{"id":14873,"date":"2025-03-12T15:46:08","date_gmt":"2025-03-12T15:46:08","guid":{"rendered":"https:\/\/support.buildsoft.eu\/?post_type=ht_kb&p=14873"},"modified":"2026-03-30T09:04:28","modified_gmt":"2026-03-30T09:04:28","slug":"dt-ec-02-lateral-torsional-buckling-constant","status":"publish","type":"ht_kb","link":"https:\/\/support.buildsoft.eu\/nl\/knowledge-base\/dt-ec-02-lateral-torsional-buckling-constant\/","title":{"rendered":"DT EC 02: Lateral torsional buckling – constant"},"content":{"rendered":"

Description<\/h2>\n

\"\"<\/p>\n

\n\n\n\n\n\n\n\n
Geometry<\/th>\nCross-section:<\/td>\n70x221mm<\/td>\n<\/tr>\n
Material:<\/td>\nC24<\/td>\n<\/tr>\n
Load<\/th>\nULS FC:<\/td>\n5.37kNm<\/td>\n<\/tr>\n
Standard<\/th>\n<\/td>\nEN 1995-1-1 [- -]<\/td>\n<\/tr>\n
Design parameters<\/th>\nkmod<\/sub>:
\nLLT<\/sub>:<\/td>\n		0.8
\n3m<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Independent reference results<\/h2>\n
<\/span>Open handcalculations<\/div>
\n

The effective beam length \"L_{ef}\" is given in Table 6.1 from EN 1995-1-1.<\/p>\n

  <\/span>   <\/span>\"\begin{align*}<\/p>\n

Although Diamonds assumes the loads act in the shear center, \"+ 2 \cdot h\" is always added to \"L_{ef}\" to take into account that loads might act in the compression zone.
\nDiamonds uses a factor 0.9 because there’s a uniform load on the beam. For deviating load distrutions and boundary conditions this method Serna, Lopez, Puente and Young<\/em><\/a> is used to determine \"C_1\". The 0.9 for a uniform load corresponds to a \"C_1=\frac{1}{0.9}=1.11\".
\nThe user can also impose C1<\/sub> via \"\".<\/p>\n

Next we determine the critical bending stress \"\sigma_{m.crit}\":<\/p>\n

(6.31) <\/span>   <\/span>\"\begin{align*}<\/p>\n

The relative slenderness for bending \"\overline{\lambda_{m}}\":<\/p>\n

(6.30) <\/span>   <\/span>\"\begin{align*}<\/p>\n

Factor for the reduced bending strength \"k_{crit}\":<\/p>\n

(6.34) <\/span>   <\/span>\"\begin{align*}<\/p>\n

The unity check UC:<\/p>\n

(6.35) <\/span>   <\/span>\"\begin{align*}<\/p>\n<\/div><\/div><\/div>\n

Diamonds results and comparison<\/h2>\n

\"\"<\/p>\n

Stability verification of the beam according to EN 1995-1-1<\/strong><\/p>\n

\"\"<\/p>\n

Intermediate results in Diamonds for lateral torsional buckling<\/strong><\/p>\n

\n\n\n\n\n\n\n\n\n
Results<\/th>\nIndependent reference<\/th>\nDiamonds<\/th>\nDifference<\/th>\n<\/tr>\n
\"L_{ef}\"<\/td>\n3.14m<\/td>\n3.14m<\/td>\n0,00%<\/td>\n<\/tr>\n
\"\sigma_{m.crit}\"<\/td>\n40.57MPa<\/td>\n40.57MPa<\/td>\n0,00%<\/td>\n<\/tr>\n
\"\overline{\lambda_{m}}\"<\/td>\n0.77<\/td>\n0.77<\/td>\n0,00%<\/td>\n<\/tr>\n
\"k_{crit}\"<\/td>\n0.98<\/td>\n0.98<\/td>\n0,00%<\/td>\n<\/tr>\n
Unity check<\/td>\n64.91%<\/td>\n64.91%<\/td>\n0,00%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

References<\/h2>\n