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Research about the influence of compressive membrane action on the loading capacity of laterally restrained prestressed concrete slabs. The thesis consists of four parts: - literature research; - comparison New Zealand code; - investigation theory's; - investigation FEM-analysis.

The report contains a research on UHCP and the theory of thin shell structures. The combination of these aspects is used for a complete structural design for a dome structure with a span of 150m. The conclusion and recommendations which where found were then applied for a preliminary design for 'Fiere Terp', a architectural design for a sports-dome in Leeuwarden.

Onderzoek en dataverzameling en -analyse m.b.t. vervormingsmetingen bij afgezonken tunnels. Onderzoek naar het gedrag en de capaciteit van de segmentvoegen/dilatatievoegen van de Kiltunnel.

New and current materials for bridge bearings are subjected to tests, according to the European Standards (NEN-EN 1337). With these tests the materials are not subjected to forces, displacements and rotations that are similar to those in practice. In order to give a critical opinion about the tests, it is necessary to obtain more knowledge about the variable load and movement history of bridge bearings of a concrete bridge, the ‘Dintelhavenbrug’. The load and movement history of bridge bearings of the ‘Dintelhavenbrug’ are analyzed by means of a finite element model. In this model the loads caused by traffic en temperature are considered. The traffic loads follow from a fatigue load model with 12 types of trucks, based on the European Standard for traffic loads (NEN-EN 1991-2) and measurements of traffic on the bridge near ‘Moerdijk’. The temperature loads follow from the European Standards (NEN-EN 1991-1-5). For both types of (static) loadings the forces, displacements, rotations and slide paths, which occurs during the lifetime of the different bridge bearings, are determined for each bearing. These results are compared with the values which are presented in the tests of NEN-EN 1337 Part 2: Sliding elements and NEN-EN 1337 Part 5: Pot bearings.

Anchor bolts are often used in concrete or steel structures. Nevertheless still empirical design procedures are used in order to determine the dimensions of the structure. Non linear fracture mechanics tries to describe fracture of heterogeneous materials like concrete. In the classical representation of concrete fracturing (figure 1.1), cohesive forces in the micro-crack-zone (ahead of the cracktip) contribute to the carrying capacity of the structure and cause softening of concrete. This concretesoftening can also be explained by discontinuous cracks that grow along aggregate particles and cause bridging of the cracks (crack-face bridging, see Van Mier (1991)). Insight in non linear fracture mechanics as well as increasing computer techniques finally gave the opportunity to investigate the behaviour of anchor bolts embedded in concrete in a proper way. The main goal of this study is to improve the knowledge about pull-out anchor bolts. Therefore several tests and numerical simulations have been performed in order to determine the maximum load, the deflection of the upper end of the anchor bolt and the load-deformation curve. In this report results of the numerical simulations of pull-out anchor bolts in a plane stress situation are presented.

Due to the collaboration between the T.U. Delft and the Stufib (Studievereniging fib Nederland), I had the opportunity to realize an interesting, practical and current research. The Stufib is an association of people, working in the building industry, who want to promote the development of structural concrete, theoretically and practically. Study-cell 11 has done research on cracking of structural in situ toppings on prefabricated, prestressed hollow core slabs. The report is available via the Stufib, (www.stufib.nl). Prefabricated, prestressed hollow core slabs, are concrete floor slabs with longitudinal holes with spans up to 18 meters. Because of the holes, hollow core slabs save up to 30% in material and weight. The hollow core slabs will shorten and bent because of the prestressed tendons, which are positioned low in the cross-section. Creep effects will continue the deformation. Dispersal in temperature, relative humidity, wind, concrete composition and the age of the concrete influence the creep behaviour.

