This thesis presents the results of research on sandwich panel construction, with the aims of developing tools for modelling sandwich panel fire performance and hence to use the tools to aid the development of sandwich panel construction with improved fire resistance. The research focuses on sandwich panels made of thin steel sheeting and a polyisocyanurate (PIR) foam core. For non-loadbearing sandwich panel construction, fire resistance is measured in terms of thermal insulation and integrity only. However, these two parameters are affected by mechanical performance of sandwich panel construction due to the high distortion and large deformation nature of sandwich panel construction under fire attack. Therefore, it is necessary to consider both thermal and mechanical performances of sandwich panels under fire conditions. The work in this thesis includes development of a thermal conductivity model for PIR foam as this thermal property is one of the key values in determining heat transfer through sandwich panels; this thermal conductivity model is based on the effective thermal conductivity of porous foams proposed by Glicksman (1994) and includes the effects of polymer decomposition and increases in foam cell size. It is validated against fire tests carried out on PIR sandwich panels 80mm and 100mm thick with steel facings of thickness 0.5mm. A large 3D sequentially coupled thermal-stress model of a full scale fire test has been developed in the commercial finite element analysis (FEA) software ABAQUS to provide insight into the way sandwich panels behave in a fire resistance test and also to assess different modelling techniques. Aspects and stages of the simulation that agree well with test data are explained. Limitations of the ABAQUS software for simulating sandwich panel fire tests are highlighted; namely, it is not possible to simulate the correct radiation heat transfer through panel joints, as cavity radiation cannot be specified in a fully coupled thermal-stress analysis. Joints are key components of sandwich panel construction. In order to obtain temperature development data for modelling joints, a number of fire tests have been carried out. These fire tests were conducted with different joint configurations and panel thicknesses under realistic fire conditions using timber cribs. The joint fire tests revealed significant ablation of the foam core within the joints of sandwich panels at high temperatures. At the beginning of fire exposure, the joint temperature on the unexposed surface was lower than that on the panel due to the better insulation property of air compared to the foam. However, as the joint gap increased due to ablation of the foam, the joint temperatures became higher than in the panel. A numerical simulation model has been created to investigate this behaviour. Using the aforementioned thermal model, numerical simulations have been carried out to examine the influences of possible changes to sandwich panel design on sandwich panel construction fire performance. It was suggested that if the maximum gap in the joints can be limited to 5mm, for example, by applying intumescent coating strips within the sandwich panel joints to counter the increasing gap formed due to core ablation, then the joint temperature on the unexposed surface would not exceed that of the panel surface, hence the joint would cease to be the weak link. To increase the panel fire resistance, the use of graphite particles in the PIR foam formulation may be considered to lower the contribution of radiative heat transfer within the foam cells by reducing the transmissivity of the cell walls. Graphite particles may offer considerable increases in the thermal resistance of PIR foam at high temperatures by limiting the radiation contribution which dominates heat transfer above 300oC.

