{"id":9311,"date":"2008-02-01T14:52:40","date_gmt":"2008-02-01T14:52:40","guid":{"rendered":"http:\/\/www.newsteelconstruction.com\/wp\/?p=9311"},"modified":"2012-08-24T15:07:37","modified_gmt":"2012-08-24T15:07:37","slug":"ad-318-tolerances-on-plan-position-of-steelwork-in-bridges","status":"publish","type":"post","link":"https:\/\/www.newsteelconstruction.com\/wp\/ad-318-tolerances-on-plan-position-of-steelwork-in-bridges\/","title":{"rendered":"AD 318: Tolerances on plan position of steelwork in bridges"},"content":{"rendered":"

\"\"<\/a><\/p>\n

There has been some debate\u00a0about the build-up of tolerances in bridge steelwork and the accuracy with which the steelwork can be positioned on the substructure. The tolerance of \u00b15 mm given in clause 6.302 iii) of the Model Appendix 18\/1 (publication P170) is now generally accepted as being unrealistic and an over-simplification of what is
\na complex issue. The following diagrams and table show typical longitudinal and transverse deviations in plan position (at datum temperature) between the various components, together with a brief commentary. The Model Appendix 18\/1 needs to be modified to reflect these comments.<\/p>\n

\n
\n

It is not intended to print a modified version of P170 but the electronic version that is available on Steelbiz (currently the Third Edition) will be updated as follows:<\/p>\n

In clause 6.302 (\u201cThe tolerance on steelwork dimensions and levels at completion is as follows:\u201d), the wording of (iii) will be modified and item (v) will be added.\u00a0iii) on plan position of steelwork at bearings (structure at datum temperature):<\/p>\n

\"\"<\/a>Transverse position of bearing top and bottom plates relative to substructure: \u00b115 mm
\nLongitudinal position of bearing top plate relative to bottom plate: \u00b1(10 mm+Ls\/10000)<\/p>\n<\/div>\n

\n

Longitudinal position of\u00a0bearing bottom plate relative to substructure: \u00b110 mm<\/p>\n

Where Ls is distance from the\u00a0fixed point.<\/p>\n

v) on spacing of top flanges\u00a0where permanent formwork is to be used: \u00b110mm.<\/p>\n

It is also not intended to modify any of the Guidance Notes (publication P185) at present, because they will be updated in about a year\u2019s time, to align with\u00a0recommendations in the Eurocodes and in the execution standard,<\/p>\n<\/div>\n

\n

EN 1090-2. However, the following additional comments should be noted, in relation to GN 1.04 and GN 5.03:<\/p>\n

In GN 1.04, under the heading of \u201cBasic principles for good articulation\u201d, add the following advice:<\/p>\n

\u201cAllow for fabrication tolerances in calculating design translations for the bearings<\/p>\n

Include an allowance for systematic growth\/shrinkage of the steelwork due to fabrication\u00a0tolerances, as quantified in GN 5.03\/3 Tolerances on Length.\u201d In GN 5.03, the above change to\u00a0the Model Appendix 18\/1 clause 6.302 iii) makes some of the text<\/p>\n<\/div>\n

\n

in GN 5.03 redundant. Under the heading \u201cTolerances on length\u201d, disregard the comments in paragraphs 2 & 3 (i.e. from \u201cModel Appendix 18\/1 clause …\u201d to \u201c… unnecessary tolerances upon each other.\u201d).<\/p>\n

Contact: David Iles<\/span>
\n Tel: 01344 636525<\/span>
\n Email: advisory@steel-sci.com\u00a0<\/a><\/span><\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

There has been some debate\u00a0about the build-up of tolerances in bridge steelwork and the accuracy with which the steelwork can be positioned on the substructure. The tolerance of \u00b15 mm given in clause 6.302 iii) of the Model Appendix 18\/1 (publication P170) is now generally accepted as being unrealistic and an over-simplification of what is […]<\/p>\n","protected":false},"author":3,"featured_media":9312,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[79,5],"tags":[82],"class_list":["post-9311","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ad","category-tech","tag-advisory-desk"],"jetpack_featured_media_url":"https:\/\/www.newsteelconstruction.com\/wp\/wp-content\/uploads\/2012\/08\/AD-Dig1.jpg","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p3WsLP-2qb","_links":{"self":[{"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/posts\/9311","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/comments?post=9311"}],"version-history":[{"count":2,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/posts\/9311\/revisions"}],"predecessor-version":[{"id":9315,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/posts\/9311\/revisions\/9315"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/media\/9312"}],"wp:attachment":[{"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/media?parent=9311"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/categories?post=9311"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsteelconstruction.com\/wp\/wp-json\/wp\/v2\/tags?post=9311"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}