4.1 Concrete setup for 1D member

This setup is available from tree Concrete > 1D member > Setup. After clicking on this item the dialog in the picture below is opened

The global setting is divided to the following sheets:

Blue coloured parameters might be changed for each member by using local setting (Member data).

Concrete setup can be opened too via action button Concrete setup or via Code setup in the single check

Action button Concrete setup

Button Code setup in the single check

4.1.1 Design default

This group is divided into three main parts. It is possible to define minimal concrete cover, set default values for member design, such as reinforcement diameters, and materials both independent for main reinforcement and stirrups. It is also possible to define sway type here.

4.1.1.1 Group general

4.1.1.1.1 Minimal concrete cover

User may choose from two possibilities to determine concrete cover:

4.1.1.1.1.1 User defined concrete cover

By selecting this possibility, program will enable edit boxes for concrete cover, both for upper and lower surface, and user defines his own value to be used.

4.1.1.1.1.2 Use min concrete cover

By this possibility, user let SCIA Engineer to evaluate minimum concrete cover, which may be used according to the Code. Parameters used for this evaluation may be defined in Concrete cover dialog, which is shown below. Here user may redefine type of concrete cover, situation and some more addition to the value due to the corrosive environments.

4.1.1.2 Reinforcement

Default value of reinforcement and stirrup diameters together with default material used are to be defined here. User may define default settings separately for beams, columns and beam slabs members, in each of three folders. Design defaults for Beams are shown on the first picture of this chapter. In 2D concrete setup dialog, different folders will be displayed. They are named Plates, Walls and Shells. Values from Plates folder are the similar to those, which are stored in Beam slabs folder in 1D concrete setup.

4.1.1.3 Sway type

This is option for calculation of slenderness and internal forces in 1D members. If the check box is active, it indicates that members are prone to sway from the respective axis. This setting has least priority when compared to Buckling data library and Buckling data set for the member.

4.1.2 General

Here user may check or even adjust important design material characteristics of concrete and non-prestressed reinforcement steel.

4.1.2.1 Tab sheet Concrete

4.1.2.1.1 Minimum value of fc’

The value sets minimum value of compression strength of concrete. According to the Code, concrete shall be proportioned to provide an average compressive strength, fcr  and shall satisfy the durability criteria. For concrete designed and constructed in accordance with the Code, fc′ shall not be less than 17 Mpa = 2500 psi.

4.1.2.1.2 Maximum value of fc’

The value sets maximum value of compression strength of concrete. Because of a lack of test data and practical experience with concretes having compressive strengths greater than 70 MPa, the Code imposed a maximum value of 8.3 MPa on √fc’ for use in the calculation of shear strength of concrete beams, joists, and slabs. Exceptions to this limit were permitted in 11.1.2.1.

4.1.2.1.3 Coefficient for specified compressive strength

This coefficient reduces concrete compression strength. According to the Code, concrete stress of 0.85fc′ shall be assumed uniformly distributed over an equivalent compression zone bounded by edges of the cross section and a straight line located parallel to the neutral axis.

4.1.2.2 Tab sheet Non-prestressed reinforcement

4.1.2.2.1 Maximum value of fy

Here the maximum design strength of non-prestressed reinforcement is defined. Code defines maximum of the values of fy and fyt , used in design calculations, shall not exceed 550 MPa, except for prestressing steel and for spiral transverse reinforcement in 10.9.3.

Minimum and maximum value of fc’ together with maximum value of fy are also limit values for concrete and reinforcement steel material parameters. It is not possible to input appropriate values in material properties. If so, en error message will be displayed.

4.1.3 General > Calculation

The user can set general parameters for calculation of 1D member and special parameters for calculation and design reinforcement for beams and column.

4.1.3.1 Group General

There is possible to define parameters, which will be used for beams and columns

4.1.3.1.1 Number of iteration steps

Group

General > Calculation

Type of parameter

Edit box

Default:

100 (Limit values from 1 to1000)

Local setting

NO

Influence

All iterative calculation in concrete design

This setting is used for iterative calculation in concrete. If iterative calculation does not finish after reaching number of steps, the calculation is finished. In this case, the result will not be presented and user has to make some changes in calculated structures or decrease precision of iteration (see chapter "4.1 Concrete setup for 1D member") or increase number of iteration steps.

4.1.3.1.2 Precision of iteration

Group

General > Calculation

Type of parameter

Edit box

Default:

1% (Limit values from 0.0001 to10)

Local setting

NO

Influence

All iterative calculation in concrete design

This setting is used for iterative calculation in concrete. Iterative calculation is finished if difference of results of two consecutive iteration steps is lesser than this precision. If iterative calculation does not finish after reaching number of steps, the calculation is finished. In this case, the result will not be presented and user has to:

4.1.3.1.3 Check selected section only

Group

General > Calculation

Type of parameter

Check box

Default:

OFF

Local setting

NO

Influence

All results in concrete with exception of service  Concrete slenderness

If this check box is ON, then the results are calculated and presented only at the ends of the member and in user defined sections. It follows, that calculation is much faster. The user sections can be defined in tree Structure > Model data > Section on beam

There is comparison of results if this setting is ON/OFF and some user sections are defined (in thirds of member length)

Check selected section only is OFF

 

Check selected section only is ON and user section are defined

 

4.1.3.1.4 Use iterative calculation for design reinforcement

Group

General > Calculation

Type of parameter

Check box

Default:

OFF

Local setting

NO

Influence

Design reinforcement for 1D member

Design strength of the structure is calculated multiplying the nominal strength by a strength reduction factor  φ. This factor depends on the strain in tensile reinforcement, but this strain is unknown before design reinforcement. It follows, that for calculation of this value:

If this check box Use iterative calculation for design of reinforcement is OFF, then strength reduction factor loaded from concrete setup (see chapters ) will be used. It means that:

Else if this check box is ON, then iterative calculation for strength reduction factor will be used for design reinforcement to beam ("8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)") and for column ("8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)")

There is comparison of results if this setting is ON/OFF for simply supported beam.

