# Rebars bending (es-ES)

The structural frame
The construction (es-ES)
The reinforcement I (es-ES)
The reinforcement II (es-ES)
Quantity/Cost estimation (es-ES)
Detailing drawings (es-ES)
Tomo A´ - Introducción

Wind and Seismic Forces > (es-ES)
Structural model and Analysis (es-ES)
Modelling slabs (es-ES)
Slabs (es-ES)
Seismic behavour of frames (es-ES)
Appendix A (es-ES)
Appendix B (es-ES)
Appendix C (es-ES)
Appendix D (es-ES)
Tomo B´ - Introducción

Materials (es-ES)
To be continued > (es-ES)
Tomo C´ - Introducción

## Minimum bending pin diameter for rebars

Reinforcement bars are being bent either in order to follow the stresses developed in the member or to get properly anchored.
The minimum diameter Øm (mandrel diameter) to which a bar is bent shall be such to avoid bending cracks to the bar and ensure the integriy of concrete inside the bent of the bar where large forces appear. The smaller the mandrel diameter is, the larger these forces are and consequently the concrete may fail thus leading to the disintegration of the cross-section.

Practically, the minimum bend diameters are:

Bending Pin Øm=4Ø για Ø≤16 mm Bending Pin Øm=7Ø για Ø>16 mm

## Minimum bending pin diameter for wired meshes

In wired meshes:
(a) The anchor should be at least 5Ø (Thus for a wired mesh with Ø10 wires, at least 50 mm)

(b) The bending pin should be at least 5Ø (Thus, in the example is Øm=50 mm) for all cases except when the transverse reinforcement wire is external and in distance ≤3Ø (thus, in the example 30 mm), where the pin should be 20Ø! (Thus, in the example Øm=200 mm!!!)

## Simple hook anchorage

When the bar anchorage for slabs or beams is referred to as ‘simple hook anchorage’ then metal pins with a diameter ≥Ø should be placed in the interior of the bending curves.

## Drum Anchorage

In columns that have a small dimension in the anchorage direction, (see the table below) adequate beam rebar anchoring is ensured by bending the rebars using a large diameter drum.
The minimum diameter of the drum is inversely proportional to the strength of the concrete and proportional to the steel strength.

## C30/37 concrete and B500 steel

 Ø (mm) 14 16 18 20 22 25 28 32 40 C30/37 Minimum Drum Diameter Øm (mm) 190 220 250 290 330 390 450 530 700 Minimum Column Dimensions bmin (mm) 220 250 280 310 340 390 440 500 640

For grade C30/37 concrete and B500 steel, for various bar diameters, the minimum bending drum diameters and the minimum column dimensions are displayed in the following table

## Drum Anchorage

Rebar anchorage in a small sized column using a large diameter drum.