• Steel and Composite Structures
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• v.29 no.1
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• pp.91-106
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• 2018

This paper investigates the deflection of the steel-concrete composite truss beam (SCCTB) at the serviceability limit state. A precise solution for the distributed uplift force of the SCCTB, considering five different loading types, is first derived based on the differential and equilibrium equations. Furthermore, its approximate solution is proposed for practical applications. Subsequently, the shear slip effect corresponding to the shear stiffness of the stub connectors, uplift effect corresponding to the axial stiffness of the stub connectors and shear effect corresponding to the brace deformation of the steel truss are considered in the derivation of deflection. Formulae for estimating the SCCTB deflection are proposed. Moreover, based on the proposed formulae, a practical design method is developed to provide an effective and convenient tool for designers to estimate the SCCTB deflection. Flexure tests are carried out on three SCCTBs. It is observed that the SCCTB stiffness and ultimate load increase with an increase in the shear interaction factor. Finally, the reliability of the practical design method is accurately verified based on the available experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.43-50
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• 2010

To address the problems caused by the corrosion of steel rebar, active research has recently been carried out on members where fiber-reinforced polymer (FRP) is used in place of rebar. As FRP bar is highly brittle and has a low modulus of elasticity, further research is needed on the evaluation of serviceability, in other words on the deflection of flexural concrete members reinforced with FRP rebars. Taking the reinforcement ratio as a variable, this paper analyzes the flexural capacity of concrete beams reinforced with CFRP rebar. The test results of specimens reinforced with CFRP rebar show an increase in stiffness and resisting force along with an increase in the reinforcement ratio. A reinforcement ratio of about 1.3 is needed for the member reinforced with CFRP rebar to show same section property of a steel member. Through a comparison for the value of an effective moment of inertia, the equation suggested by Bischoff & Scanlon predicted values closest to the actual results.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.796-803
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• 2002

T-shaped walls have different strength, stiffness and ductility in the two opposite directions parallel to the web when subjected to horizontal in-plane loads. When the flange is in tension, the extent that the flange reinforcement contributes to the flexural strength will be subjected to shear-lag effect. Because of this shear-lag effect, the flange may not participate fully in the action with the web, and the effective flange width is needed for predicting the actual strength and stiffness of structures. The objective of this paper is to evaluate the effective flange width and actual strength of the T-shaped wall with Korean code specified detailing of the wall web. Three specimens were tested with cyclic lateral loading applied at top of the wall. A constant axial load of approximately 0.1f$\_$ck/$.$A$\_$g/ is maintained during the testing. Test results show that the effective flange width increases with increasing drift level, such that the entire overhanging flange of h/3 is effective at the maximum strength level. Therefore, the use of PCI or KBC(Korean Building Code) value of h/10 is unconservative with respect to detailing at the wall web boundary.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.56-63
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• 2018

The present study examined the reversal cyclic flexural behavior of walls with jacket section approach for seismic strengthening through forming the boundary elements at both ends of the wall. The prestressed wire ropes were used for the lateral reinforcement to confine the boundary element of the wall. The main parameter investigated was the height of the jacket section for strengthening. The limit height of the strengthening jacket section was determined by comparing the moment distributions between the existing and strengthened walls. Test results showed that the examined jacket section approach was significantly effective in enhancing the flexural resistance of walls, indicating 46% higher stiffness at peak strength and 210% greater work damage indicator, compared with the flexural performance of the unstrengthened wall. The ductility of the strengthened walls was insignificantly affected by the height of the jacket section when the height is greater than twice the wall length. The flexural capacity of the strengthened walls was 22% higher than the predictions obtained using the equivalent stress block specified in ACI 318-14.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.5
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• pp.455-468
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• 2013

In recent, various types of steel pipe-roof methods, which is reinforced by mortar after propulsion of steel pipe into the ground, have been used for the construction of trenchless underpass. Integrated steel pipe-roof has flexural stiffness and can resist against overburden load and reduce the stress acting on the concrete underpass structures. Due to arching effect, vertical and horizontal stress distribution around the steel pipe-roof is changing. In this study, therefore, the characteristic of stress distribution around the underpass induced by the construction of integrated steel pipe-roof is investigated by using numerical method. To examine the soil-structure interaction, interface element is introduced. Results show that vertical stress acting on the concrete structure placing inside the steel pipe-roof is significantly reduced due to arching effect and flexural stiffness of integrated steel pipe-roof. Design load can be reduced and effective design of underpass will be available if the earth pressure reduction due to arching effect is considered in the design stage.

