Steel arches may be useful in the exam for designing tied arch road bridges, or suspension footbridges.
The cheat sheet below describes how to determine some key arch geometry and section properties, and use it to check the following buckling modes using methods consistent with the Eurocodes:
This cheat sheet is for calculating the flexural buckling or "strut buckling" capacity of a column in compression. It could also be used to calculate the capacity of a compression flange between effective restraints.
The rules in the cheat sheet are taken from the Eurocode 3, which is based on Euler buckling theory but also includes an allowance for geometric imperfections (via figure 6.4).
The relationship between non-dimensional slenderness and the critical buckling load from Euler theory Ncr is shown below:
Plate girder design is required for many types of structure, including footbridges, steel rail/road bridges, and composite bridges in the temporary condition (supporting the weight of wet concrete during casting of the deck).
This cheat sheet aims to summarise all of the information you would need to carry out bending and shear checks on a typical plate girder.
It is assumed that the structure is a bridge, constructed in S355 steel.
It covers:
Half-through bridges are useful in the IStructE exam as they minimise construction depth and are therefore ideal for situations where there is limited headroom clearance, a common constraint.
If you are using a U-frame bridge then you need to demonstrate that you understand it will have a significant reduction in bending capacity due to buckling.
Some people just use engineering judgement to "guess" a buckling reduction factor (say 0.7 depending on span), but it's possible to calculate it reasonably quickly using this method.