Function
- Determine the design code and the special provisions for seismic design (if required) to perform the design or the strength verification for RC members according to the following Concrete Design Criteria:
EN 1992-1-1:1994 Eurocode2, Design of concrete structures Part 1 (Eurocode2:04)
ENV 1992-1-1:1992 Eurocode2, Design of concrete structures Part 1 (Eurocode2)
Ultimate Strength Design, the American Concrete Institute (ACI318-19/14/11/08/05/02/99/95/89)
Colombian Earthquake Resistance Building Code Ultimate Strength Design (NSR-10)
Canadian Standards Association of Concrete Structures (CSA-A23.3-94)
British Standard, Structural use off concrete Part 1 (BS8110-97)
Taiwanese Standard (TWN-USD111/100/92)
Indian Standard (IS456:2000)
Architectural Institute of Japan (AIJ-WSD99)
China Standard (GB50010-10/02)
Architectural Institute of Korea (AIK-USD94)
Korean Society of Civil Engineers (KSCE-USD96)
Korean Concrete Institute (KDS41 30:2018/ KCI-USD12/07/03/99)
Architectural Institute of Korea (AIK-WSD2K)
National Structural Code of the Philippines (NSCP-2015)
Note 1
If the user omits the design code, the Concrete Structure Design Code of the European Standard (Eurocode2:04) is applied by default.
Note 2
Following section types and shapes are applicable in Steel Code Checking.
Applicable section type: DB/User type
Applicable section shape for Beam: Solid Rectangle, T-Section
Applicable section shape for Column: Solid Rectangle, Solid Round, Pipe
Call
From the Main Menu select [Design] tab > [Type : RC Design] > [Design Input Data] > [Design Code Option]
Input
[When Eurocode2:04 is selected]
Design Code
RC design code.
National Annex
National Annex for Eurocode2:04.
Note
Available National Annexes are as follows:
Recommended
Italy
Sweden
Singapore
Apply NTC
NTC2008
Option to apply the capacity design rule as per NTC2008
NTC2012
Option to apply the capacity design rule as per NTC2012
NTC2018
Option to apply the capacity design rule as per NTC2018
Note
Apply Special Provisions for Seismic Design
Option to apply the capacity design rule as per EN1998-1:2004
Note
Strut Angle for Shear Resistance
The angle between the concrete compression strut and the beam axis perpendicular to the shear force
Effective Creep Ratio
()
is used in the following formula.
Calculation of "A" in slenderness limit() as per EN1992-1-1:2004
Calculation of Factor for accounting creep in additional second order moment as per EN1992-1-1:2004 and NTC2018
Where,
M2 : Additional second order moment (=Ned x e2)
e2 : Deflection
l0 : Effective Length
c: depends on curvature distribution, program uses c=10 as recommended by code.
The value of c cannot be changed by user.
Kr : (nu-n)/(nu-nbal) Correction factor for axial load
n=Ned/Ac fcd relative axial force
=0.105 (Recommended) Different value cannot be specified.
nbal =0.4 (Recommended) Different value cannot be specified.
Default Value of =2.14
In Eurocode, Default value of "A" is 0.7, and to satisfy "A=0.7" is "2.14".(see"Slenderness Limit")
Slenderness Limit
(5.13N) in EN1992-1-1:2004
(Default value is '0.7'.)
(Default value is '1.1'.)
(Default setting is 'Calculate by Program'.)
(5.13N) in NTC2018
n = Ned / (Ac x fcd)
Ned : Axial force
Ac : Area of cross section
Strong Column Weak Beam
Define the ratio to satisfy the ductility condition at all the joints. Default value is '1.3'.
eq. (4.9) in EN1998-1:2004
Select Ductility Class
For EC8:04
DCH : High ductility level
DCM : Medium ductility level
For NTC2018
CD "A" : High ductility level
CD "B" : Medium ductility level
Non-Dissipative : Low ductility level
Design Method of Non-Dissipative Member
Define method of non-dissipative member design as per NTC2018.