• Journal of Korean Society of Steel Construction
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• v.13 no.3
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• pp.265-277
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• 2001

This paper present a study on the flexural behavior of composite slabs using the flat-type profiled(ACE-DECK) steel deck plate which are developed recently. Forty eight composite slabs with different thickness, span, shear span and deck profile were tested to evaluate the flexural capacity and compared to the existing traperzodial deck profiles (KEM, ALPHA-DECK) According to the experiment results, flat-type profiled steel deck plate indicates more excellent capacity than existing traperzodial deck profiles in strength, stiffness, and ductility. The equation proposed by ASCE code for the effective moment of inertia are more acceptable than the equation proposed by ACI code. Thus, in this paper, test results are summarized by strength, stiffness, and deformation capacity for the specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.349-352
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• 2008

The research conducts a four-point loading test by making two reinforced concrete beams(HSCC test specimen and conventional concrete test specimen) in order to apply an HSCC with a normal strength(30MPa) to a structure. Also, it compares and analyzes the characteristics of the flexural behavior of HSCC and conventional concrete. The stiffness and ductility of the test specimens of HSCC and conventional concrete show similar behavior, but HSCC is more effective in crack control than conventional concrete. The result of the research demonstrates that HSCC can be applied in the construction site.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.54-58
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• 2008

The structural intensities have been applied to understand a source point and the path of vibrational energy flows in interested structures by many researchers. In this paper, a feasibility study was carried out to investigate the characteristics of a damaged beam with a inflicted open crack using the structural intensities. The damaged beam was taken as a continuous system with equivalent bending stiffness and the flexural vibrations were only considered in numerical simulation and experiments. A four(4)-transducer array was used to measure the flexural vibrations of the beam and the structural intensities were estimated by means of cross spectral density method. As a result, the magnitude changes of the structural intensities could be observed in the vicinity of the damage location and a damage index was newly proposed to identify the damage zone. It has been confirmed that the measurement of the structural intensities was simple and effective method to find out the damage zone.

• Steel and Composite Structures
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• v.8 no.4
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• pp.313-328
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• 2008

This study attempts to suggest bending reinforcement method by applying bending reinforcement to composite profile beam in which the concept of prefabrication is introduced. Profile use can be in place of framework and is effective in improvement of shear and bending strength and advantageous in long-term deflection. As a result of experiment, MPB-CB2 with improved module had higher strength and ductility than the previously published MPB-CB and MPB-LB. In case of bending reinforcement with deformed bar and built-up T-shape section based on MPB-CB2, the MPB-RB series reinforced with deformed bar were found to have higher initial stiffness, bending strength and ductility than the MPB-RT series. The less reinforcement effect of the MPB-RT series might be caused by poor concrete filling at the bottom of the built-up T-shape. In comparison between theoretical values and experimental values using minimum yield strength, the ratio between experimental value and theoretical value was shown to be 0.9 or higher except for MPB-RB16 and MPB-RT16 that have more reinforcement compared to the section, thus it is deemed that the reinforced modular composite profiled beam is highly applicable on the basis of minimum yield strength.

• Structural Engineering and Mechanics
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• v.84 no.3
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• pp.361-373
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• 2022

This paper examines the flexural performance of concrete beams reinforced with glass fibre-reinforced polymer (GFRP) bars under fatigue loading. Experiments were carried out on concrete beams of size 1500×200×100 mm reinforced with 10 mm and 13 mm diameter GFRP bars under fatigue loading. Experimental investigations revealed that fatigue loading affects both strength and serviceability properties of GFRP reinforced concrete. Experimental results indicated that (i) the concrete beams experienced increase in deflection with increase in number of cycles and failed suddenly due to snapping of rebars and (ii) the fatigue life of concrete beams drastically decreased with increase in stress level. Analytical model presented a procedure for predicting the deflection of concrete beams reinforced with GFRP bars under cyclic loading. Deflection of concrete beams was computed by considering the aspects such as stiffness degradation, force equilibrium equations and effective moment of inertia. Nonlinear finite element (FE) analysis was performed on concrete beams reinforced with GFRP bars. Appropriate constitutive relationships for concrete and GFRP bars were considered in the numerical modelling. Concrete non linearity has been accounted through concrete damage plasticity model available in ABAQUS. Deflection versus number of cycles obtained experimentally for various beams was compared with the analytical and numerical predictions. It was observed that the predicted values are comparable (less than 20% difference) with the corresponding experimental observations.