Alasdair points out that the calculated web resistance has changed over the years as new codes have been introduced, and codes revised. This is to be expected as more knowledge and experience are gained. Web resistance is only one of many things that have changed considerably as codes have been revised. BS 449 assumed an effective length of 0.5d when calculating the buckling resistance of the web. As this is only theoretically possible when both ends of a strut are fully built-in, perhaps we might agree with hindsight that it seems optimistic. In Amendment 8 of BS 449, the assumed effective length was increased to 0.7d. This accounts almost entirely for the change in resistance. This increased effective length also appears in BS 5950:1985.
展开▼
