• Title/Summary/Keyword: Premature failure load

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Premature Failure Load of Reinforced Concrete Beams with Flexural Strengthened by Steel Plates (강판으로 휨 보강된 철근콘크리트 보의 조기파괴하중 산정)

  • Kim, Haeng-Jun;Kim, Woo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.1
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    • pp.283-292
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    • 2005
  • This paper predicts premature failure load of reinforced concrete beams by epoxy-boned partially steel plates. A parametric study is conducted to estimate premature failure load of beams such as with or without stirrups, unplated length ratio, steel and reinforcement ratio, shear span to depth ratio of reinforcement beam. By results of finite element analysis, it turned out that the unplated length played a dominant role in partially plated beams but reinforcement ratio and shear span to depth ratio effected the premature failure load. The approximate expression with regard to combined design variables is compared with experimental results. It shows closely agreement.

A Experimental Study on the Control of Premature Failure of RC Beams strengthened by Steel Plates (강판으로 보강된 RC보의 조기파괴제어에 관한 실헙적 연구)

  • 심종성;한만엽;김규선;이인범
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.585-591
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    • 1998
  • In the case of reinforced concrete beams strengthening by steel plate, sometimes these beams collapse due to the stress concentration at the ends of steel plates before the design expected failure. This kind of failure is called premature failure. This study analyzes the behavior of strengthened RC beams to control premature failure of these plated beams with either changing the geometries at the ends of plates or strengthening steel plates beside the ends. The results from the former cases show that, the effect of expanded plates sections at the ends was very small, and the beams which are rounded the ends of plates effectively increased the initial rip-off loads about 14% compared with control beam but the ultimate loads was almost same. However, the beams in the latter cases effectively increased the initial and the ultimate rip-off loads with changing failure mode, especially around 14~19% in the ultimate rip-off load comparing with control beam.

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Analytical evaluation of a modular CFT bridge pier according to directivity

  • Kim, Dongwook;Jeon, Chiho;Shim, Changsu
    • Steel and Composite Structures
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    • v.20 no.6
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    • pp.1193-1203
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    • 2016
  • This paper focuses on the analytical behavior of modular circular concrete-filled tubular (CFT) column with enhanced bracing details. To design a full-scale bridge pier of multiple circular concrete-filled tubes, numerical analysis was used to evaluate structural performance according to load directivity. In previous research (Ma et al. 2012, Shim et al. 2014), low cycle fatigue failure at bracing joints was observed, so enhanced bracing details to prevent premature failure are proposed in this analysis. The main purpose of this research is to investigate seismic performance for the diagonal direction load without premature failure at the joints when the structure reaches the ultimate load. The ABAQUS finite-element software is used to evaluate experimental performance. A quasi-static loading condition on a modular bridge pier is introduced to investigate structural performance. The results obtained from the analysis are evaluated by comparing with load-displacement responses from experiments. The concrete-filled tubes with enhanced bracing details showed higher energy dissipation capacity and proper performance without connection failure for a diagonal load.

Debonding failure analysis of prestressed FRP strengthened RC beams

  • Hoque, Nusrat;Jumaat, Mohd Z.
    • Structural Engineering and Mechanics
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    • v.66 no.4
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    • pp.543-555
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    • 2018
  • Fiber Reinforced Polymer (FRP), which has a high strength to weight ratio, are now regularly used for strengthening of deficient reinforced concrete (RC) structures. While various researches have been conducted on FRP strengthening, an area that still requires attention is predicting the debonding failure load of prestressed FRP strengthened RC beams. Application of prestressing increases the capacity and reduces the premature failure of the beams largely, though not entirely. Few analytical methods are available to predict the failure loads under flexure failure. With this paucity, this research proposes a method for predicting debonding failure induced by intermediate crack (IC) for prestressed FRP-strengthened beams. The method consists of a numerical study on beams retrofitted with prestressed FRP in the tension side of the beam. The method applies modified Branson moment-curvature analysis together with the global energy balance approach in combination with fracture mechanics criteria to predict failure load for complicated IC-induced failure. The numerically simulated results were compared with published experimental data and the average of theoretical to experimental debonding failure load is found to be 0.93 with a standard deviation of 0.09.

