3.3.2 Metoda nelineární

Metoda nelineární

Performing a design according to the Nonlinear method requires a license of the add-on module RF-CONCRETE NL. This method for the serviceability limit state design is described in detail in chapter 2.8.

The following columns are described in the previous chapter 3.3.1:

• Materiál
• Tloušťka
• w_k,-z(top) / w_k,+z(bottom)
• σ_c,max
• σ_s,max

For orthotropic surfaces, no serviceability limit state design according to the nonlinear method is possible.

The values in the columns D through J are controlled in the tabs below. The settings specified in them are applied to all surfaces by default. It is also possible to only assign the current settings to specific surfaces: Clear the All check box. Then, enter the numbers of the relevant surfaces or use to select them graphically. With you can assign the current settings to these surfaces.

The assignment is only applicable for the active tab, for example Stress Check.

The parameters for creep must be defined in the Creeping tab (see Figure 2.144). Based on these conditions, the program determines the creep coefficient φ. For the effective component thickness h₀, the program applies the surface thickness d.

Determining the creep coefficient is described in chapter 2.8.4.1.

This column shows the shrinkage strain. The relevant parameters are defined in the Shrinkage tab (see Figure 2.147). Based on these conditions, the program determines the shrinkage strain ε_cs. For the effective component thickness h₀, the program applies the surface thickness d.

Determining the shrinkage strain is described in chapter 2.8.4.2. If you do not wish to apply any shrinkage strain to a surface, set a user-defined shrinkage strain of zero in the Shrinkage tab and then assign it to the surface.

For pure plates that are defined as the model type 2D - XY (u_Z/φ_X/φ_Y), shrinkage cannot be considered: There are only degrees of freedom for bending.

This value represents the maximum allowable deformation that must be observed in the design of the serviceability limit state. The design criteria are defined in the Deformation Analysis tab.

The serviceability for "common structures", for example according to EN 1992-1-1, clause 7.4, is ensured if the deflection in the quasi-permanent action combination does not exceed the following limit values.

The Minimum border line, Maximum border line, and User-defined relative options determine which effective length l_eff is applied. For the two border line options, the program applies the smallest or largest border line of the respective surface.

When you choose the User-defined relative option, you can enter the length directly or select it graphically between any two points in the RFEM model with . In addition, you must define a divisor by which the lengths are divided for all three options.

It is also possible to specify the allowable maximum deformation u_z,max as User-defined absolute.

The deformation design criterion uses the deflection of a surface – the vertical deformation relative to the straight line connecting the points of support. The Deformation Analysis tab (see Figure 3.20) provides three options for calculating the local deformation u_z,local applied in the design.