Applies To
	Product(s):	STAAD Advanced Concrete Design
	Version(s):	Connect Edition
	Environment:
	Area:	Concrete Design
	Subarea:	Beam Design
	Original Author:	Aaradhya Rahate, Bentley Technical Support Group

Is there a Customized curtailment provision in RCDC ?

• Each beam is divided and designed at-least at 13 stations i.e. 12 section; along the length of the beam.
• Each section is designed for each load combination to arrive at required areas of longitudinal reinforcement at top and bottom and shear reinforcement.
• Further, the lapping locations are available as per user inputs. Default location for lapping of top reinforcement is L/4. As RCDC design the beam for 12 zones, the options of L/3, L/4 and L/6 are available for lapping at top and bottom reinforcement.  User can choose the lapping location as per design requirements.
  • For any beam under consideration, as the bending moment is parabolic in nature and not a linear one, it is not feasible in RCDC to interpolate the BM "in between the section length". So, the lapping locations provided in RCDC are all multiple of 12 i.e. L/3, L/4 & L/6 ---- where 12 is the number of section in which a beam is divided.
• RCDC provides all the Lapping location as mentioned in SP34 except for L/10 so as to avoid the interpolation of Bending moment in between a section length. 

• At top location, the lapping is provided at curtailment locations. i.e. L/3,L/4 or L/6 distance from column face. Here the distance 2xD is not checked for curtailment. If we start providing curtailments for beams as per the beam depth, it would be complicated. The curtailment location will vary as per the beam depth. The location of curtailments might fall between two stations. Checking reinforcement curtailments at any location as per 2D would not be simple and might not give the desire result. Interpolation of forces is not possible for in between values. Even if we consider on higher side, it would not be consistent to all beams and curtailments will not match the distance 2D for all beams. Also, it is very difficult to handle Ast calculations and shear check location for individual beams.
• For Bottom location, RCDC provides the lapping at face of the beam. The higher diameter rebars extends to lower diameter to make sure that the it satisfies the bending and shear check criteria. Also, the confining of the reinforcement exists up to twice the distance from the column face.
  • If we provide lapping away from the twice the beam depth, it might reach in the middle zone of the beam which is also needs to avoid as it is governed by permanent loads. In this case we might need to handle ductile and Non-ductile beams separately. For ductile beam lapping will place away from the 2D and for Non-ductile it is possible to provide within 2D.

Note that there is an option in RCDC to perform local curtailment by modifying the reinforcement locally for any station of a zone. On the design output window, you can click on the 'Detail' feature and by double click on each zone, you can modify the 'Top reinforcement', 'Bottom reinforcement' & 'Shear reinforcement' also. 

Further, in case you want to use the same reinforcement configuration for other zone by avoiding this step, there is further tool available to 'copy reinforcement' & then 'paste reinforcement' to other beam with same size and same material used for design.

Refer the attached video for understanding how this can be done.