| Product(s): | SACS |
| Version(s): | 23.00. |
| Area: | Collapse |
Can you please provide some background information with regards to the rationale behind the plastic ratio? What is the physical meaning?
Can we output the maximum plastic strains on the pile? We need to be able to compare the levels of plastic strains in relation to the theoretical critical plastic strain of the section.
The plastic ratio on the pile section is the ratio of the number of cross-sections’ plastic sub-areas vs the total number of sub-areas. For each sub-area, SACS determines the plasticity by calculating the amount of strain which exceeds the von Mises-Hencky stress envelope. The plastic strain is retained for each subarea of each sub-element through-out the loading sequence to facilitate the unloading of a sub-area if required. Physically, it can be considered as the fraction of total cross-sectional area which has entered the plastic zone. As shown in Collapse Manual Section 4.4.2, in SACS any cross section can be sub divided into multiple segments and then each sub area plasticity is calculated. The numbers of sub areas which produce the plastic hinges, are the numerator of plastic ratio. Denominator of plastic ratio is total numbers of sub area. This is just a high-level way of viewing which members have plasticity and are only really used for visualization and reporting purposes.
Setting Ductility Limits for the pile elements (PLGDUC or PILDUC) enables SACS to track and report if the pile has exceeded the critical plastic strain limit and will report when this happens. See section 3.7.3 of the Collapse Advanced manual for more details.