[Load] Tab > [Lateral] > [Wind Load] > [Wind Load Function]

Wind Load Function

< Define Arrangement of Rebar Dialog >

Defined wind load can be reviewed as actual wind pressure acting on the structure.

Function Name : Enter the name of wind load function.

Design Wind Load :  Define and select wind load to be applied through the dialog which can be accessed through .

Equation : User can create function to calculate wind pressure. Function of height(variable) is used and z values are inputted.

User defined function 5*z, Inc : 1 will output following function. Wind Pressure along the height and graph can be checked.

Wind Pressure Tab per direction : Check wind pressure on windward side of X and Y direction wind load.

Other Wind Pressure Table : Wind pressure and internal pressure of leeward, side windward roof and leeward roof can be checked.

Wind Pressure Graph : Windward wind pressure along the height can be checked by the graph and corresponding wind pressure can be shown in Tag if graph is clicked.

Design Wind Load

Calculate wind load/pressure factors according to wind load code and height of structure to apply wind load, basic wind speed and structure type.

Mutual Clause

Name : Enter the name of wind load.

Design Code : Select wind load design code. Following wind load standards are supported by midas nGen.

ASCE 7-10 (IBC 2012) : US, International Building Code 2012

ASCE 7-05 (IBC 2009) : US,  International  Building Code 2009

UBC 1997 : US, UBC 97 standards

EN 1991 : 2005 : Europe, Basis of Design and Actions on Structures

KBC 2009 : KR, Korea Building Code 2009

Range(Z) : Define the height from the ground. Define the height of wind load function to be generated. This is used for calculation of wind pressure in accordance of windward height. If EN 1991 : 2005 code is used, Z value will be used for calculation of wind pressure of windward, leeward and side.

Although the actual height of structure is lower than defined height, corresponding wind pressure of the structure height will be automatically applied. If actual height of structure is lower than defined Z value, wind pressure at maximum Z value will be applied to the structure over height Z.

Average Roof Height (H) : Enter the average roof height. If not defined, maximum Z value is applied and it is used in calculation of windpressure at leeward, side and roof. H value is used to calculate internal pressure and wind pressure at roof when EN 1991 : 2005 code is used.

KBC 2009

< Design Wind Load Dialog - KBC 2009 Standards >

Design Wind Speed

Enter the variables to calculate design wind speed.

Basic Wind Speed

Exposure Category

Importance Factor

Topographic Factor

Gust Factor and Pressure Coefficient

Enter the variables to calculate gust factor and wind pressure.

Structure : Select structure type

(Partial) Enclosed

Opened or Others

Rigid : Rigid structure with natural frequency over 1Hz.

Flexible : Rigid structure with natural frequency below 1Hz.

Internal : Check to consider internal pressure factor.

 Roof : Check to wind pressure at roof separately.

Auto Calculate by Structure Information : Variables can be inputted to calculate Wind pressure factor and wind load factor.

Structure Information – Opened or ETC Type

< Structure Information Dialog when Opened or ETC-Opened Sturture is selected >

< Structure Information Dialog when Opened or ETC-Chimney, Tank and Similar is selected >

< Structure Information Dialog when Opened or ETC-Truss Tower is selected >

Structure Information

Structure type : If 'Opened or Others' type is selected from Design Wind Load dialog, then select detail type of structure

Opened Structure

Chimney, Tank and Similar

Truss Tower

Breadth : Enter breadth of building to calculate gust factor.

a : Length of structure in a+90-direction (length of surface which is subject to a-direction wind load).

a+90 : Length of structure in a-direction (length of surface which is subject to a+90-direction wind load).

Cross Section : If structure type is chimney, tank and similar type, select section shape as subsection. (Refer to Table 0305.7.4)

Square (Wind normal to face)

Square (Wind along diagonal)

Hexagonal or Octagonal

Round (Moderately Smooth)

Round (Rough)

Round (Very Rough)

Circle

Plane Type : Select plane type if Structure Type is defined as Truss Type.

Square (Steel Pipe) : Select if plane of truss tower is rectangle and formed with steel members.

Square (Rectangle) : Select if plane of truss tower is rectangle and formed with rectangle sections.

Square (Other Type) : Select if plane of truss tower is rectangle and formed with other members.

Triangle (Steel Pipe) : Select if plane of truss tower is triangle and formed with steel members.

Triangle (Rectangle) : Select if plane of truss tower is triangle and formed with rectangle sections.

Triangle (Other Type) : Select if plane of truss tower is triangle and formed with other members.

