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Flexural Strength Evaluation of RC Members Laminated by Carbon Fiber Sheet

  • Park, Hae-Geun
    • KCI Concrete Journal
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    • v.14 no.1
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    • pp.1-7
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    • 2002
  • This paper reports the experimental and analytical investigations for evaluating the flexural strength of a RC slab strengthened with carbon fiber sheet (CFS). The evaluation of the ultimate flexural strength of a slab is tried under the assumption that the failure occurs when the shear stress mobilized at the interface between the concrete bottom and the glued CFS reaches its bond strength. The shear stress is evaluated theoretically and the bond strength is obtained by a laboratory test. The ultimate flexural strength is obtained by flexural static test of the slab specimen, which corresponds to the part of a real slab. From the results, the new approach based on the bond strength between concrete and CFS looks feasible to evaluate the flexural strength of the CFS and RC composite slab.

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Interface friction in the service load assessment of slab-on-girder bridge beams

  • Seracino, R.;Kerby-Eaton, S.E.;Oehlers, D.J.
    • Steel and Composite Structures
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    • v.5 no.4
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    • pp.259-269
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    • 2005
  • Many slab-on-girder bridges around the world are being assessed because they are approaching the end of their anticipated design lives or codes are permitting higher allowable loads. Current analytical techniques assume that the concrete and steel components act independently, typically requiring full-scale load testing to more accurately predict the remaining strength or endurance of the structure. However, many of the load tests carried out on these types of bridges would be unnecessary if the degree of interaction resulting from friction at the steel-concrete interface could be adequately modeled. Experimental testing confirmed that interface friction has a negligible effect on the flexural capacity of a slab-on-girder beam however, it also showed that interface friction is significant under serviceability loading. This has led to the development of an improved analytical technique which is presented in this paper and referred to as the slab-on-girder mixed analysis service load assessment approach.

Dynamic response of pile foundations with flexible slabs

  • Kaynia, Amir M.
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.495-506
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    • 2012
  • An elasto-dynamic model for pile-soil-pile interaction together with a simple plate model is used in this study to assess the effect of flexible foundation slabs on the dynamic response of pile groups. To this end, different pile configurations with various slab thicknessesare considered in two soil media with low and high elastic moduli. The analyses include dynamic impedances and seismic responses of pile-group foundations. The presented results indicate that the stiffness and damping of pile foundations increase with thickness of the foundation slab; however, the results approach those for rigid slab as the slab thickness approaches twice the pile diameter for the cases considered in this study. The results also reveal that pile foundations with flexible slabs may amplify the earthquake motions by as much as 10 percent in the low to intermediate frequency ranges.

Finite strip method in probabilistic fatigue analysis of steel bridges

  • Li, W.C.;Cheung, M.S.
    • Steel and Composite Structures
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    • v.2 no.6
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    • pp.429-440
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    • 2002
  • A finite strip method is developed for fatigue reliability analysis of steel highway bridges. Flat shell strips are employed to model concrete slab and steel girders, while a connection strip is formed using penalty function method to take into account eccentricity of girder top flange. At each sampling point with given slab thickness and modulus ratio, a finite strip analysis of the bridge under fatigue truck is performed to calculate stress ranges at fatigue-prone detail, and fatigue failure probability is evaluated following the AASHTO approach or the LEFM approach. After the failure probability is integrated over all sampling points, fatigue reliability of the bridge is determined.

Probability Based Determination of Slab Thickness Satisfying Floor Vibration Criteria (수직진동 사용성 기준을 고려한 바닥판 두께 제안)

  • Lee Min-Jung;Nam Sang-Wook;Han Sang-Whan
    • Journal of the Korea Concrete Institute
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    • v.17 no.5
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    • pp.687-694
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    • 2005
  • In current design practice, the thickness of the floor slab has been determined to satisfy requirement for deflection control. However, previous study shows that the floor thicknesses in residential buildings may not satisfy the floor vibration criteria, even though the thickness is determined by the serviceability requirements in current design provisons. Thus it is necessary to develop the procedure to determine slab thickness that satisfies the floor vibration criteria. This study attempts to propose slab thickness for flat plate slab systems that satisfies floor vibration criteria against occupant induced floor vibration(heel drop load). Two boundary conditions(simple and fixed support), three square flat plates(4, 6, 8m), and five concrete strength($18\~30$ MPa) are considered. Since there are large uncertainties in loading and material properties, probabilistic approach is adopted using Monte-Carlo simulation procedures.

