{"id":928,"date":"2017-04-24T15:51:17","date_gmt":"2017-04-24T15:51:17","guid":{"rendered":"http:\/\/buildsoftsupport.com\/?post_type=ht_kb&p=928"},"modified":"2025-04-15T15:08:20","modified_gmt":"2025-04-15T15:08:20","slug":"why-do-concrete-and-diamonds-give-different-results","status":"publish","type":"ht_kb","link":"https:\/\/support.buildsoft.eu\/fr\/knowledge-base\/why-do-concrete-and-diamonds-give-different-results\/","title":{"rendered":"Why do ConCrete and Diamonds give different results"},"content":{"rendered":"

You have made a beam or plate element in Diamonds and ConCrete and you do not get the same results from both programs.<\/p>\n

Solution<\/h2>\n

You probably have not made the same assumptions in both programs. To get the same results, you should model the same.<\/p>\n

Verify all items in the check list below to obtain the same results. The sequence is important. It has no use comparing reinforcement\/ cracked deformation if the elastic results between the software is not the same.<\/p>\n

Check list 1: geometry and loads<\/h3>\n\n\n\n\n\n\n\n\n\n
Geometry<\/em><\/td>\nCheck<\/td>\n<\/tr>\n<\/tbody>\n
Span length<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n
Cross-section<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n
Plate behaviour<\/strong>
\nA plate in ConCrete is calculate as a beam (= a plate bearing perfectly in one direction).
\nWhile in Diamonds multiple plate types are possible. The equivalent icon for a plate bearing in one direction in Diamonds is \"\", or a beam with width 1000m en height equal to the thickness of the plate in Concrete.<\/td>\n		\u2610<\/td>\n<\/tr>\n
Concrete properties<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n
Reinforcement properties<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n\n\n\n\n
Loads<\/em><\/td>\nCheck<\/td>\n<\/tr>\n<\/tbody>\n
Partial safety factors<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n
Load combinations factors<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n
Chessboard pattern<\/strong> (relevant when beam\/ plate\u00a0has multiple spans).
\nDiamonds cannot automatically generate a chessboard pattern of the life loads. So If you haven’t entered the chessboard pattern manually in Diamonds, you must turn OFF the chessboard pattern in ConCrete by making the little guys hold hands FOR ALL USED LOADGROUPS.<\/td>\n		\u2610<\/td>\n<\/tr>\n
Eq 6.10 or Eqs 6.10a & 6.10b<\/strong>
\nEurocode allows you to generate combinations according to equation 6.10 or 6.10a\/b.ConCrete will uses equation 6.10.
\nIn Diamonds you can choose depending on the national annex. So choose equation 6.10 in Diamonds.<\/td>\n		\u2610<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

>> The internal forces (bending moments, shear force) and elastic deformation are now the same.<\/strong><\/p>\n

Check list 2: elastic analysis & longitudinal reinforcement<\/h3>\n\n\n\n\n\n\n\n\n
<\/td>\nCheck<\/td>\n<\/tr>\n
Bending moments reduction<\/strong>
\nDon\u2019t reduce the bending moment near the supports in ConCrete. This feature is not available in Diamonds.<\/td>\n		\u2610<\/td>\n<\/tr>\n
Concrete cover<\/strong>
\nIn Concrete you enter the net cover. Concrete will add 10mm to that to find the gross cover. You enter the gross cover in Diamonds. When you enter 30mm in Concrete, you should enter 40mm in Diamonds.<\/td>\n		\u2610<\/td>\n<\/tr>\n
Design standard<\/strong>
\nEN 1992-1-1 + NA is used for structures that still need to be build. ENV 1992-1-1 is an old standard. Both give different results.
\nIn ConCrete you can change the standard using Preferences<\/em> > Calculation method<\/em>.
\nIn Diamonds you can change the standard using Analysis<\/em> > Concrete standard<\/em>.<\/td>\n		\u2610<\/td>\n<\/tr>\n
Minimum reinforcement<\/strong>
\nThe minimum longitudinal reinforcement in beams equals \"A_{s.min}=\rho_{min} \cdot b \cdot d=max\left( 0.26 \frac{f_{ctm}}{f_{yk}}, 0.0013\right) \cdot b \cdot d\" according to EN 1992-1-1 \u00a79.2.1.1 (9.1N).In Diamonds \u03c1min<\/sub> is automatically calculated based on the selected concrete quality. It is impossible to set A_{s.min} to zero. Because Diamonds also offers the possibility to make more complex cross-section shapes in concrete than ConCrete, Diamonds calculates the minimum reinforcement with \"h\" instead of \"d\".
\nIn ConCrete \u03c1min<\/sub> depends on fck<\/sub>. If you change fck<\/sub> (in this dialog \"\"), you should click on the calculator (in this dialog \"\") to update \u03c1min<\/sub><\/em>.<\/td>\n		\u2610<\/td>\n<\/tr>\n
Additional reinforcement for stress limitations in SLS states<\/strong>
\nEN 1992-1-1 \u00a77.2 states that the concrete and steel stresses should be limited in SLS states. If the stresses are too high, the reinforcement amounts are increased. However, Diamonds and ConCrete do not increase the reinforcement amounts the same way.<\/p>\n

