Welded portal frame eaves moment connection

Welded portal frame eaves moment connection | Idea Statica Web Eshop

Description

In this chapter, the component-based finite element method (CBFEM) for a welded portal frame eaves moment connection is verified on the component method (CM). An open section beam is welded to an open section column. The column is stiffened with two horizontal stiffeners opposite to beam flanges. Compressed plates, e.g. horizontal stiffeners of a column, column web panel in shear, compressed beam flange, are limited to 3^rd class to avoid buckling. The rafter is loaded by shear force and bending moment.

Analytical model

Five components are examined in the study, namely the web panel in shear, the column web in transverse compression, the column web in transverse tension, the column flange in bending, and the beam flange in compression. All components are designed according to EN 1993-1-8:2005. Fillet welds are designed not to be the weakest component in the joint. The verification study of a fillet weld in a stiffened beam-to-column joint is in chapter 4.4.

Web panel in shear

The thickness of the column web is limited by slenderness to avoid stability problem; see EN 1993‑1‑8:2005, Cl 6.2.6.1(1). A class 4 column web panel in shear is studied in chapter 6.2. Two contributions to the load capacity are considered: resistance of the column panel in shear and the contribution from the frame mechanism of the column flanges and horizontal stiffeners; see EN 1993‑1‑8:2005, Cl. 6.2.6.1 (6.7 and 6.8).

Column web in transverse compression

Effect of the interaction of the shear load is considered; see EN 1993-1-8:2005, Cl. 6.2.6.2, Tab. 6.3. Influence of longitudinal stress in the column panel is considered; see EN 1993-1-8:2005, Cl. 6.2.6.2(2). The horizontal stiffeners are included in the load capacity of this component.

Column web in transverse tension

Effect of the interaction of the shear load is considered; see EN 1993-1-8:2005, Cl. 6.2.6.2, Tab. 6.3. The horizontal stiffeners are included in the load capacity of this component.

Column flange in bending

Horizontal stiffeners brace column flange; this component is not considered.

Beam flange in compression

The horizontal beam is designed to be class 3 cross-section or better to avoid buckling.

Overview of the considered examples and the material are given in the Tab. 9.1.1. Geometry of the joint with dimensions is shown in Fig. 9.1.1. The considered parameters in the study are beam cross-section, column cross-section, and thickness of the column web panel.

Tab. 9.1.1 Examples overview

Example			Material			Beam	Column	Column stiffener
	fy	fu	E	\(\gamma_{M0}\)	\(\gamma_{M2}\)	Section	Section	bs	ts
	[MPa]	[MPa]	[GPa]	[-]	[-]			[mm]	[mm]
IPE140	235	360	210	1	1,25	IPE140	HEB260	73	10
IPE160	235	360	210	1	1,25	IPE160	HEB260	82	10
IPE180	235	360	210	1	1,25	IPE180	HEB260	91	10
IPE200	235	360	210	1	1,25	IPE200	HEB260	100	10
IPE220	235	360	210	1	1,25	IPE220	HEB260	110	10
IPE240	235	360	210	1	1,25	IPE240	HEB260	120	10
IPE270	235	360	210	1	1,25	IPE270	HEB260	135	10
IPE300	235	360	210	1	1,25	IPE300	HEB260	150	10
IPE330	235	360	210	1	1,25	IPE330	HEB260	160	10
IPE360	235	360	210	1	1,25	IPE360	HEB260	170	10
IPE400	235	360	210	1	1,25	IPE400	HEB260	180	10
IPE450	235	360	210	1	1,25	IPE450

Example			Material			Beam	Column	Column stiffener
	fy	fu	E	\(\gamma_{M0}\)	\(\gamma_{M2}\)	Section	Section	bs	ts
	[MPa]	[MPa]	[GPa]	[-]	[-]			[mm]	[mm]
HEB160	235	360	210	1	1,25	IPE330	HEB160	160	10
HEB180	235	360	210	1	1,25	IPE330	HEB180	160	10
HEB200	235	360	210	1	1,25	IPE330	HEB200	160	10
HEB220	235	360	210	1	1,25	IPE330	HEB220	160	10
HEB240	235	360	210	1	1,25	IPE330	HEB240	160	10
HEB260	235	360	210	1	1,25	IPE330	HEB260	160	10
HEB280	235	360	210	1	1,25	IPE330	HEB280	160	10
HEB300	235	360	210	1	1,25	IPE330	HEB300	160	10
HEB320	235	360	210	1	1,25	IPE330	HEB320	160	10
HEB340	235	360	210	1	1,25	IPE330	HEB340	160	10
HEB360	235	360	210	1	1,25	IPE330	HEB360	160	10
HEB400	235	360	210	1	1,25	IPE330

