Baigiamajame magistro darbe atliekama plieninių neskėtrių arkinių tiltų pastovumo plokštumoje analizė. Pirmajame skyriuje apžvelgiami pavienių gniuždomųjų strypų, arkų ir arkinių tiltų pastovumo tikrinimo metodai, pateikiamos projektavimo normos ir jų taikymo sritys. Antrajame skyriuje pateikiamas analiziniais ir skaitiniais metodais apskaičiuotų pavienių strypų ir arkų pastovumo parametrų palyginimas. Konstrukcijų pastovumo analizei atlikti naudojamas programinis paketas „Sofistik“. Skaičiuojant pastovumo parametrus vertinama arkos geometrinė apybrėža, apkrovimo pobūdis, lenkiamasis standis, aukščio ir tarpatramio santykis. Nustatomi racionalūs arkos geometriniai parametrai. Trečiajame skyriuje nagrinėjami dvimačiai neskėtrių arkinių tiltų modeliai. Vertinama tinklelio pakabų skaičiaus ir išdėstymo įtaka pastovumui. Palyginami neskėtrių arkinių tiltų stabilumo analizės rezultatai. Pateikiamos išvados ir rekomendacijos. Darbą sudaro: įvadas, trys skyriai, bendrosios išvados ir rekomendacijos, literatūros sąrašas, priedai. Darbo apimtis – 96 puslapiai, 66 paveikslai, 26 lentelės, 32 bibliografiniai šaltiniai. / The master thesis is carried out for in plane stability analysis of tied steel arch bridges. In first chapter overview of the individual compression bars, arches and arch bridges stability testing methods is presented. The first chapter also provides design standards and their application areas. The whole structural stability analysis was performed using “Sofistik” finite element software. Using software two dimensional models of arches and arch bridges were made. Second chapter concludes comparison of analytical and numerical stability analysis of single arches. Stability parameter and effective length factor was calculated according to arch geometric outlines, load type, bending stiffness, height and span ratio. The third chapter consists of stability analysis of two dimensional arch bridge models. Different suspension cable grids were used in order to compare and evaluate stability analysis results. Comparison of stability factors of various versions of arch bridges was made. Conclusions and recommendations are presented in the final chapter. The work contains: introduction, three chapters, conclusions and recommendations, references and appendices. The whole work consists of – 96 pages, 66 figures, 26 tables, 32 references.

This study aims to comprehend the bistable and multi-stable behaviour of flexible straws with the intention of utilising it for future engineering applications. This behaviour is achieved by the multiple inversions of conical frustum shells within the corrugation of a flexible straw. This study examined the effects of various material models, geometry variables and loading methods on the inversion of close-top and open-top conical frustum shells via experiments and FEM simulations. This thesis consists of three main parts, and the second and the third parts are complementary to each other: First, we investigated the effects of applying a uniform vertical load to the upper rim of open-top frustum shells via FEM simulations. A reference model was simulated based on the measurements of an ordinary polypropylene flexible straw specimen, using two material models - linear elastic and elastically perfectly plastic. The effects of the interactions between frusta of the corrugated segment of a flexible straw were also studied by evaluating the difference in responses between an individual frustum and conjugated models of two or three frusta. It was found that by constraining the rotation of its bottom rim, an individual frustum can fairly reproduce the complex bistable behaviour of the shorter frustum within the corrugated part of a flexible straw. Furthermore, detailed parametric studies that focused on the effects of various geometric parameters were conducted and generalised formulas that predicted the critical force were derived. A comparison between the simulated results and the analytical model in predicting progressive inversion was made to distinguish the geometric boundaries that separate the one-off snap-through to the progressive inversion of frustum shells. Next, the behaviour of close-top frustum shells in response to vertical point loading at various locations on the top surface was evaluated. A hyperelastic material was used to fabricate the physical specimens. During the experiments, the corresponding deformed shapes were recorded by 3D scanning in addition to measurements of the displacement and reaction force. We observed a close resemblance between the experimental and FEM simulated results, which validated the FEM models. Two local peaks were observed before the structure was fully inverted into its secondary stable state and the overall critical force of the structure was defined by the higher one of the two. The relationship between their magnitudes and the loading locations was analysed and an optimal loading location which gave the minimum critical force was proposed and verified by additional simulations. Furthermore, generalised formulas in predicting critical force were also acquired based on parametric studies. The optimal loading location was found to be constant in spite of variations in height and thickness. The third part of this thesis discussed the effects of lateral point loading on both close-top and open-top frustum shells at various locations on the side surface and supplemented the second part. It is found that the removal of the top surface could cause the critical force to decrease if a point load was applied laterally. Moreover, we were able to fully invert the structure with a lower critical force through lateral loading in comparison to vertical loading.

