CLASS GUIDELINE DNVGL-CG-0128 Edition October 2015 Buckling The electronic pdf version of this document, available free of charge from http://www.dnvgl.com, is the officially binding version. DNV GL AS FOREWORD DNV GL class guidelines contain methods, technical requirements, principles and acceptance criteria related to classed objects as referred to from the rules. © DNV GL AS Any comments may be sent by e-mail to [email protected] If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of DNV GL, then DNV GL shall pay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compensation shall never exceed USD 2 million. In this provision "DNV GL" shall mean DNV GL AS, its direct and indirect owners as well as all its affiliates, subsidiaries, directors, officers, employees, agents and any other acting on behalf of DNV GL. CHANGES – CURRENT This is a new document. Changes - current Class guideline — DNVGL-CG-0128. Edition October 2015 Page 3 Buckling DNV GL AS CONTENTS Changes – current...................................................................................................... 3 Contents Section 1 Introduction............................................................................................... 7 1 Objective.................................................................................................7 2 Buckling methods................................................................................... 7 3 Assumptions – limitations...................................................................... 8 4 Buckling checks flow chart – link to rules.............................................. 8 Section 2 Ultimate strength - principles...................................................................10 1 Objectives............................................................................................. 10 2 General principles.................................................................................10 2.1 Ultimate strength – plastic buckling......................................................10 2.2 Elastic buckling and postbuckling......................................................... 11 2.3 Usage factor definitions.......................................................................13 2.4 Acceptance levels – safety formats.......................................................15 Section 3 Closed form method (CFM) - Buckling capacity.........................................17 1 General................................................................................................. 19 1.1 Scope............................................................................................... 19 2 Plate and stiffeners.............................................................................. 19 2.1 Overall stiffened panel capacity............................................................19 2.2 Plate capacity.................................................................................... 20 2.3 Stiffeners...........................................................................................37 2.4 Primary supporting members............................................................... 45 3 Corrugated bulkhead............................................................................ 47 4 Struts, pillars and cross ties.................................................................48 4.1 Buckling utilisation factor.................................................................... 48 4.2 Elastic column buckling stress..............................................................48 4.3 Elastic torsional buckling stress............................................................49 4.4 Elastic torsional/column buckling stress.................................................50 5 Bars and framework............................................................................. 54 5.1 Introduction.......................................................................................54 5.2 Buckling utilisation factor.................................................................... 56 5.3 Characteristic buckling resistance......................................................... 56 5.4 Non-dimensional buckling curves..........................................................56 5.5 Members exposed to pure axial compression (columns)...........................59 Class guideline — DNVGL-CG-0128. Edition October 2015 Page 4 Buckling DNV GL AS 5.6 Members exposed to pure bending (beam)............................................ 59 5.7 Members exposed to axial load and bending (beam-columns)...................60 5.8 Overall buckling of built-up members....................................................61 6 Spherical Shells................................................................................... 65 6.1 Introduction.......................................................................................65 Contents 6.2 Stresses............................................................................................ 65 6.3 Shell buckling, general........................................................................66 6.4 Buckling of dished ends convex to pressure...........................................68 Section 4 Semi-analytical buckling models (PULS)...................................................69 1 General................................................................................................. 69 2 Objective...............................................................................................69 3 Theory fundamentals............................................................................ 69 3.1 General............................................................................................. 69 3.2 Basic theory...................................................................................... 70 3.3 Load history...................................................................................... 73 3.4 Margins to collapse - usage factor........................................................74 4 Elements and their validity...................................................................77 4.1 General............................................................................................. 77 4.2 Unstiffened regular plate; U3...............................................................77 4.3 Uni-axially or orthogonally stiffened regular plate;S3.............................. 78 4.4 Non-regular stiffened plate; T1............................................................ 79 4.5 Open corrugated trapezoidal panel; K3................................................. 80 4.6 FRP Composite plate buckling element – C1.......................................... 80 5 Acceptance criteria............................................................................... 81 6 References............................................................................................ 81 Section 5 Ultimate Hull girder capacity.................................................................... 82 1 General................................................................................................. 82 2 Objective...............................................................................................82 3 Scope.................................................................................................... 82 4 Methods................................................................................................ 83 5 Design safety formats...........................................................................83 6 Simple models...................................................................................... 83 6.1 General............................................................................................. 83 6.2 Multi-step method.............................................................................. 83 6.3 Single-step........................................................................................ 85 7 Direct approach; non-linear FE............................................................. 87 Section 6 Structural Capacity Using Non-Linear FE.................................................. 88 Class guideline — DNVGL-CG-0128. Edition October 2015 Page 5 Buckling DNV GL AS 1 General................................................................................................. 88 2 Independent assessment by the Society...............................................88 3 Objectives............................................................................................. 88 4 Scope.................................................................................................... 88 5 Non-linear FE methods......................................................................... 88 Contents 5.1 General............................................................................................. 88 5.2 Non-linear geometrical behaviour......................................................... 88 5.3 Non-linear material behaviour.............................................................. 89 5.4 Geometrical out-of flatness..................................................................90 5.5 Load shedding between elements......................................................... 90 5.6 Load history.....................................................................................