Ultimate Strength Analysis of Slab-Column Joints Subjected to Lateral Loads Using 3-Dimensional Grid Strut-Tie Model Approach (3차원 격자 스트럿-타이 모델 방법을 이용한 횡하중을 받는 슬래브-기둥 접합부의 극한강도 평가)

  • Son, Woo-Hyun;Yun, Young-Mook
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.265-268
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    • 2008
  • Slab-column joints have been used in the constructions of many structures and buildings. However, as the prediction of the failure behavior and ultimate strength of the joints subjected to lateral loadings is very difficult, the current building and structural design codes do not explain the failure behavior of the joints clearly. In this study, the applicability of the 3-dimensional grid strut-tie model approach, suggested for analysis and design of 3-dimensional structural concrete with disturbed regions, to the ultimate analysis and design of the joints is examined by evaluating the failure strengths of 43 slab-column joints tested to failure. The validity of the 3-dimensional grid strut-tie model approach is also verified by comparing the strength evaluation results with those by ACI 318-05 and FIB 1999.

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A Fundamental Study for the Behavior of Lightweight Aggregate Concrete Slab Reinforced with GFRP Bar (GFRP bar를 휨보강근으로 사용한 경량골재콘크리트 슬래브의 거동에 관한 기초적 연구)

  • Jeon, Sang Hun;Shon, Byung Lak;Kim, Chung Ho;Jang, Heui Suk
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.3
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    • pp.99-108
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    • 2012
  • In this paper, to intend anticorrosive effect and weight reduction of conventional reinforced concrete slab, lightweight concrete slab reinforced with glass fiber reinforced polymer(GFRP) bar was considered and some basic behaviour of the slab were investigated. Measurement of splitting tensile strength and fracture energy of the concrete, a number of flexural experiment of the slab, numerical analysis using nonlinear finite element analysis, and comparison of the experimental results to the numerical analysis, were conducted. As a result, even the weight of the lightweight concrete slab could be reduced by about 28% than the normal concrete slab, failure load of the lightweight concrete slab was 36% smaller than the normal concrete slab. Such a thing can be attributed to the lower axial stiffness and lower bond strength of GFRP bar. In the numerical analysis, to consider decreasing property of bond strength of the lightweight concrete, interface element was used between the concrete and the GFRP bar elements and this method was shown to be a better way for the numerical analysis to approach the experimental results.

Design approach for a FRP structural formwork based steel-free modular bridge system

  • Cheng, Lijuan;Karbhari, Vistasp M.
    • Structural Engineering and Mechanics
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    • v.24 no.5
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    • pp.561-584
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    • 2006
  • The paper presents results of parametric studies, and an overall approach for the design of a modular bridge system which incorporates a steel-reinforcement free concrete slab cast on top of carbon FRP stiffened deck panels which act as both structural formwork and flexural reinforcement, spanning between hollow box type FRP girders. Results of the parametric studies are highlighted to elucidate important relationships between critical configurational parameters and empirical equations based on numerical studies are presented. Results are discussed at the level of the individual deck and girder components, and as a slab-on-girder bridge system. An overall design methodology for the components and bridge system including critical performance checks is also presented.

A simplified approach for fire-resistance design of steel-concrete composite beams

  • Li, Guo-Qiang;Wang, Wei-Yong
    • Steel and Composite Structures
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    • v.14 no.3
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    • pp.295-312
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    • 2013
  • In this paper, a simplified approach based on critical temperature for fire resistance design of steel-concrete composite beams is proposed. The method for determining the critical temperature and fire protection of the composite beams is developed on the basis of load-bearing limit state method employed in current Chinese Technical Code for Fire safety of Steel Structure in Buildings. Parameters affecting the critical temperature of the composite beams are analysed. The results show that at a definite load level, section shape of steel beams, material properties, effective width of concrete slab and concrete property model have little influence on the critical temperature of composite beams. However, the fire duration and depth of concrete slab have significant influence on the critical temperature. The critical temperatures for commonly used composite beams, at various depth of concrete and fire duration, are given to provide a reference for engineers. The validity of the practical approach for predicting the critical temperature of the composite beams is conducted by comparing the prediction of a composite beam with the results from some fire design codes and full scale fire resistance tests on the composite beam.

Layered finite element method in cracking and failure analysis of RC beams and beam-column-slab connections

  • Guan, Hong;Loo, Yew-Chaye
    • Structural Engineering and Mechanics
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    • v.5 no.5
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    • pp.645-662
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    • 1997
  • A nonlinear semi-three-dimensional layered finite element procedure is developed for cracking and failure analysis of reinforced concrete beams and the spandrel beam-column-slab connections of flat plates. The layered element approach takes the elasto-plastic failure behaviour and geometric nonlinearity into consideration. A strain-hardening plasticity concrete model and a smeared steel model are incorporated into the layered element formulation. Further, shear failure, transverse reinforcement, spandrel beams and columns are successfully modelled. The proposed method incorporating the nonlinear constitutive models for concrete and steel is implemented in a finite element program. Test specimens including a series of reinforced concrete beams and beam-column-slab connections of flat plates are analysed. Results confirm the effectiveness and accuracy of the layered procedure in predicting both flexural and shear cracking up to failure.