Function
- In Gen NX, the automatic data entry of equivalent static seismic loads according to various standards is applicable for common buildings where each story can be defined and can reasonably act as a rigid diaphragm.
1. Model the structure. The structure must be modeled so that the gravity acts in the direction opposite to the GCS Z-direction.
2. Convert the self-weight of the structure included in the modeling into mass data, if the self-weight is to be considered for the equivalent static seismic load calculation. Use "Converting Type of Model weight to Masses" in Structure Type to assign the directions to be considered for the mass components and enter the value in the "Gravity Acceleration" field.
The procedure of converting the self-weight of the model into mass data by stories to calculate the equivalent static seismic load is as follows :
Calculate the self-weight of the members. Divide and assign the self-weight equally to the connection nodes, which then become the story mass data when the connection nodes are on a story plane (refer to step 4). If the connection nodes fall in between the stories, the nodal masses are considered to exist at the upper story.
3. Use Building > Control Data to enter the position of the ground level in GCS Z-axis coordinate.
Once the ground level is entered, the base shear is calculated at the ground level. The parts below this level are considered as underground floors. All the entered mass data are neglected in the equivalent static seismic load calculation. If the ground level is not defined, the lowest part of the structural model is assumed to be the ground level by default.
4. Use Story to define stories and their floor rigid diaphragm characteristics. Enter the eccentricities to consider the accidental eccentricity moments at each story. The Use Auto Generate Story Data... Button to auto-generate the data necessary for the stories and the application of seismic loading.
Once the floor diaphragm is defined in Story, the X-, Y-displacement degrees-of-freedom and the rotational degree-of-freedom about the Z-axis between all the nodes on the plane (plane parallel to the GCS X-Y plane) are constrained.
In addition, a part or all of constrained nodes can be separated from the floor rigid diaphragm using Floor Diaphragm Disconnect.
Note
If, at a specific story, Story Diaphragm is released, the Story Force at the corresponding story is considered to be zero. Even if the user specifies Additional Seismic Loads, the program considers the Story Force to be zero.
Use Nodal Masses, Floor Diaphragm Masses or Load to Masses to enter the mass components not included in the model.
Use Static Seismic Loads to select the desired standards and enter the data for the calculation of equivalent static seismic loads.
IBC2012(ASCE7-10) : International Building Code 2012
IBC2009(ASCE7-05) : International Building Code 2009
IBC2000(ASCE7-98) : International Building Code 2000
UBC (1997) : UBC 97 standards
UBC (1991) : UBC 91 standards
ATC 3-06 (1982) : ATC 3-06 Provision
NBC (1995) : National Building Code of Canada
NTC 2008 : Italian Design Code
NTC 2012 : Italian Design Code
Eurocode-8 (1996) : Design provisions for earthquake resistance of structures. General rules. Strengthening and repair of buildings.
Eurocode-8 (2004) Elastic : Design provisions for earthquake resistance of structures. General rules.
Strengthening and repair of buildings.
Note Available National Annexes are as follows:
Recommended
Singapore
IS1893 (2002) : Indian Standard
Taiwan (2011) : Seismic Design Specifications and Commentary of Buildings
Taiwan (2006) : Seismic Design Specifications and Commentary of Buildings
Taiwan (1999) : Seismic Design Specifications and Commentary of Buildings
NSR-10 : Colombian Earthquake Resistance Building Code Ultimate Strength Design
(available upon request)
Japan (Arch, 2000) : Japan, Arch. Assoc.- Building structure loading & comm.
KBC (2009) : Korea Building Code, 2009
Korean (KBC, 2005) : Korea Building Code-Structural, KBCS
Korean (Arch, 2000) : Buildings loading criteria and commentaries
Korean (Arch, 1992) : Regulations related to structural criteria for buildings
China Shanghai (DGJ08-9-2003) : Shanghai Code for Seismic Design of Buildings
China (GB50011-2010/2001) : Chinese Code for Seismic Design of Buildings
Fig. Equivalent static seismic load generation
- Once the data required for the calculation of seismic loads are defined, auto-calculate seismic loads for each story in connection with the story data generated in Story. The Use Seismic Load Profile... Button to verify the auto-calculated seismic loads.