In many tunnel designs, reinforced concrete tunnel lining design is selected based on construction requirements rather than design loads. A constant cross-section is typically used along a tunnel even if the design loads change from one location to another, especially for tunnels constructed by tunnel boring machines (TBM). Factor of safety against failure is not constant along the length of tunnel and is typically high at shallow depth regions. Factor of safety during a rare event is usually much less than the ones set for service load states. Rare events such as earthquake, train derailment, explosion and long duration fires do not happen daily and generally a minor reparable damage is targeted at the structure during those types of events. The focus of this study is to analytically investigate structural fire safety of reinforced concrete circular tunnel linings in terms of reduction in service load safety and to develop recommendations for preliminary assessment of structural fire endurance of circular tunnel linings. Analytical methods accounting for thermal non-linearity, material degradation, tunnel lining-ground interaction and fire time stages are available to assess the structural fire safety of the concrete tunnel linings. Analytical results are determined to be in good agreement with tunnel key segment hydrocarbon fire test.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-03-16T13:53:53Z No. of bitstreams: 1 Michael Anderson Bica Moreira_.pdf: 4568329 bytes, checksum: 2900c09b4d7ad560e4f7bdbd2456a86d (MD5) / Made available in DSpace on 2017-03-16T13:53:53Z (GMT). No. of bitstreams: 1 Michael Anderson Bica Moreira_.pdf: 4568329 bytes, checksum: 2900c09b4d7ad560e4f7bdbd2456a86d (MD5) Previous issue date: 2016-12-21 / itt Performance - Instituto Tecnológico em Desempenho da Construção Civil / Construrohr / A partir da vigência da norma de desempenho, parâmetros aquém dos de durabilidade vêm sendo estudados por projetistas e pesquisadores no Brasil. A segurança contra incêndio vem tendo maior preocupação entre os profissionais, apesar de ainda ser um tema desconhecido por parte do mercado. Busca-se que, em caso de sinistro, a edificação tenha meios de propiciar aos usuários a evacuação segura e rápida, a facilidade de acesso das ações de combate do corpo de bombeiros e a segurança do patrimônio. De acordo com os critérios de segurança contra incêndio, os recursos para dificultar os princípios de incêndio e a propagação, bem como o tempo requerido de resistência ao fogo (TRRF), são definidos em função das especificidades de cada sistema projetado. O concreto, por ser um material com baixa condutividade térmica, apresenta um desempenha um bom desempenho frente ao fogo, quando comparado a outros sistemas estruturais. No entanto, este compósito, quando submetido a altas temperaturas, tem as suas propriedades mecânicas alteradas. Com a tendência de industrialização da construção civil, o uso de peças pré-fabricadas de concreto vem sendo uma alternativa de uso nas construções, no entanto o seu comportamento em casos de incêndio é pouco difundido no meio técnico. Dentre os fatores de influência que podem prejudicar a resistência ao fogo destas peças estão o teor de umidade e a pressão interna. Estes fatores, combinados ou isolados, são responsáveis por manifestações patológicas oriundas das altas temperaturas, como desplacamentos, fissurações, perda de umidade, deformações, entre outros. Ainda, uma lacuna no meio técnico é a idade de cura para realização de ensaios que possam avaliar o tempo de resistência ao fogo (TRF) de elementos de concreto. Utiliza-se como parâmetro 28 dias de idade de cura, baseados nas normas norteadoras de ensaios para avaliação da resistência à compressão de corpos de prova cilíndricos. A partir deste parâmetro são realizados os ensaios de resistência ao fogo. Com baixas idades de cura, o concreto já apresenta resistência à compressão satisfatória, no entanto, o teor de umidade das peças ainda é muito alto, o que prejudica o desempenho nos ensaios de resistência ao fogo. Desta forma, projetistas optam pela alteração de projeto, aumentando o cobrimento das armaduras, fazendo adições ao concreto, etc. Assim, esta pesquisa buscou avaliar a influência do teor de umidade e da pressão interna em peças pré-fabricas de concreto, tendo como variável apenas a idade de cura das amostras, propondo um método para quantificar o teor de umidade e a pressão interna. Foram ensaiadas, em forno vertical normatizado, amostras com 7, 14, 28, 56 e 84 dias cura, submetidas à cura ambiente, logo com teores de umidades distintos. Com base nos ensaios realizados, as amostras com 84 dias de cura, as quais apontaram menores teores de umidade, apresentaram melhor desempenho frente às altas temperaturas, evidenciando a influência deste fator. / From the validity of the Brazilian performance law, parameters other than durability have been studied by designers and researchers in Brazil. Fire safety has been a major concern among professionals, although it still is not known by most of the market. In case of accidents, the building must have means of allowing the users to evacuate safe and rapidly, while providing easy access to the actions of firefighters and security of assets. According to the values of fire safety, the resources for hindering the principles of fire and propagation, as well as the fire-resistance rating (FRR), are defined with respect to the specificities of each system designed. The concrete, as a material with low thermal conductivity, presents a good performance against fire when compared to other structural systems. However, this composite, when submitted to high temperatures, has its mechanical properties altered. With the civil construction’s tendency of industrialization, the use of prefabricated concrete pieces has been seen as an alternative to use on buildings, although their behavior in fire situations is not so widespread in the technical field. Among the influence factors that can impair the fire resistance of these pieces are the moisture content and the internal pressure. These factors, combined or isolated, provoke pathological manifestations originated from high temperatures, such as spalling, cracking, loss of moisture, deformations, and others. Still, a blank in the technical field is the age of cure for performing the tests that evaluate FRR of concrete elements. The curing age of 28 days is used as a parameter, based on standards that orientate the tests for evaluating compressive strength of cylindrical specimens. The fire resistance tests are then performed from this this parameter. The concrete already presents satisfactory compressive strength at lower curing ages, however, the moisture content of the pieces is still very high, thus hindering the performance during the fire resistance tests. That way, designers choose to modify projects, increasing the covering of the armors, making additions to concrete, etc. Therefore, this research aimed to evaluate the influence of moisture content and internal pressure on prefabricated concrete pieces, considering only the samples’ curing age as a variable and proposing a method for quantifying moisture content and internal pressure. The test was performed in a standardized vertical oven, and the specimens were tested with 7, 14, 28, 56 and 84 days of curing, all cured outdoors, thus displaying different moisture contents. Based on the test results, the samples with 84 days of curing, which displayed the smallest moisture contents, presented better performance regarding high temperatures, indication the influence of this factor.

This master‘s thesis is focused on the study of the behavior of cement concrete at high temperatures with a focus on monitoring the impact of aggregate and cement type. This work describes the processes in aggregates and cement matrix at high temperatures. The theoretical part describes the selestion of a suitable aggregate and cement for the surroundings with potential exposure to high temperatures. In the experimental part is given design of composition of a concrete with two types of aggregates and four cements. It has been suggested 8 recipes. Changes were observed densities, compressive strength and tensile strength in bending, calculate the velocity of propagation of waves with ultrasonic pulsed method. Also evaluated the appearance of the surface samples after thermal load – cracks on the surface and measure the maximum crack width.

Diploma thesis summarizes knowlegde related to the behavior of structures and material in the fire, focusing mainly on concrete and reinforced concrete structures. It deals with the design and implementation of diagnostic work of Building no. 103 in complex Svit Zlín affected by a large fire. There are presented evaluation of laboratory experiments of samples and static analysis.