M-C Curve : Elastic moment resistance (M'yd) is obtained from Moment-Curvature Curve.
Approximate Method : Elastic moment resistance (M'yd) = Reduction factor * Ultimate moment resistance (M_Rd)
Shear Force for Design (Gamma_rd)
Define the factor accounting for possible overstrength due to steel strain hardening
Default value is as follows:
| Beam | Column | Wall | Joint | ||
| EC8-1:2004 | DCM | 1 | 1.1 | - | - |
| DCH | 1.2 | 1.3 | 1.2 | 1.2 | |
| NTC2008 | CD"B" | 1 | 1.1 | - | - |
| CD"A" | 1.2 | 1.3 | 1.2 | 1.2 | |
| NTC2012 | CD"B" | 1 | 1.1 | - | 1.1 |
| CD"A" | 1.2 | 1.3 | 1.2 | 1.2 | |
| NTC2018 | Non-Dissipative | 1 | 1.1 | - | 1.1 |
| CD"B" | 1.1 | 1.1 | - | 1.1 | |
| CD"A" | 1.2 | 1.3 | 1.2 | 1.2 |
Non-Dissipative Element
Define the Non-dissipative elements in order to carry out the elastic design
- Concept and reference of Non-dissipative elements Design
Flowchart of Non-dissipative elements Design (NDED) using Gen NX
Secondary Seismic Element
Define the secondary seismic elements in order to preclude the capacity design rule
Structure Information
Structure Type : Define structure type to calculate behavior factor and determine the wall design method
Behavior Factor (q) : Behavior factor to account for energy dissipation capacity shall be derived for each design direction as follows:
Calculate by Program : Behavior factor is automatically calculated and applied to the capacity design.
Alpha u / Alpha 1 : The multiplication factor for buildings which are regular in plan.
User Input : Behavior factor is directly entered by the user.
Note
eq.(5.1) in EN1998-1:2004
Where,
qo : Basic value of the behaviour factor for systems regular in elevation
Alpha u / Alpha 1 : The following approximate values may be used:
kw : The factor reflecting the prevailing failure mode in structural systems with walls
Elastic Response Spectrum
Default By Function : Select response spectrum function defined in Response Spectrum Function. The spectrums of 'Eurocode8' and 'User Type' are available.
Spectrum Parameters
Soil Factor (S)
Tb : The lower limit of the period of the constant spectral acceleration branch
Tc : The upper limit of the period of the constant spectral acceleration branch
Td : The value defining the beginning of the constant displacement response range of the spectrum
Ref. Reak Ground Acc. (AgR) : The design ground acceleration on type A ground
Importance Factor (I)
Viscous Damping Ratio (xi)
Consider Ved of elastic strength Load combination for primary members
V_Ed_1= V_Ed by LC_U
V_Ed_2 = Min [M_Rd_top+M_Rd_bot)/L for ULS, V_Ed by LC_E]
Here,
LC_U : Load combinations for checking Ultimate Limit state (ULS)
LC_E : Load combinations for checking Elastic Limit State (ELS)
Design shear force (V_Ed) = Max [V_Ed_1, V_Ed2]
Friction Coefficient for Wall Sliding
Define the concrete-to-concrete friction coefficient under cyclic actions, which may be assumed equal to 0.6 for smooth interfaces and to 0.7 for rough ones. The default value is 0.7.
Torsion Design
Check to consider torsion in design.
Consider Shear Strength of Concrete for Checking
Ignore the shear strength of concrete in the calculation of shear resistance for the walls and columns. By checking off this option, the shear resistance of members will be determined by shear reinforcement regardless of the amount of shear strength of concrete. This option works with the Concrete Code Check function.
