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

Why RCDC didnt consider the highest bending moment to be calculated in providing the Reinforcement? In my case My (27.84kNm due to selfweight beam) and Mx(43.83kNm due to wind load). RCDC used 27.84kNm (My) to calculate the reinforcement...Why RCDC not considered to use 43.84 (Mx) for Reinforcement calculation, (To avoid the beam get failure due to Wind Load). 

The My moment is acting in the vertical plane and MX here is acting in the horizontal plane. In concrete structure generally lateral loads are transferred through the slab system and hence beams are subjected to less horizontal bending moment compared to vertical bending moment. Generally in manual design also we consider vertical bending along with shear and torsion to design the beams. Hence here My has been considered in design by default.

However, there may be cases where significant amount of lateral bending is observed in the beam and we need to consider that moment in our design. I believe you will agree that the reinforcement provided to resist MX moment will be different from My moment as both the moments are acting in different plane. So, as self-weight and lateral load can act together, the beam will be subjected to biaxial bending and the design will be done as per the design methodology adopted for column. To accomplish such cases we have a special option in RCDC under general settings namely "Bending and axial force design". If you check that option and click on "More" additional options will be available and you can set it up as per your requirement. Once you set this setting the design will be done considering both axis moment as we do for column design.