Call
From the Main Menu select [Load] tab > [Type : Static Load] > [Lateral] group > [Seismic Loads]
Input
Access Seismic Loads to activate the dialog box defining the seismic loads. Click the Add Button to display the dialog box shown below.
Load Case Name
Select the load case name to be associated with the seismic load. Click the ... Button to the right to enter or modify new load cases.
Seismic Load Code
Select the standards to be applied to the seismic load calculation.
IBC2012(ASCE7-10) : International Building Code 2012
IBC2009(ASCE7-05) : International Building Code 2009
IBC2000(ASCE7-98) : International Building Code 2000
UBC (1997) : UBC 97 standards
UBC (1991) : UBC 91 standards
ATC 3-06 (1982) : ATC 3-06 Provision
NBC (1995) : National Building Code of Canada
NTC 2008 : Italian Design Code
NTC 2012 : Italian Design Code
Eurocode-8 (1996) : Design provisions for earthquake resistance of structures. General rules. Strengthening and repair of buildings.
Eurocode-8 (2004) Elastic : Design provisions for earthquake resistance of structures. General rules. Strengthening and repair of buildings.
Note Available National Annexes are as follows:
Recommended
Singapore
P100-1 (2013) Design : Rumanian Seismic Code
P100-1 (2013) Elastic : Rumanian Seismic Code
IS1893 (2002) : Indian Standard
Taiwan (2022) : Seismic Design Specifications and Commentary of Buildings
Taiwan (2011) : Seismic Design Specifications and Commentary of Buildings
Taiwan (2006) : Seismic Design Specifications and Commentary of Buildings
Taiwan (1999) : Seismic Design Specifications and Commentary of Buildings
NSR-10 : Colombian Earthquake Resistance Building Code Ultimate Strength Design
(available upon request)
Japan (Arch, 2000) : Japan, Arch. Assoc.- Building structure loading & comm.
KBC (2009) : Korea Building Code, 2009
Korean (KBC, 2005) : Korea Building Code-Structural, KBCS
Korean (Arch, 2000) : Buildings loading criteria and commentaries
Korean (Arch, 1992) : Regulations related to structural criteria for buildings
China Shanghai (DGJ08-9-2003) : Shanghai Code for Seismic Design of Buildings
China (GB50011-2010/2001) : Chinese Code for Seismic Design of Buildings
DPT 1301/1302-61:2018 : Thailand Code for Seismic Design of Buildings
Description
Enter a short description.
Seismic Load Parameters
Enter the parameters to be applied to the seismic load calculation.
