Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Plastic shrinkage cracking (PSC) is the cracking caused by the early age shrinkage of concrete within the first few hours after the concrete has been cast. It results in unsightly surface cracks that serve as pathways whereby corroding agents can penetrate the concrete which shortens the expected service life of a structure. PSC is primarily a problem at large exposed concrete surfaces for example bridge decks and slabs placed in environmental conditions with high evaporation rates. Most precautionary measures for PSC are externally applied and aimed to reduce the water loss through evaporation. The addition of a low dosage of polymeric fibres to conventional concrete is an internal preventative measure which has been shown to reduce PSC. The mechanisms involved with PSC in conventional and low volume fibre reinforced concrete (LV-FRC) are however not clearly understood. This lack of knowledge and guidance leads to neglect and ineffective use of preventative measures. The objective of this study is to provide the fundamental understanding of the phenomena of PSC. To achieve the objective, an in depth background study and experiments were conducted on fresh conventional concrete and LV-FRC. The three essential mechanisms required for PSC are: 1→ Capillary pressure build-up between the particles of the concrete is the source of shrinkage. 2→ Air entry into a concrete initiates cracking. 3→ Restraint of the concrete is required for crack forming. The experiments showed the following significant findings for conventional and LV-FRC: PSC is only possible once all the bleeding water at the surface has evaporated and once air entry has occurred. The critical period where the majority of the PSC occurs is between the initial and final set of concrete. Any preventative measure for PSC is most effective during this period. The bleeding characteristics of a mix have a significant influence on PSC. Adding a low volume of polymeric fibres to concrete reduces PSC due to the added resistance that fibres give to crack widening, which increases significantly from the start of the critical period. The fundamental knowledge gained from this study can be utilized to develop a practical model for the design and prevention of PSC in conventional concrete and LV-FRC. / AFRIKAANSE OPSOMMING: Plastiese krimp krake (PSK) is die krake wat gevorm word a.g.v. die vroeë krimping van beton binne die eerste paar ure nadat die beton gegiet is. Dit veroorsaak onooglike oppervlak krake wat dien as kanale waardeur korrosie agente die beton kan binnedring om so die dienstydperk van die struktuur te verkort. Dit is hoofsaaklik ʼn probleem by groot blootgestelde beton oppervlaktes soos brug dekke en blaaie wat gegiet is in klimaat kondisies met hoë verdamping tempo’s. Meeste voorsorgmaatreëls vir PSK word ekstern aangewend en beperk die water verlies as gevolg van verdamping. Die byvoeging van ʼn lae volume polimeriese vesels is ʼn interne voorsorgmaatreël wat bekend is om PSK te verminder. Die meganismes betrokke ten opsigte van PSK in gewone beton en lae volume vesel versterkte beton (LV-VVB) is vaag. Die vaagheid en tekort aan riglyne lei tot nalatigheid en oneffektiewe aanwending van voorsorgmaatreëls. Die doel van die studie is om die fundamentele kennis oor die fenomeen van PSK te gee. Om die doel te bereik is ʼn indiepte agtergrond studie en eksperimente uitgevoer op gewone beton en LV-VVB. Die drie meganismes benodig vir PSK is: 1→ Kapillêre druk tussen die deeltjies van die beton is die hoof bron van krimping. 2→ Lugindringing in die beton wat krake inisieer. 3→ Inklemming van die beton is noodsaaklik vir kraakvorming. Die eksperimente het die volgende noemenswaardige bevindinge opgelewer: PSK is slegs moontlik indien al die bloeiwater van die beton oppervlakte verdamp het en indien lug die beton ingedring het. Die kritiese periode waar die meerderheid van die PSK plaasvind is tussen die aanvanklike en finale set van die beton. Enige voorsorgmaatreël vir PSK is mees effektief gedurende die periode. Die bloei eienskappe van ʼn meng het ʼn noemenswaardige effek op die PSK. Die byvoeging van ʼn lae volume polimeriese vesels tot beton verminder die PSK deur die addisionele weerstand wat die vesels bied teen die toename in kraakwydte. Die weerstand vergroot noemenswaardig vanaf die begin van die kritiese periode. Die fundamentele kennis wat in die studie opgedoen is, kan gebruik word vir die ontwikkeling van ʼn praktiese model vir die ontwerp en verhoed van PSK in gewone beton en LV-VVB.

This thesis deals with building survey and diagnostics of residential house in Brno, which since its construction showed extensive faults. The theoretical presents to the general issue of building technical surveys, diagnostics reinforced concrete structures and describes methods for diagnosis of reinforced concrete structures. Practical part deals with building survey and diagnostics of the object including static assessment. Overall assessment is given in the conclusion.

The topic of this thesis is a project documentation of a Nursery School located in Trencin part Juh. The object had been designed as a stand-alone three storey building. The topic of this thesis is a project documentation of a nursery school located in Trencin quarter - Juh. The object has been designed as a stand-alone three storey building with two above- and one under-ground floors. Nursery school consists of two separate classrooms for kids, part for operations and employees, two creative areas, basement with storage space and garden. Only basic food is going to be prepared directly in the building, main courses will be brought by external provider and warmed up. A combined wall construction system made of Porotherm 30 Profi bricks and one reinforced concrete pillar have been used. In the basement the walls are constructed using permanent shuttering filled with concrete. Ceilings are of reinforced concrete. The object is founded on foundation stripes. The roof is then designed as one-shell flat with standard order of all layers. Above the 2nd floor the roof is projected as walk able , in the eastern part above the 1st floor as walk able with concrete paving on the rectification pads and above western part of the 1st floor it is designed as green vegetation roof. The access road to the object leads to the northern side of the building. In the eastern part of the estate an independent parking lot for parents is located, in the western part then one for employees and supplying. The southern part of the object is occupied by garden with projected area for playing and stay of the kids outside.

