You could look in the Eurocodes. EN 1992-1-1 § 3.1.5 provides a stress-strain relation for concrete in compression which can be used for non-linear structural analysis

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You can search and adopt the available stress-strain model for concrete in compression. Many researchers have performed research on that, especially for normal-type concrete material. Each model was usually verified by many of the actual stress-strain curves from the compression tests.

Most stress-strain models are functions of ultimate strength as well as strain corresponding to the ultimate strength. In the absence of strain corresponding to the ultimate strength, many equations have been proposed and verified using a hundred test data points. You can predict the strain corresponding to the ultimate strength first, and then use the equations to get the stress-strain model accordingly.

One possible way to create a stress-strain data sheet is to use the webtool provided by Concrete Damaged Plasticity Webtool.

@Ebrahim Aminifar

I do not know this specific tool, but I suppose that to simulate plasticity and the stress/strain diagram you should know other parameters, such as: type of concrete components, type of cement, granulimetry type of steel-bars, and so on. All data that I undestood you do not have. So if this is the case and you have only one point on the diagram stress - strain I suppose you have either the possibility of a linear approximation starting from zero or to figure out the most reasonable curve deemed similar on the base of other information.

Creating a stress-strain data sheet from the ultimate strength of concrete involves several steps.

In the absence of a comprehensive stress-strain curve, including the initial slope and ultimate strength, one may adopt an empirical method to derive an approximate representation. Employing a simplified approach, one can assume a linear elastic behavior up to the ultimate strength, followed by a descending linear segment.

While this approach lacks the precision of a detailed stress-strain curve, it provides a basic framework for assessing concrete behavior in the absence of comprehensive data. However, it is crucial to note that this method involves certain assumptions and simplifications, and the accuracy may vary based on concrete mixtures and conditions.