A beam may be designed as a cased beam if

• section is of double open channel form with the webs not less than 40 mm apart
• overall depth and width of the steel section do not exceed 750 and 450 mm respectively.
• beam is solidly encased in concrete with 10 mm aggregate having 28 days strength 160 kg/cm2
• width of the solid casing is kept at least 100 mm more than the width of the steel flange and having a concrete cover of 50 mm
• all the above.