{"id":3217,"date":"2024-08-28T15:34:53","date_gmt":"2024-08-28T10:04:53","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=3217"},"modified":"2025-10-13T17:02:41","modified_gmt":"2025-10-13T11:32:41","slug":"loads-for-gantry-girders","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ce\/design-of-steel-structures\/loads-for-gantry-girders","title":{"rendered":"Loads for Gantry Girders"},"content":{"rendered":"<p style=\"text-align: justify;\">In general gantry girders are laterally unsupported beam except at the column locations.<\/p>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3218 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/08\/gantry-girders.jpg\" alt=\" Gantry Girders\" width=\"326\" height=\"190\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/08\/gantry-girders.jpg 326w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/08\/gantry-girders-300x175.jpg 300w\" sizes=\"auto, (max-width: 326px) 100vw, 326px\" \/><\/p>\n<p style=\"text-align: justify;\">Above figure shows the various forces that act on a girder and are summarized below:<br \/>\n(a) Crane girder reaction acting vertically downwards.<br \/>\n(b) Longitudinal thrust due to starting and stopping of the crane acting in the longitudinal direction.<br \/>\n(c) Lateral thrust due to starting and stopping of the crab acting horizontally<\/p>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3219 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/08\/gantry-girder.jpg\" alt=\" Gantry Girder\" width=\"333\" height=\"323\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/08\/gantry-girder.jpg 333w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/08\/gantry-girder-300x291.jpg 300w\" sizes=\"auto, (max-width: 333px) 100vw, 333px\" \/><\/p>\n<h2 style=\"text-align: justify;\">Vertical Loads<\/h2>\n<ul style=\"text-align: justify;\">\n<li style=\"text-align: left;\">Reaction from the crane girder comprising of self-weight of the crane, self-weight of crab and the crane capacity constitute vertical load on the gantry girder.<\/li>\n<li style=\"text-align: left;\">The wheels attached to the crane girder transfer this vertical load to the gantry girder.<\/li>\n<li style=\"text-align: left;\">Thus design reaction is computed from the maximum crane wheel load and it occurs when the crane is nearest to the gantry girder. Self-weight of the rail also constitutes the vertical load.<\/li>\n<\/ul>\n<h3 style=\"text-align: justify;\">Lateral Loads \/ Surge Loads<\/h3>\n<p style=\"text-align: justify;\">Lateral loads on crane girders are caused due to the following:<br \/>\n(a) Sudden stopping of the crab and the load when traversing the carb girder.<br \/>\n(b) Crab dragging weights across the shop floor.<br \/>\nThe lateral load is assumed to act in the plane of center of gravity of the upper flange. Now this lateral force has a lever arm that produces torque which is quite small and can be neglected safely. It is assumed that tensile flange of the gantry girder does not offer any resistance to the lateral loads.<\/p>\n<h3 style=\"text-align: justify;\">Longitudinal Loads \/ Drag Loads<\/h3>\n<ul style=\"text-align: justify;\">\n<li>Starting and stopping of the crane girders produce longitudinal forces on the gantry girders.<\/li>\n<li>This thrust is produced along the rails.<\/li>\n<li>Maximum longitudinal force acts when electrically operated crane applies brakes suddenly.<\/li>\n<li>The frictional resistance developed due to locked wheels is supplied by the rails and in turn gets distributed to the crane columns.<\/li>\n<\/ul>\n<h3 style=\"text-align: justify;\">SPECIFICATION FOR GANTRY GIRDERS<\/h3>\n<ul>\n<li style=\"text-align: justify;\">Gantry girders are subjected to vertical loads along with horizontal thrust\/loads simultaneously.<\/li>\n<li style=\"text-align: justify;\">Thus the allowable stresses are enhanced by 10% but this enhancement in allowable stresses is not<br \/>\nin addition to that allowed for erection loads with or without wind or seismic forces.<br \/>\nOf the two horizontal forces as specified in <strong>Table 9.1<\/strong> only one is able considered to act at a time along with<br \/>\nthe vertical load.<\/li>\n<\/ul>\n<table style=\"height: 237px;\" width=\"816\">\n<tbody>\n<tr>\n<td width=\"35\"><\/td>\n<td colspan=\"2\" width=\"413\">\n<p style=\"text-align: center;\"><strong>Table 9.2 Vertical Deflection Limits for Gantry Girders<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td width=\"35\">S<strong>.No.<\/strong><\/td>\n<td width=\"285\"><strong>Crane Type<\/strong><\/td>\n<td width=\"129\"><strong>Permissible Deflection<\/strong><\/td>\n<\/tr>\n<tr>\n<td width=\"35\">\n<p style=\"text-align: center;\">1.<\/p>\n<p style=\"text-align: center;\">2.<\/p>\n<p style=\"text-align: center;\">3.<\/p>\n<p style=\"text-align: center;\">4.<\/p>\n<\/td>\n<td style=\"text-align: center;\" width=\"285\">Manually operated cranes<\/p>\n<p>Electrically operated cranes of capacity up to 500 kN<\/p>\n<p>Electrically operated cranes of capacity exceeding 500 kN<\/p>\n<p>Other moving loads like the charging cars etc.<\/td>\n<td width=\"129\">\n<p style=\"text-align: center;\">L\/500<\/p>\n<p style=\"text-align: center;\">L\/750<\/p>\n<p style=\"text-align: center;\">L\/1000<\/p>\n<p style=\"text-align: center;\">L\/600<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>L = Span of the gantry girder<\/p>\n<p style=\"text-align: center;\"><a class=\"btn btn-danger\" role=\"button\" href=\"https:\/\/study.madeeasy.in\/ce\/design-of-steel-structures\/plate-girder\/\" target=\"_blank\" rel=\"noopener\">&lt;&lt; Previous<\/a> | <a class=\"btn btn-success\" role=\"button\" href=\"https:\/\/study.madeeasy.in\/ce\/design-of-steel-structures\/beam-column-behavior\/\" target=\"_blank\" rel=\"noopener\"> Next &gt;&gt;<\/a><br \/>\n<strong> Must Read: <\/strong> <a href=\"https:\/\/study.madeeasy.in\/subjects\/steel-structure-building-design\/\" target=\"_blank\" rel=\"noopener\"><strong>What is Power Electronics?<\/strong><\/a><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In general gantry girders are laterally unsupported beam except at the column locations. Above figure shows the various forces that<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[861,2],"tags":[901,902,903],"class_list":["post-3217","post","type-post","status-publish","format-standard","hentry","category-design-of-steel-structures","category-ce","tag-drag-loads","tag-surge-loads","tag-vertical-loads"],"_links":{"self":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/3217","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/comments?post=3217"}],"version-history":[{"count":0,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/3217\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/media?parent=3217"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/categories?post=3217"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/tags?post=3217"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}