This thesis examines punching shear response of reinforced-concrete flat slabs under fire conditions. The shear behaviour of concrete in fire is relatively poorly understood compared to its flexural response. Failures such as the Gretzenbach car park failure in Switzerland (2004) have prompted concerns over the punching shear capacity of flat slabs in fire. The shear behaviour of reinforced-concrete in fire depends on degradation of the individual material properties with temperature, their interaction, and more recently recognised, the effects of restrained thermal expansion. Through experimental testing this thesis aims to build a foundation understanding of the punching shear behaviour of flat reinforced-concrete slabs in fire conditions. A series of shear blocks, tested after exposure to elevated temperature (realistic fire temperature), were used to develop an understanding of the effects of elevated temperature on the shear transfer performance of reinforced-concrete. These tests allowed the complex interplay of shear-carrying mechanisms at ambient temperature to be extended to the case of post-elevated temperature. Fifteen slab-column punching shear specimens were tested under both applied load and extreme heating. In particular, the effects of restrained thermal expansion were experimentally investigated by altering the support conditions of the slab-column specimens. A purpose-built restraint frame allowed the boundary support conditions to be either fully restrained or unrestrained. This experimental series is the only series to have tested restrained specimens at elevated temperatures, though previous researchers have simulated the thermal restraint effects and reported the importance of restrained thermal expansion and curvature on the behaviour of punching shear. Parameters of slab thickness and reinforcement ratio were also varied to investigate their respective impacts on punching shear behaviour at elevated temperature. The thicker 100 mm reinforced slabs failed in punching shear, whereas the 50 mm and 75 mm thick slabs failed in flexure-shear mechanisms and the unreinforced slabs failed in flexure. Clear behavioural differences were observed between specimens with different support conditions. Unrestrained 100 mm thick slabs under sustained load failed soon after heating began, whereas none of the corresponding restrained specimens failed during heating. One restrained, heavily reinforced specimen failed during cooling, whilst under sustained load. This is the first recorded punching shear failure during the cooling phase of an elevated temperature test and may also be the first recorded test specimen ever to have failed during the cooling phase of an elevated temperature test. This failure highlights the unknown and potentially unsafe behaviour of structures during the cooling phase. Further structural investigation of the cooling behaviour of concrete flat slabs after exposure to fire, needs to be undertaken. Most of the specimens’ central deflection was away from the heat source (in the direction of loading) during the whole test, irrespective of support condition. The test setup was assessed to investigate the unusual slab-column deflection away from the heat source, however the complex behaviour observed during the tests cannot currently be explained. It is assumed that the degradation in concrete properties and non-linear material behaviour dominates over the thermal expansion of the slabs. Quantitative and qualitative comparisons are presented, though the quantitative data is impacted by size effect, non-repeatable heating application between tests and jack friction influences on specimens with low capacities. Eurocode 2 punching shear prescriptive elevated temperature design, extends the ambient temperature equation for elevated temperature use, by degrading the temperature-dependant parameters by factors. Support conditions are not considered, with the code specifically telling the designer not to consider in-plane thermal expansion effects, therefore consequently ignoring the premature punching shear failure that can occur. Furthermore, the ambient temperature equation is based on the regression of available experimental data at the time and does not consider the reinforcement as a shear transfer mechanism. The experimental capacities of the 100 mm thick, reinforced slabs that failed in pure punching shear mechanism were similar to the Eurocode 2 punching shear prescriptive design capacity, when directly compared. The unrestrained support condition was shown to be consistently, not conservatively predicted by Eurocode 