• 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.

• Computers and Concrete
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• v.16 no.3
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• pp.357-380
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• 2015

In this study, a simple indeterminate strut-tie model which reflects complicated characteristics of the ultimate structural behavior of continuous reinforced concrete deep beams was proposed. In addition, the load distribution ratio, defined as the fraction of applied load transferred by a vertical tie of truss load transfer mechanism, was proposed to help structural designers perform the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie was introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete were reflected upon. To verify the appropriateness of the present study, the ultimate strength of 58 continuous reinforced concrete deep beams tested to shear failure was evaluated by the ACI 318M-11's strut-tie model approach associated with the presented indeterminate strut-tie model and load distribution ratio. The ultimate strength of the continuous deep beams was also estimated by the experimental shear equations, conventional design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the proposed strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables. The present study associated with the indeterminate strut-tie model and load distribution ratio evaluated the ultimate strength of the continuous deep beams fairly well compared with those by other approaches. In addition, the present approach reflected the effects of the primary design variables on the ultimate strength of the continuous deep beams consistently and reasonably. The present study may provide an opportunity to help structural designers conduct the rational and practical strut-tie model design of continuous deep beams.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.52-57
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• 2018

The pile construction method is changing from the pile driving operation to the injected precast pile method. It is to prevent environmental damage and to minimize complaints caused by noise. Therefore, economic alternatives optimized for the injected precast pile method are required. In this study, the enhanced spun reinforced concrete piles manufactured by high strength materials were proposed. Experimental tests were conducted to evaluate their structural safety and nonlinear finite element analysis was performed to improve the reliability of experimental results. The experimental results and the analytical results were in good agreement with each other and the proposed enhanced spun reinforced concrete pile has better performance than that required by the design. However, the performance of the joint using the existing method used in the PHC pile was considered to be insufficient.

• Advances in concrete construction
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• v.8 no.4
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• pp.321-333
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• 2019

The present study targets to access the consequence of utilization of coarse aggregates retrieved from waste concrete as a substitution of coarse fraction of natural aggregates and silica nano-particles as partial substitution of cement using principles of factorial design. Furthermore, procedures of design of experiments are employed to examine the effect of use of recycled aggregates and nano-silica. In this investigation, compressive strength found after at 7, 28, 90 and 365 days, split and flexural tensile strength, ultrasonic pulse velocity and rebound number and are chosen as responses, whereas the percentages of recycled coarse aggregates (RCA%) and nano-silica (NS(%)) are selected as factors. Analysis of Variance has been conducted on the experimental results for the selected responses with consideration the both factors, which indicates that RCA (%) and NS (%) have substantial impact on the various responses. However, the present analysis depicts that interaction between factors has considerable effect on the chosen parameters of concrete. Furthermore, validation experiments are carried to validate these models for compressive and tensile strength for 100% RCA and 1% NS. The results of comparative study indicates that that the error of the estimation determined using the relevant models are found to be small (±5%) in comparison with the analogous experimental results, which authenticates the calculated models.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.165-173
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• 2003

The purpose of this paper is to analysis of initial behavior of concrete pavement with initial measurement strain gauge for concrete pavement at field, and to investigate the field test results for field applicability testing. The early-age behaviors of concrete pavement slabs were measured using the strain gauges. From the slab depths and positions, the outputs from each gauges were recorded at initial curing period. The initial measurement of concrete pavement and check of crack at the joint were performed, the results could be summarized as follows. From the results of concrete strength, compressive strength and flexural strength were showed $271kgf/cm^2$, $43kgf/cm^2$ respectively. From the tests of early-age strain measurement, it was found that the strain varied at the maximum value of $150{\mu}{\varepsilon}$ and early behavior of concrete slab was showed a tensile strain. However, for long-term was showed a compressive strain due to dry-shrinkage.

