Compressive behavior of circular hollow and concrete-filled steel tubular stub columns under atmospheric corrosion

Shan Gao,Zhen Peng,Xuanding Wang,Jiepeng Liu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.4

This paper aims to study the compressive behavior of circular hollow and concrete-filled steel tubular stub columns under simulated marine atmospheric corrosion. The specimens after salt spray corrosion were tested under axial compressive load. Steel grade and corrosion level were mainly considered in the study. The mechanical behavior of circular CFST specimens is compared with that of the corresponding hollow ones. Design methods for circular hollow and concrete-filled steel tubular stub columns are modified to consider the effect of marine atmospheric corrosion. The results show that linear fitting curves could be used to present the relationship between corrosion rate and the mechanical properties of steel after simulated marine atmospheric corrosion. The ultimate strength of hollow steel tubular and CFST columns decrease with the increase of corrosion rate while the ultimate displacement of those are hardly affected by corrosion rate. Increasing corrosion rate would change the failure of CFST stub column from ductile failure to brittle failure. Corrosion rate would decrease the ductility indexes of CFST columns, rather than those of hollow steel tubular columns. The confinement factor <i>ξ</i> of CFST columns decreases with the increase of corrosion rate while the ratio between test value and nominal value shows an opposite trend. With considering marine atmospheric corrosion, the predicted axial strength of hollow steel tubular and CFST columns by Chinese standard agree well with the tested values while the predictions by Japanese standard seem conservative.

Transverse reinforcement for confinement at plastic hinge of circular composite hollow RC columns

Won, Deok Hee,Han, Taek Hee,Kim, Seungjun,Park, Woo-Sun,Kang, Young Jong Techno-Press 2016 Computers and Concrete, An International Journal Vol.17 No.3

Confined transverse reinforcement was arranged in a plastic hinge region to resist the lateral load that increased the lateral confinement effect in the bridge substructure. Columns increased the seismic performance through securing stiffness and ductility. The calculation method of transverse reinforcements at plastic hinges is reported in the AASHTO-LRFD specification. This specification was only proposed for solid reinforced concrete (RC) columns. Therefore, if this specification is applied for another column as composite column besides the solid RC column, the column cannot be properly evaluated. The application of this specification is particularly limited for composite hollow RC columns. The composite hollow RC column consists of transverse, longitudinal reinforcements, cover concrete, core concrete, and an inner tube inserted in the hollow face. It increases the ductility, strength, and stiffness in composite hollow RC columns. This paper proposes a modified equation for economics and rational design through investigation of displacement ductility when applying the existing specifications at the composite hollow RC column. Moreover, a parametric study was performed to evaluate the detailed behavior. Using these results, a calculation method of economic transverse reinforcements is proposed.

Seismic performances of centrifugally-formed hollow-core precast columns with multi-interlocking spirals

황진하,김강수,이득행,오재열,최승호,서수연 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.6

A precast composite column system has been developed in this study by utilizing multi interlocking spiral steel into a centrifugally-formed hollow-core precast (CHPC) column. The proposed hybrid column system can have enhanced performances in the composite interaction behavior between the hollowed precast column and cast-in-place (CIP) core-filled concrete, the lap splice performance of bundled bars, and the confining effect of concrete. In the experimental program, reversed cyclic loading tests were conducted on a conventional reinforced concrete (RC) column fabricated monolithically, two CHPC columns filled with CIP concrete, and two steelreinforced concrete (SRC) columns. It was confirmed that the interlocking spirals was very effective to enhance the structural performance of the CHPC column, and all the hollow-core precast column specimens tested in this study showed good seismic performances comparable to the monolithic control specimen.