Reliability Evaluation of Extrapolated Failure Load of Drilled Shafts Embedded in Weathered Rock (풍화암에 근입된 현장타설말뚝의 외삽 파괴하중 신뢰성 분석)

  • Jung, Sung-Jun;Lee, Sang-Inn;Jeon, Jong-Woo;Kim, Myoung-Mo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.993-1000
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    • 2009
  • In general, a drilled shaft embedded in weathered rock has a large load bearing capacity. Therefore, most of the load tests are performed only up to the load level that confirms the pile design load capacity, and stopped much before the failure load of the pile is attained. If a reliable failure load value can be extracted from the premature load test data, it will be possible to greatly improve economic efficiency as well as pile design quality. The main purpose of this study is to propose a standard for judging the reliability of the failure load of piles that is obtained from extrapolated load test data. To this aim, eleven static load test data of load-displacement curves were obtained from testing of piles to their failures from 3 different field sites. For each load-displacement curve, loading was assumed as 25%, 50%, 60%, 70%, 80%, and 90% of the actual pile bearing capacity. The limited known data were then extrapolated using the hyperbolic function, and the failure load was re-determined for each extrapolated data by the ASCE 20-96 method (1997). Statistical analysis was performed on the reliability of the re-evaluated failure loads. The results showed that if the ratio of the maximum-available displacement to the failure-load displacement exceeds 0.6, the extrapolated failure load may be regarded as reliable, having less than a conservative 20% error on average. The applicability of the proposed standard of judgment was also verified with static load test data of driven piles.

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Strength assessment of RC deep beams and corbels

  • Adrija, D.;Geevar, Indu;Menon, Devdas;Prasad, Meher
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.273-291
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    • 2021
  • The strut-and-tie method (STM) has been widely accepted and used as a rational approach for the design of disturbed regions ('D' regions) of reinforced concrete members such as in corbels and deep beams, where traditional flexure theory does not apply. This paper evaluates the applicability of the equilibrium based STM in strength predictions of deep beams (with rectangular and circular cross-section) and corbels using the available experiments in literature. STM is found to give fairly good results for corbel and deep beams. The failure modes of these deep members are also studied, and an optimum amount of distribution reinforcement is suggested to eliminate the premature diagonal splitting failure. A comparison with existing empirical and semi empirical methods also show that STM gives more reliable results. The nonlinear finite element analysis (NLFEA) of 50 deep beams and 20 corbels could capture the complete behaviour of deep members including crack pattern, failure load and failure load accurately.

Load carrying capacity of Structural Composite Hybrid System (Green Frame) (철골 프리캐스트 콘크리트 합성보 성능 분석 연구)

  • Hong, Won-Kee;Kim, Sun-Kuk;Kim, Seung-Il
    • KIEAE Journal
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    • v.10 no.1
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    • pp.25-31
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    • 2010
  • An experimental investigation of composite beams composed of wide flange steel and precast concrete is presented. The bottom flange of the steel section is encased in precast concrete. The composite beams tested in this study were designed to reduce the depth of the slab and beam. The slabs are constructed on top of the edges of the Structural Composite Hybrid System, instead of on top of the steel flange, decreasing the depth of the beams. When concrete is cast on the metal deck plate located on the edges of the precast concrete, the weight of the concrete slabs and other construction loads must be supported by the contacts between the steel and the precast concrete. This interface must not exhibit bearing failures, shear failures, and failures caused by torque due to the loading of the precast concrete. When the contact area between the concrete and the bottom flange of the steel beam is small, these failures of the concrete are likely and must be prevented. The premature failure of precast concrete must not also be present when the weight of the concrete slabs and other construction loads is loaded. This paper presents a load carrying capacity of Structural Composite Hybrid System in order to observe the failure mode. The symmetrically distributed loading that caused the failure of the composite beam was found. The paper also provides design recommendations of such type of composite structure.