2, whereas the restrained support condition capacities were conservatively predicted. It is comforting to know that the Eurocode 2 design predicts the restrained supported slabs conservatively, as real buildings are more likely to have supports closer to the restrained condition rather than the unrestrained support condition. A sensitivity analysis of the Eurocode 2 prescriptive design equation shows it is highly sensitive to the concrete strength degradation and not the variable, cp, which was used to make a support condition comparison in this thesis. This indicates how the Eurocode 2 equation for punching shear capacity lacks in its consideration of whole structural behaviour. The Critical Shear Crack Theory has been proposed as the background to a harmonised shear design approach, called Model Code 2010. The Critical Shear Crack Theory was safe in predicting the experimental punching shear capacities. There were large variances for the 100 mm thick slabs, however they are consistent with the original model comparison to test data. An expansion of the Critical Shear Crack Theory for elevated temperature requires further validation with experimental restrained thermal expansion tests, such as those presented in this thesis. Finally, a digital image correlation technique has been proven to be a reliable method to measure structural displacements of concrete at elevated temperatures. Digital image correlation allowed the crack locations and slab rotation angles to be visualized throughout testing. No other measurement techniques are able to provide similar versatility in fire testing such as that presented herein.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-08-12T13:31:38Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertação final Tulio.pdf: 2889761 bytes, checksum: 052b78ab493e64aa19addbe0117d79a0 (MD5) / Made available in DSpace on 2016-08-12T13:31:38Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertação final Tulio.pdf: 2889761 bytes, checksum: 052b78ab493e64aa19addbe0117d79a0 (MD5) Previous issue date: 2015-08-31 / CNPq / Em lajes de concreto armado sem vigas, apoiadas em pilares, a resistência à punção torna-se um ponto crítico para seu dimensionamento. Até recentemente, os modelos mecânicos para se calcular a resistência à punção das lajes de concreto armado, eram muito complexos, sem praticidade para se aplicar em projetos. O dimensionameto à punção na maioria das normas são baseados em resultados experimentais sem uma modelação física. Uma das formas de se aumentar a resistência à punção é a utilização de capitéis. Para esse trabalho foi definido a utilização de capitéis curtos. As poucas informações sobre a utilização de capitéis curtos deixam os engenheiros receosos quanto a sua utilização. O objetivo desse trabalho é elucidar mais um pouco sobre esse tipo de solução para combate à punção. É apresentado como a litetura aborda a utilização dos capitéis curtos e como a sua utilização e suas dimensões são orientadas. Também é apresentado como os métodos normativos, ACI- 318/2014, NBR 6118/2014 e FIB MODEL CODE 2010 abordam a sua utilização e dimensionamento. É selecionado um caso de uma laje submetida à punção e feito o seu dimensionamento segundo os três métodos já mencionados. Também é feita uma comparação com os resultados experimentais obtidos na literatura, os quais são poucos, com os três métodos já citados. / In flat plates without beams, supported directly on columns, punching shear strength becomes critical in design. Until recently mechanically based models for punching shear computation in reinforced concrete slabs were too complex for routine design work. Punching shear strength checks are basically empirical for most design codes, without a mechanical model basis. A possible alternative to enhance punching shear capacity is to locally increase slab thickness through shear caps or drop panels. In this work, the shear cap option is studied in detail. Due to lack of information, designers are generally wary of the usage of shear caps. This work aims at gaining a better understanding of this type of solution for punching shear strengthening. A literature review is presented on shear cap usage as well as guidance with respect to its geometry. Also presented are design check procedures according to ACI-318/2014, NBR 6118/2014 and FIB MODEL CODE 2010. A case study of a slab subjected to punching shear is selected and its design reviewed according to the three abovementioned codes. Punching shear capacity of shear caps of the very few experimental results are compared with the presented verification procedures.