강관으로 보강된 중공 RC 기둥의 중공비에 따른 거동

최준호,윤기용,한택희,강영종,Choi. Jun-Ho,Yoon. Ki-Yong,Han. Taek-Hee,Kang. Young-Jong 한국방재학회 2007 한국방재학회논문집 Vol.7 No.3

중공 RC 기둥은 중실 RC 기둥에 비해 자중의 감소 및 재료 절감에 대한 장점을 가진다. 그러나 중공 RC 기둥은 안쪽면의 취성파괴로 인하여 낮은 연성 거동을 할 가능성이 있다. 이러한 문제점을 해결하기 위해 중공 부재 내의 콘크리트 3축 구속 상태로 존재하게 하는 강관으로 보강된 중공 RC 기둥이 개발되었으며, 본 연구에서는 강관으로 보강된 중공 RC 기둥의 중공비를 <TEX>$0.50{\sim}0.85$</TEX>까지 변화 시켜 중공비에 따른 작용하중에 대한 안전율, 연성도, 재료비, 교각 총 중량에 대한 거동 특성을 파악하였다. The hollow RC(Reinforced concrete) column has the effect of reducing weight and materials compared to solid RC column. However, the hollow RC column shows a low ductile behavior due to brittle failure of inside concrete. To overcome this problem, the internally confined hollow reinforced concrete column has been developed. In this study, the behavior of internally confined hollow RC columns were evaluated with safety ratio, ductility, total material cost, the total weight of the pier, etc. The hollow ratio is varied from 0.50 to 0.85.

철근콘크리트 원형 교각의 전단성능에 대한 횡방향철근의 영향

고성현,Ko, Seong Hyun 한국지진공학회 2021 한국지진공학회논문집 Vol.25 No.5

In seismic design, hollow section concrete columns offer advantages by reducing the weight and seismic mass compared to concrete section RC bridge columns. However, the flexure-shear behavior and spirals strain of hollow section concrete columns are not well-understood. Octagonal RC bridge columns of a small-scale model were tested under cyclic lateral load with constant axial load. The volumetric ratio of the transverse spiral hoop of all specimens is 0.00206. The test results showed that the structural performance of the hollow specimen, such as the initial crack pattern, initial stiffness, and diagonal crack pattern, was comparable to that of the solid specimen. However, the lateral strength and ultimate displacement of the hollow specimen noticeably decreased after the drift ratio of 3%. The columns showed flexure-shear failure at the final stage. Analytical and experimental investigations are presented in this study to understand a correlation confinement steel ratio with neutral axis and a correlation between the strain of spirals and the shear resistance capacity of steel in hollow and solid section concrete columns. Furthermore, shear strength components (V_c, V_s·, V_p) and concrete stress were investigated.

Seismic shear behavior of rectangular hollow bridge columns

Mo, Y.L.,Jeng, Chyuan-Hwan,Perng, S.F. Techno-Press 2001 Structural Engineering and Mechanics, An Int'l Jou Vol.12 No.4

An analytical model incorporating bending and shear behavior is presented to predict the lateral loading characteristic for rectangular hollow columns. The moment-curvature relationship for the rectangular hollow sections of a column is firstly determined. Then the nonlinear lateral load-displacement relationship for the hollow column can be obtained accordingly. In this model, thirteen constitutive laws for confined concrete and five approaches to estimate the shear capacity are used. A series of tests on 12 model hollow columns aimed at the seismic shear behavior are reported, and the test data are compared to the analytical results. It is found that the analytical model reflects the experimental results rather closely.

Seismic Performance Assessment of Hollow Reinforced Concrete and Prestressed Concrete Bridge Columns

Tae-Hoon Kim,Dai-Jeong Seong,Hyun Mock Shin 한국콘크리트학회 2012 International Journal of Concrete Structures and M Vol.6 No.3

The aim of this study is to assess the seismic performance of hollow reinforced concrete and prestressed concrete bridge columns, and to provide data for developing improved seismic design criteria. By using a sophisticated nonlinear finite element analysis program, the accuracy and objectivity of the assessment process can be enhanced. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), is used to analyze reinforced concrete and prestressed concrete structures. Tensile, compressive and shear models of cracked concrete and models of reinforcing and prestressing steel were used to account for the material nonlinearity of reinforced concrete and prestressed concrete. The smeared crack approach was incorporated. The proposed numerical method for the seismic performance assessment of hollow reinforced concrete and prestressed concrete bridge columns is verified by comparing it with the reliable experimental results. Additionally, the studies and discussions presented in this investigation provide an insight into the key behavioral aspects of hollow reinforced concrete and prestressed concrete bridge columns.

