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Faouzi Ghrib - One of the best experts on this subject based on the ideXlab platform.

  • flexural strengthening of Reinforced Concrete Slab column connection using cfrp sheets
    Construction and Building Materials, 2014
    Co-Authors: Hazem A Elenein, Khaled Sennah, Hossein Azimi, Faouzi Ghrib
    Abstract:

    Abstract The objective of this paper is to investigate experimentally the effectiveness of application of carbon fiber Reinforced polymer (CFRP) sheets as a strengthening technique of a Reinforced Concrete (RC) Slab–column connection in one-way flat-plate system to enhance its flexural strength. The experimental study was particularly conducted to examine whether there is enough anchorage with the use of CFRP wrapping to the discontinuous longitudinal CFRP sheets at column stub. Series of tests were conducted on six flat Slab–column connection specimens organized in two groups of three specimens each. The first group included three control specimens with central, eccentric, and edge columns, respectively. The second group was geometrically identical to the first group, though with CFRP sheets installed on the tension side of the Slab to increase flexural capacity at the negative moment region. The specimens with eccentric and edge columns are those having geometrical eccentricity and whose results are compared with those obtained for specimens with central column to study the effect of column eccentricity. The experimental work included fabrication of specimens and testing them under increasing monotonic gravity loads up to failure. Experimental results demonstrated that the flexural ultimate load carrying capacity increased by 33%, 37% and 67% for the tested specimens with central, eccentric, and edge column, respectively, when strengthened using CFRP sheets. The cross-sectional analysis was also undertaken to compare the experimental results with those obtained from Canadian Standards for FRP design for buildings.

  • rehabilitation of interior Reinforced Concrete Slab column connections using cfrp sheets
    Construction and Building Materials, 2010
    Co-Authors: Wafa Polies, Faouzi Ghrib, Khaled Sennah
    Abstract:

    Abstract The present work discusses results of an experimental study of interior Slab–column connection rehabilitation using carbon fiber-Reinforced polymers (CFRP). The objective is to investigate the efficiency of CFRP sheets for rehabilitating and strengthening a flat-plate Slab–column connection subjected to monotonic shear and unbalanced moment. The effect of the load eccentricity is selected as the main design parameter for the present study. A series of tests was conducted on six specimens organized in three groups according to the eccentricity of the applied load. The first specimen of each group (control specimen) is loaded up to failure, whereas the load is applied in two steps on the second specimen: during the first loading step, the specimen is loaded up to approximately 70% of the ultimate load of the corresponding control specimen, creating flexural cracks in the tension zone; in the second step, the cracked specimen is Reinforced using CFRP sheets bonded on the tension-cracked surface then re-loaded to failure in the second loading phase. The results show that the rehabilitation technique is able to restore and enhance the ultimate load capacity and stiffness of all cracked specimens. However, the ductility index is reduced after rehabilitation even if the failure mode did not change. Furthermore, it is found that the effectiveness of the rehabilitation technique is reduced when the load eccentricity increases.

Khaled Sennah - One of the best experts on this subject based on the ideXlab platform.

  • flexural strengthening of Reinforced Concrete Slab column connection using cfrp sheets
    Construction and Building Materials, 2014
    Co-Authors: Hazem A Elenein, Khaled Sennah, Hossein Azimi, Faouzi Ghrib
    Abstract:

    Abstract The objective of this paper is to investigate experimentally the effectiveness of application of carbon fiber Reinforced polymer (CFRP) sheets as a strengthening technique of a Reinforced Concrete (RC) Slab–column connection in one-way flat-plate system to enhance its flexural strength. The experimental study was particularly conducted to examine whether there is enough anchorage with the use of CFRP wrapping to the discontinuous longitudinal CFRP sheets at column stub. Series of tests were conducted on six flat Slab–column connection specimens organized in two groups of three specimens each. The first group included three control specimens with central, eccentric, and edge columns, respectively. The second group was geometrically identical to the first group, though with CFRP sheets installed on the tension side of the Slab to increase flexural capacity at the negative moment region. The specimens with eccentric and edge columns are those having geometrical eccentricity and whose results are compared with those obtained for specimens with central column to study the effect of column eccentricity. The experimental work included fabrication of specimens and testing them under increasing monotonic gravity loads up to failure. Experimental results demonstrated that the flexural ultimate load carrying capacity increased by 33%, 37% and 67% for the tested specimens with central, eccentric, and edge column, respectively, when strengthened using CFRP sheets. The cross-sectional analysis was also undertaken to compare the experimental results with those obtained from Canadian Standards for FRP design for buildings.

