Having determined the loading, verify the chosen stiffener size by checking the adequacy of the effective stiffener section to act as a column for combined axial load and bending moment as required by EN clause 9.4. These loads may generate bending moments in the stiffener section. There will be horizontal loading to consider to resist F S forces as given in PD 6695-2 clause 10, there may also be horizontal loading from the bearing if it is fixed. The majority of the loading on the stiffener will be the vertical loading from the bearing reaction. The loads to be considered for the design of bearing stiffeners are given in PD 6695-2 clause 16. Guidance on design of bearing stiffeners is given in Section 8.3.2 of SCI P356. Note that multi-leg stiffeners must be split into separate effective cross sections and the loads divided between them. Having decided that bearing stiffeners are to be provided, to verify the design of bearing stiffeners, determine the effective stiffener section in accordance with EN clause 9.1 (2). If a rigid end post is required then minimum stiffener requirements are given in EN clause 9.3.1. Although older riveted girders in the UK may have a rigid end post end detail, more recent UK practice has not been to provide rigid end posts but to provide a “non-rigid end post”. A rigid end post will benefit the shear resistance as calculated by EN clause 5.3. In all cases the addition of a relatively small stiffener to a slender plate can increase the resistance to local buckling substantially.Īt end supports, if bearing stiffeners are to be provided, then a decision has to be made as to whether to provide a “rigid end post”, as shown in EN, Figures 5.1 and 9.6.

a web subjected to a bearing reaction, longitudinal compression load e.g. Local buckling can occur due to transverse compression load e.g. The webs of bridge beams are usually vulnerable to local buckling, but flanges are usually much thicker and inherently more resistant to buckling. Local buckling occurs when a cross section is slender enough for buckling to occur within the cross section, due either to compression or shear. Stiffeners have one or both of the following functions: Stiffeners can also be doubled up, or even trebled, to form multi-leg stiffeners. Usually bearing stiffeners are double sided, while intermediate web stiffeners are single sided. Stiffeners can be attached on one side of the plate (single sided), or on both sides (double sided). A variety of sections have been historically used as stiffeners, however the simple flat stiffener is the type almost always used in modern designs.

Splitt steel beam