Nonlinear Analysis of Prestressed Concrete Frames

Kang, Young-Jin; Scordelis, Alexander C.

doi:10.1061/jsdeag.0005367

Cited by 55 publications

(9 citation statements)

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“…For cases (2) and (3) in the prestressing phase the stress losses were caused by friction. Immediately after completed prestressing this decrease in the middle of the tendon was 2.6 per cent greater from the initial force in the tendon for case (2), and 4 per cent for case (3). The structure failure occurred at loading factor 2.9 in both cases.…”

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confidence: 82%

“…Numerical modelling of non-linear prestressed structures has been studied by many authors [1][2][3][4][5][6]. The model presented in this paper is applied to non-linear analysis of post-tensioned concrete structures, partially or fully prestressed.…”

Section: Introductionmentioning

confidence: 99%

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Non‐linear finite element analysis of post‐tensioned concrete structures

Nikolić

Mihanović

1997

Engineering Computations

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IntroductionNumerical modelling of non-linear prestressed structures has been studied by many authors [1][2][3][4][5][6]. The model presented in this paper is applied to non-linear analysis of post-tensioned concrete structures, partially or fully prestressed.The stress in prestressed tendons is decreased as a result of various influences which directly affect the bearing capacity of the structure. Consequently, all changes should be computed as precisely as possible. The model developed in this paper makes it possible to compute friction losses, losses in the anchorage zone caused by concrete deformation and standard losses caused by the short-term linear and non-linear deformation of concrete.The prestressed tendons and reinforcing bars are embedded into the concrete [7][8][9]. They were modelled by one-dimensional isoparametric threenode elements. These elements make it possible to model generally curved prestressing tendons and reinforcing bars. The influence of the prestressed tendon on the concrete is modelled by distributed normal and tangential load along the tendon and the two forces concentrated on the anchors.The computation for post-tensioned structures is organized in phases. In the phase which precedes the prestressing of the tendons the structure is computed taking into account the dead load and one part of the permanent load. In the prestressing phase the tendons are tensioned individually. The prestress force can be applied at once or incrementally. In the third phase, which follows the tensioning of all tendons, the structure is computed taking into account the remaining part of the dead load and the live load. Material modellingA brief description of the material models adopted in this analysis is presented herein. Further details may be found in [8,9]. Compressive behaviour of concreteIn the present analysis an elasto-viscoplastic approach[10] was employed to model the compressive behaviour of the concrete. The yield condition was formulated in terms of the first two stress invariants [11][12][13].

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confidence: 82%

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confidence: 99%

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Non‐linear finite element analysis of post‐tensioned concrete structures

Nikolić

Mihanović

1997

Engineering Computations

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“…In the second option, creep similarly to other free strains, in general do not satisfy compatibility, thus unbalanced forces will develop in time without variation of forces which activates the Newton-Raphson iteration process in order to preserve equilibrium, as used by Kabir and Scordelis [30], Kang and Scordelis [31] and Mari [2]. Therefore, together with the equilibrium conditions, this approach will produce equivalent results to the visco-elastic material formulation.…”

Section: Time-dependent Constitutive Model For Concretementioning

confidence: 99%

Influence of time-dependent restrained strains in the shear response of RC frames

2016

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The final publication is available at Springer via http://dx.doi.org/10.1617/s11527-016-0875-8Time-dependent strains, when restrained, can lead to important tensile forces and damage, affecting, among other aspects, the shear response and ultimate load carrying capacity of shear-critical RC frames. This paper presents a detailed study of this problematic by means of an extension of a shear-sensitive fibre beam model to time dependent behaviour of concrete. The model is firstly validated with experimental tests on diagonally pre-cracked beams under sustained loads. From these analyses, the contributions of shear distortions and bending curvatures to the total long-term deflection of the beams are discerned. Afterwards, the model is applied to study the influence of restraining strains due to long-term creep and shrinkage in the service and ultimate shear response of frames. In contrast with flexural resistant mechanisms, delayed strains may influence the latter shear resistance of integral structures by reducing the concrete contribution to shear resistance and leading to a sooner activation of the transversal reinforcement. These aspects can be relevant in assessing existing structures and this model, due to its relative simplicity, can be advantageous for practical applications.Peer ReviewedPostprint (author's final draft

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“…This makes the proposed model less sensitive to the failure of a single material point than the TINSA model.As in the previous cases, a significant decrease of the degrees of freedom used by the proposed model (243 DOF) with respect to the FE model of TINSA[22] with the same number of fibers (1808 DOF) is made. A speedup of around 5 is obtained with the proposed model in comparison with the FE model in similar computational conditions.The section state at the ultimate load is shown in Fig (9)…”

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confidence: 99%