152
INTRODUCTION: For simply supported span the end moments is zero ant the
2
maximum positive moments for uniformly load w /per ft. is given by 1/8 wl . For continues
beams and frames the end moments is not equals to zero and usually negative at the faces of
2, 2 2
the interior and exterior support (1/10wl 1/12wl , & 1/9 wl ). The end moments varying
upon the type of loadings thus for a uniform load of w Lbs/Ft Please refer figure below as
shown. Approximate moment diagram only.
Ma Mb Mc
W Lbs per Ft.
Lc
Va Shear Diagram
Mb (maximum moment) Vc
Moment Diagram
Ma Mc Neg steel
● ● ● ● ● ● ● ●
● ● ● ● ● Pos steel
, 153
BAR CUT OOF AND BEND POINTS
1) Every bar should be continued at least a distance equal to the effective depth of the
beam or 12 d bar diameter (whichever is the larger) beyond the point at which it is
theoretically no longer required to resist the stress.
2) At least one third (1/3) of the positive moment steel (one fourth in continuous span)
must be continued uninterrupted along the same face of the beam a distance at least
6” into the support.
3) At least one third (1/3) of the total reinforcement provided for negative moment at
the support must be extended beyond the extreme position of the point of inflection a
distance not less than one sixteen (1/16) the clear span or 12db,whichever is
greater.
BAR CUT OFF RECQUIREMENTS
If the positive bars are cut off, they must project past the point of theoretical maximum
moment, as well as d, or 12db beyond the cutoff point from the positive moment diagram.
The remaining positive bars must extend Ld past the theoretical point of cutoff bars and must
extend at least 6” into the face of the support.
Development length of deformed bars in Compression
a) Basic development length Ld -----------------0.02dbfy’’/fc’ but not less than 0.003dbld.
b) Modification factors to be applied to ld reinforcements in excess of that required by
analysis same as tension.
Development length of deformed bars and deformed wire in tension
A) basic development length ld
No 11 bars and smaller -----------------------------------0.045Abfy /fc’ but not to exceed
0.0004dbfy
No 14 bars --------------------------------------------------------------------------------------.0.85fy/fc’
INTRODUCTION: For simply supported span the end moments is zero ant the
2
maximum positive moments for uniformly load w /per ft. is given by 1/8 wl . For continues
beams and frames the end moments is not equals to zero and usually negative at the faces of
2, 2 2
the interior and exterior support (1/10wl 1/12wl , & 1/9 wl ). The end moments varying
upon the type of loadings thus for a uniform load of w Lbs/Ft Please refer figure below as
shown. Approximate moment diagram only.
Ma Mb Mc
W Lbs per Ft.
Lc
Va Shear Diagram
Mb (maximum moment) Vc
Moment Diagram
Ma Mc Neg steel
● ● ● ● ● ● ● ●
● ● ● ● ● Pos steel
, 153
BAR CUT OOF AND BEND POINTS
1) Every bar should be continued at least a distance equal to the effective depth of the
beam or 12 d bar diameter (whichever is the larger) beyond the point at which it is
theoretically no longer required to resist the stress.
2) At least one third (1/3) of the positive moment steel (one fourth in continuous span)
must be continued uninterrupted along the same face of the beam a distance at least
6” into the support.
3) At least one third (1/3) of the total reinforcement provided for negative moment at
the support must be extended beyond the extreme position of the point of inflection a
distance not less than one sixteen (1/16) the clear span or 12db,whichever is
greater.
BAR CUT OFF RECQUIREMENTS
If the positive bars are cut off, they must project past the point of theoretical maximum
moment, as well as d, or 12db beyond the cutoff point from the positive moment diagram.
The remaining positive bars must extend Ld past the theoretical point of cutoff bars and must
extend at least 6” into the face of the support.
Development length of deformed bars in Compression
a) Basic development length Ld -----------------0.02dbfy’’/fc’ but not less than 0.003dbld.
b) Modification factors to be applied to ld reinforcements in excess of that required by
analysis same as tension.
Development length of deformed bars and deformed wire in tension
A) basic development length ld
No 11 bars and smaller -----------------------------------0.045Abfy /fc’ but not to exceed
0.0004dbfy
No 14 bars --------------------------------------------------------------------------------------.0.85fy/fc’