Check box =OFF

Check box =ON

If concrete member data are defined on the member and Type of strength reduction factor Phi = User input, then this check box has not influence to calculation strength reduction factor , because strength reduction factor is directly loaded from concrete member data

4.1.3.1.5 Columns
4.1.3.1.5.1 Advanced setting

Group

General > Calculation > tab-sheet Columns

Type of parameter

Check box

Default:

OFF

Local setting

NO

Influence

Design reinforcement for columns

If this check box is ON, there are only basic parameters in tab-sheet Column , which can be edit. After switching ON this check box Advanced setting, there are much more parameters for setting calculation of the columns.

4.1.3.1.5.2 Corner design only

Group

General > Calculation > tab-sheet Columns

Type of parameter

Check box

Default:

OFF

Local setting

NO

Influence

Design reinforcement for columns

Corner design only is special type of calculation, where the reinforcement is designed only in corner of cross-section with internal angle 90 deg. It is an iterative calculation, where number of bars is same, but the diameter of bars increases. This parameter has influence only for basic concrete cross-section, see table below.

Section

Rectangular section

I section

T section

L section with lower flange

L section with upper flange

Number of bars

4

8

6

5

5

Shape

This type of calculation is supported only for basic concrete cross-section (see chapter "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)"), for other type of cross-section calculation finished with error 683 (The design of main reinforcement area for the column is not supported for this type of cross-section)

There is comparison of design reinforcement with using method Only corner design for rectangular column with different value of internal forces.

4.1.3.1.5.3 Use buckling data

Group

General > Calculation > tab-sheet Columns

Type of parameter

Check box

Mode:

Basic mode

Default:

ON

Local setting

YES

Influence

Internal forces and design reinforcement to column

This setting allows taking into account second order eccentricity (magnified moments calculated according to clause 10.12 and 10.13 in ACI 315-05, see chapter "7.2 Internal forces for 1D members (beam, beam as slab, column)". The second order eccentricity in direction of local axis will be taken into account only if slenderness of the column in this direction is greater than limit slenderness and this check box is ON.

The detailed information about calculation of these magnified moments are presented in numerical output in the service Internal forces (tree Concrete >1D member), if the value My,recalc or Mz, recalc is selected.

4.1.3.1.5.4 Optimize the number of bars in c-s for biaxial calculation

Group

General > Calculation > tab-sheet Columns

Type of parameter

Check box

Mode:

Basic mode

Default:

ON

Local setting

NO

Influence

Only design reinforcement  to column with rectangular section

The design reinforcement with using biaxial methods depends on value Ratio y/z (ratio of reinforcement in direction of y and z of LCS),see chapter . If this check box is ON, then the biaxial method is independent on value Ratio y/z and program tries to find the best arrangement of bars in cross-section with the minimum number of bars. It is iterative calculation, where program checked all possible arrangements of bars of reinforcement according to interaction formula ( see chapter "4.1 Concrete setup for 1D member") and select this one, which result of interaction formula is the nearest to one.

This setting has influence to speed of calculation, because if the check box is ON, iterative calculation is used and therefore the speed of calculation is slower, but the  result of design in many cases is better, see table below.

There is comparison of results if this setting is ON/OFF for column with the same load, but with different size of diameter of longitudinal reinforcement.

Check box Optimize…is OFF

Check box Optimize…is ON

4.1.3.1.5.5 User estimate of reinf. for design of reinforcement

Group

General > Calculation > tab-sheet Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

2% (Limit values from 0 to10)

Local setting

yes

Influence

Only design reinforcement

There are some values in design of reinforcement, which are dependent on area of reinforcement, for example:

These values should be calculated before design of reinforcement, but before design we do not know area of reinforcement. It follows that for calculation of this value

The third solution is implemented in SEN via edit box User estimate of reinf. for design of reinforcement, where user can set ratio of reinforcement, which will be used for calculation of the values above. The calculation moment of inertia of reinforcement depends on type of method and shape of concrete cross-section too. There are the following methods for calculation the radius of gyration of the total reinforcement:

                As = Ratiolon ⋅Ac

              A1si = As/ns

              

As = Ratiolon ⋅Ac

      ,  

if  σy = 0 MPa and  σz = 0 MPa , then  ratio_y = ratio_z = 0,5 

As,y(z) = ratio_y(z)⋅As

                

As = Ratiolon ⋅Ac

                

where

Ratiolon

is reinforcement ratio loaded from concrete setup 

Ac

is cross sectional area of concrete

ns

is number of bars in cross-section (the number of bars for Only corner design depends on shape of cross-section, see chapter "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)")

A1si

is the cross-sectional area of i-th bar of reinforcement

zs,y(z)i

is the  position of i-th bar of reinforcement from centroid of concrete cross-section in direction of y(z) axis of LCS (the positions of bars for Only corner design depends on shape of cross-section, see chapter "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)""4.1 Concrete setup for 1D member")

σy(z)

is the bending stress in concrete calculated for uncracked concrete cross-section according to formulas:

                                         

Mu,y(z)

is the 1st order factored moment around  of y (z) axis of LCS (in SEN value My(z))

Wg,y(z)

is the section modulus of concrete cross-section around y (z) axis of LCS

zs,y(z)

is the  position of reinforcement from centroid of concrete cross-section in direction of y (z) axis for rectangular section (the positions of bars for Only corner design depends on shape of cross-section, see chapter "4.1 Concrete setup for 1D member")

zs,y = 0,5⋅b- (c + dss + 0,5⋅ds), zs,z = 0,5⋅h- (c + dss + 0,5⋅ds)

zs

is th  position of reinforcement from centroid of concrete cross- for circular section

zs = 0,5⋅D- (c + dss + 0,5⋅ds),

b

is width of rectangular cross-section

h

is height of the rectangular cross-section

D

is diameter of circular cross-section

cnom

is nominal concrete cover loaded from concrete setup (Design default) or from concrete member data, if member data are defined on calculated column

ds

is diameter of longitudinal reinforcement  loaded from concrete setup (Design default) or from concrete member data, if member data are defined on calculated column

dss

is diameter of transverse reinforcement (stirrup)  loaded from concrete setup (Design default) or from concrete member data, if member data are defined on calculated column

If required designed area is lesser than 80% of estimated area setting in concrete setup or concrete member data and Equation for calculation EI for critical load Pc = 10-11(see chapter ), program gives warning 270 (The percentage of additional reinforcement is lesser than 80% of user estimate ratio). In this case, the value of user estimate ratio in concrete setup (if member data is not defined) or in concrete  member data (if it is defined) should be decreased.

