Loadings


Loading

In SFA, Loads can be imported from STAAD. Pro model with a superstructure or can be locally generated inside SFA. If any SFA V9 model is imported to new SFA, then also loads are imported along with other modelling data. Currently SFA supports different types of Loadings like Nodal Load and Reaction, Point Load, Line Load and Area Load) and Load types (like Dead, Live, Wind, Seismic, Surcharge etc). Features like different types of load combinations (ACI, ASCE and IS code), Load Envelope, load association etc. are also available. Loading Tab provides various options to handle loads and load combinations.

Loading Specification-

  1. Primary Load Case-

Click “Primary Load Case”, icon -> a page named “Create Load Case” would appear in place of “Properties” page. It provides four options-

  1. Load Case- Provide a name of the new Load case you want to generate. In the snap we can see a new load case named “Basement Finish” is being generated.
  2. Associated Load Case- If user needs to associate this load case with any other existing load case type, then select that load case from dropdown list at right side. A newly created load case can be associated with an imported load case (one defined in a STAAD. Pro or SFA v9 file). If load combinations are present in the imported model, then after association, the program will create a new load combination that includes the newly created load case together with the same load factor as the associated load case (with its associated load factor).
  3.  
In current snap we can see four existing load cases are available, among them, Dead load is being selected, so that this new load case would be associated with dead load.
Suppose this model already have five combinations-

f1A Dead Load + f2A Live Load
f1B Dead Load + f2B Live Load + f2B Wind Load X
f1C Dead Load + f2C Live Load - f2C Wind Load X
f1D Dead Load + f2D Live Load + f2D Wind Load Z
f1E Dead Load + f2E Live Load - f2E Wind Load Z
(f1A to f2E are load factors for respective load cases for respective combinations.)
Picture 2, Picture
So, after generation of Basement Finish, associated with Dead Load, the combination would be as follows-
f1A Dead Load + f1A x f x Basement Finish + f2A Live Load
f1B Dead Load + f1B x f x  Basement Finish + f2B Live Load + f2B Wind Load X
f1C Dead Load + f1C x f x  Basement Finish + f2C Live Load - f2C Wind Load X
f1D Dead Load + f1D x f x Basement Finish + f2D Live Load + f2D Wind Load Z
f1E Dead Load + f1E x f x Basement Finish + f2E Live Load - f2E Wind Load Z
  (f = associated Load Factor)
If no association is required, keep “None”.

iii. Load Type- Select “Load Type” from drop down list. Currently available Load Types are-

  1. Dead
  2. Live
  3. Wind
  4. Seismic Horizontal
  5. Seismic Vertical
  6. Reducible Live
  7. Reducible Roof Live
  8. Fluid
  9. Roof Live
  10. Snow
  11. Soil
  12. Rain
  13. Dust
  14. Traffic
  15. Temperature
  16. Imperfection
  17. Accidental
  18. Flood
  19. Ice
  20. Crane
  21. Mass
  22. Gravity
  23. Earth Pressure
  24. Permanent Surcharge
  25. Temporary Surcharge
  26. Hydrostatic Lateral
  27. Hydrostatic Vertical
  28. Wind on Ice

iv. Associated Load Factor- By default it remains 1.

You can specify the load factor of a newly created load case and associate the newly created load case with the imported load case by means of an Associated Load Factor.
Suppose two load cases ‘DL’ and ‘LL’ and a combination ‘100: 1.2 DL + 1.6 LL’ are imported into SFA.
A new load case named ‘Soil’ is required in SFA and to be associated with DL, with the Associated Load Factor specified as 1.3.

When you click “Create” a new load case named ‘Soil’ will be created with the combination ASL_100: 1.2 DL + 1.6 LL + 1.56 Soil.
The load factor for the newly created load case equals the Associated Load Factor multiplied by the load factor of associated load case, i.e., 1.3 x 1.2 = 1.56.
Press “Create” button to finalize new load case creation.

 

View and Edit Load Cases through Project explorer-

Click Project-> Physical Model-> Loads-> select respective Load case and a page named “Properties- Load Case” would appear in place of “Properties” page showing the details. Here user can edit Name, Association and Association Load Factor. Here A load case named “Test Load Case” is selected in project explorer and “Properties” window is showing its’ details.

a. Load Combination-

Load combinations can be imported from SFA V9 or STAAD Pro model and can be generated inside SFA.
Importing Load Combinations from STAAD. Pro/SFA V9-
When you import an SFA v9/ STAAD. Pro model into SFA, the program automatically imports all the load combinations. You can select the load combinations to import.

Use “Load Combination” button under “Loading” tab for generation of new load combinations.

Click “Load Combination”, two options would be expanded- Manual and Auto. In Manual, you can generate combinations one by one, whatever you want. In Auto, different country code and version wise templates are available which can be used to generate all necessary combinations in one shot.

Manual- Click “Load Combination” -> “Manual”. a page named “Create Load Combination- Manual” would appear in place of “Properties” page. It provides four options-

  1. Name- Provide a name of the new combination. In the snap a new combination is being generated, with a name Load Combination1
  2. Type- Click “Select” button beside “Type”. A page would pop up. Select the type as Service or ultimate through tick button. Click “OK” to finalize load combination type selection.
  3. Combination Stage- It remains pre analysis and non-editable now.
  4. Load Cases- Here the combination factors and load cases are being managed. Click “Select’ beside “Load Cases”.  A new page named “Component” would pop up. Select the load types you want to include in this load combination and provide respective Factors at “Factor” column. If the tick box beside “Select” is ticked, then all load cases would be selected. Default Factor remains 1.