Solid Area / Gross Area : Fidelity Factor, ratio of actual area facing the wind to the gross area, fidelity ratio

a : Fidelity ratio in a-direction of wind load

a+90 : Fidelity ratio in a+90 direction of wind load

Structure Information – (Partial) Enclosed Type

<  Structure Information Dialog when (Partial) Enclosed is selected >

Structure Information

Breadth : Enter breadth of building to calculate gust factor.

a : Length of structure in a+90-direction.

a+90 : Length of structure in a-direction.

Roof Information

Wind Dir

Parallel to Wind Direction

Normal to Wind Direction

Slope Angle

Loading Width : Check to define Loading Width of wind load manually.

Internal Pressure

Enclosure : Type of enclosure

Enclosed

Partially Opened

Excellent Opening

Structure Information – Flexible Structure

<Structure Information Dialog when Flexible is selected>

Flexible Structure

If 'Flexible' is selected from Design Wind Load dialog, Natural Frequency and Damping Ratio can be defined in Structure Information dialog.

Natural Frequency(Hz)

a : Natural frequency of structure in a-direction.

a+90 : Natural frequency of structure in a+90-direction.

Damping Ratio

ASCE 7-10 (IBC 2012), ASCE 7-05 (IBC 2009)

< Design Wind Load Dialog as per ASCE7-10 >

Design Wind Speed

Enter variables to calculate design wind speed.

Basic Wind Speed

Exposure Category

Directionality : Apply 0.85 as default value.

Topographic Effects

Enter the variables to calculate toropraphic coefficient.

Hill Shape : Refer to Figure 6-4, ASCE 7-10.

2-D Rigid or Valley

2-D Escarpment

3-D Axisym. Hill

Building Location

Upwind : Select if building is located at upwind direction.

Downwind : Select if building is located at downwind direction.

Hill Height

Hill Length

Crest-Building Distance : Distance between crest and building.

Minimum Load

Select to apply minimum wind load.

UBC 1997

< Design Wind Load Dialog as per UBC 1997 >

Common Parameters

Basic Wind Speed

Exposure Category

Importance Factor

Pressure Coefficients

Structure : Select structure type and click 'Auto Calculation of Pressure Coefficient' to obtain wind load/pressure factors automatically.

Primary frames and systems

Primary Partially Enclosed frames

Chimneys, tanks and solid towers (Square or Rectangular)

Chimneys, tanks and solid towers (Hexagonal or octagonal)

Chimneys, tanks and solid towers (Round or elliptical)  

Open-frame towers (Square-Diagonal)  

Open-frame towers (Square-Normal)

Open-frame towers (Triangle)

EN 1991 : 2005

< Design Wind Load Dialog as per UBC 1997 >

< Design Wind Load Dialog as per EN1991:2005 >

Common Parameters

Terrain Category

Basic Wind Speed

Directional Factor

Seasonal Factor

Turbulence Factor

Default values are set as recommended values. Please refer to design standards to apply precise factors.  

Orographic Effects

Orographic Factors

Orography Category

Cliff or Escarpment

Hills or Ridges

Building Location

Upwind : Select if building is located at upwind direction.

Downwind : Select if building is located at downwind direction.

Height of Topographic Feature

Length of Upwind Slope : Length of slop (in upwind direction).

Length of Downwind Slope : Length of slop (in downwind direction).

Crest Building Distance : Distance between crest and building.

Effects of Neighboring High-rise Structures

Enter the variables to calculate change in wind speed due to neighboring high-rise structures.  (Please refer to Annex A.4)

Avg. Height of Nearby Structures

Distance to the High-Rise:

Feature of the Neighboring High-rise Structure

Larger Horizontal Dimension

Height

Raising of Displacement Height

Enter the variables to calculate change in wind speed due to densely packed structures and obstacles in neighborhood

(Please refer to Annex A.5)

Obstruction Height

Upwind Spacing

Raising of Displacement Height option can be selected if Terrain category is defined as Ⅳ.

Structure Factor

Structural Factor(CsCd)

Input Parameters for Structural Factor

Along Wind Breadth

Along Wind Depth

Along Wind Natural Frequency

Logarithmic Decrement of Damping : Enter 'Logarithmic Decrement of Damping' the click Calculate to obtain structural factor. (refer to Annex B)

Pressure and Force Coefficient

Check the results which took into account wind pressure and force coefficients.

Please refer to corresponding design standards for detail information of wind load calculation.

Click 'Report' to obtain wind load report.