• Title/Summary/Keyword: cyclic load ratio

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Tubular Web Reduced Beam Section (TW-RBS) connection, a numerical and experimental study and result comparison

  • Zahrai, Seyed M.;Mirghaderi, Seyed R.;Saleh, Aboozar
    • Steel and Composite Structures
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    • v.23 no.5
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    • pp.571-583
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    • 2017
  • A kind of accordion-web RBS connection, "Tubular Web RBS (TW-RBS)" connection is proposed in this research. TW-RBS is made by replacing a part of web with a tube at the desirable location of the beam plastic hinge. This paper presents first a numerical study under cyclic load using ABAQUS finite element software. A test specimen is used for calibration and comparison of numerical results. Obtained results indicated that TW-RBS would reduce contribution of the beam web to the whole moment strength and creates a ductile fuse far from components of the beam-to-column connection. Besides, TW-RBS connection can increase story drift capacity up to 9% in the case of shallow beams which is much more than those stipulated by the current seismic codes. Furthermore, the tubular web like corrugated sheet can improve both the out-of-plane stiffness of the beam longitudinal axis and the flange stability condition due to the smaller width to thickness ratio of the beam flange in the plastic hinge region. Thus, the tubular web in the plastic hinge region improves lateral-torsional buckling stability of the beam as just local buckling of the beam flange at the center of the reduced section was observed during the tests. Also change of direction of strain in arc shape of the tubular web section is smaller than the accordion webs with sharp corners therefore the tubular web provides a better condition in terms of low-cycle fatigue than other accordion web with sharp corners.

Seismic Performance of Built-up Concrete Filled Square Composite Column-to beam Connection with Through Diaphragm (관통형 다이아프램을 갖는 조립형 콘크리트 충전 각형 합성기둥-보 접합부의 내진성능)

  • Kim, Sun Hee;Yom, Kyong Soo;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.26 no.5
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    • pp.431-439
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    • 2014
  • Concrete filled tubular columns are widely used because the mutual reaction between the concrete and the tube improves strength and ductility of the columns. In an attempt to secure efficient use of members, built-up square columns featuring large width-thickness ratio and the use of thin steel plates are suggested in this study. In order to evaluate the structural characteristics and seismic performance of the column-to-beam connections of the new shape columns, cyclic load test of T-shaped column-to-beam connections was conducted with variables of diaphragms and concrete-filling. Moment-rotational angle relationship, dissipated energy and failure behavior were compared to evaluate stress transfer mechanism of the new shape built-up square column-to-beam connections associated with the variables.

Evaluation on Cyclic Flexural Behavior of HSRC (Hybrid H-steel-reinforced Concrete) Beams Connected with Steel Columns (강재 기둥과 하이브리드 강재 보-RC 보 접합부의 반복 휨 거동 평가)

  • Kwon, Hyuck-Jin;Yang, Keun-Hyeok;Hong, Seung-Hyun
    • 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.

Crack growth analysis and remaining life prediction of dissimilar metal pipe weld joint with circumferential crack under cyclic loading

  • Murthy, A. Ramachandra;Gandhi, P.;Vishnuvardhan, S.;Sudharshan, G.
    • Nuclear Engineering and Technology
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    • v.52 no.12
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    • pp.2949-2957
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    • 2020
  • Fatigue crack growth model has been developed for dissimilar metal weld joints of a piping component under cyclic loading, where in the crack is located at the center of the weld in the circumferential direction. The fracture parameter, Stress Intensity Factor (SIF) has been computed by using principle of superposition as KH + KM. KH is evaluated by assuming that, the complete specimen is made of the material containing the notch location. In second stage, the stress field ahead of the crack tip, accounting for the strength mismatch, the applied load and geometry has been characterized to evaluate SIF (KM). For each incremental crack depth, stress field ahead of the crack tip has been quantified by using J-integral (elastic), mismatch ratio, plastic interaction factor and stress parallel to the crack surface. The associated constants for evaluation of KM have been computed by using the quantified stress field with respect to the distance from the crack tip. Net SIF (KH + KM) computed, has been used for the crack growth analysis and remaining life prediction by Paris crack growth model. To validate the model, SIF and remaining life has been predicted for a pipe made up of (i) SA312 Type 304LN austenitic stainless steel and SA508 Gr. 3 Cl. 1. Low alloy carbon steel (ii) welded SA312 Type 304LN austenitic stainless-steel pipe. From the studies, it is observed that the model could predict the remaining life of DMWJ piping components with a maximum difference of 15% compared to experimental observations.