If required designed area is greater than 120% of estimated area setting in concrete setup or concrete member data and Equation for calculation EI for critical load Pc = 10-11(see chapter ), program gives warning 271 (The percentage of additional reinforcement is greater than 120% of user estimate ratio). In this case, the value of user estimate ratio in concrete setup (if member data is not defined) or in concrete  member data (if it is defined) should be increased.

There is design of reinforcement for rectangular columns with different load and with different area of reinforcement column with.

4.1.3.1.5.6 Group Calculation method

Group

General > Calculation > tab-sheet Columns

Type of parameter

Radio buttons

Mode:

Advanced mode only

Default:

Automatic determination

Local setting

YES

Influence

Only design reinforcement  to column with rectangular section

There are supported only following cross-section for design reinforcement to column in SEN:

Type of method can be selected by user via radio buttons, see picture below

If Calculation Method = Automatic determination, then user can input limit ratio of bending moments, when the biaxial calculation will, be used, see chapter  "4.1 Concrete setup for 1D member"

If Calculation Method = Biaxial bending calculation (interaction formula), then user can select type of biaxial method , which will be used for design of reinforcement, see chapter  "4.1 Concrete setup for 1D member"

 

4.1.3.1.5.6.1 Uniaxial bending calculation if ratio of biaxial moments is less than

Group

General > Calculation > tab-sheet Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

10% (Limit values from 0 to100)

Local setting

YES

Influence

Only design reinforcement  to column with rectangular section and  with Calculation method = Automatic determination

Type of method, which will be used for design reinforcement, if Calculation Method =Automatic determination is selected, depends on ratio bending moments.

                                    Ratio(My/Mz) =

where

Mu,y 

is factored (magnified) value of the bending moment around y –axis (including second order effect)

Mu,z 

is factored (magnified) value of the bending moment around z –axis (including second order effect)

If this ratio is lesser than limit value set in this edit box, then for design of reinforcement in the section of the column Uniaxial bending calculation (max) will be used. Otherwise the Biaxial bending calculation will be used for design of reinforcement

This edit box is active only in the case, if in the combo box Type of calculation method item Automatic determination is selected

There is comparison of results for automatic determination type of method for design of reinforcement for column with different value of bending moment.

If bending moments in both direction are zero, then reinforcement is designed only for normal force and calculation type =N/A

4.1.3.1.5.6.2 Type of biaxial method

Group

General > Calculation > tab-sheet Columns

Type of parameter

Combo box

Mode:

Advanced mode only

Default:

Bressler reciprocal load method

Local setting

YES

Influence

Only design reinforcement  to column with rectangular section and  with Calculation method = Biaxial or Automatic determination

Biaxial method is iterative calculation, where the bars of reinforcement are added to cross-section depending on ratio y/z (see chapter "4.1 Concrete setup for 1D member") or number of bars is optimized (see chapter "4.1 Concrete setup for 1D member") as long as interaction formula is not fulfilled.

There are supported three types of method for biaxial calculation:

where

Pu

factored axial force

Poy

Maximum uniaxial resistance of the column with a moment of Muy, it means axial resistance for bending moment Muy. It is intersection of interaction diagram and  vertical line ( parallel with axis P) across the point with coordinate [Pu,Muy,0]

Poz

Maximum uniaxial resistance of the column with a moment of Muz, it means axial resistance for bending moment Muz. It is intersection of interaction diagram and  vertical line ( parallel with axis P) across the point with coordinate [Pu,0, Muz]

Po

Maximum axial resistance without bending moments. It is intersection of interaction diagram and  vertical line ( parallel with axis P) across the point with coordinate [Pu,0, 0]

Muy(z) 

Factored (magnified) moment at section about  the y (z) axis of LCS of the member

f

Strength reduction factor calculated by iterative calculation, loaded from concrete setup or from concrete member data, see chapter "4.1 Concrete setup for 1D member"

where

Muy(z) 

Factored (magnified) moment at section about  the y (z) axis of LCS of the member

Mnoy(z) 

nominal uniaxial moment resistance about the y (z) axis of LCS of the member

f

Strength reduction factor calculated by iterative calculation, loaded from concrete setup or from concrete member data, see chapter "4.1 Concrete setup for 1D member"

α

Exponent of interaction formula, which can be set in concrete setup, "4.1 Concrete setup for 1D member"

where

b

Exponent of interaction formula, which can be set in concrete setup, "4.1 Concrete setup for 1D member"

The combo box for selection type of biaxial method is active only if  Calculation method = Biaxial or Automatic determination

4.1.3.1.5.7 Group Design reinforcement using (biaxial and only corner design)

There are two basic properties in this group:

4.1.3.1.5.7.1 Area of reinforcement type

Group

General > Calculation > Columns

Type of parameter

Radio button

Mode:

Advanced mode only

Default:

Real area of reinforcement bar

Local setting

NO

Influence

Only design reinforcement  to column for biaxial and only corner design

This setting allows to set type of area of reinforcement for biaxial and only corner design, which will be used for design of reinforcement.  There are two possibilities:

Concrete setup (Design default)

Member data

        The comparison of results for different reinforcement type and different delta are of reinforcement for columns with different size number of reinforcement is in table below.