Seismic Load Parameters
Short Period Site Coefficient (Fa)
Spectral Response Acceleration Parameter (Sds)
Long Period Site Coefficient ( Fu)
Occupancy Category
Period Coefficient
Approximate Period
Risk Category
Site Class
Mapped Spectral Response Acceleration at Short Periods (Ss)
Mapped Spectral Response Acceleration at 1 Second Periods (S1)
Importance Factor
Seismic Load Parameters
Short Period Site Coefficient (Fa)
Spectral Response Acceleration Parameter (Sds)
Long Period Site Coefficient ( Fu)
Occupancy Category
Period Coefficient
Approximate Period
Site Class
Mapped Spectral Response Acceleration at Short Periods (Ss)
Mapped Spectral Response Acceleration at 1 Second Periods (S1)
Importance Factor
Seismic Design Categories
Site Class
Mapped Spectral Response Acceleration at Short Periods (Ss)
Mapped Spectral Response Acceleration at 1 Second Periods (S1)
Importance Factor
Soil Profile Type
Seismic Zone Factor
Seismic Source Type
Closest Distance to Known Seismic Source: Distance to the verified epicenter
Importance Factor
Soil Profile Type
Zone Factor
Importance Factor
Soil Profile Coefficient
Effective Peak Velocity
Zonal Velocity Ratio (v) : The specified zonal horizontal ground velocity expressed as a ratio to 1 m/s
Acceleration Zone (Za) : Acceleration-related seismic zone
Velocity Zone (Zv) : Velocity-related seismic zone
Importance Factor (I)
Foundation Factor (F)
Seismic Load Parameters :
(1) Spectrum parameters
Clause 3.2 Seismic Action
Table 3-2 Topographic categories : T1, T2, T3, T4
(2) Spectral Parameters (Tc*, ag , F0 )
Tc*: Period of commencement of the tract at a constant speed in the horizontal acceleration of the
Spectrum
ag : maximum horizontal acceleration at the site
F0 : maximum value of the amplification factor of the spectrum in the horizontal acceleration
Seismic Load Parameters :
(1) Spectrum parameters
Clause 3.2 Seismic Action
Table 3-2 Topographic categories : T1, T2, T3, T4
(2) Spectral Parameters (Tc*, ag , F0 )
Tc*: Period of commencement of the tract at a constant speed in the horizontal acceleration of the
Spectrum
ag : maximum horizontal acceleration at the site
F0 : maximum value of the amplification factor of the spectrum in the horizontal acceleration
Ground Type : Soil type (A, B, C, D, E, S1 and S2)
Soil Factor (S) : Soil factor (range: S > 0)
Spectrum Parameters
Tb : Lower limit of the period of the constant spectrum acceleration branch
Tc : Upper limit of the period of the constant spectrum acceleration branch
Td : Value defining the beginning of the constant displacement response range of the spectrum
Design ground acceleration (Ag) : Design ground acceleration (range: Ag > 0)
Behavior factor (q) : Behavior factor (range: q> 0)
Lower bound factor (b) : Lower bound factor for the design spectrum (range: b> 0)
Importance Factor (I) : Importance factor (range: I > 0)
Soil Class
Basic Behavior Factor (q0)
Ductility Class (Kd)
Elevation Regularity (Kr)
Failure Mode Factor (Kw)
Ratio of Design ground acceleration to gravity acceleration (alpha)
IS1893 (2002)
Seismic Zone Factor (Z)
Soil Type
Importance Factor(I)
Damping (%)
Damping Multiplying Factor:
Damping Multiplying Factor is automatically calculated by linear interpolation based on the table shown below.
|
Damping (%) |
0 |
2 |
5 |
7 |
10 |
15 |
20 |
25 |
30 |
|
Damp |
3.20 |
1.40 |
1.00 |
0.90 |
0.80 |
0.70 |
0.60 |
0.55 |
0.50 |
1. Seismic Zone (Z)
2. Seismic Zone Related Data
[For General Zone]
- Horizontal Spectral Accel.
Short Period (Ss) : Horizontal Spectral Acceleration at short periods
1Sec Period (S1) : Horizontal Spectral Acceleration at 1 second periods
- Site Magnify Factor
Soil Type
a. Short Period (Fa) : Site Magnify Factor at short periods
b. 1Sec Period (Fv) : Site Magnify Factor at 1 second periods
- Near Fault Zone
[For Near Fault Zone]
- Near Fault Seismic Effect
[For Taipei Basin]
- Sub Zone
- Horizontal Spectral Accel.
a. Short Period (Ss) : Horizontal Spectral Acceleration at short periods
- Trans. Period: Transfer period
a. T0 : S1/Ss
3. Importance Factor (I)
4. Seismic Magnify Factor (ay)
Seismic Zone (Z)
Seismic Zone Related Data
General Zone
Horizontal Spectral Accel.
Short Period (Ss) : Horizontal Spectral Acceleration at short periods
1 Sec Period (S1) : Horizontal Spectral Acceleration at 1 second periods
Site Magnify Factor
Soil Type
Short Period (Fa) : Site Magnify Factor at short periods
1 Sec Period (Fv) : Site Magnify Factor at 1 second periods
Near Fault Zone
Horizontal Spectral Accel.
