The methods that are currently available in the Eurocodes for the design of bridge plate girders to lateral torsional buckling are outlined and discussed. The inapplicability of the classic elastic critical moment theory for deep girders, which are common in bridge practice, is demonstrated. The simplified method of the equivalent flange in compression is applied instead, and its results are compared with those of specialised software which can accurately predict the elastic critical load of bridge girders. These widely accepted methods of design are compared to a previously published truss model which has been proposed for the simplified, yet accurate, modelling of bridge plate girders. The results of both the critical load and the design load according to the Eurocodes are compared. For the truss model, the general method for the calculation of the design load is used. A variety of cross-sectional dimensions, lateral restraints and bridge configurations is examined. Emphasis is given in a two-span, two-girder steel concrete composite bridge with various bracing configurations, where many aspects of lateral torsional buckling design can be demonstrated. The advantages of the use of a 3D truss model from practicing engineers are discussed.

概述并讨论了欧洲规范中目前用于桥板大梁横向扭转屈曲设计的方法。证明了经典的弹性临界弯矩理论不适用于桥梁实践中的深梁。取而代之，采用压缩时等效法兰的简化方法，并将其结果与可以准确预测桥梁大梁的弹性临界载荷的专用软件进行比较。将这些被广泛接受的设计方法与先前提出的桁架模型进行了比较，该模型已被提出用于简化但精确的桥梁板梁建模。比较了根据欧洲规范的关键载荷和设计载荷的结果。对于桁架模型，使用计算设计载荷的通用方法。检查了各种横截面尺寸，侧向约束和桥构造。重点放在具有不同支撑构型的两跨，两梁双钢混凝土组合桥中，可以在侧面扭转屈曲设计的许多方面进行演示。讨论了实际工程师使用3D桁架模型的优势。