• Steel and Composite Structures
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• 제38권5호
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• pp.497-521
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• 2021

In this study, an effective numerical method is introduced for nonlinear inelastic analyses of rectangular concrete-filled steel tubular (CFST) frames for the first time. A steel-concrete composite fiber beam-column element model is developed that considers material, and geometric nonlinearities, and residual stresses. This is achieved by using stability functions combined with integration points along the element length to capture the spread of plasticity over the composite cross-section along the element length. Additionally, a multi-spring element with a zero-length is employed to model the nonlinear semi-rigid beam-to-column connections in CFST frame models. To solve the nonlinear equilibrium equations, the generalized displacement control algorithm is adopted. The accuracy of the proposed method is firstly verified by a large number of experiments of CFST members subjected to various loading conditions. Subsequently, the proposed method is applied to investigate the nonlinear inelastic behavior of rectangular CFST frames with fully rigid, semi-rigid, and hinged connections. The accuracy of the predicted results and the efficiency pertaining to the computation time of the proposed method are demonstrated in comparison with the ABAQUS software. The proposed numerical method may be efficiently utilized in practical designs for advanced analysis of the rectangular CFST structures.

• 콘크리트학회지
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• 제4권4호
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• pp.15-22
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• 1992

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.91-110
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• 2013

This paper proposes a novel iterative procedure for the design of planar reinforced concrete structures in which the reinforcement is designed for stresses calculated in a nonlinear finite element analysis. The procedure is intended as an alternative to strut and tie modeling for the design of complex structures like deep beams with openings. Practical reinforcement arrangements are achieved by grouping the reinforcement into user defined horizontal and vertical bands. Two alternative strategies are proposed for designing the reinforcement which are designated A and B. Design constraints are specified in terms of permissible stresses and strains in the reinforcement and strains in the concrete. A case study of a deep beam with an opening is presented to illustrate the method. Comparisons are made between design strategies A and B of which B is shown to be most efficient. The resulting reinforcement weights are also shown to compare favorably with those previously reported in the literature.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 춘계학술논문발표회 논문집
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• pp.11-14
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• 2008

This paper is currently being conducted to develop a nonlinear finite element analysis methods for predicting the structural behavior of reinforced concrete structures, exposed to fire. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. Although, this study considers codes standard fire for reinforced concrete frame, any other time-temperature relationship can be easily incorporated.

• Structural Engineering and Mechanics
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• 제41권4호
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• pp.441-458
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• 2012

The shear strength is an important factor in the design of prestressed concrete beams. Therefore, researchers have utilized various methods to determine the shear strength of these elements for the design purposes. To evaluate some of the proposed theoretical methods, numerous models of post-tensioned beams with or without vertical prestressing are selected and analyzed using the finite element method and assuming nonlinear behavior for the materials. In this regard the validity of modeling is evaluated based on some tests results. In the second part of the study two beam specimens are built and tested and their load-deformation curve and cracking pattern are studied. The analytical results consist of compressive strut slope and mid span load deflection are compared with some experimental results, and the results of some codes' formulas. Finally comparing the results of nonlinear analysis with the experimental values, a new formula is proposed for determining strut slopes in prestressed concrete beams.

• Structural Engineering and Mechanics
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• 제36권4호
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• pp.421-445
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• 2010

In this paper the formulation of an efficient frame element applicable for nonlinear analysis of 3D reinforced concrete (RC) frames is outlined. Interaction between axial force and bending moment is considered by using the fibre element approach. Further, section warping, effect of normal and tangential forces on the torsional stiffness of section and second order geometrical nonlinearities are included in the model. The developed computer code is employed for nonlinear static analysis of RC sub-assemblages and a simple approach for extending the formulation to dynamic cases is presented. Dynamic progressive collapse assessment of RC space frames based on the alternate path method is undertaken and dynamic load factor (DLF) is estimated. Further, it is concluded that the torsional behaviour of reinforced concrete elements satisfying minimum standard requirements is not significant for the framed structures studied.

• Structural Engineering and Mechanics
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• 제62권2호
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• pp.179-196
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• 2017

The paper focuses on dynamic analyses of a series of simply-supported symmetric composite steel-concrete bridges loaded by an ICE-3 train moving at high speeds up to 300 km/h. The series includes five bridges with span lengths ranging from 15 m to 27 m, with repeatable geometry of the superstructures. The objects, designed according to Polish standards valid from 1980s to 2010, are modelled on the bridges serviced on the Central Main Line in Poland since 1980s. The advanced, two-dimensional, physically nonlinear model of the bridge-track structure-high-speed train system takes into account unilateral nonlinear wheel-rail contact according to Hertz's theory and random vertical track irregularities equal for both rails. The analyses are focused on the influence of random track irregularities on dynamic response of composite steel-concrete bridges loaded by an ICE-3 train. It has been pointed out that certain restrictions on the train speed and on vertical track irregularities should be imposed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.341-344
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• 2006

A study for the nonlinear analysis of segmentally erected curved PSC(prestressed concrete) cable-stayed bridge considering the effects due to large deflections is presented. Various case studies regarding the effects of the material nonlinearities and the geometric nonlinearities on the behavior of segmentally erected curved PSC cable-stayed bridge are conducted. The numerical results on the bridge which has relatively low stress profile through the bridge deck section like the example herein show that the geometric nonlinearities has more significant effects on the structural behavior than the material nonlinearities.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.147-154
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• 2003

The purpose of this study is to investigate analytically the flexural behavior characteristics of Circular concrete beams confined by carbon sheet. Nonlinear analysis method is presented to simulate the structural behavior beam models. The proposed analytical hardening models were considered the confinement effect of concrete and the tensile effect of carbon sheet in tensile region of concrete. Prandtl-Reuss numerical formula was used to nonlinear analysis of finite element models. Comparisons analytical models with experimental data obtained from flexural testing in the laboratory were presented. Analytical and experimental models show similar behavior.

• Earthquakes and Structures
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• 제8권1호
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• pp.133-152
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• 2015

This paper investigates the soil effect on seismic behaviour of reinforced concrete (RC) buildings by using the spread plastic hinge model which includes material and geometric nonlinearity of the structural members. Therefore, typical reinforced concrete frame buildings are selected and nonlinear dynamic time history analyses and pushover analyses are performed. Three earthquake acceleration records are selected for nonlinear dynamic time history analyses. These records are adjusted to be compatible with the design spectrum defined in Turkish Seismic Code. Interstory drifts and damages of selected buildings are compared according to local soil classes. Also, capacity curves of these buildings are compared with maximum responses obtained from nonlinear dynamic time history analyses. The results show that, soil class influences the seismic behaviour of reinforced concrete buildings, significantly.