[When ACI318-08/11/14/19 is selected]
Design Code
RC design code (refer to Note 1)
Check Beam Deflection (Only ACI318-14,19 / ACI318M-14,19)
Options for calculation and evaluation of short/long-term deflection of beam
Apply Special Provisions for Seismic Design
Option to apply the special provisions for seismic design
Select Frame Type
Select the type of frame for seismic zone.
Special Moment Frames : Moment frame in strong-motion seismic zone
Intermediate Moment Frames : Moment frame in intermediate-motion seismic zone
Ordinary Moment Frames : Moment frame in weak-motion seismic zone
Shear Wall Type
Option to apply special structural walls. Select the condition as per Boundary Element Method.
Note
Boundary Element Methods are provided as per clause 21.9.6.2 and clause 21.9.6.3 of ACI 318-08 .
Shear for Design
Apply Scale up Factor for Shear as per special provisions for seismic design.
The Update By Code Button : Apply Scale up Factor for Shear as per a relevant code.
R*Vc(a1*SUM(Mpr)/L>max(Ve1,Ve2)/2)
R : ACI318-05 Clause 21.3.4.2 indicates that " Transverse reinforcement shall be proportioned to resist shear assuming Vc=o when ...". In midas, even though such conditions occur, the user can include a part of shear strength of concrete as well as shear reinforcement.
Method : Select a method to apply Scale up Factor for Shear.
Max(Ve1, Ve2) : Use the larger of the shear forces to which Scale up Factors for Shear (a1, a2) will have been applied.
Min(Ve 1, Ve 2) : Use the lesser of the shear forces to which Scale up Factors for Shear (a1, a2) will have been applied.
Ve 1 : Select to apply Scale up Factor for Shear (a1).
Ve 2 : Select to apply Scale up Factor for Shear (a2).
Member Types to be excluded in Seismic Design :
Select the member types for which Seismic Design is to be excluded .We can also select individual members from Seismic Design Type.
The OK Button : Enter the selection and close the dialog box.
The Close Button : Do not enter the selection and close the dialog box.
[When ACI318-05 is selected]
Design Code
RC design code (refer to Note 1)
Apply Special Provisions for Seismic Design
Option to apply the special provisions for seismic design
The OK Button : Enter the selection and close the dialog box.
The Close Button : Do not enter the selection and close the dialog box.
Select Frame Type
Apply different Scale up Factor for Shear for each seismic zone (This is applicable for ACI318-89, 95, 99, 02,05).
Special Moment Frames : Moment frame in strong-motion seismic zone
Intermediate Moment Frames : Moment frame in intermediate-motion seismic zone
Ordinary Moment Frames : Moment frame in weak-motion seismic zone
Shear for Design
Apply Scale up Factor for Shear as per special provisions for seismic design.
The Update Button : Apply Scale up Factor for Shear as per a relevant code.
R*Vc(a1*SUM(Mpr)/L>max(Ve1,Ve2)/2)
R : ACI318-05 Clause 21.3.4.2 indicates that " Transverse reinforcement shall be proportioned to resist shear assuming Vc=o when ...". In midas, even though such conditions occur, the user can include a part of shear strength of concrete as well as shear reinforcement.
Method : Select a method to apply Scale up Factor for Shear.
Max(Ve1, Ve2) : Use the larger of the shear forces to which Scale up Factors for Shear (a1, a2) will have been applied.
Min(Ve 1, Ve 2) : Use the lesser of the shear forces to which Scale up Factors for Shear (a1, a2) will have been applied.
Ve 1 : Select to apply Scale up Factor for Shear (a1).
Ve 2 : Select to apply Scale up Factor for Shear (a2).
[When TWN-USD111/100 is selected]
Apply Special Provision for Seismic Design
Option to apply the special provision for seismic design.
Shear for Design
Apply Scale up Factor for Shear as per special provisions for seismic design.
The Update By Code Button : Apply Scale up Factor for Shear as per a relevant code.