Cyclic Lateral Load Test on the Punching Shear Strength and the Lateral Displacement Capacity of Slab-Column Connections (슬래브-기둥 접합부의 펀칭강도 및 횡변위 성능에 관한 반복 횡하중 실험)

  • Choi, Jung-Wook;Song, Jin-Gyu;Kim, Jun-Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.4
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    • pp.99-108
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    • 2007
  • In the flat-plate slab design of the KCI and ACI building code, the punching shear strength of connections with shear reinforcement can increase one and half times to that of connections without shear reinforcement. And the ACI-ASCE committee 352 recommendations propose limiting the direct shear ratio $V_g$/$V_c$ on interior connections to 0.4 to insure adequate drift capacity. In this study, four interior column-slab connections were tested to look into the punching shear strength and the lateral displacement capacity of the flat-plate slab with and without shear reinforcement under cyclic lateral loading. Based on the test results, it is found that the provision about punching shear strength in the codes may appropriate for the gravity loading only whereas it is unconservative for the lateral loading and that the limit of ACI-ASCE committee 352 appears conservative.

Seismic Behavior of High-Strength Reinforced Concrete Bridge Columns (고강도 철근콘크리트 교각의 내진 거동)

  • Hwang Sun-Kyoung;Lee Chin-Ok;Ryu Hyo-Jin;Yun Hyun-Do;Lim Byung-Hoon
    • Journal of the Korea Concrete Institute
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    • v.17 no.4 s.88
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    • pp.505-511
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    • 2005
  • This experimental investigation was conducted to examine the seismic performance of reinforced concrete bridge columns. The columns were subjected to a constant axial load and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research were the volumetric ratios of transverse reinforcement (ps=0.96, 1.44 percent) and axial load ratios (P/Po=0.05, 0.1, 0.2) and concrete strengths (35, 60MPa). Test results showed that bridge columns with $44\%$ higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behavior. For bridge columns with axial load ratio(P/Po) less than 0.2, the ratio of $M_{max}\;over\;M_{ACI}$, nominal moment capacity predicted by ACI 318-02 provisions, was consistently greater than 1 with approximately a $20\%$ margin of safety.

Seismic damage evaluation of steel reinforced recycled concrete filled circular steel tube composite columns

  • Hui, Ma;Xiyang, Liu;Yunchong, Chen;Yanli, Zhao
    • Earthquakes and Structures
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    • v.23 no.5
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    • pp.445-462
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    • 2022
  • To investigate and evaluate the seismic damage behaviors of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns, in this study, the cyclic loading tests of 11 composite columns was carried out by using the load-displacement joint control method. The seismic damage process, hysteretic curves and performance indexes of composite columns were observed and obtained. The effects of replacement rates of recycled coarse aggregate (RCA), diameter thickness ratio, axial compression ratio, profile steel ratio and section form of profile steel on the seismic damage behaviors of composite columns were also analyzed in detail. The results show that the failure model of columns is a typical bending failure under the combined action of horizontal loads and vertical loads, and the columns have good energy dissipation capacity and ductility. In addition, the replacement rates of RCA have a certain adverse effect on the seismic bearing capacity, energy consumption and ductility of columns. The seismic damage characteristics of composite columns are revealed according to the failure modes and hysteretic curves. A modified Park-Ang seismic damage model based on the maximum displacement and cumulative energy consumption was proposed, which can consider the adverse effect of RAC on the seismic damage of columns. On this basis, the performance levels of composite columns are divided into five categories, The interlayer displacement angle and damage index are used as the damage quantitative indicators of composite columns, and the displacement angle limits of composite columns at different performance levels under 80% assurance rate are calculated as 1/105, 1/85, 1/65, 1/28, and 1/25 respectively. On this basis, the damage index limits corresponding to each performance level are calculated as 0.045, 0.1, 0.48, 0.8, and 1.0 respectively. Finally, the corresponding relations among the performance levels, damage degrees, interlayer displacement angles and damage indexes of composite columns are established. The conclusions can provide reference for the seismic design of SRRC filled circular steel tube composite columns, it fills the vacancy in the research on seismic damage of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns.

