• Architectural research
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• v.2 no.1
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• pp.55-60
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• 2000

Recently, there is a great demand for precast reinforced concrete (RC) construction methods on the purpose of simplicity in construction. Nishimatsu Construction Company has developed a construction method with precast reinforced concrete members in medium-rise building. In this construction method, how to joint precast members, especially the anchorage of the main bar of beam, is important problem. In this study, the structural performance of exterior joints with precast members was investigated. The parameters of the test specimens are anchorage type of the main bar of beam (U-shape anchorage or anchorage plate) and the ratio of the column axial force to the column strength. Specimens J-3 and J-4 used U-shape anchorage and the ratio of the column axial force of specimen J-4 was higher. On the other hand, specimens J-5 and J-6 used anchorage plate, and the anchorage lengths are 15d and 18d, respectively. Experimental results are summarized as follows; 1) For the joints with beam flexural failure mode, it was found that the maximum strength of specimen with anchorage plate is equal to or larger than that of specimen with conventional U-shaped anchorage if the anchorage length of more than 15d would be ensured, 2) Each specimen shows stable hysteretic curves and there were no notable effects on the hysteretic characteristics and the maximum strength caused by the anchorage method of beam main bar and the difference of column axial stress level.

• Journal of Korean Society of Steel Construction
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• v.9 no.1 s.30
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• pp.107-120
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• 1997

The purpose of this study is to develop composite structural system which is to have versatility in plan design and to improve economical efficieney, to maximise structural capacity than existing structural system. In this viewpoint, it was investigated to the properties of structural behaviors for i oint consisting of concrete filled steel square tube column and P.C reinforced concrete beam through a series of hysteretic behavior experiment. In the previous report, researched to the properties of joints with key parameters. such as Axial Force ratio and section types. From the based on previous results, this study investigated the properties of this joints with key parameters, such as strength of concrete, size of panel zone and Axial Force ratio. The obtained results are summarised as follows. (1) Investigating for the failure mode of the beam-to-column joint, the specimens of S,LL and LH series(except for L5H) presented flexural failure mode. (2) The initial stiffness of joint was increasd as the decrease of axial force ratio and increase of the concrete strength. (3) The rotation resisting capacity was effective as the increment of the concrete strength and decrement of the axial force ratio. (4) The emprical formula to predict the ultimate capacity of joint model to introduce decrease coefficient according to the axial force ratio to superimpose shearing strength of steel web(H section) and bending strength of reinforced concrete beam was expected.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.291-298
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• 2017

The objective of the present study is to evaluate the cyclic flexural behavior of a hybrid H-steel-reinforced concrete (HSRC) beam at the connection with a H-steel column. The test parameter investigated was the configuration of dowel bars at the joint region of the HSRC beam. The HSRC beam was designed to have plastic hinge at the end of the H-steel beam rather than the RC beam section near the joint. All specimens showed a considerable ductile behavior without a sudden drop of th applied load, resulting in the displacement ductility ratio exceeding 4.6, although an unexpected premature welding failure occurred at the flanges of H-steel beams connecting to H-steel column. The crack propagation in the RC beam region, flexural strength, and ductility of HSRC beam system were insignificantly affected by the configuration of dowel bars. The flexural strength of HSRC beam system governed by the yielding of H-steel beam could be conservatively evaluated from the assumption of a perfect plasticity state along the section.

• Steel and Composite Structures
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• v.22 no.1
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• pp.141-159
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• 2016

Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (B/t) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.631-639
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• 2013

Non-linear finite element analysis for newly developed precast concrete details for beam-to-column connection which can be used in moderate seismic region was carried out in this study. Developed precast system is based on composite structure and which have steel tube in column and steel plate in beam. Improving cracking strength of joint under reversed cyclic loading, joint area was casted with ECC (Engineering Cementitious Composites). Since this newly developed precast system have complex sectional properties and newly developed material, new analysis method should be developed. Using embedded elements and models of non-linear finite element analysis program ABAQUS previously tested specimens were successfully analyzed. Analysis results show comparatively accurate and conservative prediction. Using finite element model, effect of axial load magnitude and flexural strength ratio were investigated. Developed connection have optimized performance under axial load of 10~20% of compressive strength of column. Plastic hinge was successfully developed with flexural strength ratio greater than 1.2.