Short Period (Ss) : Horizontal Spectral Acceleration at short periods
1 Sec Period (S1) : Horizontal Spectral Acceleration at 1 second periods
Near Source Factor
Short Period (Na) : Near Source Factor at short periods
1 Sec Period (Nv) : Near Source Factor at 1 second periods
Site Magnify Factor
Soil Type
Short Period (Fa) : Site Magnify Factor at short periods
1 Sec Period (Fv) : Site Magnify Factor at 1 second periods
Taipei Basin
Sub Zone
Horizontal Spectral Accel.
Short Period (Ss) : Horizontal Spectral Acceleration at short periods
Trans. Period : Transfer period
T0 : S1/Ss
Importance Factor(I)
Seismic Magnify Factor
Seismic Zone (Z)
Soil Type
Importance Factor (I)
Seismic Magnifying Factor
Design Spectral Response Acceleration
Site Class
Effective Peak Acc. (Aa)
Effective Peak Vel. (Av)
Site Coeff. at Short Period (Fa)
Site Coeff. at 1sec. Period (Fv)
Period Coef. (Cu)
Importance Factor (I)
Phi : Reduction factor for Basic Ductility Factor(R0) (= Phi,a * Phi,p * Phi,r)
(available upon request)
Seismic Zone Factor (Z)
Soil Period (Tc)
Std. Base Shear Factor (C0)
Seismic Base Shear Distribution Factor (Ai)
Note
Ai is automatically calculated or entered by the user.
Design Spectral Response Acceleration
Seismic Zone
Site Class
Sds : Spectral response acceleration at short periods
Sd1 : Spectral response acceleration at a period of 1 sec
Seis. Use Group
City Plan Region
Importance(Ie)
Seis. Design Category
Soil Profile Type
Earthquake Zone
Importance Factor
Soil Profile Type
Earthquake Zone
Importance Factor
Seis. Fortification Intensity
Site Class
Structure Type
Damping ratio
Frequent Earthquake
Scarce Earthquake
Masonry Multistory, Framed 1st Story, Interior Frame - Exterior Masonry Structure
Near Source Category
Seis. Fortification Intensity
Site Class
Structure Type
Damping Ratio
Frequent Earthquake
Scarce Earthquake
Masonry Multistory, Framed 1st Story, Interior Frame - Exterior Masonry Structure
Seismic Load Parameters
Seismic Zone
Soil type
Importance Factor
Damping
Damping Multiplying
Structural Parameters
Enter the parameters defining the characteristics of the structure.
Period (Analysis) : Obtained by eigenvalue analysis
Approximate Period : Obtained by the Code method
Response Modification Coefficient (R)
Period (Analysis) : Obtained by eigenvalue analysis
Approximate Period : Obtained by the Code method
Response Modification Coefficient (R)
Period (Analysis) : Obtained by eigenvalue analysis
Period (Code) : Obtained by the Code method
Response Modification Coefficient (R)
Period : Periods of the structure calculated from the equation in the code
Ductility Coefficient (R) : Numerical coefficients representative of the inherent overstrength and global ductility capacity of a lateral force resisting system
Period (Analysis) : Natural periods of the structure from eigenvalue analysis
Period (Code) : Natural periods of the structure calculated from the equations in the code
Ductility Coefficient (Rw) : Numerical coefficients representative of the inherent overstrength and global ductility capacity of a lateral force resisting system.
Period (Analysis) : Natural periods of the structure from eigenvalue analysis
Period (Code) : Natural periods of the structure calculated from the equations in the code
Response Modification Coeff.