Boundary Conditions and Fire Behavior of Concrete Filled Tubular Composite Columns

Rodrigues, Joao Paulo C.,Correia, Antonio J.M.,Kodur, Venkatesh Council on Tall Building and Urban Habitat Korea 2018 International journal of high-rise buildings Vol.7 No.4

Concrete-filled steel tubular (CFST) members are commonly used as composite columns in modern construction. However, the current guidelines for members' fire design (EN1994-1-2) have been proved to be unsafe in case the relative slenderness is higher than 0.5. In addition, the simplified design methods of Eurocode 4 are limited to circular and square CFST columns, while in practice columns with rectangular and elliptical hollow sections are being increasingly used because of their architectural aesthetics. In the last years a large experimental research has been carried out at Coimbra University on the topic. They have been tested concrete filled circular, square, rectangular and elliptical hollow columns with restrained thermal elongation. Some parameters such as the slenderness, the type of cross-section geometry as well as the axial and rotational restraint of the surrounding structure to the column have been tested in order to evaluate their influence on the fire resistance of such columns. In this paper it is evaluated the influence of the boundary conditions (pin-ended and semi-rigid end-support conditions) on the behavior of the columns in case of fire. In these tests it could not be seen a marked effect of the tested boundary conditions but it is believed that the increasing of rotational stiffness increases the fire resistance of the columns.

Prediction of Axial Compression Capacity of Cold-Formed Steel Oval Hollow Section Columns Using ANN and ANFIS Models

Trong-Ha Nguyen,Ngoc-Long Tran,Duy-Duan Nguyen 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

The steel oval hollow section (OHS) provides an aesthetic architecture and a greater local buckling strength. However, the existing design codes do not specify the eff ective width in calculating the load-bearing capacity of OHS members. This study aims to predict the axial compression capacity (ACC) of cold-formed steel OHS columns using artifi cial neural network (ANN) and adaptive neural fuzzy inference system (ANFIS) models. A total of 128 data sets collected from the literature were utilized to develop the ANN and ANFIS models. The performance of the two machine learning models was compared with three existing design codes. The results demonstrated that the developed ANN and ANFIS models predicted the ACC of steel OHS columns more accurately compared to the existing formulas. Specifi cally, the ANN model revealed a superior performance with the highest coeffi cient of determination and the smallest root means square errors. Moreover, the formulas based on ANN and ANFIS models, which accommodates all input parameters, were proposed to predict the ACC of coldformed steel OHS columns. The thickness of the cross-section was the most infl uential parameter on the ACC of the OHS column. By contrast, the column length negatively aff ected the ACC value of the steel column. Finally, a graphical user interface tool was developed to readily calculate the ACC of the steel OHS columns.

강합성 중공 RC 기둥의 기둥-기초 접합부에 대한 실험적 연구

원덕희,이정화,맹령영,강영종 한국방재학회 2016 한국방재학회논문집 Vol.16 No.1

The main reinforcements of reinforced concrete(RC) column are connected to the reinforcement of footing as column-footing connection. On the other hand, it is important to connect with inner tube to reinforce the connection of composite hollow RC column and footing, because inner tube is located at hollow section. In this paper, two connection methods of welding coupler connection method and anchor bolting method were proposed for the connection of composite hollow RC column-footing in addition to penetrated connection method proposed by previous researchers. To evaluate performance such as strength, ductility and behavior of the connections, finite element analysis and experimental tests were performed. Finally, it was found that the welding coupler connection method are suitable for the column-footing connection. 철근콘크리트 기둥에서 기둥-기초 연결법으로서 기둥의 주철근은 기초의 철근에 연결된다. 반면에 강합성 중공 RC 기둥에서는 중공단면에 내부 강관이 설치되기 때문에, 강합성 중공 RC 기둥과 기초 접합부를 보강하기 위하여 내부 강관을 연결시키는 것이 중요하다. 본 연구에서는 선행연구에서 제시된 기초 철근과의 간섭을 피하여 내부 강관을 관통하는 연결방법 외에 강관과 기초부 철근을 용접커플러로 연결하는 방법과 앵커볼트로 연결하는 2가지 접합방법을 추가로 제시하였다. 제안된 기둥-기초 접합법의 강도, 연성도, 거동 등의 성능을 평가하기 위하여, 해석 및 실험 연구를 수행되었다. 연구결과, 용접 커플러 접합법이 강합성 중공 RC 기둥과 기초의 접합부로서 가장 적합한 것으로 나타났다.