement, the increase of 𝑎/ℎ ratio from 1.0 to 1.7 led to reductions in the load carrying capacity by about 33% and 29% for beams with overall depths of 300 mm and 600 mm, respectively. Additionally, a considerable reduction occurred in the shear strength due to the increase of the section depth from 300 mm to 600 mm. The experimental results confirmed the impacts of web reinforcement and size effect that were not considered by the strut-and-tie method (STM) of the only code provision, the Canadian S806-12, that addressed such elements. In this study, the STM was illustrated and simplified to be adopted for GFRP RC continuous deep beams, and then, the experimental results obtained from this study were employed to assess the performance of the effectiveness factors suggested by the STMs of the American (ACI 318-2014), European (EC2-04) and Canadian (S806-12) codes as well as those factors recommended by the previous studies to predict the load capacities. It was found that these methods were unable to reflect the influences of member size and/or web reinforcement reasonably, the impact of which has been confirmed by the current experimental investigation. Therefore, a new effectiveness factor was recommended to be used with the STM. Additionally, an upper bound analysis was developed to predict the load capacities of the tested specimens considering a reduced bond strength of GFRP bars after assessing the old version recommended for steel RC continuous deep beams. A good agreement between the predicted results and the measured ones was obtained with the mean and coefficient of variation values for experimental/calculated results of 1.02 and 5.9%, respectively, for the STM and 1.03 and 8.6%, respectively, for the upper-bound analysis. A 2D finite element analysis using ABAQUS/Explicit approach was carried out to introduce a model able to estimate the response of GFRP RC continuous deep beams. Based on the experimental results extracted from the pullout tests, the interface between the longitudinal reinforcement and concrete surface was modelled using a cohesive element (COH2D4) tool available in ABAQUS. Furthermore, a perfect bond between the longitudinal reinforcement and surrounding concrete was also modelled to evaluate the validity of this assumption introduced by many previous FE studies. To achieve a reasonable agreement with the test results, a sensitivity analysis was implemented to select the proper mesh size and concrete model variables. The suitability and capability of the developed FE model were demonstrated by comparing its predictions with the test results of beams tested experimentally. Model validation showed a reasonable agreement with the experiments in terms of the failure mode, total failure load and the load-deflection responses. The perfect bond model has overestimated the predicted results in terms of stiffness behaviour and failure load, while the cohesive element model was more suitable to reflect the behaviour of those specimens. The validated FE model was then employed to implement a parametric study for the key parameters that govern the behaviour of beams tested and to achieve an in depth understanding of such elements. The parametric study showed that the higher the 𝑎/ℎ ratio the more pronounced the effect of web and the longitudinal reinforcements and the lower the effect of concrete compressive strength; and vice versa when 𝑎/ℎ ratio reduces.

Made available in DSpace on 2014-07-29T15:03:41Z (GMT). No. of bitstreams: 1 David Rosa Rodrigues.pdf: 6647846 bytes, checksum: 0949b9b9e50ce27a724b92ea2943c5d1 (MD5) Previous issue date: 2009-09-29 / This research presents the results of an experimental comparison between the types of shear reinforcement "stud rails" and "double headed studs" to combat the punching shear of a reinforced concrete flat slabs. It also presents a comparison of experimental results with those provided under the ACI 318/2005, CEB-FIP MC/1990, EUROCODE 2/2004 and NBR 6118:2003. The motivation was to investigate the efficiency of these shear reinforcement for the differences between them. It was tested six slabs of concrete to concentric load, with dimensions of 2400 mm x 2400 mm x 150 mm. It was concreted a column of section 500 mm x 200 mm to 850 mm total height next to the slab. The main variables were the type of shear reinforcement "stud rails" x "double headed studs, the "studs" diameter and the shear reinforcement area per layer. The slabs were tested until the failure. It was monitored the deflection, reinforcement deformation of bending and shear. All slabs failed by punching with internal surface rupture. The experimental results after being compared with the expected standard in each individual calculation showed conservative values. Slabs of Group 1 with "stud rails" presented failed loads greater than those in Group 2 with "double headed studs. Codes/standards 318/2005 ACI, CEB-FIP MC/1990, EUROCODE 2 / 2004 and NBR 6118:2003 safely predict the failed loads of all slabs. The base of the shear reinforcement type "stud rails" moving inside the column may have reduced the failed load of the slab L3. Shear reinforcement type stud rails it is easer of assembly and play than the type double headed studs . / Esta pesquisa apresenta os resultados de uma comparação experimental entre os tipos de armadura de cisalhamento stud rails e double headed studs para combate à punção em lajes cogumelo de concreto armado. Apresenta, também, uma comparação dos resultados experimentais com os previstos segundo o ACI 318/2005, CEB-FIP MC/1990, EUROCODE 2/2004 e a NBR 6118:2003. A motivação foi investigar a eficiência destas armaduras de cisalhamento a procura de diferenças entre elas. Foram ensaiadas seis lajes maciças de concreto armado à punção centrada, com dimensões 2400 mm x 2400 mm x 150 mm. Foi concretado junto à laje um pilar de seção 500 mm x 200 mm com altura total 850 mm. As principais variáveis foram o tipo de armadura de cisalhamento: stud rails x double headed studs , o diâmetro dos studs e a área de armadura de cisalhamento por camada. As lajes foram ensaiadas até a ruptura. Foram monitoradas as flechas, deformações da armadura de flexão e cisalhamento. Todas as lajes romperam por punção com superfície de ruptura interna. Os resultados experimentais após serem comparados com os esperados segundo cada norma de cálculo apresentaram valores conservadores. As lajes do Grupo 1 com stud rails apresentaram cargas de ruptura maiores que as do Grupo 2 com double headed studs . Os códigos/normas ACI 318/2005, CEB-FIP MC/1990, EUROCODE 2/2004 e a NBR 6118:2003 previram com segurança as cargas de ruptura de todas as lajes. A base da armadura de cisalhamento tipo stud rails avançando dentro do pilar pode ter reduzido a carga de ruptura da Laje L3. A armadura de cisalhamento tipo stud rails apresenta maior facilidade de montagem e execução que a tipo double headed studs .

The subject of this diploma thesis is the design of the underground parts of the building. Part of this thesis is to comapare alternative designs and subsequentli evaluate the interaction of the upper structure with subsoil and pile fundantion. A detailed static assessment and implementation documentation is then prepared for the selected variant. The design of the base plate and reinforced concrete walls of the underground section are designed with respect to the crack width according to the principles for designing the white box. The theoretical part contains principles for designing and implementing a white box and evaluating design variants.

The diploma thesis is focused on design and assessment selected parts of the reinforced concrete structure supporting six storey office building with regard to the ultimate and serviceability limit state.This thesis contains a static calculation and technical drawings of concrete slab above first floor, staircase and two columns. For calculation of internal forces was created a 3D structural model in Scia Engineer 16. Assessment of all designed parts of the structure is done according to Eurocode 2 (ČSN EN 1992-1-1).