门式刚架半刚性节点的试验研究

1、门式刚架半刚性节点的试验研究 及有限元分析摘 要门式刚架结构是目前国内外单层工业厂房及单层大跨民用建筑中应用最广泛的结构，转角节点是门式刚架的主要连接部分，其连接性能将直接影响到门式刚架结构在荷载作用下的整体行为。同时，该类节点的构造特点也决定了其刚度特征为半刚性。本文将通过数值模拟和试验方法，就不同标准的梁柱腹板高厚比、翼缘外伸宽厚比以及转角节点区高宽比的门式刚架转角半刚性节点进行了系统的研究。建立了三折线弯矩转角模型，得出了弯矩转角关系曲线表达式。关键词 门式刚架; 半刚性节点; 足尺试验; 有限元分析Experimental Research and Finite Element Ana

2、lysis on Semi-RigidJoints of Gabled FramesWANG Yu, LIU Yong-jun (School of Civil Engineering, Shenyang Jianzhu University, Shenyang110168, China)LI Hao-bang (China Northeast Architectural Design and Research Institute, Shenyang 110006,China)Abstract At present, the structure of gabled frames is the

3、most extensively-applied structure in the single-storey industrial building and long-span single-storey buildings. The joints of corner are main connecting part of gabled frames, of which the performance directly affects the integral behavior of its structure subject to load. At the same time, the c

4、onstruction of joints also determine its features of the semi-rigid stiffness. In this paper, numerical simulation and experimental research are conducted to investigate semi-rigid connection of corner joints in gabled frames with different height-thickness ratios of beam-column web, width-thickness

5、 ratios of flange, and height-width ratios in corner joints. The three-folder-line moment-rotation relation model has been established and the expression concerning moment-rotation relation obtained.Key Words gabled frame; semi-rigid joint; full-scale experiment; finite element analysisIntroductionT

6、he steel portal frame structure is at home and abroad and single-layer workshop and single-layer large-span civil building in the most widely used structure, corner nodes is door frame of the main connection parts, its connection performance will directly affect the door frame structure under load t

7、he overall behavior of 1. Meanwhile, this type of node structure feature also determines its rigidity feature for semi-rigid. But with the door frame of corner nodes connected the complexity and diversity of the node, regulate a detailed design prescribed state very few, this article will numerical

8、simulation and experimental methods, By studying door frame structure corner nodes the mechanical properties, obtained for the design and application of the node reference conclusion 2.2.Test specimen, Device and Loading method2.1 Test SpecimenAiming at the door frame of corner nodes (figure 1) the

9、structural types are studied, specimen specific size change parameter see table 1.Table 1 Door Rigid-framed Corner Nodes Specimens Parameters2.2 Test DeviceThe steel portal frame corner nodes the experiment device as figure2 shows.Figure 1 Door Rigid-framed Corner Jionts SpecimensFigure 2 Doors Rigi

10、d-framed Corner Jionts Testing EquipmentFigure 3 Node Specimens Failure PatternFigure 4 Node Moment-rotation Curve2.3 Loading MethodUnder normal circumstances, the door frame of corner nodes are bending moment M, shear stress V and axial force N three. Refer to state standard "steel structure d

11、esign codes" (GB50017-2003) first 7.4.2 bars, portal frame is concerned, general span bigger, roofing lighter weight. In this case, the stress in bending moment contribution node is the largest, it plays a decisive role in the corner, and the influence of the shear and axial force is negligible

12、. Based on the approximate consideration, will greatly simplified trial loading, the analysis work. For ease of intuitive, this trial comparing the component all adopts real measurements, we choose Q235 steel, the sectional dimensions shown in table 1. To ensure accurate specimen stress, considering

13、 the jack loading will generate friction, contact with specimens in force point corresponding bottom specimens beam center location into two root round steel to offset the friction, at the same time, make use of the allocated beam specimens dint even 3-5.Comprehensive analysis of this test results t

