Constructive measuresLongitudinal reinforcementSections requirementsMinimum sectionMaximum sectionAnchoring lengthOverlap lengthOffset length of bending moment curvesSteel bars installationTransverse reinforcementMinimum sectionShape of transverse steel
In accordance with Eurocode 2 and its French Annex, the section of the longitudinal reinforcements must be such that :
The section of longitudinal reinforcement must not exceed, outside overlapping areas, the maximum value allowed by Eurocode 2 is:
The ultimate adhesion stress between the steel bar and the concrete
Compressive strength of concrete (MPa) (its value depends on the situation)
Adhesion conditions are considered good = 1.0 // poor= 0.7
Parameter that depends on the diameter of the bar
Reference anchor length: this is the length required to anchor a bar where a force is developed, with a limit adhesion stress assumed to be constant.
where is the stress in the bar, computed at the section from which the anchor is measured:
where is considered for Fundamental ULS.
Coefficient | Description |
---|---|
Influence factor, depends on the shape of the bars (straight anchorage) | |
Influence factor, depends on the coating (straight anchorage) with where is the coating of the longitudinal bar and is the distance between the longitudinal bars | |
Influence factor, depends on confinement by the transversal reinforcements not welded to longitudinal reinforcements | |
Influence factor, depends on confinement by welded transversal reinforcement | |
Influence factor, depends on transversal compression confinement |
Condition t be fulfilled:
Minimum anchorage length
Pessimist assumption: compressed bar
Finally, the value of the anchor length to be retained for a bar is:
This calculation uses the coefficients previously calculated for the anchor length. We add:
Overlap length:
Minimum overlap length:
Calculation of the lever arm:
h: wall thickness
: centre of gravity of tensioned reinforcement
Calculation of the offset length that has to be considered:
: Inclination of concrete rods ()
Some rules to follow:
The percentage of transversal reinforcement is calculated as follows :
Even when no shear reinforcement is necessary, a minimum transverse reinforcement is required.
Several types of transverse steels exist:
Additional length required to guarantee the loading lengths (depending on the diameter of the bar) :