The development length Ld is given by ______, where ϕ = nominal diameter of the bar, σs = stress in the bar at the section considered at design load, and τbd = design bond stress.
1
\(\frac{{\Phi {\sigma _s}}}{{4{\tau _{bd}}}}\)
2
\(\frac{{\Phi {\sigma _s}}}{{{\tau _{bd}}}}\)
3
\(\frac{{4\Phi {\sigma _s}}}{{{\tau _{bd}}}}\)
4
\(\frac{{{\sigma _s}}}{{4\Phi {\tau _{bd}}}}\)