H-shaped Beams Research Articles

PLASTIC DEFORMATION CAPACITY AND POST-BUCKLING BEHAVIOR OF H-SHAPED BEAM WITH LARGE DEPTH-THICKNESS RATIO UNDER CYCLIC LOADING

In the past, it was shown that H-shaped beams with large depth-thickness ratio are useful as a seismic design beam. But, under cyclic loading, the characteristics of these beams have not been examined enough. So in this study, the cyclic behavior, plastic deformation capacity and energy absorption ability of H-shaped beams having larger depth-thickness ratio than the limit of current standard are examined by cyclic experiments and numerical analysis. And the new limit value of plate slenderness are proposed. The plate local post-buckling behaviors of these beams are considered and modeled for progressive use in the future.

Seismic Behaviour of Semi-Rigid Joints to Concrete Filled Steel Tubular Columns

This paper discussed the results of experiments on bolted moment connection joints of square or circular concrete filled steel tubular (CFST) columns and H-shaped steel beam using high-strength blind bolts under cyclic loading. The objective of this work was to study the seismic performance of the blind bolted flush endplate connections to CFST columns. The test parameters varied were the column section type and the thickness of the endplate. The feasibility of the proposed beam-column connection is successfully verified by the experiments. The test results showed that under cyclic loading the tested specimens displayed large rotation ductility capacities and could satisfy the request of the structural seismic design. When subjected to cyclic loading, most of failure modes of the tested joints are similar to those under monotonic loading. Moreover, the energy dissipation of the type joints is influenced by the column section type and the thickness of the endplate.

Research on end-plate connection with non-completely penetrated welds

A series of tests were executed for H-shaped beams whose flanges were connected to end-plate by non-completely penetrated welds. The welds were designed by equal capacity rule and the beams were mainly composed of non-compact or slender elements. The parameters introduced are width–thickness ratios of beam flange and web, end-plate thickness, angle between flange plane and end-plate plane and so on. 24 pieces of specimens were tested to failure under monotonic loading and 6 under cyclic loading. For comparison, a few of the specimens are those with completely penetrated groove welds. Finite element (FE) analysis was also carried out to study the effect of parameter change on the resistance of the welds. The parameters involved end-plate thickness, weld size, column flange thickness and bolt gauge. The results show that thinner end-plate and greater bolt gauge will deteriorate the resistance of weld. As long as the components are properly designed, as done in tests, the connections will not fail at the welds no matter what kind of weld form is adopted. In addition, weld form has no obvious effect on the ultimate loads and cyclic behavior of specimens. It is confirmed that the non-completely penetrated welds connecting flanges of H-shaped beams and end-plates can be used both under static loading and seismic loading in low-rise building structure where local buckling of the member is the predominant factor.

EVALUATION OF WIDTH-THICKNESS RATIO LIMITATION OF H-SHAPED BEAM MEMBERS BASED ON COUPLED BUCKLING ANALYSIS

Width-thickness ratio limitation of thin plate is defined in current standard by considering boundary condition and stress situation under either pure compression or pure shear. On one hand, considering the effect of bending force, the larger width-thickness ratio of thin plate is able to be used in many cases of H-shaped beams when overall buckling does not happen. On the other hand, overestimation may be caused in cases of light-gauge thin plates formed H-shaped beams with long span which are easily affected by overall buckling. This paper is to study the proper evaluation of limitation about width-thickness ratio of H-shaped beam members under bending and shear based on the coupled buckling analysis in previous studies by energy method, and an easy evaluation method is proposed.

UNSTABLE BEHAVIOR OF SPATIAL RIGID STEEL FRAME SUBJECTED TO OVER LOAD

Collapse behavior of spatial rigid steel frame while vertical load at one place of the beam continues to increase gradually is investigated experimentally and numerically. The spatial frame consists of four columns and four beams. Lateral buckling of the H-shaped beam induced the collapse of frame. The tips of both square tube columns supporting the beam were drawn inward. The center of the beam was twisted and at the portion the plastic hinge was formed by weak axis bending. The torsion or sway behavior of frame was hardly observed in this study. The experimental results of small steel frames are illustrated that the numerical prediction by the elasto-plastic beam-column FEM developed by the authors has adequate precision.

THEORETICAL ANALYSIS AND EVALUATION FOR CUPLED BUCKLING STRENGTH OF H-SHAPED BEAMS UNDER BENDING SHEAR

Buckling behaviors of open section steel members are generally divided into two styles which called local buckling and overall buckling depending on the assumption of boundary condition. However, local buckling and overall buckling may happen at the same time when thin plates are widely used in steel structures, and somewhat overestimation will cause without considering the interaction of each other. As the results shown in the previous studies, buckling behavior may be dominated by coupled buckling. Therefore, it is important to solve this problem by theoretical method especially for seismic design. This paper uses an energy method of analysis to study coupled buckling of H-shaped beams under bending shear. Moreover, on the basis of the theoretical analysis results, the evaluation of coupled buckling strength is proposed by using parameter of geometrical shape of H-shaped member.