Real area of reinforcement bars

Delta area of reinforcement (0.2inch2)

Delta area of reinforcement (0.02inch2)

For method Only corner design the following principles are used

For real area of reinforcement bars – the diameter of bar increases according to list of basic diameter, which can be different for each code.  The initial value of diameter for calculation is loaded from concrete setup, item Design default or from concrete member data.

For delta area of reinforcement – the diameter of bar is calculated from input value of delta area. The value delta area represents increasing area of one bar of reinforcement in each iteration step. The diameter of bars in each iteration step is calculated and it is rounded up to integer number.

4.1.3.1.5.7.2 Delta area of reinforcement

Group

General > Calculation > Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

10 mm2 (Limit values from 0 to100000)

0.0155 inch2 (Limit values from 0.0155 to 1550)

Local setting

NO

Influence

Only design reinforcement  to column for biaxial and only corner design

This edit box is used for inputting area of reinforcement, which will be used for biaxial and only corner design. It is active only, if item Delta area of reinforcement is selected from combo box Area of reinforcement type.

4.1.3.1.5.8 Group Interaction formula and exponents

In this group are described interaction formulas for biaxial bending calculation and user can set exponent for interaction formula

4.1.3.1.5.8.1 Alpha

Group

General > Calculation > tab sheet Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

1.5 (Limit values from 1 to 5)

Local setting

NO

Influence

Only design reinforcement  to column for biaxial bending calculation and Bressler load contour method

       Exponent of interaction formula for Bressler load contour method can be inputted via this paramet, see chapter see chapter "4.1 Concrete setup for 1D member". If exponent of interaction formula (value Alpha ) is 1,0, then Bressler load contour method can be used only for design reinforcement to column , where the following conditions is fulfilled

                    

where

Pu

factored axial force

f

Strength reduction factor calculated by iterative calculation, loaded from concrete setup or from concrete member data, see chapter "4.1 Concrete setup for 1D member"

fc’

specified compressive strength of concrete

Ag

gross area of concrete section

                   If value Alpha =1 and conditions above is not fulfilled, then program finishes with errors 854 (Bresler load contour method cannot be used, because Pu > 0,1*fc*Ag*Phi. Use different value Alpha or different method)

4.1.3.1.5.8.2 Beta

Group

General > Calculation > tab sheet Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

0.65  (Limit values from 0.5 to 1)

Local setting

NO

Influence

Only design reinforcement  to column for biaxial bending calculation and PCA load contour method

       Exponent of interaction formula for PCA load contour method can be inputted via this parameter, see chapter "4.1 Concrete setup for 1D member"

4.1.3.1.5.9 Group Ratio y/z

The one of the most important parameter for biaxial bending calculation is ratio of reinforcement in  y and z direction. There are three parameters which have influence to the ratio of the reinforcement

4.1.3.1.5.9.1 Ratio type

Group

General > Calculation > tab sheet Columns

Type of parameter

Radio buttons

Mode:

Advanced mode only

Default:

Automatic

Local setting

Yes

Influence

Only design reinforcement  to rectangular column for biaxial bending calculation

There are three possibilities for calculation ratio of reinforcement in biaxial bending calculation:

     Ratio y/z = if  σy = 0 MPa and  σz = 0 MPa , then  ratio_y/z = 1 

where

σ y

The bending stress around y-axis, σy = Muy/Wc,B,y

σz

The bending stress around y-axis, σz = Muz/Wc,B,z

Muy(z) 

Factored (magnified) moment at section about  the y (z) axis of LCS of the member

Wc,B,y(z)

Section modulus for biaxial calculation around y (z) axis calculated concrete cross-section without concrete cover

 

b,h

dimension of rectangular cross-section

c

Concrete cover of the stirrup

where

x

Input value in parameter Ratio y/z

where

ny is number of bars in y direction of LCS including corner bars

nz is number of bars in z direction of LCS including corner bars

 

 

The user reinforcement can be defined for code ACI 318-05 only in local setting (via member data)

This option From user reinforcement will be taken into account only if some user reinforcement is defined in the column .If this condition is not fulfilled, the ratio y/z will be calculated automatically (Ratio type = Automatic).

4.1.3.1.5.9.2 Ratio y/z

Group

General > Calculation > tab sheet Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

0,5  (Limit values from 0 to10)

Local setting

Yes

Influence

Only design reinforcement  to rectangular column for biaxial bending calculation

This edit box allows to input user value of ratio y/z. The ratio of reinforcement in y direction is inputted and the ratio in z direction is calculated by the program. This property is active, only  if Ratio type = Manual

4.1.3.1.5.9.3 Limit stress ratio

Group

General > Calculation > tab sheet Columns

Type of parameter

Edit box

Mode:

Advanced mode only

Default:

4 (Limit values from 0 to100)

Local setting

No

Influence

Only design reinforcement  to rectangular column for biaxial bending calculation

Design reinforcement with using biaxial bending calculation depends on value ratio y/z (ratio of reinforcement in y/z ), if check box Optimize the number of bars in c-s for biaxial calculation is OFF. If the ratio y/z is big, the program has to design many bars in one direction to  interaction formula was fullfilled, but result of interaction formula is small. This solution is often uneconomical design of reinforcement, therefore user can set limit ratio y/z via property Limit stress ratio (ratio y/z )lim). If   ratio y/z > (ratio y/z )lim or ratio y/z < 1/(ratio y/z )lim ,then program gives warning 245 (An unusual design situation encountered: the stress ratio y/z exceeds the preset limit of the required reinforcement is hardly acceptable.Please, check the concrete setup) and user should:

The possibilty of correction calculation, when warning 245 is appeared, is presented in the table-.

