![]() ![]() This is calculated in accordance with BS 5950-1 Clause 4.8.3.2 but substituting P yd for p y The reduced design strength can then be calculated using the equation below The reduced design strength, P yd, is calculated following the procedure given in Section 6.3.2 of King and Brown (2001):Ĭalculate the out-of-plane bending stress: The curvature of the rafter induces bending stresses in the flanges, which combine with the axial stress to reduce the effective yield stress of the section. Plastic analysis is common for portal frames with straight members, and may also be used, within limits, to analyse portal frames with curved rafters.įrom the analysis, the maximum forces between B and C (assumed to coexist). The member resistance checks for structures designed elastically. Σ 2 = 3σ 1b 2/RT Frame analysis – elastic or plastic?Īccording to King and Brown (2001), elastic frame analysis may be used for any frame with members curved in elevation, provided that the geometry of the curved elements is allowed for. The out-of-plane bending stress of an I-section is given by This applies to both open sections and box sections. ![]() The flanges of curved rafters subject to in-plane bending or axial loads must also resist the out-of-plane component of loads resulting from the curvature of the member. ![]() Out-of-plane bending of flanges due to curvature The residual stresses will therefore be limited to those caused by the curving process, and are not in addition to those in a straight beam. Because the curving process induces strains in excess of the yield strain, the curving process will remove the residual stresses from the straight beam. This level of residual stress is well within the range commonly found in straight beams due to the differential rate of cooling at the mills between the web and the flange tip. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |