No description available.

Fibre reinforcement polymers (FRP) are non-corrodible materials used instead of conventional steel and have been approved to be an effective way to overcome corrosion problems. FRP, in most cases, can have a higher tensile strength, but a lower tensile modulus of elasticity compared to that of conventional steel bars. This study aimed to examine flat slab specimens reinforced with glass fibre reinforced polymer (GFRP) and steel bar materials for punching shear behaviour. Six full-scale two-way slab specimens were constructed and tested under concentric load up to failure. One of the main objectives is to study the effect of reinforcement spacing with the same reinforcement ratio on the punching shear strength. In addition, two other parameters were considered, namely, slab depth, and compressive strength of concrete. The punching shear provisions of two code of practises CSA S806 (Canadian Standards 2012) and JSCE (JSCE et al. 1997) reasonably predicted the load capacity of GFRP reinforced concrete flat slab, whereas, ACI 440 (ACI Committee 440 2015) showed very conservative load capacity prediction. On the other hand, a dynamic explicit solver in nonlinear finite element (FE) modelling is used to analyse a connection of column to concrete flat slabs reinforced with GFRP bars in terms of ultimate punching load. All FE modelling was performed in 3D with the appropriate adoption of element size and mesh. The numerical and experimental results were compared in order to evaluate the developed FE, aiming to predict the behaviour of punching shear in the concrete flat slab. In addition, a parametric study was created to explore the behaviour of GFRP reinforced concrete flat slab with three parameters, namely, concrete strength, shear load perimeter to effective depth ratio, and, flexural reinforcement ratio. It was concluded that the developed models could accurately capture the behaviour of GFRP reinforced concrete flat slabs subjected to a concentrated load. Artificial Neural Networks (ANN) is used in this research to predict punching shear strength, and the results were shown to match more closely with the experimental results. A parametric study was performed to investigate the effects of five parameters on punching shear capacity of GFRP reinforced concrete flat slab. The parametric investigation revealed that the effective depth has the most substantial impact on the load carrying capacity of the punching shear followed by reinforcement ratio, column perimeter, the compressive strength of the concrete, and, the elastic modulus of the reinforcement.

No description available.

Concrete pavements are a suitable alternative for high-traffic volume roads, concentrated loads and roads exposed to severe weather conditions. In Sweden, among other reasons, the scarcity of concrete pavements is attributed to the need for more national knowledge and expertise in the field. The most recent concrete pavement was constructed seventeen years ago in Uppsala. Concrete pavements are renowned for their longevity and durability. Jointed plain concrete pavements (JPCP) are the most frequent type of concrete pavements. However, it is important to note that the joints in concrete pavements are critical components that can lead to various distresses, necessitating rehabilitation. Rehabilitating concrete pavements is particularly challenging in areas with heavy traffic and requires substitute routes because of the imperative to maintain traffic flow during construction. Developing effective detours might involve significant alterations to the existing routes or building temporary roads, which entails substantial cost investment and time consumption. A literature review has been conducted to study the available methods that can be used to repair concrete pavements. The strategy for selecting a repair technique is based on rehabilitating the concrete pavement within a short work window, deterring traffic congestion and ensuring the long service life of the pavements. The study showed that the precast concrete technology based on the precast slab is a promising technology that effectively shortens the lane closure for repairing damaged pavements and produces durable pavements, thereby extending the service life of pavements. However, the construction or rehabilitation cost of concrete pavement using precast slabs is 1.6 to 4 times higher than that of conventional cast-in-place concrete. Therefore, rehabilitation using precast slabs is inappropriate for low-traffic roads and temporary routes. Joints are crucial for the rehabilitation of concrete pavements with precast slabs. The structural performance of concrete pavement is, however, greatly affected by the joints, as the presence of joints creates a discontinuity between adjacent slabs and thus diminishes the load transfer to the abutting slab. To maintain the structural integrity of the pavement system, dowel bars are used at the transverse joints. A numerical study has been conducted to evaluate the influence of various dowel-related parameters on the interaction between adjacent concrete slabs. The study revealed that the dowel bar’s position, mislocation and diameter had an obvious effect on joint efficiency, while the bond between the concrete slab and the dowel bar slightly affected the load transfer efficiency. It was also investigated that the dowel bar’s intended performance, i.e., load transfer efficiency, was reduced as the joint gap between adjacent slabs increased. / Betongbeläggningar är ett lämpligt alternativ för högtrafikerade vägar, koncentrerad belastning och vägar utsatta för svåra väderförhållanden. I Sverige är betongvägar sällsynta vilket bl.a. beror på brist på kunskap och kompetens. Den senaste betongvägen byggdes för sjutton år sedan i Uppsala.Betongbeläggningar är kända för sin långa livslängd och hållbarhet. Den vanligaste typen av betongvägar är fogade, oarmerade betongbeläggningar. Ändå är det viktigt att notera att fogarna i betongbeläggningar är kritiska komponenters om kan leda till olika olägenheter, vilket kräver rehabilitering. Att rehabilitera betongbeläggningar är särskilt utmanande i områden med intensiv trafik som kräver ersättningsvägar på grund av nödvändigheten att upprätthålla trafikflödet under reparationsarbetena. Att ta fram en effektiv omledning av trafiken kan innebära antingen väsentliga förändringar och förlängningar av befintliga rutter eller byggande av tillfälliga vägar, vilket medför betydande kostnadsinvesteringar och tidsåtgång. En litteraturöversikt har genomförts för att studera de tillgängliga metoderna som kan användas för att reparera betongbeläggningar. Strategin för valet av reparationsmetod bygger på att rehabilitera betongbeläggningen inom ett kort arbetsfönster, förhindra trafikstockningar och säkerställa lång livslängd för beläggningen. Studien visade att förtillverkade betongplattor är en lovande metod som effektivt förkortar avstängningen av körfält för att reparera skadad beläggning och producerar hållbara betongbeläggningar med lång livslängd. Rehabiliterings kostnaden för betongbeläggning med prefabricerade plattor är emellertid 1,6 till 4 gånger högre än den för konventionell platsgjuten betong. Därför är rehabilitering med förtillverkade betongplattor olämplig för vägar med låg trafik och temporära rutter. Fogar är vidare nödvändiga vid reparation med förtillverkade betongplattor.Betongbeläggningens strukturella prestanda påverkas dock kraftigt av fogar, eftersom förekomsten av fogar skapar en diskontinuitet mellan intilliggande plattor och därmed minskat lastöverföringen till den angränsande plattan. För att upprätthålla den strukturella integriteten hos beläggningssystemet används dymlingar i de tvärgående fogar. En numerisk studie har genomförts med olika parametrar för att utvärdera dymlingens inverkan på fogens effektivitet. Studien visade att dymlingens position, felplacering och diameter har en tydlig inverkan på fogens effektivitet, medan vidhäftningen mellan dymling och betongplatta enbart verkar ha en marginell inverkan på fogens effektivitet. Studien visade också att dymlingens prestanda, dvs. lastöverföringsförmågan, minskade då fogöppningen eller glappet mellan två närliggande plattor ökade. / <p>QC 240207</p>