• Journal of Construction Engineering and Project Management
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• v.7 no.4
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• pp.13-19
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• 2017

This study is based on the use and performance of bamboo reinforcements in construction of low-cost structures. This study investigated the physical and mechanical properties of bamboo reinforcements. Bamboo reinforced concrete beam specimens were tested with different reinforcement ratios and observed the load capacity, deflection and failure patterns. It was observed that, flexural strength of bamboo reinforced column is sufficient higher than plain cement concrete and comparable to steel reinforced concrete beams. Bamboo reinforced concrete columns with different reinforcement ratio also tested and observed the ultimate compressive strength and failure pattern. It found, all columns failed in a similar pattern due to crushing of concrete. According to cost analysis, bamboo reinforced beams and columns with moderate reinforcement ratio showed the best strength-cost ratio among plain cement concrete and steel reinforced concrete.

• Steel and Composite Structures
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• v.39 no.3
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• pp.337-352
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• 2021

The study presented experimental and numerical investigation on the seismic performance of steel reinforced concrete (SRC) L-shaped column- reinforced concrete (RC) beam joints. Various parameters described as steel configuration form, axial compressive ratio, loading angle, and the existence of slab were examined through 4 planar joints and 7 spatial joints. The characteristics of the load-displacement response included the bearing capacity, ductility, story drift ratio, energy-dissipating capacity, and stiffness degradation were analyzed. The results showed that shear failure and flexural failure in the beam tip were observed for planar joints and spatial joint, respectively. And RC joint with slab failed with the plastic hinge in the slab and bottom of the beam. The results indicated that hysteretic curves of spatial joints with solid-web steel were plumper than those with hollow-web specimens. The capacity of planar joints was higher than that of space joints, while the opposite was true for energy-dissipation capacity and ductility. The high compression ratio contributed to the increase in capacity and initial stiffness of the joint. The elastic and elastic-plastic story deformation capacity of L-shaped column frame joints satisfied the code requirement. A design formula of joint shear resistance based on the superposition theory and equilibrium plasticity truss model was proposed for engineering application.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.361-373
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• 2014

As the height and beam span of buildings built in the construction market increase, increasingly higher quality is being required of the construction materials. In response to this trend, 800MPa tensile strength class steel was developed in domestic company. Currently, experiments applying flexural member, compression member, and connections are continuously conducted, but a design guideline for high strength steel has yet to be established. Among those construction materials, for the high strength steel beam-to-column connections, the evaluation of implementing ductile connections for the high strength steel beam-to-column connections is producing pessimistic results and the number of related researches is inadequate because of the high yield ratio, which is the characteristic of high strength steel. This study on implementation of ductile connections made of high strength steel was conducted using the connection detail as the variable, for the purpose of enhancing the deformation capacity of high strength steel beam-to-column connections. Cyclic loading test and nonlinear finite element analysis were conducted with full-scale mock-up connection models with the applied connection details. As a result, the structural performance of high-strength steel beam-to-column connection with presented detail was contented with demand of Special Moment Frames of KBC standard.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.387-395
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• 2000

The purpose of this research is to evaluate the capacity of strength and plastic deformation of those members, and provide experimental data on the seismic behavior of these members as a basis for developing guidelines for designing seismically resistant concrete-filled steel tubular columns. Eighteen cantilever-type specimens were tested under constant axial load and cyclically lateral load as models of bottom columns in high-rise building. The parameters studied in the test program included, are width-thickness ratio of steel tube, slenderness ratio (Lo/D) and axial force ratio. From the test results, the effects of parameters on the strength, the deformation capacity, energy absorption capacity are discussed. The specimen flexural capacity under combined axial and lateral loading was found to be almost accurately predicted by criteria AIJ and AISC-LRFD providing conservative results. Therefore KSSC for encased composite column can be applied to the concrete filled column if composite section and elastic modulus are modified according to AIJ and AISC-LRFD. Finally, the proposed flexural capacity considering confinement effects is a food agreement on the tests results.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.53-56
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• 2008

Reinforced concrete rahmen structures has been required ductility as well as strength of beam-column joint in seismically hazard area. Some investigations have been presented for retrofitting and/or strengthening structural elements in structure. Strain-hardening cementitious composite(SHCC) has been expected excellent reinforcement performance in beam-column joint area. The properties of reinforcing fiber, as tensile strength, aspect ratio and elastic moudulus, have great effect on the fracture behavior of SHCC. The purpose of this experimental study is to evaluate structural performance of exterior reinforced concrete beam-column joint strengthened with SHCC under cyclic loading.