DESIGN OF REINFORCED CONCRETE BEAM AS PER IS-456-2000.

PROGRAM INFO / LIMITATIONS.

This program designs singly or doubly reinforced concrete beam as per the given loading .

f y ( characteristic strength of reinforcement )   = 415 N / mm2 .

Clear Cover = Nominal Cover +  Diameter of Links .

In case the nominal cover exceeds 40 mm, additional measures such as application of fire     resistant finishes, false ceiling, & sacrificial steel in tensile zone  should be adopted to give protection against spalling.

Side face reinforcement shall be provided for depth greater than 750 mm. The total area of  steel shall not exceed 0.10 % of web area and shall be distributed equally on two faces at a  spacing not exceeding 300 mm or web thickness whichever is greater.

Slenderness limit for isolated beams (Tie/Plinth/Lintel) to ensure lateral stability :

For simply supported or continuous beam the clear distance between lateral restrain should not exceed 60 b or 250 b2/d, whichever is less.

For cantilever beam the clear distance between lateral restrain should not exceed 25b  or  100 b2/d, whichever is less.

Some salient features of CODE regarding durability are as under. The cement content, maximum w/c ratio, and concrete grade corresponds to normal 20 mm size aggregate.

 

EXPOSURE	CRACK WIDTH (MM)	CEMENT CONTENT (KG/M3)	MAX.W/C RATIO	MIN. CONCRETE GRADE	NOMINAL COVER (MM)
MILD	0.30	300	0.55	M20	20
MODERATE	0.20	300	0.50	M25	30
SEVERE	0.10	320	0.45	M30	45
VERY SEVERE	0.10	340	0.45	M35	45
EXTREME	0.10	360	0.40	M40	70

 

FIRE RESISTANCE	MINIMUM BEAM WIDTH	NOMINAL COVER ( MM)
( HOURS )	( MMS )	SIMPLY SUPPORTED BEAM	CONTINUOUS BEAM
0.50	200	20	20
1.0	200	20	20
1.50	200	20	20
2	200	40	30
3	240	60	40
4	280	70	50

SR_NO.	NOMINAL MAXIMUM AGGREGATE SIZE  [MM]	ADJUSTMENT TO MINIMUM CEMENT CONTENTS TO TABLE  ABOVE. [KG/M3]
I	10	+  40
II	20	= 0 =
III	40	-  30

 

MAXIMUM CLEAR DISTANCE BETWEEN BARS IN MMS.
% REDISTRIBUTION CARRIED OUT.
-30%	-15%	=0=	15%	30%
125	155	180	210	235