  • rehabilitation of interior Reinforced Concrete Slab column connections using cfrp sheets
    Construction and Building Materials, 2010
    Co-Authors: Wafa Polies, Faouzi Ghrib, Khaled Sennah
    Abstract:

    Abstract The present work discusses results of an experimental study of interior Slab–column connection rehabilitation using carbon fiber-Reinforced polymers (CFRP). The objective is to investigate the efficiency of CFRP sheets for rehabilitating and strengthening a flat-plate Slab–column connection subjected to monotonic shear and unbalanced moment. The effect of the load eccentricity is selected as the main design parameter for the present study. A series of tests was conducted on six specimens organized in three groups according to the eccentricity of the applied load. The first specimen of each group (control specimen) is loaded up to failure, whereas the load is applied in two steps on the second specimen: during the first loading step, the specimen is loaded up to approximately 70% of the ultimate load of the corresponding control specimen, creating flexural cracks in the tension zone; in the second step, the cracked specimen is Reinforced using CFRP sheets bonded on the tension-cracked surface then re-loaded to failure in the second loading phase. The results show that the rehabilitation technique is able to restore and enhance the ultimate load capacity and stiffness of all cracked specimens. However, the ductility index is reduced after rehabilitation even if the failure mode did not change. Furthermore, it is found that the effectiveness of the rehabilitation technique is reduced when the load eccentricity increases.

Eva O. L. Lantsoght - One of the best experts on this subject based on the ideXlab platform.

  • Determination of Loading Protocol and Stop Criteria for Proof Loading with Beam Tests
    High Tech Concrete: Where Technology and Engineering Meet, 2018
    Co-Authors: Eva O. L. Lantsoght, Yu-guang Yang, Cor Van Der Veen, Ane De Boer, Dick A. Hordijk
    Abstract:

    Proof loading of existing bridges is an interesting option when insufficient information about a bridge is available. To safely carry out a proof loading test, high loads are placed on the bridge. To avoid permanent damage to the structure, a controlled loading protocol needs to be described, and the measurements need to be closely monitored to identify the onset of distress. The criteria from existing codes and guidelines to evaluate the measurements, called stop criteria, are not universally applicable. To develop recommendations for proof loading of Reinforced Concrete solid Slab bridges, beam experiments were analysed. The beams were heavily instrumented to evaluate the existing stop criteria, and possibly develop new stop criteria. The result of these experiments is the development of a standard loading protocol for the proof loading of Reinforced Concrete Slab bridges. Recommendations for the use of the stop criteria are also formulated. These insights are used to develop a new guideline for the proof loading of Reinforced Concrete Slab bridges in the Netherlands.

  • pilot proof load test on viaduct de beek case study
    Journal of Bridge Engineering, 2017
    Co-Authors: Eva O. L. Lantsoght, Rutger Koekkoek, Cor Van Der Veen, Dick A. Hordijk, Ane De Boer
    Abstract:

    For existing bridges, proof-load testing can be a suitable assessment method. This paper addresses the evaluation of a posted Reinforced Concrete Slab bridge over a highway through proof-load testing, detailing the preparation, execution, and analysis of the test. As the target proof-load and the required measurements for proof-load testing currently are not well-defined in the existing codes, this pilot case was used to develop and evaluate proposed recommendations for proof-load testing for a future guideline on proof-load testing for the Netherlands. Moreover, the pilot proof-load test is used to study the feasibility of proof-load testing for both shear and flexure

  • Development of recommendations for proof load testing of Reinforced Concrete Slab bridges
    Engineering Structures, 2017
    Co-Authors: Eva O. L. Lantsoght, Cor Van Der Veen, Da Dick Hordijk, Ane De Boer
    Abstract:

    As the bridge stock in the Netherlands and Europe is ageing, various methods to analyze existing bridges are being studied. Proof load testing of bridges is an option to experimentally demonstrate that a given bridge can carry the prescribed live loads. Based on extensive research on proof load testing of Reinforced Concrete Slab bridges carried out in the Netherlands, recommendations for proof load testing of Reinforced Concrete Slab bridges were developed. The recommendations for the preparation, execution, and post-processing of a proof load test are summarized in this paper. The novelty of the recommendations is that proof load testing for shear is studied, and that a proposal for stop criteria for shear and bending moment has been formulated. Further research on the shear behavior is necessary, after which the recommendations will be converted in guidelines for the industry.

