Computational Technology Resources - CCP

Keywords: structural engineering, patch loads, component method, numerical simulations, column web panel, steel connections.

Summary

In beam-to-column joints, the column web panel comprises three basic components, the column web panel in tension, column web panel in shear and column web panel in compression. In the case of internal nodes, the column web panel is connected to beams on both sides. The simpler case of beams of equal depth is directly covered by Part 1.8 of Eurocode 3 using a transformation parameter ? that takes into account the relative values of the internal forces acting on each side of the column web. However, for beams of different heights, the stress state induced in the column web panel becomes more complex and is currently not covered by the code of practice [1], that specifically states that the actual distribution of shear stresses in the column web panel should be taken into account when determining the design moment resistance.

To explore the behaviour of the column web panel under asymmetrical patch loading, a finite element analysis is carried out on three models, a basic double-sided configuration (Model A) and two single-sided joints that correspond to the double-sided configuration without the right-hand (Model B) or left-hand (Model C) beam, respectively. The relative dimensions of the various sections were selected such that the column web panel controls the resistance of the joint. To achieve this purpose, the column is a HE160B section, 3318.5 mm long, the right-hand beam corresponds to an IPE300, 1500 mm long and the left-hand beam is a modified IPE160 section with a flange thickness of 25 mm and a web thickness of 12 mm, 760 mm long. Both beams are aligned at the upper flange level.

Figure 1 illustrates the stress contours for Model A, revealing an asymmetry in the stress field, with a fairly uniform tensile band along the alignment of top flanges of the two beams but a diagonal varying compression in the bottom part of the column web panel. The shear stress distribution is also completely localised below the level of the bottom flange of the left-hand beam.

Figure 1: Stress contours for double-sided joint.


a) Model A: Horizontal normal stresses	b) Model A: Shear stresses

Table 1 summarizes the forces on the three components (tension, compression and shear), calculated by integration of the stress fields associated with each component, multiplied by the thickness of the column web.

Table 1: Stress resultants for the three components

Model	Tension (kN)			Compression (kN)			Shear (kN)
	Line 1	Line 2	Line 3	Line 1	Line 2	Line3
A	768.76	831.22	971.67	767.66	809.19	936.94	465.84
B	635.25	422.96	172.77	644.37	424.43	174.51	439.92
C	137.54	444.86	711.97	171.07	462.25	719.55	510.09

The numerical analysis presented in this paper reveals some differences in the response of the column web panel whenever two beams of different heights are connected to the column faces. Proper characterisation of the behaviour of the column web panel in these circumstances, currently not yet covered by Eurocode 3, requires, however, a systematic evaluation for various loading scenarios, an issue currently being addressed by the authors.

References

1: CEN, Eurocode 3, prEN - 1993-1-8 : 2003, Part 1.8, Eurocode 3: Design of Steel Structures, Draft 49 Rev., 5 May 2003, CEN, European Committee for Standardization, Brussels, 2003.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £135 +P&P)