Orientador: Claudio Alexandre Gobatto / Banca: Sérgio Cunha / Banca: Eduardo Kokubun / Banca: Sebastião Gobbi / Banca: Sérgio Eduardo de Andrade Perez / Resumo: O modelo de avaliação da potência crítica - Pcrit (Monod e Scherrer, 1965) é uma construção teórica, derivada da aplicação de uma série de testes, com cargas constantes até exaustão ou tempos limites (tlim). Muitos estudos têm examinado a aplicação e limitações metodológicas decorrentes da Pcrit em diferentes modalidades de exercícios cíclicos, mas poucos têm analisado as suas respostas aplicadas ao modelo de exercício resistido com peso (ERP). O objetivo geral deste estudo foi verificar a validade do modelo da Pcrit, como método de determinação da máxima fase estável de lactato (MFEL), aplicado ao ERP, no supino reto (SR) e verificar associações entre a capacidade de impulso anaeróbio (CIA), com a carga máxima (Cmax), média (Cmed) e índice de fadiga (IF) obtidos em testes anaeróbios de Wingate adaptado (WgtAd) no SR. Participaram da pesquisa 15 homens, fisicamente ativos em ERP, habituados com exercícios de intensidades elevadas [média (±) dp, idade de 21,33 ± 2,85 anos; massa corporal total de 78,48 ± 13,53 kg; estatura de 178,21 ± 7,44 cm e IMC de 24,63 ± 3,42 kg/m2]. Foram aplicados teste e re-teste de 1-RM, para determinação da carga máxima dinâmica em diferentes pegadas (padrão - PGP, aberta - PGA e fechada - PGF). Determinouse em PGP as cargas relativas a 30%, 40%, 50% e 60% para verificação dos tlim, os quais foram ajustados com procedimentos de regressão linear e não linear, determinando a força crítica (Fcrit) e a capacidade de impulso anaeróbio (CIA). Para a validade do parâmetro aeróbio, foi aplicado o teste de MFEL, levando em consideração três cargas de Fcrit (90%, 100% e 110%), e para o parâmetro anaeróbio, o teste de WgtAd com cargas diferenciadas da massa corporal total (MCT). A creatina quinase (CK), como marcador de lesão muscular, e a frequência cardíaca (FC), com variável hemodinâmica, foram analisadas para... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The evaluation model of Critical Power - PCrit (Monod and Scherrer, 1965) is a theoretical construct, derived from the application of a series of tests with constant load until exhaustion or timeouts (tlim). Many studies have examined the application and methodological limitations arising PCrit into different types of cyclic exercise, but few have analyzed their responses applied to the model of Resistance Exercise with Weight (ERP). The aim of this study was to verify the validity of the model PCrit as a method of determining the Maximum Lactate Steady State (MLSS), applied to the ERP, the Bench Press (BP) and examine associations between the Anaerobic Capacity Boost (CIA) with the maximum load (Cmax), average (Cav) and Fatigue Index (FI) obtained in the Wingate anaerobic test adapted (WgtAd) in SR. Fifteen men participated in this study, physically active in the ERP, used to high exercise intensities [mean (±) SD, age 21.33 ± 2.85 years, total body mass of 78.48 ± 13.53 kg, height of 178.21 ± 7.44 cm and BMI 24.63 ± 3.42 kg/m2]. Were applied to test and re-test 1-RM to determine the maximum load dynamics in different footprints (default - PGP, open - PGA and closed - PGF). PGP was determined in the charges relating to 30%, 40%, 50% and 60% for verification of tlim, which were adjusted by regression procedures for linear and nonlinear, determining the Critical Force (Fcrit) and Anaerobic Capacity Boost (CIA). For the validity of the parameter aerobic test was applied to the MLSS, taking into consideration three loads Fcrit (90%, 100% and 110%), and for parameter anaerobic test WgtAd with different loads of Total Body Mass (MCT). Creatine Kinase (CK) as marker of muscle damage, and Heart Rate (HR), with a variable hemodynamics, were analyzed to determine the sensitivity regarding the volume and intensity imposed during and after the tests. It was concluded that the mathematical model... