Experimental study on the fundamental frequency of prestressed concrete bridge beams with parabolic unbonded tendons

Bonopera, Marco; Chang, Kuo‐Chun; Chen, C.C.; Sung, Yu‐Chi; Tullini, Nerio

doi:10.1016/j.jsv.2019.04.038

Cited by 34 publications

(27 citation statements)

References 29 publications

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“…The schematic diagram of loading devices for the bending test are shown in Figure 4 . Two pinned-end supports were arranged at the RC beams’ ends, to simulate the most common end constraints of RC members, resulting in a calculated span of 2100 mm, whereas lengths of pure bending and shear span were both of 700 mm [ 32 , 33 ]. Loads were imposed by using a hydraulic long column tester on the I-beam, to exert loads symmetrically at three dividing points.…”

Section: Experimental Rc Beamsmentioning

confidence: 99%

Stressing State Analysis of Reinforced Concrete Beam Strengthened by CFRP Sheet with Anchoring Device

et al. 2021

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This paper investigates the working performance of reinforcement concrete (RC) beams strengthened by Carbon-Fiber-Reinforced Plastic (CFRP) with different anchoring under bending moment, based on the structural stressing state theory. The measured strain values of concrete and Carbon-Fiber-Reinforced Plastic (CFRP) sheet are modeled as generalized strain energy density (GSED), to characterize the RC beams’ stressing state. Then the Mann–Kendall (M–K) criterion is applied to distinguish the characteristic loads of structural stressing state from the curve, updating the definition of structural failure load. In addition, for tested specimens with middle anchorage and end anchorage, the torsion applied on the anchoring device and the deformation width of anchoring device are respectively set parameters to analyze their effects on the reinforcement performance of CFRP sheet through comparing the strain distribution pattern of CFRP. Finally, in order to further explore the strain distribution of the cross-section and analyze the stressing-state characteristics of the RC beam, the numerical shape function (NSF) method is proposed to reasonably expand the limited strain data. The research results provide a new angle of view to conduct structural analysis and a reference to the improvement of reinforcement effect of CFRP.

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Section: Experimental Rc Beamsmentioning

confidence: 99%

Stressing State Analysis of Reinforced Concrete Beam Strengthened by CFRP Sheet with Anchoring Device

et al. 2021

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“…Bonopera et al [50,51] found that the fundamental frequency of uncracked PC girders with a parabolic tendon is unaffected by the prestress force because the course of the "compression-softening" theory being cancelled out by the increase of elastic modulus due to the concrete's consolidation/hardening with time [52].…”

Section: Numerical Investigationsmentioning

confidence: 99%

“…Looking at the relevant works above mentioned, id est, at Hamed and Frostig [45], Jaiswal [46], Limongelli et al [47], and Luna Vera et al [53], no significant agreement between the effect of prestress force and dynamics of uncracked PC girders was observed (Table 2). As a result, natural frequencies are generally considered inappropriate parameters for determining prestress losses, as also indicated by Saiidi et al [32] and Bonopera et al [50,51].…”

Section: Numerical Investigationsmentioning

confidence: 99%

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State-of-the-Art Review on Determining Prestress Losses in Prestressed Concrete Girders

2020

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Prestressing methods were used to realize long-span bridges in the last few decades. For their predictive maintenance, devices and dynamic nondestructive procedures for identifying prestress losses were mainly developed since serviceability and safety of Prestressed Concrete (PC) girders depend on the effective state of prestressing. In fact, substantial long term prestress losses can induce excessive deflections and cracking in large span PC bridge girders. However, old unsolved problematics as well as new challenges exist since a variation in prestress force does not significantly affect the vibration responses of such PC girders. As a result, this makes uncertain the use of natural frequencies as appropriate parameters for prestress loss determinations. Thus, amongst emerging techniques, static identification based on vertical deflections has preliminary proved to be a reliable method with the goal to become a dominant approach in the near future. In fact, measured vertical deflections take accurately and instantaneously into account the changes of structural geometry of PC girders due to prestressing losses on the equilibrium conditions, in turn caused by the combined effects of tendon relaxation, concrete creep and shrinkage, and parameters of real environment as, e.g., temperature and relative humidity. Given the current state of quantitative and principled methodologies, this paper represents a state-of-the-art review of some important research works on determining prestress losses conducted worldwide. The attention is principally focused on a static nondestructive method, and a comparison with dynamic ones is elaborated. Comments and recommendations are made at proper places, while concluding remarks including future studies and field developments are mentioned at the end of the paper.

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“…Diversos autores têm se dedicado ao estudo do comportamento das estruturas em concreto protendido, corroborando seus diversos benefícios, bem como validando e desenvolvendo procedimentos de cálculo (DE OLIVEIRA e JÚNIOR, 2016;MARTÍ et al, 2016;MOURA et al, 2018). No mais, os trabalhos recentes dividem-se basicamente no estudo de peças de concreto protendido com armadura não aderente (DU et al, 2016;MOREIRA et al, 2018;BONOPERA et al, 2019) e elementos de concreto protendido reforçados com fibras (CHEN et al, 2015;SHIN et al, 2016;BISCHOFF et al, 2018).…”

Section: Introductionunclassified

Investigação Numérica Da Importância De Armaduras De Fretagem Em Vigas Pós-Tracionadas Não Aderentes

Almeida

Nicoletti

Wolenski

et al. 2020

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No concreto protendido, em razão da aplicação da força de protensão, a região das ancoragens é submetida à elevadas tensões. Ao longo de um trecho, denominado comprimento de regularização, a distribuição dessas tensões não é uniforme, estando a tensão de compressão, atuante na direção longitudinal do elemento estrutural, acompanhada de tensões nas direções transversais. Para resistir aos esforços transversais de tração, faz-se necessário a adoção de armaduras complementares, denominadas armaduras de fretagem, comumente utilizadas na forma de espirais, estribos secundários ou a combinação de ambos. Neste contexto, este trabalho teve como objetivo investigar o comportamento e a distribuição de tensões ao longo do comprimento de regularização de elementos protendidos, avaliando numericamente no software Abaqus® a influência e importância de armaduras de fretagem em tais elementos. Para tanto, foram simulados dois modelos numéricos, VE e VEF, com mesma quantidade de armadura longitudinal e transversal, diferenciando somente pelo fato de o modelo VEF possuir 3 estribos adicionais de fretagem em cada uma das extremidades da viga. No modelo VE o valor da tensão na armadura atingiu a tensão de escoamento do aço, situação indesejável em condições de serviço, enquanto no modelo VEF a tensão foi aproximadamente 20% menor, evidenciando, portanto, a importância de armaduras de fretagem em atendimento à segurança de vigas pós-tracionadas sem aderência.

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Experimental study on the fundamental frequency of prestressed concrete bridge beams with parabolic unbonded tendons

Cited by 34 publications

References 29 publications

Stressing State Analysis of Reinforced Concrete Beam Strengthened by CFRP Sheet with Anchoring Device

Stressing State Analysis of Reinforced Concrete Beam Strengthened by CFRP Sheet with Anchoring Device

State-of-the-Art Review on Determining Prestress Losses in Prestressed Concrete Girders

Investigação Numérica Da Importância De Armaduras De Fretagem Em Vigas Pós-Tracionadas Não Aderentes

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