Bond-slip Effect of Reinforced Concrete Building Structure under Seismic Load using Finite Element Analysis (유한요소해석을 활용한 지진하중에 대한 철근콘크리트 건축물의 부착성능 효과 연구)

  • Kim, Yeeun;Kim, Hyewon;Shin, Jiuk
    • Journal of Korean Association for Spatial Structures
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    • v.22 no.4
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    • pp.99-107
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    • 2022
  • Existing reinforced concrete building structures constructed before 1988 have seismically-deficient reinforcing details, which can lead to the premature failure of the columns and beam-column joints. The premature failure was resulted from the inadequate bonding performance between the reinforcing bars and surrounding concrete on the main structural elements. This paper aims to quantify the bond-slip effect on the dynamic responses of reinforced concrete frame models using finite element analyses. The bond-slip behavior was modeled using an one-dimensional slide line model in LS-DYNA. The bond-slip models were varied with the bonding conditions and failure modes, and implemented to the well-validated finite element models. The dynamic responses of the frame models with the several bonding conditions were compared to the validated models reproducing the actual behavior. It verifies that the bond-slip effects significantly affected the dynamic responses of the reinforced concrete building structures.

Behavior of Precast Concrete Shear Walls with C-Type Connections (C형 접합부를 이용한 프리캐스트 콘크리트 전단벽의 거동)

  • Lim, Woo-Young;Hong, Sung-Gul
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.461-472
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    • 2010
  • This paper investigates the behavior of precast concrete (PC) shear walls with a new vertical connections for a fast remodeling construction. The C-type vertical connections for the PC wall systems are proposed for transfer of bending moment between top and bottom walls in the vertical direction while a shear key in the center of wall is prepared to transfer shear forces by bearing action. The proposed vertical connections allows easy fabrication thanks to slots at the edges of wall in opposite directions. The plane PC wall systems subject to lateral load are compared with ordinary wall systems by investigating the effects of connection on the stiffness, strength, ductility, and failure modes of whole systems. The load-displacement relationship and influence of premature failure of connections are examined. The experimental test showed that the longitudinal reinforcing steel bars placed at the edges of walls yielded first and the ultimate deformation were terminated due to premature failure of connections. The diagonal reinforcements for efficient shear transfer in the walls were not effective. The strength and deformation obtained through the section analysis were generally in agreement with the experimental data, and indicated that. Gap opening contributed to the deformation behavior more than any other factors.

Effects of the location and size of web openings on shear behavior of clamped-clamped reinforced concrete beams

  • Ceyhun Aksoylu;Yasin Onuralp Ozkilic;Ibrahim Y. Hakeem;Ilker Kalkan
    • Computers and Concrete
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    • v.33 no.3
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    • pp.251-264
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    • 2024
  • The present study pertains to the effects of variations in the location and size of drilled web openings on the behavior of fixed-fixed reinforced concrete (RC) beams. For this purpose, a reference bending beam with a transverse opening in each half span was tested to failure. Later, the same beam was modeled and analyzed with the help of finite element software using ABAQUS. Upon achieving close agreement between the experimental and numerical results, the location and size of the web opening were altered to uncover the effects of these factors on the shear strength and load-deflection behavior of RC beams. The experimental failure mode of the tested beam and the numerical results were also verified by theoretical calculations. In numerical analysis, when compared to the reference (D0) specimen, if the distance of the opening center from the support is 0 or h or 2h, reduction in load-bearing capacity of 1.5%-22.8% or 2.0%-11.3% or is 4.1%-40.7%. In other words, both the numerical analyses and theoretical calculations indicated that the beam behavior shifted from shear-controlled to flexure-controlled as the openings approached the supports. Furthermore, the deformation capacities, energy absorption values, and the ductilities of the beams with different opening diameters also increased with the decreasing distance of the opening from supports. Web compression failure was shown to be the predominant mode of failure of beams with large diameters due to the lack of sufficient material in the diagonal compression strut of the beam. The present study indicated that transverse openings with diameters, not exceeding about 1/3 of the entire beam depth, do not cause the premature shear failure of RC beams. Finally, shear damage should be prevented by placing special reinforcements in the areas where such gaps are opened.