This thesis presents the results of an experimental, numerical and analytical study to develop a design method to calculate punching shear resistance for a new shearhead system between tubular steel column and reinforced concrete flat slab. This shearhead system enables two of the most popular structural systems, i.e. reinforced concrete flat slab floor and steel tubular column, to be used to produce efficient structures of low cost and short construction time. This research investigates slabs without and with a service hole adjacent to the column. The new shearhead system should not only possess sufficient punching shear resistance, but should also be efficient for construction. The main methodology for this project was based on numerical finite element simulations verified by two full scale tests. These two tests were carried out in the University of Manchester's Structural Testing Laboratory. The two specimens had the same slab size, thickness and reinforcement ratio, but differed in the column shape (rectangular or circular), central reinforcement arrangement (continuous or discontinuous), shearhead position in the slab thickness and shearhead fabrication arrangement. Recorded load-deflection and load-strain relationships, crack development and critical perimeter were used for detailed validation of using the commercial finite element software ABAQUS. The validated ABAQUS model was used to conduct a comprehensive parametric study to investigate the effects of a number of design parameters, including the effect of varied column size, shearhead arm length, shearhead arm cross section, shearhead arm angle, amount of flexural reinforcement, slab thickness, shearhead positions and hole positions. The main conclusion from the parametric study was that the shearhead system could be treated as an enlarged column in normal flat slab structure. The parametric study enabled pressure distribution below the shearhead arms to be approximated for checking whether the shearhead arms would be sufficient for the enlarged column assumption to be valid. The parametric study results were also used to determine the effective depth of the flat slab and critical punching shear perimeter of the slab with and without a service hole.Using the enlarged column assumption, the punching shear resistance of all structures used in the parametric study were re-calculated using Eurocode 2 (EC2), British stand 8110 (BS8110) and American Concrete Institute code 318 (ACI 318). Comparison of calculation results using these three design methods indicates that both EC2 and BS8110 predicted very close value which reached very good agreement with the ABAQUS simulation (normally within 10%). Among these three design methods, ACI 318 was the only code that explicitly considered shearhead system. ACI 318 was not able to predict the slab critical perimeter length with good accuracy, however, its prediction of slab punching shear resistance achieved reasonably good agreement with numerical analysis results and were on the safe side. Based on these studies, a design method for calculating punching resistance of the proposed shearhead system between reinforced concrete flat slab and steel tubular column has been developed in this thesis.

Master’s thesis deals with application of lasers in manufacturing, mainly with the technology of cutting material. This technology is compared with the technology of punching and cutting sheet metal, with the aid of control specimens. The parameters of surface structure, dimension accuracy and appearance of cut-ting surfaces are compared. By consensus of results the recommendation for practical realization was created.

This master thesis was performed at the Mechanical department at Outotec AB,Skellefte˚a. Outotec AB is a technology company as well as a project company, sell-ing complex mining technology and plant projects. Outotec’s technologies are usedfor applications such as producing base metals, processing iron ore etc. Outotec isrunning a program called ‘Fully automated smelter’ where manual hazardous workmust be avoided. A machine which automatically replaces punching bars on thepunching machine is needed. This thesis project aimed to investigate if the punching bar changer will be aproprietary purpose-build machine or an industrial robot. The five-step conceptgeneration method was used for concept development during this thesis project.For gathering knowledge and information about the project area, experts have beeninterviewed to obtain information for the start of the project. The gathered infor-mation and knowledge from interviews and literature studies have been used as abase when the concepts were generated. Seven concepts were generated and evalu-ated using a screening matrix. The concept that best satisfied the set requirementswere further developed, designed and simulated. The two scenarios have been in-vestigated and a design concept of the proprietary purpose-built machine has beenpresented. The result from concept evaluation and simulation indicated that bothalternatives are applicable in this area. But to make a decision a more in-depthcalculation of the associated cost and investigation of the design is necessary.

Experiments were conducted to investigate the punching shear behaviour of thick slabs with identical spans and depths, subjected to monotonic point load conditions. Variables included: reinforcement ratio, column size, and reinforcement size. Analytical studies conducted as part of this thesis indicate that the current CSA A23.3 and the ACI 318 can be unconservative for thick slabs with low reinforcement ratios. The new fib Model Code provisions for punching offer an effective method for determining the full load-rotation behaviour of a slab up to failure, including accurate failure predictions. A summary of the background of current design procedures and standards will be presented, and a comparison between the different design equations and theories will be given. Based on the findings of this project, it is proposed that the provisions accepted by the fib Model Code should be considered for implementation in the CSA and ACI standards.