Setting

Results

Biaxial calculation, ratio type= Automatic, Optimalization=OFF, Real area of reinforcement bar

Biaxial calculation, ratio type= Automatic, Optimalization=ON, Real area of reinforcement bar

Uniaxial calculation(Sum), ratio type= Automatic, Optimalization=OFF, Real area of reinforcement bar

Biaxial calculation, ratio type= Manual, ratio y/z = 0,5, Optimalization=OFF, Real area of reinforcement bar

Biaxial calculation, ratio type= Automatic, Optimalization=OFF, Delta area of reinforcement bar, delta = 0.02inch2

4.1.3.1.6 Beams

There are the following items in group General > Calculation > Beams.

4.1.3.1.6.1 Calculate compression reinforcement

Group

General > Calculation > Beams

Type of parameter

Checkbox

Default:

ON

Local setting

NO

Influence

Design of reinforcement

if this checkbox is set to YES, then compression reinforcement is automatically designed. This can happen when

Equilibrium was not found (583)

Depth of compression zone is bigger then allowed value – the tensile reinforcement is not fully exploited

Without compression reinforcement

Without compression reinforcement

4.1.3.1.6.2 Normal force to calculation

Group

General > Calculation > Beams

Type of parameter

Checkbox

Default:

ON

Local setting

NO

Influence

Design of reinforcement

If this checkbox is set to YES the normal force from statical analysis is also taken into account for design of reinforcement

4.1.3.1.6.3 Check compression element (chapter 10.3.5 from "10 Literature")

Group

General > Calculation > Beams

Type of parameter

Checkbox

Default:

ON

Local setting

NO

Influence

Design of reinforcement

If this checkbox is set to YES then member is checked if should be designed as column or not

IF  THEN member is considered as beam

IF   THEN member should be considered as column (E915) The user should change type of beam to column

4.1.3.1.6.4 Moment capping at the face of support/column

Group

General > Calculation > Beams

Type of parameter

Checkbox

Default:

OFF

Local setting

NO

Influence

Recalculated internal forces for design of reinforcement

 

CMD

Support width

if concrete member data does not exist width of support will be loaded from the structure,

 

if concrete member data exists width of support will be loaded from Concrete member data > Force reduction

 

The comparison of the bending moments with and without capping for standard support and for column support is done in the following table

Moment capping

NO

YES

Standard support

Column support

4.1.3.1.6.5 Shear force capping at supports

Group

General > Calculation > Beams

Type of parameter

Checkbox

Default:

OFF

Local setting

NO

Influence

Recalculated internal forces for design of reinforcement

If this checkbox is set ON then shear force is reduced according to type of reduction in recalculated forces (for more information see part related to “Reduce shear force”)

4.1.3.1.6.6 Reduce shear force

Group

General > Calculation > Beams

Type of parameter

Radio button

Default:

OFF

Local setting

NO

Influence

Recalculated internal forces for design of reinforcement

4.1.4 Design strength

In this tab-sheet are parameters, which have influence directly to calculation design strength of the structure

4.1.4.1 Coefficient for maximum allowable value Pn

Group

Design strength

Type of parameter

Edit box

Default:

0.8 (Limit values from 0.5 to1)

Local setting

No

Influence

Only design reinforcement  to column

Design axial strength φ·Pn of compression members shall not be taken greater than φ·Pn,max, computed according to ACI 318-05,clause 10.3.6.1.The percentage of maximum allowable stresses from nominal axial strength can be set by this parameter, it means that following formula is used for calculation

where

x

Coefficient for calculation maximum allowable value Pn

f

Strength reduction factor calculated by iterative calculation, loaded from concrete setup or from concrete member data, see chapter "4.1 Concrete setup for 1D member"

coeffc

coefficient for reduction specified compressive strength loaded from concrete setup

fc’

specified compressive strength of concrete

Ag

gross area of concrete section

Ast

total area of non-prestressed longitudinal reinforcement

fy

specified yield strength of reinforcement

The area of reinforcement is not subtracted from area of concrete in design reinforcement, because area of reinforcement is unknown, where this check is done

4.1.4.2 Equation for calculation EI for calculation Pc

Group

Design strength

Type of parameter

Combo box

Default:

Equation 10-11

Local setting

No

Influence

Equation for calculation stiffness for  the critical column load

In calculation magnified moments for sway or non-sway frame (see chapter "7.2 Internal forces for 1D members (beam, beam as slab, column)"), it is necessary to calculate critical column load (value Pc). This critical column load (Euler buckling load) depends on flexural stiffness of compression member (value EI), which in code ACI 318-05 can be calculated by two ways.

where

Ec

modulus of elasticity of concrete, see chapter "3.1 Concrete"

Ig,y(z)

moment of inertia of gross concrete section about  y(z) centroidal axis of LCS neglecting reinforcement

Ec

modulus of elasticity of reinforcement, see chapter "3.2 Reinforcement"

Ise,y(z)

moment of inertia of reinforcement about  y(z) centroidal axis of LCS axis of member cross section, see chapter "4.1 Concrete setup for 1D member"

βd

ratio used to compute magnified moments in columns due to sustained loads, see chapter "4.1 Concrete setup for 1D member"

The calculated values of flexural stiffness’s are presented in the service Internal forces (tree Concrete > 1D member), if values My,recalc or My,recalc are selected, see chapter "7.2 Internal forces for 1D members (beam, beam as slab, column)"

4.1.4.3 Maximum strain for non-prestressed flexural member

Group

Design strength > Strength reduction factor Phi

Type of parameter

Edit box

Default:

0.004

Local setting

NO

Influence

Design of longitudinal reinforcement for beams and beam as slab

For nonprestressed flexural members and nonprestressed members with factored axial compressive load less than 0.10fc′Ag the strain in most tensioned reinforcement (value εt) has to be greater than defined value in edit box, see chapter "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)" and "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)".

εt  ≥εt,max =0,004

If condition above is not fulfilled, then the calculation finished with error 916 (The cross-section is not ductile).