Hysteresis Behavior of Square Tube Columns to H-Beam Connections with Vertical Stiffeners

This paper deals with confirming the usability of a new connection method for steel moment-resisting frames. The connections are strengthened with vertical stiffeners to connect square tube columns and H-shaped beams. Two test methods were selected with experimental parameters given as details. The first test is performed under symmetrical loading. Beams are simply supported on both ends and test load is applied to the top of the column. The second test is performed under anti-symmetric loading. The shape of test specimens is cruciform, with a beam and a column. The top end and base of the column are simply supported, and load is applied to both ends of the beam. Test results are summarized to investigate structural performances of the connection. Nonlinear FE analysis using ANSYS for moment-resisting frames was performed to confirm the test results. It was found that all specimens had sufficient capacities exceeding the full plastic strength of beam. Therefore, the connections strengthened with vertical stiffeners were successfully verified to have possibility as a new connection method for steel moment-frames.

CFTを用いた3次元部分骨組の弾塑性挙動に関する実験的研究 : CFT 3次元骨組の弾塑性性状(その1)

Three-dimensional frames consisting of CFT columns and H-shaped beams were tested under a constant axial load on the column, constant beam loads in the minor direction, and altemately repeated beam shear in the major direction simulating the earthquake loading. The specimens were designed for two kinds of failing type; shear failing of the beam-to-column connection panel, and flexural failing of the column. The paper presents the test results, and discusses the hysteretic behavior, the maximum strength and failure mode of each specimen. It is concluded that the panel-failing specimens are generally more stable compared with the column-failing specimens.

実大柱梁接合部の試験温度による延性破壊-脆性破壊遷移

This study aims at examining the relation between the performance of steel members and the material properties. Specimens composed of H-shaped beams and box columns were subjected to seismic motions by means of shaking table test. The range of temperature was set from -50℃ to +15℃ in order to include -15℃, which is the transition temperture obtained from Charpy impact test. All specimens showed high deformation capacities above -20℃ in temperature. When temperature was below -30℃, brittle fracture occurred and the specimen showed the progress of deterioration in strength and deformation capacity according to the temperture.

上フランジ連続拘束条件下にあるH形鋼梁の塑性変形性状に関する研究

In this report, the plastic deformation behavior of H-shaped beam restrained on upper flange is discussed. First, from the examination of numerical buckling analysis, the effect of upper flange restraint for several buckling mode is described. And for the purpose of estimating more exactly the general slenderness ratio using as parameter for the plastic deformation capacity recently, the effect factor (function) of upper flange restraint that is obtained from approximation of the numerical analysis results is presented. Next, from the examination with the elastic plastic large displacement analysis for upper flange restrained or non-restrained H-shaped beam, the effect of upper flange restraint for clastic deformation behavior is explained. And the relationship between the general slenderness ratio and plastic deformation capacity is investigated. Last, the point to notice to estimate the plastic deformation capacity from the general slenderness ratio is discussed.

補剛材の添接によるH形鋼梁の塑性変形性能改善に関する研究 : 局部座屈ならびに横座屈相互の影響下にある場合

補剛材の添接によるH形鋼梁の塑性変形性能改善に関する研究 : 局部座屈ならびに横座屈相互の影響下にある場合

閉断面要素を付加したH形鋼梁の横座屈性状に関する研究 : その2 梁せい方向に鋼管を配置した場合

閉断面要素を付加したH形鋼梁の横座屈性状に関する研究 : その2 梁せい方向に鋼管を配置した場合

現場溶接接合形式の柱梁接合部におけるH形鋼梁端部の力学的性能

H-shaped steel beams of beam-to-column connections welded on site are chosen as the subject of this study. A beam flange of this type joint is welded to a column flange on site, and a beam web is jointed by high strength bolts. Three-point bending tests and finite element analysis are carried out to investigate structural behaviors of this type joint. The results are summarized as follows: (1) When a beam flange is made of steel with lower yield ratio, α value which is obtained by dividing the experimental maximum strength by full-plastic strength is increased. (2) α value is independent of transmission capacity of bending moment in bolted joints. (3) The deformation capacity of H-shaped beams without scallops is greater than that with scallops, when yield ratio of a beam flange is less than 0.65.

円形開口を有するH型鋼梁の塑性変形性能について : その2. 比較的大きい円形開口を有する梁の局部座屈機構

On the H-shaped beam with a circular hole, static characteristics of web opening and the primary properties of elastic behaviors were investigated. In this report, the local buckling mechanism of the beam with web opening that is the important factor of the elastic behavior is discribed, and the elastic behavior is grasped quantiatively. The basic buckling mechanism of the beam with web openings is explained by the prastic hinge model of Vierendeel truss. Then, as the basic research for the study of the buckling mechanism of opening, we investigated the beam with the large web opening that express the Vierendeel truss mechanism well.

