Basic methods of reinforcing steel structures - Assessment and Refurbishment of Steel Structures - page 119

Figure 4.38 State of stress of the
reinforced cross-section of a tensional
element
The procedure assumes a flexible assessment of the cross-section of a tensional element.
For land constructions, this procedure is conservative because we can use plastic
condition in checking the reliability of the cross-section of a tensional member in shapes
that assume compensation of the stress over the whole cross-section, i.e. the full use of
reinforcing elements in the cross-section, as shown in Figure 4.38b:
(4.5)
The necessary area A 2 for transferring the loading is determined by equation (4.5) to give:
(4.6)
To distinguish equations (4.5) and (4.6), the area of reinforcement is stated as A 2p . By
comparing equations (4.6) and (4.4), we can determine the efficiency of the plastic
condition approach.
(4.7)
From equation (4.7) it is apparent that the use of the plastic reserve of steel is more
significant and the saving of steel is greater the higher the original stress on the
reinforced cross-section.
Compressional elements