14、hat the door frame of corner nodes eventually destroying forms for corner nodes place beam-column webs, suggest along the inside and outside of shear buckling flange turning point setting on attachment oblique stiffener, in order to improve the node abate high shear strength.3.The Results of the Tes

15、t AnalysisFrom node specimens failure form diagram (figure 3) can be seen, the whole webs already all the inelastic phase, and the emergence of wave shape compression buckling, Outer flange of stress along ZhuanSheChu gradually increasing, finally also achieve ultimate strength, generate obvious buc

16、kling, corner nodes of shear deformation is larger, girder plate and the column flange between the relative displacement of beam tensile flange place, and gradually into the largest adopted.post board ends decrease.From node moment-rotation curve (FIG. 4) also can see, with increasing three-bit, nod

17、e area corner also always increase, reached the limit load in specimens, node area corner with three-bit decreases continue to increase, the curve become steep instead of steep.Comprehensive analysis of this test results that the door frame of corner nodes eventually destroying forms for corner node

18、s place beam-column webs, suggest along the inside and outside of shear buckling flange turning point setting on attachment oblique stiffener, in order to improve the node abate high shear strength.4The Door Frame of Semi-rigid Node of the Finite Element Analysis4.1 finite element calculation modelU

19、sing ANSYS software text-messaged rigid-framed corner nodes is simulated and analyzed, the unit adopts four nodes of six degrees of freedom SHELL181 unit. When considering the meshing mesh is modest and thick grid freedom to calculate the transition, obtain higher precision. Considering material non

20、linearity and the geometrical nonlinearity, adopt double linear servohardemning model (BKIN), solver Newton - Simpson method (Newton - Raphson) and linear Search technology (get), Line by prediction (Predictor), Adaptive decrease (Adaptive Descent) accelerating convergence technology organic combina

21、tion 6.4.2 finite element calculation of geometric parameter determinationCalculated by finite element node load force-displacement curve (FIG. 5) can be seen, the finite element calculation and test results obtained have tallied, including elastic limit load almost superposition. Numerical simulati

22、on of the plastic limit a bit low, this is due to the measured steel strength slightly higher than the numerical simulation of materials with strength, but in the end the ultimate load are almost the same. Thus, the simulation results obtained by the finite element of experiments and the measured re

23、sults consistent fem simulation, it can be argued that truly reflect the real structure, the structural behavior 7.Figure 5 Load of the Nodes Force-displacement CurveBased on the above analysis, this article through the finite element software ANSYS, from the following several aspects, consider diff

24、erent geometrical parameter text-messaged rigid-framed corner nodes semi-rigid influence:(1) Node domains of the crane girder high thickness than the door frame of light steel structure housing "technical specification (2002) CECS102: first 6.1.1 bars, i-section section beam-column component we

25、bs of its thickness calculation highly hw ratio of tw, should not > 250. Thus, this article for assembling high thickness ratio (hw/tw) were selected for 213,160,128,106 and 80.(2) Flange overhanging generous than according to the door frame of light steel structure housing "technical specif

26、ication (2002) CECS102: first 6.1.1 bars, i-section section component compression flange plate width and thickness of bf free overhanging the ratio of the tf, should not > 15. Accordingly, to investigate the different than the flange and generous transverse stiffener on node domains of the crane

27、girder constraint conditions, this paper takes the flange than (bf/tf) were selected for 15, 12.5, 9.5, 7.5 and 6.3.(3) Webs, flange thickness value according to the door frame of light steel structure housing "technical specification (2002) CECS102: first 3.5.1 track used for welding Lord bars

28、, just framework of steel webs piece, its ply is unfavorable < 4mm, when there is 3mm. When can according to" In addition, in light door frame structure of economic consideration, column webs general obtained thinner, and, in order to give full play to abate high buckling strength, this pape

29、r will perforation after the thickness were taken for 3, 4, 6 and 8 and l0mm; Flange thickness were taken for 5, 6 and 8, l0 and 12mm.(4) Node domains height-width ratio for the door frame of speaking, in the corner nodes place, beams and column under bending moment is equal, its beams and column se

