RCDC-General

• Grids cannot be imported from Auto-cad. For Staad files RCDC auto identifies the grids as per centre of columns and for E-tabs it reads if they are available. User can view or edit the grids label and location. For more information refer topic “Grid Lines” from help Content.

• Design reports are generated in platform independent html format so as to facilitate the user to open it in any software. User can open the HTML File in excel and word.

• Before starting project, settings for drawings style can be modify/update for all element. Please refer help for more details.

• Factor can’t be an input, as for sizing of footing/Pile-cap different factors are to be considered for dead, live and other load cases. However, user can create his own load combination templates by using ‘Add Load Combination’ option and creating a new template. User also can add or remove load combinations as per requirements. For more information refer Topic “Load and Load combinations” from help Content.

• RCDC refers to ACI-318M-2011 (metric units) code. If data is exported in feet and inches RCDC internally changes the forces in to kN and m. Working environment in RCDC is in MKS units. User can provide the input data in kN and M unit for RCDC. The output can be generated in inches unit. Refer ‘Style Manager’ in RCDC for the same.

6. Is the Vertical axis of STAAD and RCDC Same?

At the time of importing the loads in RCDC if we give X direction to Earthquake X and Z direction to earthquake Z, then it will convert it in its relevant direction?

• RCDC is a design software and imports the analysis forces from STAAD for design. There is no specific axis of the RCDC.

  example: for column design, RCDC get the forces along major and minor axis. whatever the load cases defined in analysis, RCDC get the forces for local member and it designs the member. 

  Defining direction for Eq forces i.e. X and Z, it just a load case type. it will just help to create load combinations as per load type. if Eq-z is available in Analysis and it is defined as Eq-Y then it doesn't affect the design forces of the member. Forces for that load case will remains same. EQ-Y is just a nomenclature for that load case.

7. How can I change the safety factor for the design codes?  I would like to keep the safety factor for shear links at 1.15?

• It is not possible to change the material safety factors in RCDC. These factors are code defined and it is not desired to change it. User can manage the material safety factors by modifying the Load combination factors of respective load type if possible.

8. Can I define concrete grade as 27 N/sqmm in RCDC for IS code design? How and what is the impact of this in design?

• Yes, RCDC allows to define any grade of concrete in design. The maximum concrete grade is 100N/sqmm. User can add any grade of concrete in list and use for the member design in RCDC.

  For section design, RCDC use the concrete grade which is defined by user. For checks like Tcmax in shear design, as the interpolation is not desire, RCDC uses the lower value defined in code as permissible shear stress in the design.

• Yes, RCDC can directly imports the repeat load cases available in STAAD and design the column, beam, footing and pile-cap.

• IS 1893-2016 – Table-10 is for percentage of Imposed Load to be considered in calculation of seismic weight. Refer below snap,

   

  The lump mass for the earthquake load is calculated based on the % of vertical load. It is assumed in the code that during earthquake live load intensity would not be full. Thus, for the calculation of seismic weight, we can reduce the live load. The dead load is considered 100%. The live load is considered as per table above. It is related to lateral loads.

  Please note that this reduction is only to calculate seismic weight which we considered for lateral load calculation for earthquake load conditions. It is not related to vertical live load on column and beam.

  It must handle in analysis part as it will govern the load to be applied laterally for earthquake.

   Please note that, it is not applicable for Wind loads, as these loads are not depending on the Building weight.

   The live load reduction given in Is 875, is for the vertical load. The reduction is applied floor wise as per the number of stories supported by column and footing. Please note that, it is not applied for beam and slab design.

   The intention of the code here is at a time, building would not be occupied by full live load for exposed area. Thus, we can take advantage of partially occupied area. Thus, the Live load reduction is as per no of stories supported by column and foundation and it is maximum 50%.

  For calculation of seismic weight 'full live load' need not be considered. For design of elements, the effect of this EQ (in member) is considered with appropriate load factor of the combination. With regards to the combination of DL+LL+EQ, one can consider the reduced LL as explained. (based on the number of levels supported)

• 11. RCDC unable to read load combinations if added in analysis file as explained below,

  I usually use load cases for basic loads like dead, live, wind (number 1, 2, 3, etc.). Then, I use another set of load cases where I use REPEAT and NOTIONAL for gravity loads only (load number 200, 201, 203, etc.). Finally I use traditional LOAD COMBINATIONS where I call repeated loads (for gravity) and basic loads (for wind and seismic).

  • There are two basic load cases exists with two repeat load cases. Two regular combinations exist which consist of repeat load cases. Presently RCDC reads Basic load cases and repeat load cases. As in any combination, dead load is must and same validation is provided in RCDC, I have assigned both the basic load cases as dead load in RCDC.

    RCDC does not identified the Regular load combinations from analysis file when it is consisting of repeat load cases. if any regular combination is consisting of basic load case + repeat load case, it would be difficult to identify the type of load from repeat load cases. Adding linear load case and Non-linear load comb (repeat) in to one regular combination is not recommended and not handled in RCDC.