TY - JOUR N2 - The study presents the results of theoretical investigations into lateral torsional buckling (LTB) of bi-symmetric I-beams, elastically restrained against warping at supports. Beam loading schemes commonly used in practice are taken into account. The whole range of stiffness of the support joints, from free warping to warping fully restrained, is considered. To determine the critical moment, the energy method is used. The function of the beam twist angle is described with power polynomials that have simple physical interpretation. Computer programs written in symbolic language for numerical analysis are developed. General approximation formulas are devised. Detailed calculations are performed for beams with end-plate joints. Critical moments determined with programs and approximation formulas are compared with the results obtained by other researchers and with those produced by FEM. Very good accuracy of results is obtained. L1 - http://www.journals.pan.pl/Content/84057/mainfile.pdf L2 - http://www.journals.pan.pl/Content/84057 PY - 2015 IS - No 4 EP - 174 KW - critical moment for lateral torsional buckling (LTB) KW - elastic end section restraint against warping KW - end-plates KW - the energy method KW - power polynomials A1 - Piotrowski, R. A1 - Szychowski, A. PB - WARSAW UNIVERSITY OF TECHNOLOGY FACULTY OF CIVIL ENGINEERING and COMMITTEE FOR CIVIL ENGINEERING POLISH ACADEMY OF SCIENCES DA - 31.12.2015 T1 - Lateral-torsional buckling of beams elastically restrained against warping at supports SP - 155 UR - http://www.journals.pan.pl/dlibra/publication/edition/84057 T2 - Archives of Civil Engineering ER -