5.3.1 Serviceability Check by Cross-Section

Serviceability Check by Cross-Section

The upper part of the window presents a summary of the governing serviceability limit state designs. The lower part shows the Detailed Results of the current member (row selected in table above) with all design-relevant parameters. You can expand or reduce the chapters by clicking [+] and [-].

The designs are sorted by cross-sections. The table shows the most unfavorable values of the criteria to be considered for the serviceability limit state design. They are based on the reinforcement groups' parameters for crack width control (see Chapter 3.6.7), the provided reinforcement, and the internal forces for the serviceability limit state.

Generally, only one of the criteria lim d_s, lim s_l, or w_k must be fulfilled for the crack width design. Clause 7.2 of EN 1992-1-1 describes the conditions under which the stresses shall be limited. This means that not all design ratios shown in Window 4.1 have to be less than 1 in order to fulfill the serviceability limit state design!

For each cross-section, the column shows the numbers of the members whose result values (column E) or design ratios (column H) are greatest. Use the [Sort] button to control the reference.

The column shows the x-location on the member where the most unfavorable values or design ratios occur. The distances refer to the start nodes of the members.

The column lists the numbers of the governing load cases, load and result combinations.

Column D indicates the criteria to be considered for the serviceability limit state design. Depending on the settings in the Serviceability tab of Window 1.6 Reinforcement, up to seven design types are displayed.

This is the absolute value of the deflection available in the direction of the local member axis z.

The allowable relative deformations are managed in Window 1.7 Deflection Data (see Chapter 3.7).

This parameter describes the concrete stresses in the serviceability limit state.

The stresses in the reinforcement for a cracked tensile zone are determined as the product of steel strain and modulus of elasticity:

${\sigma }_{s }= {\epsilon }_s · E_{s }$

The minimum area of the rebar reinforcement according to EN 1992-1-1, 7.3.2, Eq. (7.1) is:

$A_{s,\text{min}} = k_c · k · f_{ct,\text{eff}} ·\frac{A_{ct}}{{\sigma }_s}$

where

• k_c : factor for considering stress distribution in cross-section before first crack formation
• k : factor for considering self-equilibrating stresses distributed nonlinearly over cross-section
• f_{ct, eff} : mean value of effective concrete tensile strength when cracks occur
• A_ct : tension zone of concrete in uncracked state in case of first crack formation
• σ_s : allowable steel stress directly after crack formation (depending on limit diameter or maximum value of rebar spacings, where applicable)

According to the simplified design method described in EN 1992-1-1, 7.3.3, the limit diameters of the reinforcing steel are limited to the dimensions stated in Table 7.2 (see Figure 2.3).

According to the simplified design method described in EN 1992-1-1, 7.3.3, the allowable bar spacings are limited to the maximum values stated in Table 7.3 (see Figure 2.4).

The characteristic crack width is determined according to EN 1992-1-1, 7.3.4, Eq. (7.8) as follows:

$w_k = s_{r,max} · \left({\epsilon }_{sm} - {\epsilon }_{cm}\right)$

where

• s_r,max : maximum crack spacing in final crack state (see Chapter 2.2.4)
• ε_sm : mean strain of reinforcement considering contribution of concrete to tension between cracks
• ε_cm : mean strain of concrete between cracks

This column displays the values that are governing for each cross-section for the serviceability limit state designs.

The limit values are determined from the standard specifications and the load situation. The determination of limit values is described in Chapter 2.2.

Column H shows the ratio of existing value (column E) to limit value (column F). Ratios greater than 1 mean that the design criterion is not fulfilled. The length of the colored bar represents the design ratio graphically.

The final column indicates design problems or shows notes referring to difficulties that occurred during the analysis. The numbers are explained in the status bar.

To see all [Messages], use the button shown on the left. The Error Messages or Notes to Design Process dialog box appears.

The buttons below the table have the following functions:

Table 5.2 Buttons in result windows 4.1 to 4.4

Button	Description	Function
	Sort results	Sorts results by maximum ratios (column H) or maximum values (column E)
	Exceeding	Displays only rows with a ratio greater than 1
	Select member	Allows for graphical selection of member to display its results in the table
	Color bars	Displays or hides the colored relation scales
	View mode	Jumps to RFEM work window to change the view