30、ction height is usually the same. Therefore this paper nodes in the domain to 1.0 height-width ratio of high to width is given priority to, other than circumstances only computing a small amount of components, ismainly used for the correctness of the result verified.4.3 Finite element calculation re

31、sults analysisThrough the finite element software ANSYS calculation, obtained the door frame Angle initial rigidities of the joint stiffness, yield ki was, yield capacity for the values of the ultimate bearing capacity of Mp and, see table 2 and table 3.Table 2 Different Members of the Initial Rigid

32、ities Ki and Succumb Stiffness was Valuesbeam-column webs of high thickness ratio; Bf/tf is flange overhanging generous than.Table 3 Different Members of the Yield of Bearing Capacity and Limit Bearing Capacity Mp for vValueFrom table 2 and table 3 can see, although Angle initial rigidities of the j

33、oint stiffness, yield ki was, yield capacity for and the ultimate bearing capacity of beams with corner nodes Mp abate high high thickness ratio (hw/tw) and flange overhanging generous than (bf/tf) decreases, but growth of amplitude is basically the same as, can approximate linear growth, so yield s

34、tiffness and initial stiffness ratio (ki) and was/yield and bearing capacity of the ultimate bearing capacity than (wish/Mp) can be thought of as a constant. In order to guarantee the actual design safer, approximate desirable:Ki, was = 0.23 wish = 0.80 Mp (1)From table 4 listed in the different mem

35、bers of the yield of stiffness and initial stiffness ratio and yield capacity and limit bearing capacity than can be seen in the approximate selection, this paper was/ki value and the wish/Mp value and finite element simulation results with a very good consistency, its average accuracy reached 0.99,

36、 can be used as a formula parameters.Table 4 different members of the yield of stiffness and initial stiffness ratio and yield capacity and limit bearing capacity ratio5.Semi-rigid node of moment - corner relation curve expression5.1 Eurocode3 semi-rigid node M - relation curvesAlthough Eurocode3 gi

37、ven in this moment - corner relation curves including non-linear part, but the door frame of overall analysis and design, the general nonlinear section (figure in 6a segments of curve) approximate ab with linear replace (figure in ab 6b segments of curve). With the application of the three polyline

38、approximate expression analysis results, compared to the influence of non-linear part for structure are relatively small, can be ignored.Figure 6 Semi-rigid Node Bending Moment - corner Relation Curves5.2 Suggested Semi-rigid Node M - Relationship Curve ExpressionAccording to this article selects th

39、ree line moment - corner (M -), as shown in figure 6b, Oa straight segment corresponding stiffness for initial rigidities of ki. For Oa straight line for establishing linear equations,We get:M=ki×qM£4Mp （2） 5Yield stiffness Eurocode3 will curve was is based on the nonlinear section (figure

40、 in 6a segments of curve) approximate ab with linear replace (figure in 6b ab straight line for inclined section type), using linear equation, the ab straight line for establishing linear equations,We get:M-My=ky(q-My/ki)4Mp<M£Mp （3） 5As mentioned previously, type of ki, was, wish and Mp res

41、pectively for the door frame of semi-rigid corner nodes of initial stiffness, yield stiffness, yield capacity and limit bearingcapacity. Will type (1) generation into type (3), Can get:M-0.8Mp=0.23ki(q-0.8Mpki)4Mp<M£Mp （4） 5From type (2) type (5) can be seen, the bending moment - corner conn

42、ection relationship curve ki and Mp only with two parameters, three polyline expression of bending moment - corner relational expression can be expressed as the next type:4ìM=k×q , M£Mpiïï5 （6） í4ïM=0.23kq+0.62M,M<M£Mipppï5î6.Epilogue:Through the

43、portal frame of corner nodes of numerical calculation and experimental research, and obtain some beneficial to engineering practice of basic conclusion:(1) numerical simulation calculation results and experimental results show that the contrastnumerical simulation is an effective research tools, and adopted the calculation model and method are correct, the results are reliable, numerical simulation method, can give experimental research and engineering applicat