Experiments were conducted to investigate the punching shear behaviour of thick slabs with identical spans and depths, subjected to monotonic point load conditions. Variables included: reinforcement ratio, column size, and reinforcement size. Analytical studies conducted as part of this thesis indicate that the current CSA A23.3 and the ACI 318 can be unconservative for thick slabs with low reinforcement ratios. The new fib Model Code provisions for punching offer an effective method for determining the full load-rotation behaviour of a slab up to failure, including accurate failure predictions. A summary of the background of current design procedures and standards will be presented, and a comparison between the different design equations and theories will be given. Based on the findings of this project, it is proposed that the provisions accepted by the fib Model Code should be considered for implementation in the CSA and ACI standards.

This master’s project describes a proposal for manufacturing technology of a horizontal boring machine case. This case is manufactured by HESTEGO a.s. from a DC01 steel sheet, which is 2 mm thick and its production series is 200 pieces a year. Punching and bending were chosen as the most suitable methods from the considered manufacturing technologies. The theoretical part of the thesis includes a study of the chosen manufacturing technologies. Based on the analysis of the technological calculations and the available tools in the manufacturing company, a technological procedure was designed and these machines were chosen: punching machine TruPunch 5000 a servo-electronic press brake SAFAN E – BRAKE 100–3100. Technical and economical evaluation is also included in the proposal.

Atualmente, alguns códigos como o CEB/90 e o texto base da NB-1/94 (ainda em fase de apreciação pelo meio técnico) têm apresentado inovações com relação à verificação da resistência à punção. Fez-se então, neste trabalho, uma análise do texto base da NB-1/94 referente à punção, comparando suas recomendações com algumas das fornecidas pelo CEB/90. Observou-se uma certa divergência entre os dois códigos com relação a pilares de borda e de canto, fornecendo o CEB/90 um tratamento mais simplificado para essas duas situações. Além disso, observa-se que, ao contrário do CEB/90, o texto base não menciona as seguintes recomendações: utilização de uma armadura a ser disposta ao longo das bordas livres da laje, destinada a combater esforços de torção, e limitação da resistência do concreto em 50 MPa para essas verificações. Observou-se, ainda, uma omissão desses dois códigos com relação à situação de pilares internos submetidos a momentos fletores atuando em duas direções diferentes. Sugere-se, ainda, ao texto base, a inclusão de expressões que visem a facilitar e agilizar a sua aplicação. Após essa análise, foram apresentados exemplos de cálculo para pilares internos, de borda e de canto, tanto com como sem armadura de punção, verificados segundo as recomendações do texto base da NB-1/94, do EUROCODE N.2, do CEB/90 e do ACI 318/89. Por fim, comparam-se resultados experimentais com valores dados por estes códigos, visando determinar suas respectivas eficiências frente a alguns parâmetros, tais como, por exemplo, a presença de armadura transversal ou a relação entre os lados do pilar. Verifica-se que a utilização de armaduras de combate à punção pode elevar substancialmente o valor da resistência da ligação, além de torná-la mais dúctil. As observações referentes à comparação entre os valores fornecidos através de ensaios e os dados pelos códigos devem ser levadas em consideração apenas como uma indicação de seus respectivos comportamentos, necessitando-se de mais dados para uma afirmação mais conclusiva. / Nowadays, some standards like CEB/90 and the Brazilian code basic text NB-1/94 (not approved yet) have presented some innovations for the punching shear strength. In this work, a comparative analysis is presented about the NB1-94 basic text recommendations and some presented by the CEB/90. Some differences are noted between the NB1-94 basic text and the CEB/90 recommendations relatives to corner and edge columns. The CEB/90 has a simplified treatment for these situations. lt is noted that, in opposition to the CEB/90, the NB1-94 basic text about punching shear strength does not mention an additional reinforcement to be placed at the free edges of the slab, to provide torsion strength, and neither have a limit value of 50 MPa for the concrete compressive strength. lt is also noted that the CEB/90 and the NB1-94 basic text do not have a recommendation for internal columns with bending moments acting on two different directions. lt is suggested that the NB1-94 basic text includes some expressions that can make its application easier and faster. After this analysis, some examples are presented with internal, edge and corner columns, with and without shear reinforcement, verified by the NB1-94 basic text, the EUROCODE N.2, the CEB/90 and the ACI 318/89 recommendations. Finally, a comparative analysis between some experimental results and those given by the codes is presented. The experimental results were related to some parameters like, for instance, the presence of shear reinforcement or the column sides ratio. lt is verified that the shear reinforcement utilization can give more resistance and ductility to the connection. Finally, it is noted that the observations about the comparison between the experimental results and the values given by the codes can just be taken like a behavior indication for the connections. For conclusive affirmations, more experimental analysis are necessary.