• Journal of Korean Association for Spatial Structures
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• v.5 no.1 s.15
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• pp.99-105
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• 2005

The pushover analysis is becoming a popular tool for seismic design of building structures. In this paper the state-of-art on static nonlinear analysis of building structures is presented with the emphasis on the effects of analysis parameters; i. e., lateral load patterns, modeling of members, and analysis computer programs. The analysed results may have variation even if a same structure is analysed. This paper is to investigate how large the variation is and what the main causes of the variation are. The difference of analysed results, the resultant variation of lateral story shear force and flexural strength of structural members are discussed. The pushover analysis procedure are routinely used in the seismic design of building structures, but some problems must yet be clarified, such as the effects to evaluate the parameters of analysis on the basis of a lateral load patterns and modeling of members.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.103-110
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• 2004

The pushover analysis is becoming a popular tool for seismic design of building structures. In this paper the state-of-art on static nonlinear analysis of building structures is presented with the emphasis on the effects of analysis parameters; i. e., lateral load patterns, modeling of members, and analysis computer programs. The analysed results may have variation even if a same structure is analysed. This paper is to investigate how large the variation is and what the main causes of the variation are. The difference of analysed results, the resultant variation of lateral story shear force and flexural strength of structural members are discussed. The pushover analysis procedure are routinely used in the seismic design of building structures, but some problems must yet be clarified, such as the effects to evaluate the parameters of analysis on the basis of a lateral load patterns and modeling of members.

• International Journal of High-Rise Buildings
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• v.13 no.1
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• pp.85-95
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• 2024

A composite member made of concrete-filled steel tubes (CFT columns) has been recognized for its fire resistance due to the thermal mass effect of concrete inside the steel tube, as shown in various studies. In this study, the fire resistance performance of reinforced CFT columns under constant axial load was evaluated using finite element analysis with ABAQUS. For this purpose, the variables including cross-section size, steel tube thickness, and concrete cover thickness were set, and the temperature distribution in the column cross-section exposed to a standard fire was investigated using heat transfer analysis. Ultimately, a P-M interaction curve was obtained by evaluating the overall residual strength of columns, and the fire resistance time was determined by evaluating axial displacement-time responses due to the reduction in load capacity during fire through stress analysis.

• Journal of the Korean Geotechnical Society
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• v.33 no.2
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• pp.5-15
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• 2017

PHC-W retaining wall method is one of the economical retaining wall methods. PHC-W pile used in PHC-W retaining wall method has special shape with flat surfaces so that the PHW-C retaining wall, with overlapped piles, shows outstanding vertical control and impermeability. In order to evaluate two types of retaining walls, numerical analysis were performed. The selection of cases depended on N values of the ground and ground properties, and two types of PHC-W retaining walls (defined as type A and B) were constructed. For a case that consists of inorganic clay and sand with less than 30 of N value, the maximum excavation depths for type A and B were respectively 10.5 m and 11.0 m. At the other case of which N value is above 30, the depths were 17.0 m and 19.5 m. From the results, it was found that maximum excavation depth, horizontal displacement, and safety factor for flexural strength of the wall were influenced by ground properties.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.39-48
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• 2015

Reinforced concrete (RC) structures strengthened with FRP materials would cause the loss of the reinforcing effect and the sudden failure of the structure due to the debonding of FRP. The debonding fracture strength of the FRP-strengthened concrete structures has been evaluated using the same strength method as applied in RC structures based on the debonding strain of FRP. However, the values of the FRP debonding strain are different according to design guidelines. Thus, this study carried out an experimental study on RC beams reinforced with GFRP and evaluated the debonding fracture strength of the strengthened beams from each design guideline. Since the debonding failure occurs prior to reaching the ultimate value of concrete compressive strain, this study accounts for the nonlinear stress distribution of concrete. This study also proposed equations that can evaluate the debonding strength of GFRP-strengthened RC beams with similar safety to the ultimate flexural strength of non-strengthened RC beams.