{"id":1402,"date":"2018-06-26T09:23:36","date_gmt":"2018-06-26T09:23:36","guid":{"rendered":"http:\/\/buildsoftsupport.com\/?post_type=ht_kb&#038;p=1402"},"modified":"2026-08-11T14:02:12","modified_gmt":"2026-08-11T14:02:12","slug":"why-does-a-3d-diamonds-model-give-different-results-from-hand-calculations","status":"publish","type":"ht_kb","link":"https:\/\/support.buildsoft.eu\/es\/knowledge-base\/why-does-a-3d-diamonds-model-give-different-results-from-hand-calculations\/","title":{"rendered":"Why does a 3D Diamonds model give different results from hand calculations?"},"content":{"rendered":"<h3>Reason<\/h3>\n<p>Diamonds shows the real behaviour of the structure, while hand calculations\/ daily reasoning make assumptions that are only valid for some cases. For example:<\/p>\n<ul>\n<li>The hand calculations of a plate are only valid for a plate strip in the middle of the plate, far enough from the edges.<\/li>\n<li>Pr\u00e9slabs is plate type which behaviour is rahter a two-way slab than a one-way slab. Yet in handcalculations, a pr\u00e9slab is mostly approached using one-way slab behaviour.<\/li>\n<\/ul>\n<p>If the assumptions used during hand calculations are modelled in Diamonds, Diamonds will give similar results as the hand calculations.<\/p>\n<p>The question is if these hand-calculations-assumtions comply to the real behaviour of the structure? If the boundary conditions and plate-behaviour are representative for the real behavior of the structure, the Diamonds results are the most correct.<\/p>\n<h3>Example<\/h3>\n<p>Consider the example building from the image below (model attached at the end of this article). The walls have been set invisible. The loading is 12kN\/m\u00b2 on both the roof and the floor. Using hand calculations a bending moment of 167kNm is expected in the beam. Yet in Diamonds only a maximum bending moment of 4,0kNm is found.<\/p>\n<p style=\"text-align: center;\">\\[{q=12kN\/m^2 \\cdot 0.5 \\cdot 5.5m \\cdot 2 = 66kN\/m}\\]\n<p style=\"text-align: center;\">\\[M_y=\\frac{66kN\/m \\cdot (4.5m)^2}{8} = 167kNm\\]\n<table>\n<tbody>\n<tr>\n<th>Geometry (the walls have been set invisible)<\/th>\n<th>Diamonds result for My<\/th>\n<\/tr>\n<tr>\n<td> <img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-full wp-image-4000\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2018\/06\/3DvsHand5.png\" alt=\"\" width=\"731\" height=\"436\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand5.png 731w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand5-300x179.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand5-50x30.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand5-60x36.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand5-35x21.png 35w\" sizes=\"(max-width: 731px) 100vw, 731px\" \/><\/td>\n<td> <img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-large wp-image-3999\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2018\/06\/3DvsHand4.png\" alt=\"\" width=\"643\" height=\"381\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand4.png 730w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand4-300x178.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand4-50x30.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand4-60x36.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand4-35x21.png 35w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The following changes have been made to make the Diamonds-results correspond to hand calculations:<\/p>\n<ul>\n<li>Select all walls. Remove the no tension at the top of a wall-condition. &#8216;No tension at the top of a wall&#8217; is something you cannot simulate in simple hand calculations.<\/li>\n<\/ul>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-large wp-image-1682 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D1-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D1.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/p>\n<ul>\n<li>Define the slabs as bearing in one direction instead of pr\u00e9slabs. In the hand calculation, it is assumed that 50% of the loading goes to the beam. This is only true, if the slabs are bearing in one direction.<\/li>\n<\/ul>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-large wp-image-1681 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D2-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D2.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/p>\n<ul>\n<li>Put hinges at the bar ends.<\/li>\n<\/ul>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"alignnone size-large wp-image-1680 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D3-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D3.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/p>\n<ul>\n<li>Place the beams eccentric. Allow only the transfer of normal force in the rigid links.<\/li>\n<\/ul>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"size-large wp-image-1679 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D4-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/p>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"size-large wp-image-1678 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D4a-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D4a.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/p>\n<ul>\n<li>Define hinges on the floor edges.\n<ul>\n<li>Turn off the transfer of moment, normal force and in-plane shear force for all edges.&nbsp;<img decoding=\"async\" loading=\"lazy\" class=\"size-large wp-image-1677 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D5a-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5a.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/li>\n<li>Additionally, turn off the transfer of out-of-plane shear for all edges parallel to the bearing direction.<img decoding=\"async\" loading=\"lazy\" class=\"size-large wp-image-1676 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2017\/10\/3D5-1024x587.png\" alt=\"\" width=\"643\" height=\"369\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5-1024x587.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5-300x172.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5-768x440.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5-50x29.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5-60x34.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5-35x20.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2017\/10\/3D5.png 1267w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/li>\n<\/ul>\n<\/li>\n<li>The Diamonds model now approximate the hand calculations well:<\/li>\n<\/ul>\n<p><img decoding=\"async\" loading=\"lazy\" class=\"size-large wp-image-4002 aligncenter\" src=\"http:\/\/buildsoftsupport.com\/wp-content\/uploads\/2018\/06\/3DvsHand6-1024x694.png\" alt=\"\" width=\"643\" height=\"436\" srcset=\"https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6-1024x694.png 1024w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6-300x203.png 300w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6-768x520.png 768w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6-50x34.png 50w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6-60x41.png 60w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6-35x24.png 35w, https:\/\/support.buildsoft.eu\/wp-content\/uploads\/2018\/06\/3DvsHand6.png 1058w\" sizes=\"(max-width: 643px) 100vw, 643px\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Reason Diamonds shows the real behaviour of the structure, while hand calculations\/ daily reasoning make assumptions that are only valid for some cases. For example: The hand calculations of a plate are only valid for a plate strip in the middle of the plate, far enough from the edges. Pr\u00e9slabs&#8230;<\/p>\n","protected":false},"author":3,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":[],"ht-kb-category":[59],"ht-kb-tag":[1348],"_links":{"self":[{"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/ht-kb\/1402"}],"collection":[{"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/ht-kb"}],"about":[{"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/types\/ht_kb"}],"author":[{"embeddable":true,"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/comments?post=1402"}],"version-history":[{"count":2,"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/ht-kb\/1402\/revisions"}],"predecessor-version":[{"id":30823,"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/ht-kb\/1402\/revisions\/30823"}],"wp:attachment":[{"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/media?parent=1402"}],"wp:term":[{"taxonomy":"ht_kb_category","embeddable":true,"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/ht-kb-category?post=1402"},{"taxonomy":"ht_kb_tag","embeddable":true,"href":"https:\/\/support.buildsoft.eu\/es\/wp-json\/wp\/v2\/ht-kb-tag?post=1402"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}