• KCI Concrete Journal
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• 제12권2호
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• pp.73-84
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• 2000

A new form of construction utilizing structural steel as the boundary elements in ductile flexural concrete walls is proposed to solve the bar congestion problems in such a heavily reinforced region, while maintaining the ductility and energy absorption capacity comparable to their traditional form. Two wall specimens containing rectangular hollow structural sections (HSS) and channels at their ends respectively, and one companion standard reinforced concrete wall specimen with concentrated end reinforcement were constructed and tested under reversed cyclic loading to evaluate the construction process as well as the structural performance. Initially, all three specimens were chosen and detailed with some caution to have approximately the same flexural capacity without change of the original shape and dimension of a rectangular cross section correction. Analysis and comparison of test results indicated that the reversed cyclic responses of three walls showed similar hysteretic properties, but in those with steel boundaries, local buckling of the corresponding steel webs and flanges following significant yielding was a dominant factor to determine the hysteretic response. The monotonic and cyclic responses predicted based on a sectional approach was also presented and found to be in good agreement with measured results. Design recommendations considering local instability of the structural steel elements and the interaction between steel chords and a concrete web member in such a composite wall are presented.

• Advances in concrete construction
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• 제4권3호
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• pp.161-172
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• 2016

An experimental investigation was carried out on the strength and behavior plain and fiber reinforced geopolymer concrete beam column joints and the results were compared with plain and steel fiber reinforced conventional concrete beam column joints. The volume fraction of fibers used was 0.5%. A total of six Geopolymer concrete joints and four conventional concrete joints were cast and tested under reversed cyclic loading to evaluate the performance of the joints. First crack load, ultimate load, energy absorption capacity, energy dissipation capacity stiffness degradation and moment-curvature relation were evaluated from the test results. The comparison of test results revealed that the strength and behavior of plain and fiber reinforced geopolymer concrete beam column joints are marginally better than corresponding conventional concrete beam column joints.

• Computers and Concrete
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• 제13권2호
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• pp.221-234
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• 2014

A nonlinear finite element analysis using ANSYS is used to evaluate the seismic behavior of reinforced concrete exterior beam-column joints. The behavior of the finite element models under cyclic loading is compared with the experimental results. Two beam-column joint specimens (SH and SHD) with square hoop confinement in joint and throughout the column with detailing as per IS 13920 are studied. The specimen SHD was provided with additional diagonal bars from column to beam to relocate the plastic hinge formation from beam-column interface. The load-displacement relationship, joint shear stress and strain in beam obtained from numerical study showed good agreement with the experimental results. This investigation proves that seismic behaviour of reinforced concrete beam-column joints under reversed cyclic loading can be evaluated successfully using finite element modeling and analysis.

• Structural Engineering and Mechanics
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• 제70권2호
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• pp.133-141
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• 2019

The aim of the present paper is to present the cyclic behavior of strengthened reinforced concrete shear wall test specimen, which was reinforced with cold drawn welded wire mesh fabric. Two reinforced concrete shear wall specimens have been tested in the present study. The walls were tested under reversed cyclic loading with loading applied near the tip of the walls. The control wall is tested in its original state to serve as a baseline for the evaluation of the repair and strengthening techniques. The two test specimens include a control wall and a repaired wall. The control wall test specimen was designed and detailed to simulate non-ductile reinforced concrete shear walls that do not meet the modern seismic provisions. The response of the original wall was associated with the brittle failure. The control shear wall was repaired by addition of the reinforcements and the concrete and then it was reloaded. The effectiveness of the repair technique was investigated. Test results indicate that there can be a near full restoration of the walls' strength. The data from this test, augmenting other data available in the literature, will be useful in calibrating improved analytical methods as they are developed.

• 콘크리트학회논문집
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• 제19권4호
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• pp.411-420
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• 2007

본 연구는 반복 수평 하중을 받는 외부 보-기둥 접합부에서 작은 헤드를 사용한 headed bar의 사용성을 검증하기 위해 $90^{\circ}$ 표준갈고리로 정착한 실험체와 headed bar로 정착한 접합부 실험체를 제작하여 각각의 실험 결과를 비교하였다. 또한, headed bar 정착 성능에 영향을 주는 헤드 단면적, 단조 및 반복 가력 여부, 헤드와 보강근의 용접 여부등의 headed bar 인발 성능에 관한 영향을 구명하기 위한 인발실험을 병행하였다. 인발실험의 결과, headed bar의 인발강도는 헤드 면적 증가에 따라 증가하였고, 헤드와 보강근의 용접 유무, 가력 조건 (단조하중 및 반복하중)은 실험 결과에 큰 영향을 미치지 않는 것으로 나타났다. 외부 보-기둥 접합부 실험의 결과, $90^{\circ}$ 표준갈고리로 정착한 실험체와 headed bar로 정착한 실험체가 초기 균열, 균열의 발생 등 모두 거의 비슷한 양상이었으나, 최종 파괴 시에는 headed bar로 정착된 실험체가 $90^{\circ}$ 표준갈고리로 정착된 실험체에 비해 최대 강도 도달 이후 연성 거동, 연성비 및 변형 성능, 에너지소산 면적 등에서 우수한 거동을 보여주었다. 따라서 ACI 352 위원회의 설계지침을 따라서 제작된 접합부 상세와 동일한 조건으로 표준갈고리 대신 상대적으로 작은 headed bar를 사용할 수 있을 것으로 판단된다.