  • collapse test and moment capacity of the ruytenschildt Reinforced Concrete Slab bridge
    Structure and Infrastructure Engineering, 2017
    Co-Authors: Eva O. L. Lantsoght, Ane De Boer, Cor Van Der Veen, Dick A. Hordijk
    Abstract:

    A large number of existing Reinforced Concrete solid Slab bridges in the Netherlands are found to be insufficient for shear upon assessment. However, research has shown additional sources of capacity in Slab bridges, increasing their total capacity and possibly changing their failure mode. Previous testing was limited to half-scale Slab specimens cast in the laboratory. To study the full structural behaviour of Slab bridges, testing to failure of a bridge is necessary. Research on load testing is carried out in order to develop load testing guidelines. In August 2014, a bridge was tested in two spans. The bridge was load tested, and additional cycles until yielding occurred in the reinforcement were added to the experiment. Though calculations with current design provisions showed that the bridge could fail in shear, the field test showed failure in flexure before shear. The unity check for flexure was determined. The experiment shows that the methods for rating of existing Reinforced Concrete Slab bridges are conservative.

  • levels of approximation for the shear assessment of Reinforced Concrete Slab bridges
    Structural Concrete, 2017
    Co-Authors: Ane De Boer, Eva O. L. Lantsoght, Cor Van Der Veen
    Abstract:

    Many existing Reinforced Concrete bridges in The Netherlands are suspected of having insufficient shear strength, hence a methodical approach is necessary to assess them. The aim of this paper is to provide a structured approach for assessment of the Reinforced Concrete Slab bridges, which make up a considerable proportion of the Dutch bridge stock. The proposed method uses the levels of approximation introduced in the fib Model Code for Concrete Structures 2010. The recommendations at all levels are linked to experimental research. The different levels include spreadsheet-based calculations (the “Quick Scan”), linear finite element models, nonlinear finite element models, the analysis of a structure with cracked Concrete, and, for exceptional cases, proof loading of the structure. The result of this approach is a structured method of levels of assessment that can be used when many bridges need to be assessed. For most bridges, assessment at the lowest level will prove sufficient. For a limited number of cases, higher levels of assessment will offer options and guidelines for a more in-depth study of the structure being assessed.

James K. Wight - One of the best experts on this subject based on the ideXlab platform.

  • Flexurally-triggered punching shear failure of Reinforced Concrete Slab–column connections Reinforced with headed shear studs arranged in orthogonal and radial layouts
    Engineering Structures, 2016
    Co-Authors: Thai X. Dam, James K. Wight
    Abstract:

    Abstract Shear strength of Reinforced Concrete Slab–column connections can be increased through the use of headed shear studs. To reduce interference with Slab flexural reinforcement, stud rails are often placed in an orthogonal layout. In this layout, no stud rail is placed in regions extending from the corners of a column, as opposed to stud placement in a radial layout. Some experiments have found the absence of radial stud rails could lead to premature shear failure at Slab–column connections. This problem may not have been noticeable in experiments that tested Slabs with either short-spans or with a high flexural reinforcement ratio. This paper presents an experimental study to evaluate the effectiveness of these stud layouts in Slab–column connections whose Slabs have relatively low flexural reinforcement ratios. Three full-scale Slab–column connections that represent a flat plate structure with 25 ft (7620 mm) spans were tested. All three specimens had an identical flexural design, in which the reinforcement ratio was 0.8%. One specimen was built without shear reinforcement, and the remaining two specimens were Reinforced with shear studs in either a radial or orthogonal layout. For the specimens with shear studs, calculated shear strengths were higher than their estimated flexural strengths.

