Basic methods of reinforcing steel structures - Assessment and Refurbishment of Steel Structures - page 86

Figure 4.4 Reinforcing of welded
angled girders
Welded cross-sections of girders (and the girders of crane runways) are reinforced by
welding (bolting) horizontal or inclined tables, circular and rolled profiles. When
reinforcing according to Figures 4.4-7, 8, 9, 11, the horizontal strength of cross-sections
is also increased. Reinforcement according to Figures 4.4-9, 11 also solves the problem
of buckling because it results in a closed cross-section of chords. However, there is the
disadvantage that the reinforcing elements cover the original neck welds.
When there is an insufficient local stability of a web-welded girder, additional wall
stiffeners are used. The use of vertical (in tall girders also horizontal) stiffeners increases
the stability of the girder wall. Local swelling of the wall reduces stability and decreases
the capacity of girder wall. Where the swelling has reached the wall area within a limit of
1/3 h (Figure 4.5), the wall can be stabilized temporarily by welding additional vertical
stiffeners. In the girders of crane runways, where the upper pressed area carries the wheel
pressures, local swelling of the wall is limited to the value of 1/10 h .