Question

Question 2: Determine the required the tensile development length considering 90° hook for the uncoated 25 bars shown if normal-weight concrete is used. Consider fe 20 MPa and fy 420 Mpa Assume side, top and bottom cover to be at least 75 mm. 510mm 75し 3@120ーし75 75 4025 10@200 mm 685 760mm

Answer 1

Given:

Fy=420 Mpa

Fc=20 Mpa

4#25 mm bars

Cb=75 mm or Cb=0.5(120)=60 mm, select 60 mm as cover

L_dh=0.24$\psi$_eFyd_b/$\lambda$$\sqrt$(Fc)

L_dh=0.24x1.0x420x25/1.0$\sqrt$(20)

L_dh=564mm

As there are stirrups placed, it should be multiplied by 0.8

L_dh=0.8x564=451.2mm is the development length