Example			Material			Beam	Column		Column stiffener
	fy	fu	E	\(\gamma_{M0}\)	\(\gamma_{M2}\)	Section	Section	tw	bs	ts
	[MPa]	[MPa]	[GPa]	[-]	[-]			[mm]	[mm]	[mm]
tw4	235	360	210	1	1,25	IPE330	HEA320	4	160	10
tw5	235	360	210	1	1,25	IPE330	HEA320	5	160	10
tw6	235	360	210	1	1,25	IPE330	HEA320	6	160	10
tw7	235	360	210	1	1,25	IPE330	HEA320	7	160	10
tw8	235	360	210	1	1,25	IPE330	HEA320	8	160	10
tw9	235	360	210	1	1,25	IPE330	HEA320	9	160	10
tw10	235	360	210	1	1,25	IPE330	HEA320	10	160	10
tw11	235	360	210	1	1,25	IPE330	HEA320	11	160	10
tw12	235	360	210	1	1,25	IPE330	HEA320	12	160	10
tw13	235	360	210	1	1,25	IPE330	HEA320	13	160	10
tw14	235	360	210	1	1,25

Fig. 9.1.1 Joint geometry and dimensions

Numerical model

Nonlinear elastic-plastic material status is investigated in each layer of an integration point. Assessment is based on the maximum strain given according to EN 1993-1-5:2006 by the value of 5%.

Global behavior

Comparison of the global behavior of a portal frame moment connection, described by moment-rotation diagram, is presented. Main characteristics of the moment-rotation diagram are initial stiffness, elastic resistance, and design resistance. An open section beam IPE 330 is welded to a column HEB 260 in the example. A portal frame moment connection with horizontal stiffeners in the column is considered according to component method as a rigid joint with S_j,ini= ∞. Therefore a joint without horizontal stiffeners in the column is analyzed. The moment-rotation diagram is shown in Fig. 9.1.2, and the results are summarised in Tab. 9.1.2. The results show very good agreement in initial stiffness and joint global behavior.

Tab. 9.1.2 Rotational stiffness of a portal frame moment connection in CBFEM and CM

		CM	CBFEM	CM/CBFEM
Initial stiffness Sj,ini	[kNm/rad]	48423,7	58400,0	0,83
Elastic resistance 2/3 Mj,Rd	[kNm]	93,3	93,0	1,00
Design resistance Mj,Rd	[kNm]	140,0	139,0	0,99

Fig. 9.1.2 Moment-rotation diagram for a joint without column stiffeners

Verification of resistance

The results calculated by CBFEM are compared with CM. The comparison is focused on the design resistance and the critical component. The study is performed for three different parameters: beam cross-section, column cross-section, and thickness of the column web panel.

An open section column HEB 260 is used in an example where the parameter is beam cross-section. The column is stiffened with two horizontal column stiffeners of thickness 10 mm opposite to the beam flanges. The width of stiffeners is corresponding to the width of beam flange. The beam IPE sections are selected from IPE 140 to IPE 500. The results are shown in Tab. 9.1.3. The influence of beam cross-section on the design resistance of a welded portal frame moment connection is shown in Fig. 9.1.3.

Tab. 9.1.3 Design resistances and critical components in CBFEM and CM

Parameter	Component method		CBFEM
	Resistance	Critical component	Resistance	Critical component
	[kN/kNm]		[kN/kNm]
IPE140	24	Beam flange in compression	27	Beam flange in compression
IPE160	33	Beam flange in compression	34	Beam flange in compression
IPE180	44	Beam flange in compression	48	Beam flange in compression
IPE200	59	Beam flange in compression	67	Beam flange in compression
IPE220	77	Beam flange in compression	80	Beam flange in compression
IPE240	98	Beam flange in compression	103	Beam flange in compression
IPE270	113	Beam flange in compression	125	Beam flange in compression
IPE300	142	Web panel in shear	142	Beam flange in compression
IPE330	155	Web panel in shear	145	Web panel in shear
IPE360	168	Web panel in shear	167	Web panel in shear
IPE400	186	Web panel in shear	183	Web panel in shear
IPE450	209	Web panel in shear	202	Web panel in shear
IPE500	231	Web panel in shear	223	Web panel in shear

Fig. 9.1.3 Sensitivity study of beam size in a portal frame moment connection

An open section beam IPE330 is used in an example where the parameter is column cross-section. The column is stiffened with two horizontal column stiffeners with a thickness of 10 mm opposite to the beam flanges. The width of stiffeners is corresponding to the width of beam flange. The combined width of stiffeners is 160 mm. The column sections are selected from HEB 160 to HEB 500. The results are shown in Tab. 9.1.4. The influence of column cross-section on the design resistance of a welded portal frame moment connection is shown in Fig. 9.1.4.

