{"id":196,"date":"2019-05-25T15:17:00","date_gmt":"2019-05-25T15:17:00","guid":{"rendered":"https:\/\/ghothi.co.uk\/?p=196"},"modified":"2025-05-28T08:48:27","modified_gmt":"2025-05-28T08:48:27","slug":"cutting-bridge-analysis-time-by-60-by-hacking-an-obsecure-lusas-feature","status":"publish","type":"post","link":"https:\/\/ghothi.co.uk\/?p=196","title":{"rendered":"Reducing Analysis Time by 60% by hacking an obsecure LUSAS feature"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"547\" src=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-1024x547.jpg\" alt=\"\" class=\"wp-image-202\" srcset=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-1024x547.jpg 1024w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-300x160.jpg 300w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-768x410.jpg 768w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-1536x820.jpg 1536w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-500x267.jpg 500w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-150x80.jpg 150w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-1200x641.jpg 1200w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-400x214.jpg 400w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-800x427.jpg 800w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05-200x107.jpg 200w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_17-18-05.jpg 1849w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>In one of my recent bridge assessment projects, I ran into some serious inefficiency.<\/p>\n\n\n\n<p>As part of a Level 2 Finite Element Analysis (FEA), I needed to run over 10 different analysis scenarios. Each scenario included four load cases (LCs):<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>LC1<\/strong>: Dead and superimposed dead load (linear)<\/li>\n\n\n\n<li><strong>LC2<\/strong>: \u201cBirth\u201d of strengthening works (non-linear)<\/li>\n\n\n\n<li><strong>LC3<\/strong>: Combined LC1 and LC2 (linear)<\/li>\n\n\n\n<li><strong>LC4<\/strong>: Live load (non-linear and unique to each scenario)<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img decoding=\"async\" width=\"624\" height=\"145\" src=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41.jpg\" alt=\"\" class=\"wp-image-200\" srcset=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41.jpg 624w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41-300x70.jpg 300w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41-500x116.jpg 500w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41-150x35.jpg 150w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41-400x93.jpg 400w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-13-41-200x46.jpg 200w\" sizes=\"(max-width: 624px) 100vw, 624px\" \/><\/figure>\n\n\n\n<p>The problem was that LC1 to LC3 were exactly the same in every single scenario. Only LC4 changed. But the software I was using (LUSAS) was forcing me to re-run LC1 to LC3 each time before I could run LC4.<\/p>\n\n\n\n<p>This meant that each of the 10 full analysis took about <strong>2.5 hours<\/strong>, with <strong>1.5 hours <\/strong>spent re-running the same first 3 steps over and over, just so I could run the last different load case.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Run the Common Load Cases Just Once<\/h2>\n\n\n\n<p>I thought, <em>why not run LC1\u20133 once, save that point, and then branch off each LC4 from there?<\/em><\/p>\n\n\n\n<p>Basically, create some sort of Base Analysis for the shared cases (LC1-3), and then have each LC4 scenario pick up from that point, kind of like the below:<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img decoding=\"async\" width=\"623\" height=\"222\" src=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1.jpg\" alt=\"\" class=\"wp-image-199\" srcset=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1.jpg 623w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1-300x107.jpg 300w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1-500x178.jpg 500w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1-150x53.jpg 150w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1-400x143.jpg 400w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_16-14-00-1-200x71.jpg 200w\" sizes=\"(max-width: 623px) 100vw, 623px\" \/><\/figure>\n\n\n\n<p>I asked several different people quite experienced in LUSAS but was told it wasn&#8217;t possible as there&#8217;s no such feature.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The Breakthrough: A Hidden Gem Called RESTART<\/h2>\n\n\n\n<p>Still not satisfied, I contacted LUSAS directly and after spending a bit of time talking to them, I learned about something called the <strong>RESTART<\/strong> function. It was originally made for recovering unfinished analyses from a backup file that saved all model properties (like stresses and deformations) after a load case finishes in case the software crashed before it could complete.<\/p>\n\n\n\n<p>Although not intended for my use case, with a bit of help from the LUSAS team and a bit of manual hacking the analysis files to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Run LC1\u20133 once and save the results.<\/li>\n\n\n\n<li>Restart each scenario at LC4 using the saved state.<\/li>\n<\/ul>\n\n\n\n<p>It worked!<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The Result<\/h2>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"626\" height=\"570\" src=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59.jpg\" alt=\"\" class=\"wp-image-197\" srcset=\"https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59.jpg 626w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59-300x273.jpg 300w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59-500x455.jpg 500w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59-150x137.jpg 150w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59-400x364.jpg 400w, https:\/\/ghothi.co.uk\/wp-content\/uploads\/2025\/05\/2025-05-25_15-33-59-200x182.jpg 200w\" sizes=\"(max-width: 626px) 100vw, 626px\" \/><\/figure>\n\n\n\n<p>Using RESTARTs, I <strong>cut each analysis from 2.5 hours to just 1 hour, which is nearly a 60% time saving<\/strong>.<\/p>\n\n\n\n<p>Apparently RESTARTs haven&#8217;t been used for this purpose before (according to the support team I was liaising with), so just putting this out there as I&#8217;m guessing it will be useful to a lot of other engineers. On large projects with a lot of different scenarios and multiple reruns, I&#8217;m guessing this could shave off a lot of time and waiting around.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>TL;DR<\/strong>:<\/h2>\n\n\n\n<p>If you use LUSAS and are tired of re-running identical load cases, dig into the RESTART function. It could save you hours\u2014and your sanity.<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>In one of my recent bridge assessment projects, I ran into some serious inefficiency. As part of a Level 2 Finite Element Analysis (FEA), I needed to run over 10 different analysis scenarios. Each scenario included four load cases (LCs): The problem was that LC1 to LC3 were exactly the same in every single scenario. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":202,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-196","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-civil-engineering"],"_links":{"self":[{"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/196","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=196"}],"version-history":[{"count":3,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/196\/revisions"}],"predecessor-version":[{"id":357,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/196\/revisions\/357"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=\/wp\/v2\/media\/202"}],"wp:attachment":[{"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=196"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=196"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ghothi.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=196"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}