  • flexurally triggered punching shear failure of Reinforced Concrete Slab column connections Reinforced with headed shear studs arranged in orthogonal and radial layouts
    Engineering Structures, 2016
    Co-Authors: Thai X. Dam, James K. Wight
    Abstract:

    Abstract Shear strength of Reinforced Concrete Slab–column connections can be increased through the use of headed shear studs. To reduce interference with Slab flexural reinforcement, stud rails are often placed in an orthogonal layout. In this layout, no stud rail is placed in regions extending from the corners of a column, as opposed to stud placement in a radial layout. Some experiments have found the absence of radial stud rails could lead to premature shear failure at Slab–column connections. This problem may not have been noticeable in experiments that tested Slabs with either short-spans or with a high flexural reinforcement ratio. This paper presents an experimental study to evaluate the effectiveness of these stud layouts in Slab–column connections whose Slabs have relatively low flexural reinforcement ratios. Three full-scale Slab–column connections that represent a flat plate structure with 25 ft (7620 mm) spans were tested. All three specimens had an identical flexural design, in which the reinforcement ratio was 0.8%. One specimen was built without shear reinforcement, and the remaining two specimens were Reinforced with shear studs in either a radial or orthogonal layout. For the specimens with shear studs, calculated shear strengths were higher than their estimated flexural strengths.

Maria Anna Polak - One of the best experts on this subject based on the ideXlab platform.

  • Finite Element Analysis of a Reinforced Concrete Slab-Column Connection using ABAQUS
    Structures Congress 2014, 2014
    Co-Authors: Aikaterini S. Genikomsou, Maria Anna Polak
    Abstract:

    Reinforced Concrete flat Slabs are used worldwide as a construction system in many multistory buildings. The problem that can occur in flat Slabs, are high stresses in the Slab-column connection area that can result in a punching shear failure. Nonlinear Finite Element analyses can be performed in order to investigate the phenomenon of punching shear and to gain information on Slabs’ behavior. In this paper, a 3-D analysis of the Reinforced Concrete Slab with the finite element software ABAQUS using the damage-plasticity model is presented. The choice of the adequate material model is important in finite element modeling for Concrete structures. The simulations of the Reinforced Concrete Slab are compared to the behavior of a specimen that has been tested at the University of Waterloo. This study involves the investigation on the punching shear behavior of Reinforced Concrete Slab-column connections without shear reinforcement. The results of the FEA simulations indicate the reasonable response when compared to the behavior of the test specimen. The simulations give information on the punching shear capacity and the crack pattern.

  • seismic retrofit of Reinforced Concrete Slab column connections using shear bolts
    Aci Structural Journal, 2009
    Co-Authors: Maria Anna Polak
    Abstract:

    Shear bolts are a new punching shear retrofit method for existing flat Slab structures. This paper describes an experimental investigation on the application of shear bolts to Reinforced Concrete Slab-column connections subjected to increasing cyclic lateral drift and constant gravity loading. Shear bolts, as transverse shear reinforcement, were installed externally in three specimens in holes drilled through the Slabs? thickness in the vicinity of the columns. The test results show that shear bolts increase lateral load-resisting capacity, lateral drift capacity at peak and ultimate loads, and ductility of the Slab-column connections. Shear bolts also change the failure mode of the Slab-column connections from brittle to ductile and increase the energy dissipation capacity. Although the conclusions are made specifically for shear bolt retrofitted Slabs, some of these findings can also be helpful in enhancing understanding of the behavior of flat Reinforced Concrete Slabs with and without shear reinforcements.

  • Reinforced Concrete Slab-column edge connections with shear studs
    Canadian Journal of Civil Engineering, 2000
    Co-Authors: Ehab El-salakawy, Maria Anna Polak, Monir H. Soliman
    Abstract:

    The paper reports the results of an experimental investigation on the influence of shear studs on the behaviour of Reinforced Concrete Slab-column edge connections with openings. The test parameters were the location of openings around the column, the size of openings, and the existence of shear reinforcement. The objective of the paper is to present and discuss the results of large-scale tests on Slabs with shear stud reinforcement and compare these test results with those of tests on identical Slabs but without shear reinforcement. All tested Slabs contained same amounts of typical flexural reinforcement (ACI 318-95 and CSA A23.3-94). The presented test results can be used for studying the behaviour of Slab-column connections and for calibration of the predictive models.Key words: Reinforced Concrete, edge connections, flat Concrete plates, punching shear, shear strength, openings, failure, shear studs, shear reinforcement.