R*Vc(a1*SUM(Mpr)/L>max(Ve1,Ve2)/2)
R : ACI318-05 Clause 21.3.4.2 indicates that " Transverse reinforcement shall be proportioned to resist shear assuming Vc=o when ...". In midas, even though such conditions occur, the user can include a part of shear strength of concrete as well as shear reinforcement.
Method : Select a method to apply Scale up Factor for Shear.
Max(Ve1, Ve2) : Use the larger of the shear forces to which Scale up Factors for Shear (a1, a2) will have been applied.
Min(Ve 1, Ve 2) : Use the lesser of the shear forces to which Scale up Factors for Shear (a1, a2) will have been applied.
Ve 1 : Select to apply Scale up Factor for Shear (a1).
Ve 2 : Select to apply Scale up Factor for Shear (a2).
SCWB Design/Checking Method
Option for design force calculation special provision for seismic design.
Design Strength: Perform strong column-weak beam design and checking using the design strength of beams ().
Design > RC Strong Column Weak Beam Design > Ductile Design...
Concrete Code Design > Beam Design, Column Design...
Concrete Code Check > Beam Checking, Column Checking...
Note : When TWN-USD111/100 is selected, Use equations below chart.
When ACI318-19,14(including M), NSR-10, NSCP2015 is selected, Use equations below chart, but k1 factor is ignored(1.0)
Design > RC Strong Column Weak Beam Design > Strong Column Weak Beam Ratio...
Design > RC Strong Column Weak Beam Design > Strong Column Weak Beam Ratio Table...
Nominal Strength: Perform strong column-weak beam design and checking using the nominal strength of beams ().
Nominal Strength : Perform strong column-weak beam design and checking using the nominal strength of beams ().
Design > RC Strong Column Weak Beam Design > Ductile Design...
Concrete Code Design > Beam Design, Column Design...
Concrete Code Check > Beam Checking, Column Checking...
Note : When TWN-USD111/100 is selected, Use equations below chart.
When ACI318-19,14(including M), NSR-10, NSCP2015 is selected, Use equations below chart, but k1, Φc factor is ignored(1.0)
Design > RC Strong Column Weak Beam Design > Strong Column Weak Beam Ratio...
Design > RC Strong Column Weak Beam Design > Strong Column Weak Beam Ratio Table...
Torsion Design
Apply torsional design. This option is applicable for EC2:04 & ACI318-19/14/11/08 & TWN-USD111/100/92 & IS456:2000 only.
Moment Redistribution Factor for Beam
Reduce the end moment of the beam and distribute the reduced moment to the middle part.
Moment Calculation Method for Beam
Equivalent Rebar : It is calculated by convert all rabars to one rebar with the same area. (it is the existing method)
* Advantages : The design time is reduced as the calculation is simple.
** Disadvantages : If the rebars are placed as multiple layers and the neutral axis is between multiple layers, the calculation is incorrect.
Each Rebar : It is the method calculating the resistance for each rebar. (it is the added method from Gen 2022.)
* Advantages : it can make an accurate beam capacity.
** Disadvantages : It takes a lot of design time.
For Beam assigned as Member, Design with each element forces
When the force diagram is not typical shape by inputting a non-uniform load such as a concentrated load or by connecting to other elements, it can be designed with accurate member forces. But it takes a lot of time.
P-M Curve Calculation Method
Keep P Constant : the ultimate strength is determined based on the same axial force as the specified load combination (P). It is mainly used when designed by a lateral loads.
Keep M/P Constant : the ultimate strength is determined based on the same eccentricity ratio as the specified load combination (P, My and Mz). It is mainly used when designed by a gravity loads.
fs of Main bar in beam design
Select the method for calculating fs for calculating the maximum spacing (Smax) of stirrups.
2/3*fy : Apply an approximate value according to the design code.
Example
[ACI318-19]
24.3.2.1 Stress fs in deformed reinforcement closest to the tension face at service loads shall be calculated based on the unfactored moment, or it shall be permitted to take fs as (2/3)fy.
By Program : Calculate Stress fs in Gen.