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2014-06-11T19:30:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-09-03Bitstream added on 2014-06-13T20:40:43Z : No. of bitstreams: 1 meireles_cls_dr_rcla.pdf: 1546933 bytes, checksum: 54fdb56bc59cedfe2e921a5e0219b2a2 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O modelo de avaliação da potência crítica – Pcrit (Monod e Scherrer, 1965) é uma construção teórica, derivada da aplicação de uma série de testes, com cargas constantes até exaustão ou tempos limites (tlim). Muitos estudos têm examinado a aplicação e limitações metodológicas decorrentes da Pcrit em diferentes modalidades de exercícios cíclicos, mas poucos têm analisado as suas respostas aplicadas ao modelo de exercício resistido com peso (ERP). O objetivo geral deste estudo foi verificar a validade do modelo da Pcrit, como método de determinação da máxima fase estável de lactato (MFEL), aplicado ao ERP, no supino reto (SR) e verificar associações entre a capacidade de impulso anaeróbio (CIA), com a carga máxima (Cmax), média (Cmed) e índice de fadiga (IF) obtidos em testes anaeróbios de Wingate adaptado (WgtAd) no SR. Participaram da pesquisa 15 homens, fisicamente ativos em ERP, habituados com exercícios de intensidades elevadas [média (±) dp, idade de 21,33 ± 2,85 anos; massa corporal total de 78,48 ± 13,53 kg; estatura de 178,21 ± 7,44 cm e IMC de 24,63 ± 3,42 kg/m2]. Foram aplicados teste e re-teste de 1-RM, para determinação da carga máxima dinâmica em diferentes pegadas (padrão - PGP, aberta - PGA e fechada - PGF). Determinouse em PGP as cargas relativas a 30%, 40%, 50% e 60% para verificação dos tlim, os quais foram ajustados com procedimentos de regressão linear e não linear, determinando a força crítica (Fcrit) e a capacidade de impulso anaeróbio (CIA). Para a validade do parâmetro aeróbio, foi aplicado o teste de MFEL, levando em consideração três cargas de Fcrit (90%, 100% e 110%), e para o parâmetro anaeróbio, o teste de WgtAd com cargas diferenciadas da massa corporal total (MCT). A creatina quinase (CK), como marcador de lesão muscular, e a frequência cardíaca (FC), com variável hemodinâmica, foram analisadas para... / The evaluation model of Critical Power - PCrit (Monod and Scherrer, 1965) is a theoretical construct, derived from the application of a series of tests with constant load until exhaustion or timeouts (tlim). Many studies have examined the application and methodological limitations arising PCrit into different types of cyclic exercise, but few have analyzed their responses applied to the model of Resistance Exercise with Weight (ERP). The aim of this study was to verify the validity of the model PCrit as a method of determining the Maximum Lactate Steady State (MLSS), applied to the ERP, the Bench Press (BP) and examine associations between the Anaerobic Capacity Boost (CIA) with the maximum load (Cmax), average (Cav) and Fatigue Index (FI) obtained in the Wingate anaerobic test adapted (WgtAd) in SR. Fifteen men participated in this study, physically active in the ERP, used to high exercise intensities [mean (±) SD, age 21.33 ± 2.85 years, total body mass of 78.48 ± 13.53 kg, height of 178.21 ± 7.44 cm and BMI 24.63 ± 3.42 kg/m2]. Were applied to test and re-test 1-RM to determine the maximum load dynamics in different footprints (default - PGP, open - PGA and closed - PGF). PGP was determined in the charges relating to 30%, 40%, 50% and 60% for verification of tlim, which were adjusted by regression procedures for linear and nonlinear, determining the Critical Force (Fcrit) and Anaerobic Capacity Boost (CIA). For the validity of the parameter aerobic test was applied to the MLSS, taking into consideration three loads Fcrit (90%, 100% and 110%), and for parameter anaerobic test WgtAd with different loads of Total Body Mass (MCT). Creatine Kinase (CK) as marker of muscle damage, and Heart Rate (HR), with a variable hemodynamics, were analyzed to determine the sensitivity regarding the volume and intensity imposed during and after the tests. It was concluded that the mathematical model... (Complete abstract click electronic access below)