4.1.4.4 Group Ratio BetaD

Creep due to sustained load will increase the lateral deflections of a column and hence the moment magnification..This is approximated for design by reducing the stiffness EI (see chapter 4.1.4.2 Equation for calculation EI for calculation Pc) used for calculation critical column load (value Pc) by dividing EI by equation (1+βd). There are two basic properties (two type of calculation factor +βd ) in this group:

    Type of calculation

Group

Design strength

Type of parameter

Radio button

Default:

Automatic calculation

Local setting

Yes

Influence

Calculation of magnified moment for compression member

This setting allows to set type of calculation of factor βd:

For automatic calculation, factor βd is calculated in each sections of the compression column, it means that in each section at length of compression member the different value can be taking into account

For user input the same value in each section of compression member is used

    User input

Group

Design strength

Type of parameter

Edit box

Default:

0.6 (Limit values from 0 to10)

Local setting

Yes

Influence

Calculation of magnified moment for compression member

This edit box is used for inputting user input of factor βd . It is active only, if item User input is selected in group Ratio BetaD

4.1.4.5 Group Strength reduction factor Phi

Design strength of the structure is calculated multiplying the nominal strength by a strength reduction factor φ. The values of this factor for different situation are defined in ACI-318-05, clause 9.3.2. Here user can define default value of strength reduction factor for basic situation.

4.1.4.5.1 Compression controlled section

Group

Design strength > Strength reduction factor Phi

Type of parameter

Edit box

Default:

0.65

Local setting

Yes

Influence

Calculation strength reduction factor for design of longitudinal reinforcement

This factor should be used for calculation if tensile reinforcement in reinforcement (value εt) is lesser than 0.002.

For design reinforcement of beams (see chapter "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)") this factor is used in following case:

 

For design reinforcement in column (see chapter "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)") this factor is used in following cases,

4.1.4.5.3 Shear and torsion

Group

Design strength > Strength reduction factor Phi

Type of parameter

Edit box

Default:

0.75

Local setting

Yes

Influence

Calculation strength reduction factor for design of  shear reinforcement

This factor is used for calculation design shear strength, see chapter  "8.2 Design of reinforcement for 1D members (beams, beams as slab, columns)".

4.1.4.6 Reduction factor for moment of inertia

According to clause 10.1.1 in ACI 318-05, it is possible to use alternative values of moment of inertia for the calculation. Reduction factor for moment of inertia of columns and beams can be set in this group and this reduction factors will be only used for calculation value  ψAy(z) and ψBy(z), which are used for calculation  effective length factor according code ACI (code dependent method for calculation effective length factor ), see chapter "5.4 Member buckling data".

 

Beams

Group

Design strength > Reduction factor for moment of inertia

Type of parameter

Edit box

Default:

0.35  (Limit values from 0 to1)

Local setting

NO

Influence

Calculation  effective length factor according code ACI

This factor is used for reduction moment of inertia of beams in calculation coefficient ψAy(z) and ψBy(z), which are used for calculation effective length factor according to code dependent method

Ig,red,y(z) = redb· Ig,y(z)

where

Ig,y(z)

moment of inertia of gross concrete section about  y(z) centroidal axis of LCS neglecting reinforcement

redb

Reduction factor for beams set in edit box
Columns

Group

Design strength > Reduction factor for moment of inertia

Type of parameter

Edit box

Default:

0.7  (Limit values from 0 to1)

Local setting

NO

Influence

Calculation  effective length factor according code ACI

This factor is used for reduction moment of inertia of columns in calculation coefficient ψAy(z) and ψBy(z), which are used for calculation effective length factor according to code dependent method

Ig,red,,y(z) = redc· Ig,y(z)

where

Ig,y(z)

moment of inertia of gross concrete section about  y(z) centroidal axis of LCS neglecting reinforcement

redc

reduction factor for columns set in edit box

4.1.4.7 Design strength > Shear

There is only one value in part Design strength > Shear.

4.1.4.7.1 Maximal value fy and fyt for shear (chapter 11.5.2 from ACI 318-05)

Group

General > Calculation > Beams

Type of parameter

Radio button

Default:

OFF

Local setting

NO

Influence

Recalculated internal forces for design of reinforcement

This value is maximal available yield strength of the reinforcement used for the design of shear reinforcement. If user inputs bigger value then maximal value from concrete setup is taken into account

4.1.5 Detailing provisions

Generally detailing provisions are split to detailing provisions for beams and columns. Each type of memebr (beam or column) has the different detailing provisions for design of longitudinal and shear reinforcement.

4.1.5.1 Beams

4.1.5.1.1 Longitudinal reinforcement

There are the following items in the part Detailing provisions > Beams > Longitudinal reinforcement.

4.1.5.1.1.1 Min reinf. factor, x*fc’^0,5/fy (chapter 10.5.1 from ACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

ON

Local setting

NO

Influence

Design of longitudinal reinforcement

This value is minimal reinforcement factor during design of longitudinal reinforcement in beams. Value x is user defined value and default is 3,0 for US unit format and 0,25 for metric format

Unit format

Formula

US

Metric

4.1.5.1.1.2 Min reinf. factor, x/fy (chapter 10.5.1 from ACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

ON

Local setting

NO

Influence

Design of longitudinal reinforcement

This value is minimal reinforcement factor during design of longitudinal reinforcement in beams. Value x is user defined value and default is 200 for US unit format and 1,4 for metric format

Unit format

Formula

US

Metric

4.1.5.1.1.3 Max. reinf. (tensile strain eps_t for max.reinf – chapter 10.3.5 from ACI 318-05)

 

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

ON

Local setting

NO

Influence

Design of longitudinal reinforcement

This value is minimal strain in reinforcement which is allowed for beams where axial load is ; otherwise the cross-section is not ductile

4.1.5.1.1.4 Min. clear bars spacing (chapter 7.6.1 from ACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

ON

Local setting

NO

Influence

Design of longitudinal reinforcement

This value prescribes minimum clear distance between bars; default value is diameter of the bar