Pour les panneaux de grande hauteur soumis à un fort gradient thermique associé à l’incendie, ils subissent des déplacements hors plan importants qui, du fait de l’excentrement du poids propre qui en résulte, vont engendrer des efforts de flexion venant s’ajouter aux efforts de compression déjà existants. Un tel changement de géométrie, d’autant plus prononcé que le panneau est de grande hauteur, combiné à une dégradation simultanée des propriétés de résistance des matériaux sous l’effet de l’élévation de température, peut conduire à un effondrement de la structure sous poids propre. L’évaluation de la résistance au feu d’éléments de structures de grandes dimensions, repose sur la théorie du calcul à la rupture, appliquée d’une part à la détermination d’un diagramme d’interaction au feu caractérisant la résistance du panneau en chacune de ses sections, d’autre part à l’analyse de la ruine globale du panneau dans sa configuration déformée. Le programme comporte deux volets complémentaires. Le premier volet concerne l’approche expérimentale. Un mur de 9 mètre a été testé sur le grand équipement Vulcain afin de valider le modèle de calcul d’une part, qui est en cours du développement, et à identifier des phénomènes locaux éventuels non accessibles par la modélisation d’autre part. Le deuxième volet concerne le développement d’outils de modélisation et de calcul performants. Basées sur une approche cinématique, des procédures itératives qui se reposent sur la méthode de perturbation ont été construit pour chercher une solution analytique pour prédire la configuration déformée d’une plaque soumis à un fort gradient thermique. Ensuite, des méthodes numériques fondées sur la discrétisation en éléments finis du panneau déformé, traité comme une coque à faible courbure, et l’utilisation de techniques d’optimisation non-linéaires, qui ont connu récemment des progrès importants, devront pouvoir être développées et appliquées à ce problème / High rise reinforced concrete walls under fire exhibit important out-of-plane displacements, which in turn lead to an eccentricity of the self-weight with respect to the initial undeformed configuration, resulting in supplementary bending moments. This geometrical change, combined with the degradation of the stiffness and strength properties of reinforced concrete due to severe temperature increase, may lead to the failure of walls under fire.Investigation on fire resistance of reinforced concrete walls will be based on the yield design approach in order to analyze the global stability of high rise walls, taking into account the geometry changes induced by the thermal loading.The program consists of two parts.Firstly, a 9-meter high reinforced concrete wall has already been tested under fire with the equipment Vulcan. This full size experiment aims at validating the modeling of plates under large out-of-plan displacement and identifying potential local phenomenon which has not been considered in the model.Secondly, a yield design approach will carried out to analyze the stability of reinforced concrete walls. By using the perturbation method, a recursive analytical procedure based on a kinematic approach is proposed to find the deformed configuration of reinforced concrete walls under fire. The deformed configuration will be later modeled as a shallow shell, on which a yield design procedure will be performed by a non-linear optimization

The topic of this thesis is a project documentation of a Retirement home located in Prague in Novodvorská street. The building is designed as a stand-alone building with five floors of a rectangular ground plan with a receding fifth storey. The retirement home is divided into a public section - a pharmacy and a part for clients - accommodation, leisure time including facilities - a restaurant with a kitchen, a laundry room. The construction system is designed as a reinforced concrete monolitic skeleton with rectanguplar columns and the filling structures are made of ceramic blocks. The building is based on reinforced concrete footings. A waterproof concrete is proposed for the lift shaft, and the foundation sills are designed for the perimeter masonry. Roofing of the 4th and 5th floor is a warm flat roof. In the 4th floor roofing section, the roof is made as a concrete tiles paving. The main entrance to the building is from southwest and the access to the building is from the northwest side where there is a parking lot for employees and clients.

The topic of this thesis is a project documentation of a Retirement home located in Trencin part Staré zlatovce. The object had been designed as a stand-alone four storey building. The floor plan is in the shape of an "F". The Retirement home has a public part, designed for people from nearby area: There is a chapel, a Physician and flats for rent, restaurants and free-time activities. The food prepared in the objects is fairly simple. The main lunch courses are being delivered from a different provider and are only re-heated in the kitchen. A reinforced concrete monolitic skeleton has been used as a contrtuction system for the bulding with square-pillars and infill material is designed from massive wooden construction Novatop solid. The object itself is standing on reinforced concrete footings. The elevator shaft bottom will be made of water ressistant concrete. The building envelope threshold will consist of reinforced concrete as well. One part of the object, above the 3rd floor, is green-roofed, and the roofing above the 4th floor is warm flat roof. The same is designed above the 1st floor chapel - a warm flat roof with rectification pedestals and concrete paving so that the roof can be used as a terrace. Photovoltaic and phototermic collectors are placed on the roofing above the 4th floor. The driveway of the whole object is placed on the western side, just as a parkplace for employees. The parkplace for tennants and visitors is placed on the eastern side.