When a cross-section is insufficient for stresses in ConCrete, he will add 1mm\u00b2 to the lower and upper reinforcement until the stresses are sufficient.<\/p>\n

When a cross-section is insufficient for stresses in Diamonds, he will search for the most economic combination of the lower and upper reinforcement. Meaning that adding 1mm\u00b2 to the lower reinforcement, will not necessarily lead to 1mm\u00b2 being added to the upper reinforcement.<\/p>\n

If you’re looking to compare both software reagarding cracked deformation, we recommend you either<\/p>\n

    \n
  • turn off the stress limits in both softwares<\/li>\n
  • you enter the reinforcements amounts calculated by ConCrete, as practical reinforcement in Diamonds. And then run the cracked deformation calculation in Diamonds only based on the practical reinforcement.<\/li>\n<\/ul>\n<\/td>\n
\u2610<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

>> The longitudinal reinforcement is now the same. <\/strong><\/p>\n

Although small differences are still possible:<\/p>\n

    \n
  • The stress-strain diagram of concrete is bi-linear in Diamonds, while it is a parabola-rectangle diagram in ConCrete.<\/li>\n
  • Diamonds\u00a0does not redistribute the bending moments (EN 1992-1-1 \u00a75.5) while Concrete does. Therefore peak moments in Diamonds will lead to peak reinforcement, while in Concrete the longitudinal reinforcement is ‘chopped off’.<\/li>\n<\/ul>\n

    Check list 3: shear reinforcement<\/h3>\n\n\n\n\n\n
    <\/td>\nCheck<\/td>\n<\/tr>\n
    Concrete shear contribution<\/strong>
    \nSet the concrete contribution to shear capacity to 0%<\/strong> in ConCrete. In ENV 1992-1-1 the standard method was used to calculate the stirrups. This method allowed to take the concrete contribution to the shear capacity into account. In EN 1992-1-1 the variable strut inclination method is used where the concrete contribution is neglected. (in concrete parameters window)<\/td>\n    		\u2610<\/td>\n<\/tr>\n
    Application of the loads<\/strong>
    \nApply the loads to the lower fibre in ConCrete (in load parameters window).
    \nIn Diamonds you can\u2019t choose, it\u2019s always the lower fibre. More info here<\/a>.<\/td>\n    		\u2610<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    >> The shear reinforcement is now the same. <\/strong><\/p>\n

    Check list 4: cracked deformation<\/h3>\n\n\n\n\n\n\n
    <\/td>\nCheck<\/td>\n<\/tr>\n
    Practical reinforcement<\/strong><\/td>\n\u2610<\/td>\n<\/tr>\n
    Creep coefficient<\/strong>
    \nMake sure the creepfactor for deformation and the creepfactor for stresses are equal.<\/td>\n    		\u2610<\/td>\n<\/tr>\n
    Load combination for cracking<\/strong>
    \nDiamonds calculates the cracking of the section using the combination SLS RC envelope. Select the same combination in ConCrete (in concrete parameters window).<\/td>\n    		\u2610<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    >> The cracked deformation is now more or less the same.<\/strong> Small differences (<5%) are still possible because the calculation principle in Diamonds is a little different then Diamonds.<\/p>\n","protected":false},"excerpt":{"rendered":"

    You have made a beam or plate element in Diamonds and ConCrete and you do not get the same results from both programs. Solution You probably have not made the same assumptions in both programs. To get the same results, you should model the same. Verify all items in the…<\/p>\n","protected":false},"author":2,"comment_status":"open","ping_status":"closed","template":"","format":"standard","meta":[],"ht-kb-category":[54,68],"ht-kb-tag":[],"_links":{"self":[{"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/ht-kb\/928"}],"collection":[{"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/ht-kb"}],"about":[{"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/types\/ht_kb"}],"author":[{"embeddable":true,"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/comments?post=928"}],"version-history":[{"count":3,"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/ht-kb\/928\/revisions"}],"predecessor-version":[{"id":15137,"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/ht-kb\/928\/revisions\/15137"}],"wp:attachment":[{"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/media?parent=928"}],"wp:term":[{"taxonomy":"ht_kb_category","embeddable":true,"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/ht-kb-category?post=928"},{"taxonomy":"ht_kb_tag","embeddable":true,"href":"https:\/\/support.buildsoft.eu\/fr\/wp-json\/wp\/v2\/ht-kb-tag?post=928"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}