• Steel and Composite Structures
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• 제21권4호
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• pp.703-753
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• 2016

The ratcheting behavior was studied experimentally for Z2CND18.12N elbow piping under cyclic bending and steady internal pressure. Dozens of cyclic plasticity models for structural ratcheting responses simulations were used in the paper. The four models, namely, Bilinear (BKH), Multilinear (MKIN/KINH), Chaboche (CH3), were already available in the ANSYS finite element package. Advanced cyclic plasticity models, such as, modified Chaboche (CH4), Ohno-Wang, modified Ohno-Wang, Abdel Karim-Ohno and modified Abdel Karim-Ohno, were implemented into ANSYS for simulating the experimental responses. Results from the experimental and simulation studies were presented in order to demonstrate the state of structural ratcheting response simulation by these models. None of the models evaluated perform satisfactorily in simulating circumferential strain ratcheting response. Further, improvement in cyclic plasticity modeling and incorporation of material and structural features, like time-dependent, temperature-dependent, non-proportional, dynamic strain aging, residual stresses and anisotropy of materials in the analysis would be essential for advancement of low-cycle fatigue simulations of structures.

• Earthquakes and Structures
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• 제8권3호
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• pp.555-572
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• 2015

This paper presents an experimental study of three two-dimensional (2D/planar) steel reinforced concrete (SRC) T-shaped column-RC beam hybrid joints and six 3D SRC T-shaped column-steel beam hybrid joints under low cyclic reversed loads. Considering different categories of steel configuration types in column cross section and horizontal loading angles for the specimens were selected, and a reliable structural testing system for the spatial loading was employed in the tests. The load-displacement curves, carrying capacity, energy dissipation capacity, ductility and deformation characteristics of the test subassemblies were analyzed. Especially, the seismic performance discrepancies between planar hybrid joints and 3D hybrid joints were intensively compared. The failure modes for planar loading and spatial loading observed in the tests showed that the shear-diagonal compressive failure was the dominating failure mode for all the specimens. In addition, the 3D hybrid joints illustrated plumper hysteretic loops for the columns configured with solid-web steel, but a little more pinched hysteretic loops for the columns configured with T-shaped steel or channel-shaped steel, better energy dissipation capacity & ductility, and larger interlayer deformation capacity than those of the planar hybrid joints. Furthermore, it was revealed that the hysteretic loops for the specimens under $45^{\circ}$ loading angle are generally plumper than those for the specimens under $30^{\circ}$ loading angle. Finally, the effects of steel configuration type and loading angle on the seismic damage for the specimens were analyzed by means of the Park-Ang model.

• Steel and Composite Structures
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• 제20권6호
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• pp.1205-1219
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• 2016

This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the self-centering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.

• Structural Engineering and Mechanics
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• 제41권6호
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• pp.691-710
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• 2012

One of the most popular and commonly used strengthening techniques to protect against earthquakes is to infill the holes in reinforced concrete (RC) frames with fully reinforced concrete infills. In some cases, windows and door openings are left inside infill walls for architectural or functional reasons during the strengthening of reinforced concrete-framed buildings. However, the seismic performance of multistory, multibay, reinforced concrete frames that are strengthened by reinforced concrete wing walls is not well known. The main purpose of this study is to investigate the experimental behavior of vulnerable multistory, multibay, reinforced concrete frames that were strengthened by introducing wing walls under a lateral load. For this purpose, three 2-story, 2-bay, 1/3-scale test specimens were constructed and tested under reversed cyclic lateral loading. The total shear wall (including the column and wing walls) length and the location of the bent beam bars were the main parameters of the experimental study. According to the test results, the addition of wing walls to reinforced concrete frames provided significantly higher ultimate lateral load strength and higher initial stiffness than the bare frames did. While the total shear wall length was increased, the lateral load carrying capacity and stiffness increased significantly.

• Smart Structures and Systems
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• 제19권5호
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• pp.473-485
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• 2017

Ratcheting behavior of $90^{\circ}$ elbow piping subject to internal pressure 20 MPa and reversed bending 20 kN was investigated using experimental method. The maximum ratcheting strain was found in the circumferential direction of intrados. Ratcheting strain at flanks was also very large. Moreover, the effect of temperature on ratcheting strain of $90^{\circ}$ elbow piping was studied through finite element analysis, and the results were compared with room condition ($25^{\circ}$). The results revealed that ratcheting strain of $90^{\circ}$ elbow piping increased with increasing temperature. Ratcheting boundary of $90^{\circ}$ elbow piping was determined by Chaboche model combined with C-TDF method. The results revealed that there was no relationship between the dimensionless form of ratcheting boundary and temperature.