Ondergronds bouwen is in opkomst en zal in de toekomst steeds vaker worden toegepast in Nederland. Voor het uitvoeren van ondergrondse constructies moet met behulp van een damwandconstructie een bouwput worden gemaakt om de ontgraving stabiel te houden. De meest gebruikelijke manier in Nederland om een damwandconstructie te ondersteunen is, naast het gebruik van ankers, de toepassing van een tijdelijk stalen stempelraam. Een andere interessante wijze om de damwand te steunen is om een deel van de uiteindelijke vloerconstructie tijdens de bouw te gebruiken in een stempelraam. Een dergelijk permanent betonnen stempelraam is enkele malen toegepast in de Nederlandse bouwpraktijk met behulp van in-stu beton, zoals bij de uitvoering van Rotterdam Plaza. Omdat de vloerconstructie van ondergrondse constructies steeds vaker wordt opgebouwd uit geprefabriceerde elementen, is de vraag ontstaan of het ook mogelijk is om prefab vloersystemen op een dergelijke manier te gebruiken.

In hel afstudeeronderzoek "Geprefabriceerde betonnen stabiliteitsconstructies met open verticale voegen in metselwerkverband" is onderzocht wat het effect is van open verticale voegen in metselwerkverband op het gedrag van geprefabriceerde betonnen stabiliteitsconstructies. Hierbij is een viertal constructietypen beschouwd. Het onderzoek spitst zich loe op vlakke stabiliteitsconstructies meI een breedte van 14,4 m en een hoogte van 86,4 en dus een slankheid van 6:1. Hiermee mogen de constructies tot de hoogbouwconstructies worden gerekend. De vier beschouwde constructietypen variëren van een volledig gesloten stabiliteitswand tot een dragende gevel met gevelopeningen. Zo is met een aantal veelgebruikte constructietypen ook een brede range aan stijfheden van constructies beschouwd. Het gedrag van de constructies met open verticale voegen is vergeleken met dat van constructies met traditioneel uitgevoerde verticale voegen, waarbij de verticale voegen in dat geval doorlopend zijn uitgevoerd. Van deze traditionele voegtypen zijn de gladde gewapende voeg, de getande gewapende voeg en twee voegtypen waarin gelaste verbindingen worden toegepast in het onderzoek opgenomen. Eveneens is van alle constructies een monoliete variant beschouwd.

Usually, concrete bridges contain a ‘thick’ bridge deck. For various reasons, bridges are constructed with railings. This thesis discusses the stability problem of concrete bridges, which are designed with integrated railings into the carrying construction. The most important advantage, using load bearing railings, is a thinner bridge deck. This was also one of the requests of Public Works Rotterdam. The load bearing railings have to endure buckling. This phenomena is not very common in massive concrete bridges. Since the request for to alternative bridges with a thinner bridge deck, like this one, is becoming larger and larger, there is need for a simple rule of thumb. This indication is necessary for estimating the dimensions of this kind of bridge without a complicated calculation. For this thesis, the stability of a concrete pedestrian bridge with load bearing railings, has been checked in three ways. There has been focussed at the compression zone of the bridge, the handrails. 1. First the buckling force is calculated. Using the buckling force and the actual normal force in the handrails, it is possible to calculate the second order effects. 2. The total resisting moment in the handrails must be large enough to withstand the external first and second order moments. The resisting moment is based on uncracked concrete, therefore no tension stresses in the handrails are aloud. 3. If stability isn’t the problem, strength is. Hence the external normal force in the handrails most be lower than the normal force resisted. The problem has been analysed. The three checking’s are visualized in graphs over various dimensions. These graphs were used as a starting point of a parameter study to get a rule of thumb, which can be used for concrete pedestrian bridges with load bearing railings. There is also concluded that bridges with load bearing railings are more sensitive to local forces (on bridge deck and railings), than plate bridges are. The rule of thumb is applicable for bridges larger than 14 meter and smaller than 23 meter, depending on the applied concrete strength. Using this indications gives a correct estimation of the dimensions of a concrete pedestrian bridge with load bearing railings.