Conventional fixed base walls are typically characterized by yielding that results in permanent damage, residual drifts and costly losses due to the service shutdown for structural repairs. Controlled rocking masonry walls have been developed as a solution to prevent structural damage when seismic events take place. These systems purposely allow the wall to rock from its foundation and have an uplift at the base, thus replacing the typical yielding at the base of conventional fixed-base walls. Controlled rocking masonry walls have traditionally been controlled by using unbonded post-tensioning strands to provide the self-centering behaviour. Although post-tensioning has shown favourable results, its implementation is difficult in practical applications, and post-tensioning losses due to yielding of the strands at large deformations can reduce their self-centering ability. In order to overcome such issues, an alternative controlled rocking system for masonry walls was developed recently, which is designed to self-center through vertical gravity loads only, instead of the post-tensioning tendons. The rocking response of this alternative system is controlled by using energy dissipation devices, so the system is referred to as Energy Dissipation-Controlled Rocking Masonry Walls (ED-CRMWs). The vertical gravity loads are primarily transferred to the ED-CRMWs from the floor slab at each level. Therefore, the wall-slab interaction should be investigated in order to ensure a fully resilient system. In this regard, the current study identifies and categorizes the potential issues that are expected to occur due to the interaction between the wall rocking mechanism and the floor slab, and then investigates the most common of these issues using a parametric study. The parametric study focuses on the vertical incompatibility of displacements that a hollow- core slab suffers when its supporting walls uplift by different displacements during seismic events. Three different spans, four different cross-sections and two different alternatives of prestress configurations are considered in this study. The models were developed using ABAQUS 6.18 commercial software. The results show the cracking/yielding behaviour of the slabs and their displacement capacities at five different stages. The obtained results are promising for the usage of hollow-core slabs on ED-CRMWs or similar systems that require this interaction, as the range of displacement capacities can accommodate many of the vertical displacement incompatibilities expected in many potential situations. / Thesis / Master of Applied Science (MASc)

No description available.

No description available.

