﻿ Introduction > Tipology of the sections

Predefined sections

They are the ones most frequently used in the current RC structures and consist of a single region of concrete having one of the following shape: rectangular, circular, T,  rectangular with flanges (in this sub-case are included also C and L shapes).
For all the above sections except for the circular ones the armature must be defined by two rows of bars (upper and lower) to be assigned by the relative diameter and concrete cover.
For all predefined sections the bending moment to be assigned can have only the component Mx (uniaxial bending around the X axis of the reference with a positive sign if compresses the upper fibers of the section) and the corresponding neutral axis is always parallel to the X axis. This is strictly true only for symmetric sections about the Y-axis, but it is also common for unsymmetrical sections belonging to decks of buildings or to foundation decks. In these cases, in fact, is valid the prevailing hypothesis of rigid floor in its own plane; the existence of this constraint conditions allow to assume the neutral axis in the horizontal direction (i.e. in the direction perpendicular to the vertical loads plane).

The ULS capacity checks (up to 60 for a single section) can be performed in the presence (even simultaneously) of N normal force, bending moment Mx, shear and torsion Vy, T. These checks lead to the determination of resistance forces to compare to design assigned forces.
It is also possible, from the fixed size of the assigned concrete section, the design of the minimum envelope reinforcement (top, bottom bars and stirrups) able to cope with the assigned forces.
For circular predefined sections of columns it is also possible to perform an instability check according to the simplified method of "nominal  curvature".

For each section you can generate the ULS interaction diagram N-Mx .
To a single section can be assigned up to 60 SLS combinations of forces (each consisting of normal stress N and Mx) for each of the three possible types of SLS combinations (characteristic, frequent, quasi-permanent). The program determines the maximum normal stress and the crack openings by comparing their values ​​with the critical values in EC2.

General sections

Can be formed by one or more concrete regions (up to 20) polygonal shaped or circular shaped. To the concrete regions can be attributed different classes of resistance. Reinforcing bars can be assigned individually entering their coordinates and/or by means automatic generations of corner bars or linear and circular generations (thus allowing a much faster input).
The ULS checks are performed with axial and biaxial bending and shear set of forces: N, Mx, My, Vy, Vx  (up to 60 combinations).
For each combination are also calculated  two-dimensional diagrams of interaction Mx, My at constant axial force and also the three-dimensional interaction domain  N-Mx, My. It is also possible to compute a general sections imposing the neutral axis to be parallel to X reference axis (see Forces). Biaxial serviceability checks are also performed.

It is also possible, from the fixed size of the assigned concrete section, the design of the minimum envelope reinforcement (top bars, bottom bars and stirrups) able to cope with the assigned design forces.

Rectangular sections of columns

In current projects the majority of the columns  is characterized by a rectangular section and symmetrical reinforcement with respect to the principal axes of inertia. The seismic verification almost always involve the simultaneous presence of the components forces N, Mx, My, Vy, Vx.
It is therefore seemed appropriate to provide a specific type of calculation for these sections, starting from a very fast input of the geometry of the section. Automatic design of bars and stirrups is allowed. For this typology it is also possible to perform the instability check according to the "nominal curvature" method.

Rectangular sections of walls

Walls elements are characterized by an elongated cross-section with a length to thickness ratio greater than 4 (§5.1.2 EC8). The program distinguishes between ductile walls and large lightly reinforced walls (see definition in § 5.1.2 EC8). Once defined the type of wall, the size of the section, the reinforcement and the design forced (from the analysis), the program performs bending (biaxial), shear checks (uniaxial) and ductility checks (detailing too).

Polygonal section in Torsion

Torsion check is performed for sections (hollows too) with a generic polygonal contour. If shear is also present the check should be manually completed applying the eq. (6.29) EC2. Shear reinforcement must be added to shear reinforcement already calculated.

SLS deflections in single beam

A single beam can be formed by one or more sub-elements each characterized by a single rc cross-section. Short time and long time deflection are assessed from the differential equation of bending line by double integration. The calculation is performed taking in accounting for curvature evaluation cracking, creep and shrinkage (AAEM/EM method) if a large number od  cross-section along the length of the beam.