4.1.5.1.1.5 Min. clear bars spacing (chapter 7.6.1 from ACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

ON

Local setting

NO

Influence

Design of longitudinal reinforcement

This value prescribes minimum clear distance between bars; default value is 1 inch

4.1.5.1.1.6 Max. centre-to-centre bars spacing

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

OFF

Local setting

NO

Influence

Design of longitudinal reinforcement

This is the user defined value of maximal clear spacing between longitudinal bars. It is code independent value

4.1.5.1.1.7 Check max. centre-to-centre bars spacing (chapter 10.6.4 fromACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + edit box

Default:

ON

Local setting

NO

Influence

Design of longitudinal reinforcement

This item prescribes maximal allowed centre to centre bars spacing between longitudinal bars based on the chapter 10.6.4 from ACI 318-05.

4.1.5.1.2 Shear reinforcement

There are the following items in the part Detailing provisions > Beams > Shear reinforcement.

4.1.5.1.2.1 Check max. centre-to-centre spacing (chapter 11.5.5 fromACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + combobox + edit box

Default:

ON

Local setting

NO

Influence

Design of shear reinforcement

This item prescribes maximal allowed centre to centre spacing between stirrups legs based on the chapter 11.5.5 from ACI 318-05.

There are two values in combobox

Unit format

Formula

spacing
US

 

Metric
 

Where value

4.1.5.1.2.2 Check min. Area Av.min = x*bw*s/fyt (chapter 11.5.6 fromACI 318-05)

Group

 Detailing provisions > Beams

Type of parameter

Check box + combobox + edit box

Default:

ON

Local setting

NO

Influence

Design of shear reinforcement

This item prescribes minimal area of shear reinforcement based on the chapter 11.5.6 from ACI 318-05.

There are two values in combobox

Unit format Formula spacing
US

 
Metric
 
4.1.5.1.2.3 Check diameter (chapter 7.10.5.1 fromACI 318-05)

 

Group

 Detailing provisions > Beams

Type of parameter

Check box + combobox + edit box

Default:

ON

Local setting

NO

Influence

Design of shear reinforcement

This item prescribes minimal diameter of shear reinforcement based on the chapter 7.10.5.1 from ACI 318-05.

There are two values in combobox

Unit format Formula spacing
US

 
Metric
 
4.1.5.1.2.4 Maximal transverse spacing of the legs

Group

 Detailing provisions > Beams

Type of parameter

Check box + combobox + edit box

Default:

ON

Local setting

NO

Influence

Design of shear reinforcement

This item prescribes maximal allowable transverse spacing of the stirrups legs. It is code independent value

4.1.5.2 Columns

4.1.5.2.1 Group longitudinal reinforcement

There are defined detailing provisions for design of longitudinal reinforcement to column

4.1.5.2.1.1 Min. reinf. percentage

Group

Detailing provisions > tab-sheet Columns

Type of parameter

Check box +edit box

Default:

Check box is ON, value in edit box = 1%

Local setting

No

Influence

Design longitudinal reinforcement to column

If this check box is ON, then minimum area of longitudinal reinforcement is checked according to clause 10.9.1 in ACI 318-05. If area of longitudinal reinforcement is lesser than minimum area of reinforcement, then

                                           As = As,min = x·Ag /100

 

and design of longitudinal reinforcement finishes with warning 2 (The main reinforcement area was designed according to min. Required reinforcement percentage)

where

Ag

gross area of concrete section

  

x

Value of minimum percentage loaded from edit box

  
4.1.5.2.1.2 Max. reinf. percentage

Group

Detailing provisions > tab-sheet Columns

Type of parameter

Check box +edit box

Default:

Check box is ON, value in edit box = 8%

Local setting

No

Influence

Design longitudinal reinforcement to column

If this check box is ON, then maximum area of longitudinal reinforcement is checked according to clause 10.9.1 in ACI 318-05. If area of longitudinal reinforcement is greater than maximum area of reinforcement ( As> As,max = x·Ag /100 ) then design of longitudinal reinforcement finishes with warning 502 (The percentage of designed reinforcement is higher than the maximum percentage)

where

Ag

gross area of concrete section

  

x

value of maximum percentage loaded from edit box

  
4.1.5.2.1.3 Min. clear bars spacing

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box + edit box

Default:

Check box is ON, value in edit box = 1

Local setting

NO

Influence

Design longitudinal reinforcement to column

If this check box is ON, then minimum clear spacing between bars  is checked according to clause 7.6.1 in ACI 318-05. If clear spacing of bars is lesser than minimum spacing then design of longitudinal reinforcement finishes with the following warnings

Warning

Description

Cause

134

Tha bar distance for the  Y-direction is too small

The minimum spacing of bars  in direction of y-axis of LCS of the member for rectangular cross-section does not satisfy

136

Tha bar distance for the  Z-direction is too small

The minimum spacing  of bars in direction of z-axis of LCS of the member for rectangular cross-section does not satisfy

138

The bars distance is too small

The minimum spacing of bars in circular cross-section is does not satisfy
4.1.5.2.1.4 Min. clear bars spacing

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box + edit box

Default:

Check box is ON, value in edit box = 25,4 mm (1 inch)

Local setting

NO

Influence

Design longitudinal reinforcement to column

If this check box is ON, then minimum clear spacing between bars is checked according to clause 7.6.1 in ACI 318-05. If clear spacing of bars is lesser than minimum spacing then design of longitudinal reinforcement finishes with If clear spacing of bars is lesser than minimum spacing then design of longitudinal reinforcement finishes with the following warnings.