A Study Of The Fire Aspect Of Atria In Hong Kong

Previously, we have conducted measurements of heat flux and temperature distribution of the H-shape beam installed beneath a ceiling and exposed to a localized fire source. From the results ofthe experiment, heat flux distribution on every part of the beam was formulated. In this paper ,the temperature distributions were computed by the finite different method using experimental heat flux data and compared with results of the experiments to evaluate the applicability of the analytical technique The result shows that when compared with the experimental data, the temperature distribution on the axial direction of the member can be predicted with about 15% error in the range ofO.5m from the stagnation point, and with20% error or less in other positions. In order that this model may be applied to an actual building, we assume 1\\0 cases: one is that the temperature is calculated with the experimental data of heat flux approximated by a functional equation, and the other is a case that the experimental data is input in the model directly as mentioned above: and these 1\\0 cases are compared with each other in their accuracy. In the same scheme, several kinds of metal material properties data were used in the calculation to know the heating conditions which may achieve the allowable range of temperature required in the current regulation.

骨組溶接構造体の変形能に及ぼす鋼材変形特性の影響

Deformability of welded frame-structures in buildings is greatly affected by mechanical properties, especially work-hardening behaviors of steels on deformability of welded frame-structures, bending tests of specimens having a column-beam connection (H-shape beam) were carried out. For these experiments SM41B steel, SM50B steel and two kinds of HT60 steels with the different yield to tensile ratio were used.Main results obtained are summerized as follows.(1) Local buckling occurs and develops first in flange and then in web of the H-shape beams under the bending load. The maximum plateau of load-deflection curve on the H-shape beam is attained after the local buckling in web. The maximum load depends on the geometry of the H-shape beam, and decreases as the width to thickness ratio increases.(2) The maximum load value in H-shape beam is greatly affected by the tensile strength of steels used. Deflection at the load point and the absorbed energy of beam up to the maximum load, which are typical measures of the deformability of frame structures, depend on the yild to tensile ratio and uniform elongation (eT) of steels. Beams made of steels with lower yield to tensile ratio have larger deformability.(3) In order to improve the deformability of beam using steels with small eT, it is effective to enlarge their eT.(4) H-shape beam with scallop has a possibility of fracturing from the corner of the scallop.

角形鋼管柱の左右にせいの異なる梁が接合される場合の梁の剛性と耐力に関する研究

At the connection of H-shaped beams and RHS-column as shown in Fig. 2, stiffness and moment capacity of smaller depth beam are govered by rigidity of column flange. In this paper, analytical study for predicting elastic stiffness and moment capacity of beam mentioned above and experimental results are reported. The elastic stiffness of beam was derived by assumig the column flange would behave as grid beams. For the moment capacity, the theoretical expression was developed based on the yield line theory. And to confirm the precision, the analytical results were compared with the experimental results obtained from 14 simple beam type specimens under monotonic loading and 5 cruciform type specimens of beam-to-column sub-assemblage under cyclic loading. In those tests, the parameters of specimens were thickness of RHS-column, disparity between lower beam flange and diaphragm, and width of beam-flange. The analytical results were closely coinside with the corresponding test results.

骨組溶接構造体の変形能からみた鋼材の降伏比一様伸び特性のあり方

A procedure to investigate the effect of work-hardening properties of steel on the deformability of welded frame-structures having the H-shape section is described. The procedure consists of the elasticplastic deformation analysis and the local buckling analysis. The analytical results have proved to agree with the experimental results. The deformation analyses of the H-shape beam were carried out for the various combinations of the yield to tensile ratio and the uniform elongation of steel.It has been shown from the analytical results that it improves the deformability of H-shape beams, such as the amount of deformation or the absorbed energy up to the maximum load, to lower the yield to tensile ratio or to enlarge the uniform elongation of steel. In case of steels having larger uniform elongation (eT>10%), it is more effective to lower the yield to tensile ratio than to enlarge the eT. Whereas in case of steels having smaller uniform elongation (eT<10%), increasing the eT is more beneficial.

鉄骨ラーメンの弾塑性変形性状に及ぼす局部座屈の影響

Mild steel portal frame specimens are tested under the constant vertical and monotonic alternating horizontal loads, in order to clarify the influence of the local buckling on inelastic behavior of steel frames. The frame specimens are assembled by welding from H-shape columns and a rolled H-shape beam. As the experimental parameters, width-to-thickness ratio of the flange and web of column cross section and axial load of column. Twenty six specimens are tested. Load carring capacity and deformation capacity are investigated, and it is shown that experimental behavior of the locally buckling frames is well predicted by the analysis based on the plastic hinge method in which the decrease of the full plastic moment of the cross section due to the local buckling is taken into consideration.

Buckling of laterally braced beams

This paper reports on thteral buckling tests of H-shaped beams unbraced or braced laterally by purlins or a sub-beam. These tested beams were subjected to uniform moment or moment gradient. The restraining effect of adjacent members, bracing effect of purlins or a sub-beam and effect of moment gradient on load carrying capacity and the post-lateral-buckling behaviour were investigated. Elastic-plastic analysis by means of the finite element method was performed to simulate the experimental behaviour. Analytical results were found to match well with experimental behaviour for the most part. Effective length factors that incorporate the effects of moment gradient, restraining, and bracing into design of H-shaped beams are discussed and proposed, based mainly on the analytical results.