RC BEAM DESIGN

Question

Hello, 
 Does staad advanced concrete design consider (RCDC) consider the contributing effects 
 of the slab flanges in RC beam design? I examined the calculation report for some beams 
 and realized the beams are designed completely as rectangular beams. Even when you 
 specify them as flange beams, It doesn't change the design output. 
 
 Please, discuss. Thank You

Nidhi Valia · Answer

Hi, 
 RCDC can design beams with flanged action (T or L). As per design principles of flanged beam, RCDC uses this action only for mid-span bottom reinforcement. 
 Effective width of flange-action is calculated as per the provisions in code for simply-supported and continuous beams. 
 I am sharing below snip as a difference where same Beam is designed with Flanged action and without Flanged action, using Indian Code as an example.

Royal Civil Design Center · Answer

Nidhi Valia · Answer

Hi, 
 For appropriate use of this functionality, following are important points to be noted &ndash;

RCDC can import data for slabs at the same level as that of beams from the &lsquo;slab design file&rsquo; 
 RCDC processes this data and intelligently identifies beams that can be designed with &lsquo;flanged&rsquo; effect 
 In case user, does not have slab design file ready, user may input values of &lsquo;slab-thickness&rsquo; manually to avail this functionality. However in this case, RCDC would not be able to check checking things like &ndash; a) Possibility of sunk slab, b) Possibility of cut-out etc., which can affect &lsquo;flanged action&rsquo; and design.

Logic of working out effectiveness of flange action &ndash; 
 When user imports slab-data in beam design file, RCDC processes this data to collect following information &ndash;

It co-relates beams and corresponding slabs along the length of the beam 
 It can identify cut-outs in slab 
 It can locate levels of slabs and co-relate the same with beam-tops

As a result of this processing, RCDC uses following principles to determine the flange action &ndash;

Based on various thicknesses of slabs available on either side of beam, RCDC uses the least thickness for flange action. 
 All peripheral beams are designed as &lsquo;L&rsquo; beam. 
 If there is a cut-out on one side of the beam for more than 60% of mid-zone, then that beam is treated as &lsquo;L&rsquo; beam. 
 If there is a cut-out on both side of the beam for more than 60% of mid-zone, then that beam is marked as normal (without flange action) beam. 
 If the top of slab on one side of the beam does not match with the beam-top for more than 60% of mid-zone then that beam is treated as &lsquo;L&rsquo; beam. 
 If the top of slab on both sides of the beam do not match with the beam-top for more than 60% of mid-zone then that beam is treated as normal beam.

Royal Civil Design Center · Answer