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Diagnostics and assessment of prefabricated reinforced concrete structures
Kocuba, Robert ; Láník, Jaromír (referee) ; Cikrle, Petr (advisor)
This thesis deals with inspection and constructionally technical research of reinforced concrete prefabricated construction from the second half of 20th century. In theoretical part, the research of literature, documents and valid standards is performed, with a focus on production and construction of prefabricated elements and also on the metodology of research. In practical part, the detection of reinforcement of individual elements of the construction and concrete properties is performed. The result of this work is the assessment of the state of the construction, static calculation of the ceiling panel and idea proposal for eventual reconstruction.
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The Modulus of Elasticity of Air-Entrained and Non-Air-Entrained Concrete
Tichý, Aleš ; Misák, Petr (referee) ; Kocáb, Dalibor (advisor)
The bachelor thesis deals with the verification of the degree of influence of the air-entraining admixture on the modulus of elasticity of concrete. The experiment was carried out for these purposes. The values of static and dynamic modulus of elasticity were determined on drilled cores from concrete blocks of different mixtures. The magnitudes of dynamic modulus of elasticity were determined by using an ultrasonic pulse velocity method and a resonance method. The results are summarized in tabular and graphical form.
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The issue of determination of the static modulus of elasticity of concrete in structures
Halamová, Romana ; Misák, Petr (referee) ; Kocáb, Dalibor (advisor)
The thesis deals with the measurement of the elastic modulus of concrete in existing structures and possibilities of applicability of equations for the calculation of characteristic values of concrete compressive strength on the modulus of elasticity. The modulus of elasticity is determined by dynamic and static methods on specimens taken from the concrete blocks, whose composition varies by a water cement ratio and varying amounts of admixtures. In conclusion, the results of the measurements are compared and the characteristic values of the modulus of elasticity is determined.
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Creating conditions for evaluation of high-strength concrete characteristics using non-destructive testing methods
Procházka, David ; Horký,, Ondřej (referee) ; Kolář,, Karel (referee) ; Adámek, Jiří (referee) ; Brožovský, Jiří (advisor)
High-strength concrete (HSC) belongs in the recent years to frequently used types of concrete. It allows realization of static challenging structures and also shows due to its dense structure greater durability especially against aggressive media. Currently HSC construction realization abroad is not exceptional. It’s using in the Czech Republic is still limited. When realized, then in a small scale in civil engineering works. The realization of high-strength concrete structures is closely related with the concrete construction quality verification. Good efficiency of the quality control methods can provide non-destructive testing methods (NDT), especially when investigating strength of concrete built in structure. A lack on relevant data for non-destructive testing of HSC in technical and normative rules is to be considered as a significant deficiency. Evident for HSC generally is the lack in literature on deeper analysis of the factors affecting their non-destructive testing, as well a meaningful methodology or practically usable calibration relationships. HSC differs from ordinary concrete not only by used components, but also by more compact structure with different strength – elastic characteristics. Considering these differences, HSC strength prediction can not be performed by using calibration relationships developed for ordinary concrete. Moreover, the question is to what extent the current knowledge of the NDT results influencing factors can be considered as valid. The paper presents findings on the effects of the key factors affecting the measurement results of Schmidt hardness method and ultrasonic pulse method, including recommendations for the practical application of these methods. The problematic of static vs. dynamic modulus of elasticity was also solved. Calibration equations for predicting the compressive strength of HSC from the non-destructive testing parameter were elaborated, showing high cohesion among variables and practically usability.
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The Issue of testing shotcrete
Škapová, Pavla ; Hela,, Vlastimil (referee) ; Hubáček, Adam (advisor)
The master‘s thesis focuses on testing the shotcrete prepared in laboratory conditions. The main observed properties are compresive strenght of shotcrete and modulus of elasticity. The aim is assessment of methods for measuring those parameters. The calibrating correlations for strenght characteristics of shotcrete are given by obtaining the results of used methods. The shotcrete composition, amount and type of accelerating additive as well as economic aspect of using shotcrete is also assessed.
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Study of the influence of feedstock composition and the values of the modulus of elasticity of concrete
Šafrata, Pavel ; Křížová, Klára (referee) ; Hela, Rudolf (advisor)
Modulus of elasticity is significantly reflected feature of concrete, besides the compressive strength in static design nowadays. Low modulus of elasticity can cause unacceptable deflections for subtle skeletal structures. It is at least irresposible to count with empirical formulas since there is a wide range of materials and additives in production of concrete. The aim of this thesis is to study the influence of large fraction aggregate on static and dynamic modulus of elasticity of concrete and recommendation for appropriate measures to produce concrete with high modulus of elasticity. The experimental part is further following up the influence of air content in concrete on the modulus of elasticity.
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Comparison of elastic moduli of building materials
Ballon, Marek ; Hubáček, Adam (referee) ; Brožovský, Jiří (advisor)
The bachelor thesis deals with the detection of static and dynamic elastic moduli of building materials, their comparison and overview of the relationships between them. Describes methods for the determination of static modulus of elasticity in the press loading and dynamic modulus of elasticity obtained by non-destructive methods, including ultrasonic pulse method and resonance method.
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Comparison of the dynamic and static elasticity modules in damaged wood
Kloiber, Michal ; Kotlínová, M.
This work deals with evaluation of wood properties, that are obtained on the base of ultrasound testing with defectoscopic Arborsonic Decay Detector. Ultrasound waves expand with speed, that depends on wood quality. From time of stress wave propagation and wood density dynamic modulus of elasticity was calculated. The same test specimens were statically loaded afterwards, and dynamic and static modulus of elasticity were compared. These characteristics of wood according to damage by biotic factors change rapidly. This work proofs possibility of non-destructive wood properties by constructive-technical research of wood constructions.
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