Period (Analysis) : Natural periods of the structure from eigenvalue analysis
Period (Code) : Natural periods of the structure calculated from the equations in the code
The Response Modification Factor (R)
Period Calculator... Button : Auto-calculation of periods from the code equations
N : Number of Stories
H : Height of the building
Ds : Length of the wall or braced frame which constitutes the main lateral-force-resisting system in the direction parallel to the applied forces
Note
If the main lateral-force-resisting system does not have a well-defined length then D Shall be used in lieu of Ds
D : Length of the building in a direction parallel to the applied forces
Fundamental Period
The Period Calculator... Button : Auto-calculation of periods from the code equations
H : Height of the building
Ac : Combined effective area of the shear walls in the first story of building
d : lateral displacement if the top of the building due to the gravity loads applied horizontally
Fundamental Period
The Period Calculator... Button : Auto-calculation of periods from the code equations
h : Height of the building (unit: m)
d : Width of the building in a direction parallel to the seismic load at the 1st floor
Response Reduction Factor
Analytical Period : Natural periods of the structure from Eigenvalue analysis
Approximate Period : Natural periods of the structure calculated from the equations in the code
Fundamental Period
Response Modification Factor
Analytical Period : Natural periods of the structure from Eigenvalue analysis
Approximate Period : Natural periods of the structure calculated from the equations in the code
Response Modification Factor
Period (Analysis) : Obtained by eigenvalue analysis
Approximate Period : Obtained by the Code method
Response Modification Coefficient (R)
(available upon request)
Period (T)
Period Calculator
Analytical Period : Natural periods of the structure from Eigenvalue analysis
Approximate Period : Natural periods of the structure calculated from the equations in the code
The ... Button : Auto-calculation of periods from the code equations
Fundamental Period
Response Modification Factor
Period (Analysis) : Natural periods of the structure from eigenvalue analysis
Period (Code) : Natural periods of the structure calculated from the equations in the code
The Period Calculator... Button : Auto-calculation of periods from the code equations
Response Modification Coeff.
Period (Analysis) : Natural periods of the structure from eigenvalue analysis
Period (Code) : Natural periods of the structure calculated from the equations in the code
The Period Calculator... Button : Auto-calculation of periods from the code equations
Response Modification Coeff.
Fundamental Period
The Period Calculator... Button : Auto-calculation of periods from the code equations
H : Height of the building
Bx : Width of building subjected to seismic load in the Global X-axis direction
By : Width of building subjected to seismic load in the Global Y-axis direction
n : Number of Stories
Fundamental Period
The Period Calculator... Button : Auto-calculation of periods from the code equations
H : Height of the building
Bx : Width of building subjected to seismic load in the Global X-axis direction
By : Width of building subjected to seismic load in the Global Y-axis direction
n : Number of Stories
Seismic Load Direction Factor
Enter the directions and magnitudes of the seismic loads to be applied.
Scale Factor in Global X : Scale factor in GCS X-direction
Scale Factor in Global Y : Scale factor in GCS Y-direction
Accidental Eccentricity
Assign the directions to be considered with accidental eccentricities in the structure.
If the 'None' option is selected, accidental eccentricity is not considered.
Torsional Amplification
Accidental Eccentricity : Check whether or not to apply amplification to torsion due to Accidental Eccentricity.
Inherent Eccentricity : Check whether or not to apply amplification to torsion due to the eccentricity between the center of mass and the center of stiffness of the building structure.
Additional Seismic Loads
Enter additional seismic loads that the auto-calculation does not take into account
Press the Add Button to enter the stories to apply additional seismic loads and the magnitudes for each direction.
The Seismic Load Profile... Button : Display Tables and Graphs in a spreadsheet form for each loading direction and component of the auto-calculated seismic load.
Component : Assign the seismic loading direction for a graphic display
Select Profile : Select the items to be displayed
Story Force
Story Shear
Overturning Moment
The Make Seismic Load Calc. Sheet Button : Display a spreadsheet Text Output file showing the seismic load calculation process. Text Editor is automatically executed.
The Apply Button : Apply the auto-calculated equivalent static seismic loads to the model.
Note
Refer to the relevant code for details regarding the equivalent seismic load calculation.