Behavior of Wide Beam-Column Interior Joint with Slab (횡력을 받는 넓은 보-기둥 내부 접합부의 거동 평가)

  • Lee, Bum-Sik;Park, Seong-Sik;Park, Ji-Young
    • Land and Housing Review
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    • v.3 no.4
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    • pp.433-449
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    • 2012
  • An experimental investigation was conducted to study the behavior of RC wide beam-column joints with slab subjected to reversed cyclic loads under constant axial load. Six half scale interior wide beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including three specimens without slab and three specimens with slab. The primary variables were the ratio of column-to-beam flexural capacity ($M_r={\Sigma}M_c/{\Sigma}M_b$ ; 0.77~2.26), ratio of the column-to-beam width (b/H ; 1.54, 1.67). Test results are shown that (1) the current design code and practice for interior joints(type 2) are apply to the wide beam-high strength concrete column. (2) the presence of a slab have an effect on the performance of the wide beam-high strength concrete column interior joints(type 2). therefore in the design of the wide beam-high strength concrete column interior joints(type 2), the width of slab effective as a T beam flange should be considered. It was show that the case of the ratio of column-to-beam flexural capacity is more than 2.0, the effective width of slab are 2 times of an effective depth of wide beam, however if the ratio of column-to-beam flexural capacity is 1.4~2.0, the effective width of slab are not able to be considered.

A Study on the Shear Fatigue Analysis Model of Reinforced Concrete Beams (철근 콘크리트 보의 전단피로해석 모델 연구)

  • 오병환;홍경옥
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.389-392
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    • 1999
  • Fatigue is a process of progressive permanent internal structural change in a material subjected to repeitive stresses. These change may be damaging and result in progressive growth of cracks and complete fracture if the stress repetitins are sufficiently large. For structural members subjected to cyclic loads, the continuous and irrecoverable damage processes are taking place. These processes are referred as the cumulative damage processes due to fatigue loading. Moreover, increased use of high strength concrete makes the fatigue problem more important because the cross-section and dead weight are reduced by using high strength concrete. The purpose of this study is to investigate the shear fatigue behavior of reinforced concrete beams according to shear reinforcement ratio and concrete compressive strength under repeated loadings. For this purpose, comprehensive static and fatigue tests of reinforced concrete beams were conducted. The major test variables for the fatigue teats are the concrete strength and the amount of shear reinforcements. The increase of deflections and steel strains according to load repetition has been plotted and analyzed to explore the damage accumulation phenomena of reinforced concrete beams. An analytical model for shear fatigue behavior has been introduced to analyze the damage accumulation under fatigue loads. The failure mode and fatigue lives have been also studied in the present study. The comparisons between analytical results and experimental data show good correlation.

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Nonlinear Analysis and Design of Rectangular Damper (직사각형 댐퍼의 비선형 해석 및 설계)

  • Eom, Seung Hyeon;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4 s.65
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    • pp.447-456
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    • 2003
  • In this study, the proper shape of dampers was determined when the outside frame formed a rectangle. The proper shape of dampers is rectangular, having the same ratio as the outside frame. The design was based on the impact energy dissipated by the seismic performance of the mainly rectangular dampers. This study sought to compare both strength and energy dissipation between nonlinear analysis data and experimental data through load-displacement curves. The use of the ANSYS FEM software was suggested to analyze the nonlinear behavior of rectangular dampers subjected to cyclic loading. The target of this study was to determine what shape was efficient for rectangular tensile brace dampers. The safety of the developed rectangular dampers was also checked for better fabrication.