Answered by:
RKALC Admin | Date: 2/4/2024 4:38:33 AM
Sample Answer to the Sample Quesion:
If the question pertains solely to the software application, the following steps should be taken:
1- Define the concrete materials accurately by navigating to Define > Materials. Provide concrete properties to be assigned to slab sections, such as the Modulus of Elasticity in accordance with table 3.1.2 under item 3.1.2 of the AS3600-2018. Most importantly, feed the software with the modulus of rupture (concrete tension capacity under 3.1.1.3), which is 0.36*f’c^0.5. I always reduce this number by 30%. If you keep the default program calculations, the modulus of rupture will be calculated to a different standard (ACI318) and capped at around 1 MPa, resulting in very conservative results.
2- Define the load patterns as usual: DL for own weight, SDL for superimposed dead load, and LL for live load. Access this through Define > Load Patterns.
3 - Now, define three non-linear load cases as follows:
a. Navigate to Define > Load Cases, click on "Add new Case," name it Case 1, and set the analysis type to Nonlinear Cracked. In "Loads applied," add DL, SDL, and LL with a scale factor of 1.
b. Repeat the process for Case 2, adjusting the scale factor for LL to 0.3 or 0.4 (representing the sustained proportion of live load).
c. For Case 3, set the analysis type to Nonlinear (Long Term Cracked) and include DL, SDL (scale factor = 1), and LL (scale factor = 0.3 or 0.4). Provide the Creep Coefficient from table 3.1.8.3 of AS3600 or calculate it using the formulae under item 3.1.8. Additionally, input the Shrinkage Strain, obtainable from section 3 of AS3600 (table 3.1.7.2 or using formulae in the code). Use a conversion factor, leaving it as 0.00001 or adjusting for faster analysis—monitor and ensure convergence.
4- Before running the analysis, define the basic reinforcement to be used in the slab under Run > Cracking Analysis Options.
5- Once the analysis is complete, review the deflection from each load case described above. These are all service SLS load cases. The third load case will likely yield the worst deflection since the sections are cracked to a certain degree based on the applied loads.
The above instructions pertain only to the software application. If you require more in-depth information regarding code interpretation, please let me know.
Regarding the comparison with RAM Concept, I believe there is a consensus among Australian structural engineers to prefer RAM for various reasons. I am not a RAM Concept user, so my response may not provide an in-depth answer to this.
Kind Regards