ULTIMATE STRENGTH AND DUCTILITY ANALYSIS OF THE STIFFENED CONCRETE PIERS
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A new finite element procedure is developed to study the ultimate strength and ductility behavior of the concrete piers up to softening stage. In the computer code, a degenerate isoparametric curved shell element with layered model is adopted. The arc-length algorithm combined with line search acceleration is employed to overcome the numerical difficulties near and beyond the failure stage. The structural responses of the concrete piers are simulated and compared with experimental results, which shows the efficiency and reliability of the computer code. The stiffening efficiency with different stiffening lengths is discussed, and other two practical stepped concrete piers are also studied. For the covering abstract see ITRD E111699.Keywords:
Stiffening
Ductility (Earth science)
Slab
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Three Dimensional nonlinear finite element analysis was carried out to verify the enhancement of seismic performance of reinforced concrete bridge piers such as shear strength and ductility by controlling bond of longitudinal reinforcement. Proposed analytical method was found to model the global hysteretic behavior and failure mode of unbonded RC piers producing an excellent correlation with that of experimental results. The enhancement of seismic performance and alteration of the failure mode of unbonded pier was found to be due to the change in internal mechanism to the one resembling a tied arch.
Ductility (Earth science)
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Abstract The seismic resistance characteristics of a newly developed composite bridge pier system are examined via a series of experimental studies. In this innovative bridge pier system, the shear strength is provided by the steel tube and the concrete confined by the steel tube. No transverse shear reinforcement is used in this system. Axial and flexural strengths of the bridge pier are exerted by the longitudinal reinforcements and the concrete. A gap between the end of steel tube and the reinforced concrete foundation contributes to the steel tube providing shear resistance only without sharing the flexural moment. From the experimental results of this study, it is found that the flexural strength of the proposed composite bridge pier can be predicted accurately by the conventional method that was used in the reinforced concrete structures. Shear strength of the composite bridge pier can be obtained by summing up shear strengths of the concrete and the steel tube. Excellent deformation capacities are also found from the experimental studies. The proposed composite bridge pier system not only simplifies the construction work greatly, but also provides superior seismic resistance as compared with that of the conventional method. Copyright © 2010 John Wiley & Sons, Ltd.
Bridge (graph theory)
Shear Strength
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Brittleness
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이 연구의 목적은 P-delta 영향을 포함한 철근콘크리트 교각의 비탄성 거동 및 연성능력을 파악하는데 있다. 사용된 프로그램은 철근콘크리트 구조물의 해석을 위한 RCAHEST이다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열모델로서는 분산균열모델을 사용하였다. 비교적 큰 압축하중과 함께 지진하중과 같이 큰 규모의 횡하중으로 인한 대변위 문제를 고려할 수 있도록 total Lagrangian 정식화 기법을 사용하였다. 이 연구에서는 철근콘트리트 교각의 비탄성 거동 및 연성능력의 파악을 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험결과와 비교하여 그 타당성을 검증하였다. The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete bridge piers including P-delta effects. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In addition to the material nonlinear properties, the algorithm for large displacement problem that may give an additional deformation has been formulated using total Lagrangian formulation. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete bridge piers is verified by comparison with reliable experimental results.
Reinforced solid
Ductility (Earth science)
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Constructive
Reinforced solid
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Analytical models for the inelastic behavior and ductility capacity of reinforced concrete bridge piers under earthquake are presented. The models for material nonlinearity include tensile, compressive, and shear models for cracked concrete and a model of reinforcing steel where the smeared crack approach is incorporated. An interface element is used to account for local discontinuous deformations at the boundary plane caused by abrupt changes in stiffness where members with different thicknesses are connected. An analytical model is developed to express the confining effects of lateral ties that depend on the amount of transverse reinforcement. Experimental verification and results from numerical simulations are presented in the companion paper.
Ductility (Earth science)
Bridge (graph theory)
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In order to obtain the ductility a seismic performance of reinforced concrete box piers,the equivalent plastic hinge length and ultimate displacement calculation methods for reinforced concrete box piers were discussed based on bi-axial quasi-static tests of 14 piers and moment curvature analyses of reinforced concrete box cross-section under action of bi-axial load. The results showed that the piers with larger height-width ratio have bigger plastic damage area, meanwhile their ultimate curvature drops obviously; the calculated yielding displacement and ultimate displacement are close to the actual measured ones,so the ultimate displacement calculation method can be used in ductility a seismic analysis for reinforced concrete box piers.
Plastic hinge
Ductility (Earth science)
Seismic loading
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This paper describes the calibration of a two-dimensional (2D) plasticity-based upper-bound analysis model for the assessment of shear in reinforced concrete beams. This work is part of an ongoing research effort at the University of Cambridge, aimed specifically at the assessment of shear in existing concrete bridges. Due to ductility limitations in concrete, full strength may not be achieved along the assumed lines of discontinuity during collapse, as assumed in a plasticity analysis. For this reason, an ‘effective strength’ of concrete is introduced, which is simply a fraction of the compressive cube strength of the concrete. In order to develop a suitable overall (3D) collapse analysis technique for concrete beam-and-slab bridges, it is necessary to determine this effective strength of concrete in each of the beam and slab portions. Here, a 2D beam shear collapse model, and an associated expression for the effectiveness factor for the concrete, are formulated and calibrated against several test results. Restrictions on the use of this model are established and it is concluded that such an analysis technique is eminently suitable for extension to the more general 3D collapse problem in existing concrete beam-and-slab bridges.
Slab
Discontinuity (linguistics)
Ductility (Earth science)
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A research project into the ductility of bridge piers is described covering the post-elastic ductile behaviour of reinforced concrete bridge piers particularly the influence of aspect ratio on such behaviour. The units tested, two octagonal and two square sections, were designed according to the second draft of the concrete design code DZ 3101, for differential axial load levels. The testing procedure included slow static incremental loading followed by fast dynamic cyclic loading. Results are presented in the form of load-displacement hysteresis curves, curvature profiles and transverse steel strain distribution. A discussion deals with the comparison of ultimate moment capacities, measured ductilities, equivalent plastic hinge lengths, maxiumum concrete compression strains, ultimate shear forces, enhancement of concrete strength by confinement, and idealised stress-strain curves for confined concrete. Comparisons with previous projects are made and it is concluded that that the influence of aspect ratio is insignificant for piers confined in accordance with present New Zealand code provisions. (TRRL)
Plastic hinge
Ductility (Earth science)
Precast concrete
Seismic loading
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A new numerical model is developed that enables simulation of the non-linear flexural response of reinforced concrete (RC) components and sections with corroded reinforcement. The numerical model employs a displacement-based beam–column element using the classical Hermitian shape function. Material non-linearity is accounted for by updating element stiffness matrices using the moment–curvature response of the element section considering uniform stiffness over the element. The cover concrete strength is adjusted to account for corrosion-induced cover cracking and the core confined concrete strength and ductility are adjusted to account for corrosion-induced damage to the transverse reinforcement. The numerical model is validated against a benchmark experiment on a corroded RC column subject to lateral cyclic loading. The verified model is then used to explore the impact of corrosion on the inelastic response and the residual capacity of corroded RC sections. The results show that considering the effect of corrosion damage on RC sections changes the failure mode of RC columns.
Concrete cover
Ductility (Earth science)
Reinforced concrete column
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