• Steel and Composite Structures
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• v.46 no.4
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• pp.539-551
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• 2023

In order to study the fire resistance of castellated composite beams with ortho-hexagonal holes and different beam-end restraints, temperature rise tests with constant load were conducted on full-scale castellated composite beams with ortho-hexagonal holes and hinge or rigid joint constraints to investigate the temperature distribution, displacement changes and failure patterns of castellated composite beams with two different beam-end constraints during the whole course of fire. The results show that (1) During the fire, the axial pressure and horizontal expansion deformation generated in the rigid joint constrained composite beam were larger than those in the hinge joint constrained castellated composite beam, and their maximum horizontal expansion displacements were 30.2 mm and 17.8 mm, respectively. (2) After the fire, the cracks on the slab surface of the castellated composite beam with rigid joint constraint were more complicated than hinge restraint, and the failure more serious; the lower flange and web at the ends of the castellated steal beams with hinge and rigid joint constraint produced serious local buckling, and the angles of the ortho-hexagonal holes at the support cracked; the welds at both ends of the castellated composite beam with rigid joint constraint cracked. (3) Based on the simplified calculation method of solid-web composite beam, considering the effect of holes on the web, this paper calculated the axial force and displacement of the beam-end constrained castellated composite beams under fire. The calculation results agreed well with the test results.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.3
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• pp.34-40
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• 2010

In this study, vibration characteristics of reinforced concrete slab in large span educational facilities were evaluated. A 21.75m X 14.4m full scale reinforced concrete slab specimen was constructed with pre-flex hybrid beams. Vibrations were generated by three different methods such as free falling method of a 6kg sand bag, a 70kg person walking method and impact method by impulse hammer. Vibrations were generated more than 3 times at single location. Vibration characteristic data were collected by SA390 signal analyzer machine at 5 different locations.

• 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.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.115-122
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• 2008

Ductility is important in the design of reinforced concrete structures. In seismic design of reinforced concrete members, it is necessary to allow for relatively large ductility so that the seismic energy is absorbed to avoid shear failure or significant degradation of strength even after yielding of reinforcing steels in the concrete member occurs. Therefore, prediction of the ductility should be as accurate as possible. The principal aim of this paper is to present the basic data for the ductility evaluation of reinforced high-strength concrete beams. Accordingly, 23 flexural tests were conducted on full-scale structural concrete beam specimens having concrete compressive strength of 40, 60, and 70MPa. The test results were then reviewed in terms of flexural capacity and ductility. The effect of concrete compressive strength, web reinforcement ratio, tension steel ratio, and shear span to beam depth ratio on ductility were investigated experimentally.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.289-294
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• 1996

This paper persents the assessment of the minimum shear reinforcement requirements in normal, medium and high-strength reinforced concrete beams. Twelve shear tests were conducted on full-scale beam specimens having design concrete compressive strengths of 35, 70 and 100 MPa. Different amounts of minimum shear reinfrocement were investigated, including the amounts required by Korean Concrete Standard (KCI88), JCI86, ACI89 (revised 1992) and CSA94 standard. The performance of the different amounts of shear reinforcement are discussed in terms of the shear capacity, the ductility and the crack control at service load levels. An assessment of code provisions for minimum shear reinforcememt, and the prediction and comparison of the ultimate shear capacity are also presented.

• Coupled systems mechanics
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• v.6 no.4
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• pp.501-522
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• 2017

This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis.

• Steel and Composite Structures
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• v.42 no.5
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• pp.671-683
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• 2022

To investigate and predict the long-term time-dependent behavior, such as creep, shrinkage, and relaxation of PS strands, and prestress loss in prestressed steel-concrete composite beams, named Precom, full-scale tests were conducted and the collected data were compared with those obtained from the two proposed analytical models. The combined effective modulus method (EMM)-empirical model proposed with a flowchart considered the creep effect to determine the prestress loss. Conversely, the age-adjusted effective modulus method (AEMM) with CEB-FIP equation was developed to account for the concrete aging. The results indicated that the AEMM with CEB-FIP model predicts the long-term behavior of Precom effectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.851-854
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• 2008

Using the recycled aggregate not only saves landfill space but also reduces the demand for extraction of natural raw material for new construction activity. However few investigations have been carried out to study the shear behaviors of RC beams with recycled aggregates such as low absorption of recycled aggregate and full-scale specimens. In this study, six reinforced concrete beams were tested to evaluate the effects of shear strength, and shear behavior on the replacement level (0, 30, 60, and 100%) of recycled coarse aggregate and different amounts of shear reinforcement. The results showed that the beams with recycled coarse aggregates present the similar shear strength and deflections as the beam with natural aggregate on an equal amount of shear reinforcement. the reinforced concrete beams with recycled coarse aggregates present the Influence of shear span-to-depth ratio, effective depth, tension reinforcement ratio and compressive strength as the beams with natural aggregate. Shear strength were compared with the provisions in current code (KCI2007) and the equation proposed by Zsutty. The KCI equations were conservative and subsequently can be used for the shear design of recycled aggregate concrete beam.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.413-423
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• 2007

Slimfloor composite-beam systems could considerably reduce the story height of a building if the steel beam would be installed deep into the concrete floor slab. However, as the depth of the steel beam's installation is limited, it cannot cope with the various demands of building systems. To address this problem, a profiled steel beam section that can control the depth of the steel beam's and slabs' installation was developed in this study. Presented herein are the results of an experiment that was conducted focusing on the flexural behavior of the partially connected composite beams with profiled steel beams encased in composite concrete slabs. Five full-scale specimens with different slab types, with or without shear connection and reinforcement bars, were constructed and tested in this study. As a result, the shear bond stress without an additional shear connection was found to be $0.20{\sim}0.76N/mm^2$due to the inherent mechanical and chemical bond stress.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.385-397
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• 2023

This study presents an experiment and analysis to compare the seismic behavior of full-scale reinforced concrete beam-column joint strengthened by prestressed steel strips, externally bonded steel plate, and CFRP sheets. For experimental investigation, five specimens, including one joint without any retrofitting, one joint retrofitted by externally bonded steel plate, one joint retrofitted by CFRP sheets, and two joints retrofitted by prestressed steel strips, were tested under cyclic-reserve loading. The failure mode, strain response, shear deformation, hysteresis behavior, energy dissipation capacity, stiffness degradation and damage indexes of all specimens were analyzed according to experimental study. It was found that prestressed steel strips, steel plate and CFRP sheets improved shear resistance, energy dissipation capacity, stiffness degradation behavior and reduced the shear deformation of the joint core area, as well as changed the failure pattern of the specimen, which led to the failure mode changed from the combination of flexural failure of beams and shear failure of joints core to the flexural failure of beams. In addition, the beam-column joint retrofitted by steel plate exhibited a high bearing capacity, energy consumption capacity and low damage index compared with the joint strengthened by prestressed steel strip, and the prestressed steel strips reinforced joint showed a high strength, energy dissipation capacity and low shear deformation, stirrups strains and damage index compared to the CFRP reinforced joint, which indicated that the frame joints strengthened with steel plate exhibited the most excellent seismic behavior, followed by the prestressed steel strips.