Tab. 9.1.4 Design resistances and critical components of a moment connection in CBFEM and CM

Parameter	Component method		CBFEM
	Resistance	Critical component	Resistance	Critical component
	[kN/kNm]		[kN/kNm]
HEB160	73	Web panel in shear	70	Web panel in shear
HEB180	84	Web panel in shear	88	Web panel in shear
HEB200	103	Web panel in shear	101	Web panel in shear
HEB220	116	Web panel in shear	124	Web panel in shear
HEB240	139	Web panel in shear	139	Web panel in shear
HEB260	155	Web panel in shear	145	Web panel in shear
HEB280	170	Web panel in shear	179	Beam flange in compression
HEB300	198	Web panel in shear	196	Beam flange in compression
HEB320	216	Web panel in shear	226	Beam flange in compression
HEB340	226	Beam flange in compression	240	Beam flange in compression
HEB360	228	Beam flange in compression	245	Beam flange in compression
HEB400	234	Beam flange in compression	251	Beam flange in compression
HEB450	241	Beam flange in compression	258	Beam flange in compression
HEB500	248	Beam flange in compression	266	Beam flange in compression

Fig. 9.1.4 Sensitivity study of column size in a portal frame moment connection

Third example presents a portal frame moment connection made out of an open section beam IPE 330 and column HEA 320. The parameter is the thickness of the column web. The column is stiffened with two horizontal column stiffeners with a thickness of 10 mm and width 160 mm. The column web thickness is chosen from 4 to 16 mm. The results are summarised in Tab. 9.1.5. The influence of column web thickness on the design resistance of a welded portal frame moment connection is shown in Fig. 9.1.5.

Tab. 9.1.5 Design resistances and critical components of a moment connection in CBFEM and CM

Parameter	Component method	CBFEM
	Resistance	Critical component	Resistance	Resistance
	[kN/kNm]		[kN/kNm]	[kN/kNm]
tw4	82	Web panel in shear	99	Web panel in shear
tw5	94	Web panel in shear	115	Web panel in shear
tw6	106	Web panel in shear	131	Web panel in shear
tw7	118	Web panel in shear	147	Web panel in shear
tw8	130	Web panel in shear	162	Web panel in shear
tw9	142	Web panel in shear	177	Web panel in shear
tw10	155	Web panel in shear	190	Beam flange in compression
tw11	167	Web panel in shear	203	Beam flange in compression
tw12	179	Web panel in shear	216	Beam flange in compression
tw13	191	Web panel in shear	227	Beam flange in compression
tw14	203	Web panel in shear	236	Beam flange in compression
tw15	215	Beam flange in compression	240	Beam flange in compression
tw16	222	Beam flange in compression	241	Beam flange in compression

Fig. 9.1.5 A sensitivity study of column web thickness

To illustrate the accuracy of the CBFEM model, the results of the parametric studies are summarized in a diagram comparing the resistances of CBFEM and component method; see Fig. 9.1.6. The results show that the difference between the two calculation methods is less than 5%, which is a generally acceptable value. The study with parameter column web thickness gives higher resistance for CBFEM model compared to component method. This difference is caused by considering welded cross-sections. The transfer of shear load is in component method considered only in web and contribution of the flanges is neglected.

Fig. 9.1.6 Verification of CBFEM to CM

Benchmark example

Inputs

Column

Steel S235
HEB260
Column offset over beam: 20 mm

Beam

Steel S235
IPE330

Column stiffeners

Thickness t_s = 10 mm
Width 80 mm
Opposite to beam flanges

Weld

Beam flange: fillet weld throat thickness a_f = 9 mm
Beam web: fillet weld throat thickness a_w = 5 mm
Butt weld around stiffeners

Outputs

Design resistance in shear V_Rd = –145 kN
Design resistance in bending M_Rd = 145 kNm
Critical component: Column web panel in shear

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