The primary features of GTRC are noted in [6, 7], where the draft of designs system, that has been improved in comparison with existing ones is provided. The GTRC essence resides in its generalized theses and models, that forms united conceptual basis for working out the totality of designs. Herewith the starting point is namely the generalized theses, condensing the primary features of considered systems and phenomena.
The formulation of the primary thesis is the most complex step in working out the GTRC. That is because it combines the objective (accumulated facts) and subjective (mastering of facts, ability to abstracting) factors. The formulated prime theses lead to the development of models, including the mathematical ones.
The core of the GTRC includes:
1) generalized properties of concrete, reinforcement and RC;
2) generalized models of CE, RCE, CS and RCS;
3) problems solution methods of strength, crack-resistance and inflexibility of CE, RCE, CS and RCS [6, 7].
The generalized concrete properties include:
1) division of the behavior and failure types into brittle, pseudoplastic and plastic cases;
2) physical non-linearity and necessity of taking into account the descending branch of σij-Ɛij relations by the pseudoplastic behavior;
3) extreme strength criterion. Properties of reinforcement are mainly determined by its tension diagram σs-Ɛs.
The generalized RC properties include:
1) bond between concrete and reinforcement in the form of tangential and normal stresses on the contact surface «concrete - reinforcement», which are determined by the specific concrete and reinforcement properties at the place of their contact and by the SSS character of the considered RCE;
2) RCE behavior dependence under loading and failure type on the quantity of longitudinal and transverse reinforcement, resulting in division of the RCE on the reinforcing groups (see point 1.6 above);
3) unified notion «element of the bar RCS» as the RCS part with the sign-constant forces M, Q, N, T, on the length of which the only dangerous normal (cross) and inclined crack is developed and the unified design scheme of the RCE becomes to be feasible.
The CE, RCE, CS and RCS models are determined in great degree by the concrete property 1. This suggests the use of the brittle, pseudoplastic and plastic models. Herewith the brittle model is conform to the Fracture Mechanics theses, the pseudoplastic model – with Pseudoplasticity Theory, however the one which is still not completed. Therefore at present the models with two levels of accuracy are being used in the suggested version of the GTRC:
1) complete model for strength design of RCE normal (cross) section under joint action of the forces M and N when we take into account the descending branch of compression diagram σc-Ɛc and the ESC [12];
2) approximate model as the model of a rigid-plastic body [9 – 11, 13 - 15]. Sometimes it is necessary to apply the combination of the brittle and the pseudoplastic or plastic models when the RCE has compressed and tensile zones with the rupture cracks.
The methods of problem solution must be available for use among a broad community of designers and students. However the known Finite Element Method (FEM) doesn’t fall into this category because it requires the working out of complicated, laborious and expensive software, which is used by the specialists of fairly close area of expertise. Nevertheless there are acceptable methods due to their simplicity and accuracy. For example, the method of sections in the cracks theory is simple enough [31]. In the case of applicability of Perfect Plasticity Theory it is expedient to apply solutions that are grounded on the direct methods of variation calculus. Those will include the methods using the discontinuous velocities functions [30], which attract due to their simplicity and satisfactory accuracy [9 – 11, 27]. However in cases involving complex multi-tied structures, where the shape and disposal of the failure zone cannot determined easily, the FEM application is inevitable. For the fairly simple CE and RCE under the multi-axial non-uniform SSS, which often takes place in practice, the ultimate load can be determined without the use of FEM, according to the simple rigid-plastic model, mentioned above (see point 4.8).
Despite the approximate model of the perfect plastic body, the participants of the RCS design process have to pass the learning stage, connected with an extensive use of the mentioned above model (including the massive two- and three-dimensional RCE). That will simplify the transition towards the model of pseudoplastic body with its dilatation, deformation anisotropy, descending branch of F-Ɛch and σij-Ɛij curves and Extreme Strength Criterion.