Eurocode 3: BS EN 1993-1-8:2005
Panel Zone – Web Shear
The capacity of the column to resist the applied panel zone shear is calculated according to 6.2.6.1 RAM Frame assumes that bs is the distance between flanges of welded I-Sections, and the distance between the toe of the flange-to-web welds in rolled I-Sections. Where a supplementary web plate is required the program will automatically use a web plate equal in thickness to that of the column web (per 6.2.6.1 (6) – (12)), but rounded up to the closest web plate increment (see Criteria section). When the capacity is calculated only the thickness of the plate equal to that of the web is considered (per 6.2.6.1). This implementation may result in a confusing output in the following situation. If a column has an 11 mm thick web, and based on forces a 12.5 mm thick plate is required, then obviously a suitable web plate cannot be designed and the program will indicate that no web plate can be designed. However, when looking at the output the provided web plate may be 15 mm thick. This occurs as the maximum thickness of the provided web plate is 11 mm (same as column web), but this is rounded up to the next increment which if the user set to 5mm, results in a plate 15mm thick. While a 15mm thick web plate is provided, when we calculate the strength of the web plate the program only considers 11 mm of the plate effective and states that it fails. This situation will only occur when the required thickness of the plate is between the column web thickness, and the web thickness rounded up to the next thickness increment. No web buckling requirements are checked. The engineer is also responsible for specifying a web plate yield strength that is similar to that of the column (as required by specification 6.2.6.1 (8)).
Resistance of Tension Zone (Flange Bending) 6.2.6.4.3
The ability of the column flange to resist a concentrated tension force applied to its flange is calculated according to 6.2.6.4.3. For both welded and built up sections the rc value is calculated as the difference between the columns k dimension and the thickness of the column flange. For built-up sections the engineer should therefore specify the appropriate k factor in the master table to account for the web-to-flange fillet weld dimension. Where the user specifies that the member capacity is to be used to calculate forces (see ), the program will instead calculate the force as: Beff,b,fc Tfb Fyb / Gamma Mo (Eqn 6.20). Beff,b,fc is calculated according 4.10. The user should specify an over-strength factor (see ) of 1.0 if no strain hardening is to be considered.
Resistance of Tension Zone (Web Bearing) 6.2.6.3
The ability of the column web to resist a concentrated tension force applied to its flange is calculated according to 6.2.6.3. For both welded and built up sections the ab value is ignored as a complete joint penetration weld is assumed. If a web plate is used then the web plates capacity is calculated independently of the column web. If the thickness of web plate required exceeds 0.5 times the column web thickness (6.17) then no thickness of web plate is adequate, and the required thickness is reported as -25.4mm (-1.0in). Refer to flange bending section above for information on the web-to-flange weld dimension (ac) in a built up section. Note that at the top of a column (where no column exists above, the coefficient for (tfc + rc) is assumed to be 2.5 instead of 5.0.
Resistance of Compression Zone (Web Bearing) 6.2.6.2 (1)
The ability of the column web to resist a concentrated compression force applied to its flange is calculated according to 6.2.6.2. For both welded and built up sections the ab value is ignored as a complete joint penetration weld is assumed. If a web plate is used then the web plate’s capacity is calculated independently of the column web. If the thickness of web plate required exceeds 0.5 times the column web thickness (6.17) then no thickness of web plate is adequate, and the required thickness is reported as negative 25.4mm (-1.0in). Refer to flange bending section above for information on the web-to-flange weld dimension (ac) in a built up section. Note that at the top of a column (where no column exists above, the coefficient for (tfc + rc) is assumed to be 2.5 instead of 5.0. The program assumes that transverse movement of the column flanges (see Eurocode figure 6.7) is prevented. Where the capacity of the framing beams is used to perform the design, no axial load is assumed on the joint column.
Stiffener Design
Where stiffeners are required only for web bearing or flange bending checks, half column depth stiffeners will be designed. The engineer should confirm that half the column depth is adequate. The stiffener dimensions are based on the user criteria settings (see Criteria-Joints), the area required to resist the applied flange force (less the capacity of the column), and the code requirements (thickness at least equal to the adjoining beam flange thickness). The program also dimensions the stiffener thickness to ensure a fully effective section i.e. class 1 or 2, but the stiffener thickness is arbitrarily limited to three times the framing beam flange thickness. The lower of the stiffener and column web yield strengths is used for the "column" strength when performing this check. The program assumes one stiffener is provided each side of the column web.