In skew bridges torsion occurs. This leads to a substantial amount of reinforcement stirrups. Minalu already did research to torsion in bridge decks with different types of finite element models. The question when torsion cracks will really occur is still unanswered. This question is the main subject of this research. The focus of the research is on a skew bridge with a skew angle of 45 degrees. In that bridge the largest torsional moments will occur. Beside that also a straight bridge is analysed, the torsional moments in a straight bridge are always lower than in a skew one under the same loading. The loads of Eurocode 1991-2 are used. Two important load configurations governing for torsional moments and shear force are used: a configuration which is used in daily practice at Spanbeton and a configuration developed by Minalu. An attempt is made to model the whole bridge including physically non-linear behaviour with the program ATENA 3D to analyse the torsion effects. With the current state-of-the-art modelling technology that appeared to be impossible. For that reason a simplified model is developed to simulate the stress state and cracking in one ZIP girder. It was concluded that it is important to use more quadratic elements over the thickness of the web to obtain correct torsion shear stresses. From the simplified model it is concluded that, despite some shortcomings, clearly a substantial length at the ends of the girder is uncracked. To be sure that the computer model is correct a calculation of the principal stresses is carried out at the ultimate limit state. The stresses due to prestressing, own weight and the weight of the fresh poured concrete can be calculated by hand. The calculation of the force distribution of the loads on the deck can be carried out using finite element methods. Scia Engineer (orthotropic plate model) and ATENA 3D (volume elements) are used for this calculation. Especially the determination of the torsional moments from ATENA by using an analysis of the rotations is interesting. This calculation results in the torsional moments, bending moments en shear forces acting on the ends of the girder. The main conclusion of this research is that in ultimate limit state no cracking will occur in the end of the considered girder in the skew bridge. This means that only the minimal shear reinforcement must be applied and the full torsional stiffness can be used in finite element calculations. A practical method to check this for other bridges using ZIP-girders is proposed.

Problem definition The city The Hague is loosing important cultural events to other cities. This is because the current available congress centre is not good enough anymore. Introduction The architects from room for architecture made an architectural design of an underground congress centre. In this centre, different facilities are placed, like auditoria, meeting rooms and a transferium. The idea is that after completion of the underground congress centre the events that normally take place on the Malieveld must continue. Due to this, the structure is exposed to special loads from on-ground activities like concerts, circus and demonstrations. Also the activities that are related to these events, like the build-up, have to be taken into account. The architects designed an auditorium that has to accommodate 2,750 people. The dimensions of the auditorium are at least 68,2 meters squared and the internal height is 20 meters. This in combination with the special loads on the structure gives a complicated design assignment. Research Preliminary calculations showed that the design could not be made without violating the limitations. The load bearing structure that is needed, violate with the maximum available construction depth. In the assignment the maximal available height of the load bearing structure is four metres. After this conclusion other concepts for the load bearing structure were offered. These concepts do not fit all the limitations. Each of the concepts has one limitation that is not sufficed. An analysis of these concepts showed that shortening of the span was the best way to decrease the structure height. There are several ways to decrease the span with all different characteristics. The best alternative seemed to be an arch structure. This is not quite a common solution but for this special case it seems to be the best. Result The dimensions of the arch are quite big in order to reach a stable system. The width is 1,100 millimetres and the height is 800 millimetres. The arch spans the total length of 68,2 metres and the centre-to-centre distance between the arches is eight metres. A roof structure is needed to make the Malieveld flat again. Double T slabs are used for this purpose. The T slabs are supported by beams, which in turn are supported by diagonals. The arch carries the diagonals. The beam has a rectangular cross-section with a height of 1,000 millimetres and a width of 500 millimetres. The diagonals are circular with a diameter of 500 millimetres. The whole structure is designed in concrete C90/105. The choice to design in concrete is because of the good fire-resistance it provides