Warning

Description

Cause

134

Tha bar distance for the  Y-direction is too small

The minimum spacing of bars  in direction of y-axis of LCS of the member for rectangular cross-section does not satisfy

136

Tha bar distance for the  Z-direction is too small

The minimum spacing  of bars in direction of z-axis of LCS of the member for rectangular cross-section does not satisfy

138

The bars distance is too small

The minimum spacing of bars in circular cross-section does not satisfy
4.1.5.2.1.5 Max. bars spacing

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box + edit box

Default:

Check box is ON, value in edit box = 6inch (152.4mm)

Local setting

NO

Influence

Design longitudinal reinforcement to column

If this check box is ON, then centre-centre spacing between bars is checked. This is code independently check. If this centre-centre spacing of bars is bigger than maximum spacing then design of longitudinal reinforcement finishes with the following warnings

Warning

Description

Cause

133

Tha bar distance for the  Y-direction is too big

The centre-centre maximum spacing of bars  in direction of y-axis of LCS of the member for rectangular cross-section does not satisfy

135

Tha bar distance for the  Z-direction is too big

The centre-centre maximum  spacing of bars in direction of z-axis of LCS of the member for rectangular cross-section does not satisfy

137

The bars distance is big

The centre-centre maximum  spacing of bars in circular cross-section does not satisfy
4.1.5.2.1.6 Min. number of bars

Group

Detailing provisions > tab-sheet Columns

Type of parameter

Check box +edit box

Default:

Check box is ON, value in edit box = 4

Local setting

No

Influence

Design longitudinal reinforcement to column

If this check box is ON, then in design of reinforcement minimum number of bars according to clause 10.9.2 in ACI 318-05 is used for calculation, though number of bars from design reinforcement is lesser. For rectangular column minimum numbers of bars is always 4, independently on value defined in this property. This setting is used for number of bars in circular column.

4.1.5.2.2 Group transverse reinforcement

There are defined detailing provisions for design of transverse reinforcement (ties) to column

4.1.5.2.2.1 Max.spacing – number of long diameter

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box + edit box

Default:

Check box is ON, value in edit box = 16

Local setting

NO

Influence

Design of transverse reinforcement to column

If this check box is ON, then spacing of bars as multiple of diameter of longitudinal reinforcement bars   according to clause 7.10.5.2 in ACI 318-05 is taken into account for design transverse reinforcement (maximum vertical spacing of ties)

ss,min,1 = x·db

where

db

diameter of longitudinal reinforcement loaded

  • from concrete setup (Design default > Column >main), if member data is not defined on the member or
  • from concrete member data (Design > Main >diameter) , if concrete member data is defined on the member

x

value of maximum spacing  loaded from edit box
4.1.5.2.2.2 Max.spacing – least dimension of column

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box

Default:

Check box is ON

Local setting

NO

Influence

Design of transverse reinforcement to column

If this check box is ON, then spacing of bars as least dimension of column   according to clause 7.10.5.2 in ACI 318-05 is taken into account for design transverse reinforcement (maximum vertical spacing of ties)

ss,min,2 = min (b;h)

where

b,h

the dimensions of cross-section of compression member in direction of y(z) axis of LCS. For different shape of cross-section than rectangular shape, the dimensions of circumscribed rectangular is taken into account
4.1.5.2.2.3 Max.spacing – number of tie diameter

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box + edit box

Default:

Check box is ON, value in edit box = 48

Local setting

NO

Influence

Design of transverse reinforcement to column

If this check box is ON, then spacing of bars as multiple of tie diameter   according to clause 7.10.5.2 in ACI 318-05 is taken into account for design transverse reinforcement (maximum vertical spacing of ties)

ss,min,3 = x·ds

where

ds

diameter of shear reinforcement (tie diameter)

  • from concrete setup (Design default > Column >Stirrup), if member data is not defined on the member or
  • from concrete member data (Design > Stirrups >Diameter) , if concrete member data is defined on the member

x

value of maximum spacing  loaded from edit box
4.1.5.2.2.4 Check diameter

Group

 Detailing provisions > tab-sheet Columns

Type of parameter

Check box + two edit boxes

Default:

Check box is ON,

value in edit box = 3 (10)

value in edit box = 4 (13)

Local setting

NO

Influence

Design of transverse reinforcement to column

If this check box is ON, then minimum diameter of shear reinforcement (ties)   according to clause 7.10.5.1 in ACI 318-05 is checked during design of shear reinforcement. Minimum diameter of shear reinforcement depends on diameter of longitudinal reinforcement, which enclosed, see table below.

Unit format Diameter of longitudinal reinforcement Minimum shear diameter
US

Metric

If diameter of shear reinforcement   is lesser than minimum diameter of shear reinforcement, then design of shear reinforcement finishes with warning 163 (The profile diameter of shear reinforcement is lesser than permitted). In this case, value shear reinforcement has to be increased in concrete setup or concrete member data.

If diameter of shear reinforcement   is lesser than minimum diameter of shear reinforcement, then design of shear reinforcement finishes with warning 163 (The profile diameter of shear reinforcement is lesser than permitted). In this case, value shear reinforcement has to be increased in concrete setup or concrete member data.

4.1.5.2.2.5 Max transverse spacing of the legs

Group

Detailing provisions > tab-sheet Columns

Type of parameter

Check box + edit box

Default:

Check box is OFF,  edit box = 11,81 inch (300 mm)

Local setting

NO

Influence

Design of transverse reinforcement to column

The value from edit box (value st,max) is used for calculation number of cuts of shear reinforcement independently if check box is ON or OFF. This value is used for:

Number of cuts is calculated according to formula

where

ds

diameter of shear reinforcement (tie diameter)

  • from concrete setup (Design default > Column >Stirrup), if member data is not defined on the member or
  • from concrete member data (Design > Stirrups >Diameter) , if concrete member data is defined on the member

bcen

width of cross-section in centroid of concrete cross-section

hcen

height of cross-section in centroid of concrete cross-section

c

The nominal value of concrete cover, value presented in property Concrete cover

st,max

the maximum transverse spacing of the legs loaded from value defined in edit box