[pt] Em este estudo, com base nos resultados do tratamento da superfície do bambu para reforço de concreto desenvolvido na PUC-Rio (Brasil), análises teóricas e experimentais foram executados na University of Cambridge e University of Bath (Inglaterra). Para melhorar o tratamento da superfície do bambu (usando resina epóxi), um programa experimental sobre 32 espécimes de Push-out foram realizadas. Tiras de bambu (para concreto armado) preparadas a partir de bambu Phyllostachys pubescens e tratados para melhorar a aderência foram utilizados, com um comprimento embutido de 20 mm. A influência do tipo de resina, tamanho do agregado (2 mm ou 4 mm), nó do bambu e os procedimentos para limpar a sua superfície foram obtidas é analisadas em curvas de aderência-deslizamento. Usando o tratamento com melhores resultados uma laje de concreto (3000 mm x 3000 mm) reforçada nas duas direções com tiras de bambu (sem armadura de cisalhamento) foi construída e testada. A laje foi testada simplesmente apoiada nos quatro lados com carga concentrada no meio. Um modelo de elementos finitos (MEF) foi criado usando SAP2000 para analisar e projetar o reforço de bambu. A carga experimental de colapso foi aproximadamente 148,39 por cento e 110,91 por cento dos valores teoricamente previstos pelo modelo numérico e pela carga máxima de punção (seguindo BS 8110 [36]) respeitabilidade. A laje apresentou alta rigidez contra a deformação antes do colapso por punção. Finalmente, para produzir um material composto avançado usando bambu para reforço de concreto, investigações experimentais do efeito do teor de umidade à temperatura ambiente e em condições de congelamento do bambu Dendrocalamus giganteus (DG) foram realizadas. Laminas de bambu com maior fração volumétrica de fibras (Vf) foram consideradas. 2250 corpos de prova de tração e compressão foram testados. A absorção de água, propriedades mecânicas das laminas de bambu e colapsos foram analisados em detalhe, e adequadas equações matemáticas foram estabelecidas. A partir dos resultados da resistência e módulo de elasticidade à tração (TMOE) da fibra de bambu DG foram estimados. Os resultados mostraram que as laminas de Dendrocalamus giganteus (DG) com maior fração volumétrica de fibras (Vf) e baixa umidade podem ser aplicadas em materiais compósitos para a construção, campo de energia (peças estruturais das hastes de turbinas eólicas), área automotiva (estruturas de carros), e aeronáutica (aviões de pequeno porte), fornecendo um novo material alternativo de baixo consumo de carbono. / [en] In this study, based on the results of bamboo surface treatment for concrete reinforcement developed at PUC-Rio (Brazil), theoretical and experimental analyses were executed at the University of Cambridge and University of Bath (England). To improve the bamboo surface treatment (using epoxy resin) an experimental program concerning 32 push-out specimens were carried out. Bamboo strips (for reinforcing concrete) prepared from Phyllostachys Pubescens bamboo and treated to enhance surface bonding were used, with a constant embedment length of 20 mm. The influence of two resins type, gravel size (2 or 4 mm), bamboo node and procedures for cleaning the surface of the bamboo on the bond–slip curves obtained are analyzed. Using the best bamboo surface treatment a full scale (3000 mm by 3000 mm) two-way spanning concrete slab reinforced with bamboo strips (without any shear reinforcement) was constructed and tested. The experimental test was simply supported along its four sides and subjected to a central concentrated load. A finite element model was created using SAP2000 to analyse and design the bamboo reinforcement. Experimental failure load was found to be approximately 148.39 per cent and 110.91 per cent of the theoretically predicted values by the numerical model and by ultimate punching shear load (following BS 8110 [36]) respectability. The slabs exhibited high stiffness against deformation prior to collapse through punching shear load. Finally, to produce an advanced bamboo composite material for concrete reinforcement, an experimental investigation of the effect of moisture content at room temperature and frozen conditions on Bamboo Dendrocalamus giganteus (DG) layers with highest fibre volume fraction (Vf) were considered. 2250 tensile and compression test specimens were tested. The absorption of water, mechanical properties of bamboo layers and failure were analyzed in detail and appropriate mathematical equations have been established. From the results the tensile strength and tensile modulus of elasticity (TMOE) of DG bamboo fibres were estimated. The results show that Dendrocalamus giganteus (DG) bamboo layers with highest fibres volume fraction (Vf) and low moisture content can be applied in composite materials for construction, energy field (structural parts of wind turbine blades), automotive field (car structures), and aviation (small aircraft) providing a new low carbon alternative material.

No / The chapter describes the ongoing work on modeling the semi-rigid composite beam-column connections of composite beams with precast hollow core slabs. Using the finite element (FE) software ABAQUS, a three-dimensional (3D) model of a composite joint is set up. The technique of simulating bolt force, endplate, concrete elements, reinforcement, and shear connectors, and the interaction between slabs and steel beams is presented in the chapter. Preliminary results on the steel joint and simplify composite joint are also presented in the chapter. FE model for the bare steel joints and the simplified composite joints are presented, and the result of the simplified composite model showed good agreement with the experimental result but with lower joint stiffness. Further work on the full finite element model of composite joints is still going on.

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.