Net als in de meeste grote steden wordt ook in de Amsterdamse Molenwijk parkeren als één van de grootste problemen en ergernissen ervaren. De bewoners willen in een autoluwe omgeving wonen en toch in de nabijheid van de woning kunnen parkeren. Om voor deze problemen een oplossing aan te dragen is er een plan ontwikkeld om het ontoereikende aantal bestaande parkeergarages te vervangen door grotere nieuw te bouwen parkeergarages, met woon- en kantoorruimten. Naast de woningen en kantoren zullen er ook een aantal andere faciliteiten in de te bouwen parkeergarage worden ondergebracht. Dit om het gebouw meer te laten zijn dan alleen een parkeergarage, om de wijk weer aantrekkelijk te maken voor de huidige bewoners en nieuwe bewoners aan te trekken. De architect heeft hiervoor, in overleg met de opdrachtgever, een uitdagend gebouw ontworpen. De footprint van het gebouw zal op straatniveau slechts bestaan uit een drietal kernen, zodat er een gevoel van openheid zal ontstaan. Het gevolg hiervan is dat de bovenbouw zal uitkragen ten opzichte van deze kernen. De vraag die rijst is dan ook of dit voorstel voor het ontwerp zowel constructief als uitvoeringstechnisch als voldoende haalbaar kan worden geacht. In dit onderzoek is in eerste instantie een literatuurstudie verricht naar het materiaal hogesterktebeton. Dit om te onderzoeken of dit materiaal een oplossing zou kunnen bieden voor het uitdagende ontwerp. Het materiaal heeft diverse voordelen ten opzichte van een “gewone” betonsoort. De voornaamste reden waarom dit materiaal goed bruikbaar zou kunnen zijn binnen dit ontwerp, is dat deze betonsoort een hoge druksterkte heeft. Met dit materiaal zal slanker en lichter geconstrueerd kunnen worden.

One of the most basic types of breakwaters is the rubble mound breakwater which in essence is a heap of stones consisting of a core of fine material covered by an armour layer of big rock or concrete elements. Mostly unreinforced, these concrete elements exist in different sizes and geometries varying from massive concrete cubes to more complicated shapes like Dolos, Tetrapode, Accropode or Xbloc. The reaction of cement with water is exothermic and an unequal heating up and cooling down of the massive units can lead to too high tensile stresses which lead to cracking in case the actual tensile strength of the concrete is exceeded. Therefore, in this thesis, the main focus is on the production and hardening process of the units. What internal mechanisms during the hardening stage might lead to cracking and/or breakage of these colossal concrete armour units? For six different concrete mixes, the thermal and strength properties were experimentally determined and analyzed. The found results were used as input for a numerical hardening model. The model permits to give an estimation of the expected temperature rise, the eigenstress development as well as an indication of the possible cracking trajectories. Using the probabilistic approach of Van Breugel, an assessment on the risk of failure could be done at material level. A further analysis using the Mohr-Coulomb criterion gave also the possibility to evaluate possible breakage patterns at element level. For a reference mix, a parametrical study was done regarding the influence of specific hardening circumstances like type of formwork, moment of removal or the type of mix used. In a last step, the implemented hardening model has been used to analyze a specific case-study in the Netherlands where concrete armour units are severely damaged. The conducted research put in evidence the importance of maintaining the eigenstresses at low values in order to reduce considerably the risk on cracking. The different parametrical studies showed that different factors play a prominent role in getting a higher or lower risk of cracking, namely: the choice of a specific type of formwork, the demoulding stage, the sizes of the elements and the casting and environmental temperatures. Moreover, the implementation of the model to other concrete mixes, revealed the importance of the mix choice on the temperature and stress development. In case for instance fillers or binders are used to replace partly the needed amount of cement, it is important to make a thorough study on their quality and reactivity. It can be concluded the elaborated hardening model gives a good indication of expected temperature rise, stresses and cracking patterns and that the adopted calculation methods give a good indication of weak and critical points in the elements and possible cracking and breakage patterns and mechanisms. The results show high probabilities on crack occurrence and crack patterns that agree very well with the block damages observed at the practical case in the Netherlands. Further investigations regarding the influence of the shape, an analysis on micro scale of weak points in the structure and the effect of the quality of binders are recommended to get a broader scope and to extend the hardening model which was set-up. Moreover, it is of crucial importance designers integrate all together the aspects from concrete technology and hydraulic/ coastal engineering point of views to come up with a final design for concrete armour units of breakwaters.

