ACI 318 SLAB CHECKS

Question

Googevening, 
 performing concrete slab verification with staad pro (ACI Code), I noticed some discrepancies between input data definition, as reported below: 
 
 and output results obtanained from calculations are listed below: 
 
 in particular the following results report in STAAD_Pro output are not in compliance: 
 - concrete cover definition that must be equal to 75mm but staad defines cover at top and bottom equal to 19.05 mm 
 - concrete strength that must be 14.16 N/mm2 but staad defines 27.58 MPa 
 - steel reinforcement strength 450 N/mm2 but staad defines 413.68 MPa. 
 
 How these parameters are evaluated by STAAD? 
 How can I set in a correct way these input data? 
 
 Regards

Modestas · Accepted Answer

DESIGN ELEMENT 2 TO 226 command should be entered after the design parameters and before the END CONCRETE DESIGN line in the input file. Also, you should correct the CLB value to 0.075.

Modestas · Answer

Crack width checks can be performed in the Advanced Concrete Design (RCDC) workflow which is available in STAAD.Pro CONNECT Edition.

Sye · Answer

Correct. The ELEMENT DESIGN in STAAD.Pro as per the ACI 318 code just gives you the required reinforcement area. The onus is on the user to choose an appropriate bar size and spacing so that the required reinforcement area is satisfied. As you know, it is the spacing between bars in the tension face, the stress in the steel closest to the extreme tension face and the clear cover to the reinforcement from the tension face, that control the cracking. Since the ELEMENT DESIGN does not venture into these areas, the user needs to make sure that the spacing requirements are met to keep cracking within acceptable limits. If you need more detailed design, you may use the Advanced Concrete Design option.

ACI 318 SLAB CHECKS

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