Atualmente, alguns códigos como o CEB/90 e o texto base da NB-1/94 (ainda em fase de apreciação pelo meio técnico) têm apresentado inovações com relação à verificação da resistência à punção. Fez-se então, neste trabalho, uma análise do texto base da NB-1/94 referente à punção, comparando suas recomendações com algumas das fornecidas pelo CEB/90. Observou-se uma certa divergência entre os dois códigos com relação a pilares de borda e de canto, fornecendo o CEB/90 um tratamento mais simplificado para essas duas situações. Além disso, observa-se que, ao contrário do CEB/90, o texto base não menciona as seguintes recomendações: utilização de uma armadura a ser disposta ao longo das bordas livres da laje, destinada a combater esforços de torção, e limitação da resistência do concreto em 50 MPa para essas verificações. Observou-se, ainda, uma omissão desses dois códigos com relação à situação de pilares internos submetidos a momentos fletores atuando em duas direções diferentes. Sugere-se, ainda, ao texto base, a inclusão de expressões que visem a facilitar e agilizar a sua aplicação. Após essa análise, foram apresentados exemplos de cálculo para pilares internos, de borda e de canto, tanto com como sem armadura de punção, verificados segundo as recomendações do texto base da NB-1/94, do EUROCODE N.2, do CEB/90 e do ACI 318/89. Por fim, comparam-se resultados experimentais com valores dados por estes códigos, visando determinar suas respectivas eficiências frente a alguns parâmetros, tais como, por exemplo, a presença de armadura transversal ou a relação entre os lados do pilar. Verifica-se que a utilização de armaduras de combate à punção pode elevar substancialmente o valor da resistência da ligação, além de torná-la mais dúctil. As observações referentes à comparação entre os valores fornecidos através de ensaios e os dados pelos códigos devem ser levadas em consideração apenas como uma indicação de seus respectivos comportamentos, necessitando-se de mais dados para uma afirmação mais conclusiva. / Nowadays, some standards like CEB/90 and the Brazilian code basic text NB-1/94 (not approved yet) have presented some innovations for the punching shear strength. In this work, a comparative analysis is presented about the NB1-94 basic text recommendations and some presented by the CEB/90. Some differences are noted between the NB1-94 basic text and the CEB/90 recommendations relatives to corner and edge columns. The CEB/90 has a simplified treatment for these situations. lt is noted that, in opposition to the CEB/90, the NB1-94 basic text about punching shear strength does not mention an additional reinforcement to be placed at the free edges of the slab, to provide torsion strength, and neither have a limit value of 50 MPa for the concrete compressive strength. lt is also noted that the CEB/90 and the NB1-94 basic text do not have a recommendation for internal columns with bending moments acting on two different directions. lt is suggested that the NB1-94 basic text includes some expressions that can make its application easier and faster. After this analysis, some examples are presented with internal, edge and corner columns, with and without shear reinforcement, verified by the NB1-94 basic text, the EUROCODE N.2, the CEB/90 and the ACI 318/89 recommendations. Finally, a comparative analysis between some experimental results and those given by the codes is presented. The experimental results were related to some parameters like, for instance, the presence of shear reinforcement or the column sides ratio. lt is verified that the shear reinforcement utilization can give more resistance and ductility to the connection. Finally, it is noted that the observations about the comparison between the experimental results and the values given by the codes can just be taken like a behavior indication for the connections. For conclusive affirmations, more experimental analysis are necessary.