The stability of armour units is described by several formulae like Iribarren´s, Hudson´s and Van der Meer´s. In these formulae the required weight of the armour elements depends strongly on the density of the used material. Therefore it may be useful to change this density. According to the stability formulae, higher density will result in lighter and smaller units. Smaller units may reduce the costs. Literature study: In all formulae the stability of armour elements is expressed by the dimensionless stability number Hs/Δ D. This stability number is a function of several parameters like unit shape, placing method, slope angle etc. In this function Δ or ρ are not present but there is a linear relation between Hs/D and Δ. Stability formulae for breakwater armour elements are based on model experiments with elements with densities up to approximately 3200 kg/m³. In the past several improvements on stability formulae and breakwater design were made. Several different shapes of armour units were developed and wave spectra were introduced in flume testing. By these improvements the stability formulae are refined and validated. Now it is possible to make concrete with a density up to 4000 kg/m³. According to the stability formulae this will result in very small and light armour units. But the stability formulae are until now not validated for densities up to 4000 kg/m³. It is not known whether the linear relation between Hs/D and Δ is still valid for these densities or not. In order to investigate the validity of stability formulae and the linear relation between Hs/D and Δ for high densities, experiments are recommended. Flume tests: During October 1999 flume tests on concrete elements with a density up to 4000 kg/m³ were performed in the Scheldt Basin of WL | Delft Hydraulics, location "de Voorst", The Netherlands. In order to investigate whether these high-density elements behave as expected and to compare the test results also tests with normal density (approximately 2300 kg/m³) were performed. The elements were attacked by irregular waves. Elements were placed by hand as well as dumped on the slope. It is concluded that the high density and normal density concrete elements do behave in a different way during placing of the elements. High-density concrete elements tend to lay more random on a slope. In order to compare test results in a correct way a new criterion, called "laying-roughness" is developed. Conclusions The following main conclusions are drawn: * The high-density concrete elements do behave as expected based on stability formulae. * The linear relation between Hs/D and Δ in the stability formulae for armour elements is still valid for densities up to 4000 kg/m³.

In some large cities, the infrastructure is elevated high above the ground. An elevated metro system has the advantage that its construction is cheaper compared to an underground metro system. The construction time is relative limited and the physical barrier is small. The large elevation has a positive influence on the visual hindrance of an elevated metro system as it creates a more open and lighter space below the structure. In the future, Rotterdam wants to extent its existing metro system. An elevated metro system high above the city is one of the possible concepts. The engineering office of Rotterdam Public Works is interested in this concept and moreover in whether there can be gained profit on the elevated metro structure by applying Ultra High Performance Concrete (UHPC) or Fibre Reinforced Polymer (FRP) instead of conventional concrete. The objective is to determine the dimensions and normative structural verifications of the elevated metro structure when this is made of conventional concrete, UHPC or FRP and to compare these designs with each other. For the designs of the elevated metro structure made of conventional concrete, UHPC or FRP the focus is on the lightest railway girder and not on the minimum depth of the girder. The suitable elevation and span of the elevated metro structure are respectively 15 and 45 metres. The best concept for the concrete and UHPC railway girder is the precast segmental box girder with external prestressing tendons. The optimal concrete box girder has 6 prestressing tendons and a dead load of 102.02 kN/m. This optimal design is found by means of an optimisation process where the behaviour of the box girder is examined by changing several parameters. The normative structural verification of the optimal concrete box girder is fatigue of the concrete. By closer examination, it turns out that fatigue of the concrete is not normative when studied in more detail. As a consequence the verification of the ultimate resistance moment at t=0 is normative. The optimal UHPC box girder has also 6 prestressing tendons and a dead load of 69.4 kN/m. The normative structural verification of the optimal UHPC box girder is the ultimate resistance moment of the box girder at t=0. The design of the railway girder made of FRP is a sandwich girder and is based on a bridge concept. The normative structural verifications of the FRP sandwich girder are deflection of the girder and buckling of the core triangles. The dead load of the FRP sandwich girder is 34.48 kN/m. The difference in dead load between the three designed railway girders is quite large. The application of a lighter railway girder does however not result in a large reduction of the number of piles. This is due to the small weight contribution of the railway girder to the total vertical load at the piles and the large contribution of the bending moments at the foundation to the pile forces. The normative structural verification of the columns is stiffness of the viaduct. Applying UHPC or FRP instead of conventional concrete for the railway girder thus has a small impact on the substructure. The direct construction costs for the elevated metro structure with a concrete box girder are about €450,000 per span of 45 metres. When the unit price of UHPC is lower than € 450/m3, the UHPC box girder becomes a serious competitor of the conventional concrete box girder from a financial point of view. For the FRP railway girder holds that FRP is currently far too expensive to compete with the (UHP) concrete box girder.