Currently in the snap we can see one load combination is being generated as 1.4 Dead Load + 1.6 Live Load.

Click “Create” to finish execution.

  1. Auto Generate- Use this button to create code specified combination bunch in a single shot.

Click “Load Combination” -> “Auto Generate”. a page named “Create Load Combination - Auto” would appear in place of “Properties” page. It provides two options-

  1. Code- Select the relevant code and version from drop down list. Currently SFA is providing ACI 318-14 , ACI 318-19 , ASCE7-19 and IS 456-2000.

 

  1. Generate – Click “Select” option beside “Generate” to pop up a new page for generation of the combinations. Clicking “Select”, a new page pops up named as “Load Combination Generator”. The feature is little different for ACI and non ACI. In non ACI (ASCE and IS) only two rows are available at upper part- Purpose of two rows are to generate service and ultimate combinations in a single shot. Tick the option at left to activate. Now you can select service or ultimate from “Type column”. At right end column (Prefix Column) the prefix syntax can be added. By default, service prefix remains SLS and ultimate prefix remains ULS.  For ACI, four rows would be available in place of two. The reason is , factored and unfactored concept in ACI. User may go with two factors combinations (one service and one ultimate) or two unfactored combinations as per design requirements.

After selection of type and category, click generate to get the load combinations generated as per the category and type. They would be displayed at lower portion of this page. Hit “Apply” button to add them in project. This pop-up page would go away. Now, hit “Create” button at “Create Load Combination- Auto” page to apply those combinations on the model.

 

The snap above shows Service load combinations are generated for ASCE 7 through auto generation option.

View and Edit Load Combinations through Project explorer- Click Project-> Physical Model-> Loads-> select respective Load combination case and a page named “Properties- Load Case” would appear in place of “Properties” page showing the details. Here user can edit Name, Type and Arrangement (Load cases and respective factors).

  1. Custom Load Envelope-

General Idea of Load Envelope-A load envelope is the packet, holding same type of load combinations such as service or ultimate. By default, the program creates two types of load envelopes, ‘Service’ and ‘Ultimate’. If the dead load factor of a load case which is part of a load combination is a value other than '1’, then the program assigns it to a load envelope of type ‘Ultimate’. If the dead load factor is ‘1’ then the program assigns it to a load envelope of type ‘Service’. You can change the load envelope assigned to the load combination if desired. A load combination will be assigned as either a ‘Service’ or ‘Ultimate’ load envelope. As per the load envelope type assigned to load combinations, the program will consider it for the respective checks (service or ultimate limit state).

 

You can create your own load envelope type using “Custom Load Envelope”. Click “Custom Load Envelope” to display the “Create Custom Load Envelope” window. Now input Envelope Type and Description. Click at “Select” at the Load Combinations field to display the Load Combinations window. Select the load combinations to include in this load envelope. Click “OK” and then the “Create” button in the “Create Custom Load Envelope” window. The load combinations selected in “Custom Load Envelope” can be used for both service and ultimate checks. The figures show the generation of an envelope with all service load combinations available. 101-111 are service combinations, they are selected and included in an envelope named All Service.

 

Loading Association-

This Helps user to quickly edit load case type and combination type.

  1. Load Case Type- Click “Load Case Type” and “Associate Load Case Type” page would pop up. User may change the loadcase type for each existing load cases available using this form. For any existing load, expand the drop-down list and reassign a new appropriate load case type.

Click “Apply” button to execute.

 

  1. Envelope Type- This option helps user to change the load combination type (Switch between service and Ultimate). Click “Envelope Type” and “Associate Load Combination Type” page would pop up. This page gives option to switch between service and ultimate type for each available load combination.

Load Generation-

This option gives the facility to assign overburden soil on a footing. Select the respective footing and click “Assign Soil Overburden” icon. “Assign Soil Overburden” page would appear in place of “Properties” page. Select the soil type you want to assign on this footing from drop down list. In the picture below, we can see the following snap, that three soil types are available, among them SP1 is being selected. Click “Assign” to execute the assignment process.

 

Three available options are for creating and assignment of three types of loadings- Contact Area Load, Line Load and Area Load.

Contact Area Load- This is a point load applied on a small area.

  1. Create-Click Loading > Contact Area Loads then the “Create” button to display the “Add Contact Area Load” window. Select the load type from drop down list under which this loading is going to be placed. Enter Fx, Fy, Fz, Mx, My and Mz. This is a concentrated load applied to a small area. The Contact Area Length and Contact Area Breadth parameters are the dimensions of that area. You can also rotate the area by changing the angle from zero degrees to any value in the Contact Area Orientation field. Click “Create” to generate the loading.

 

b) Assign- Click “Assign” icon to get three options- Assign by Point, Assign by Object and Assign by Table. Now, only the first option is active for contact area load. Click “Assign by Point” and “Assign Contact Area Load” page would appear in place of “Properties” Window. Either select a point on a footing by mouse click or provide coordinates to “Assign Contact Area Load” page. Select the appropriate load case from drop down list and select available contact area load associated with that load case from “Load Item” drop down list. Click “Assign” to execute. If assignment is done through mouse click, then SFA automatically updates coordinates in “Assign Contact Area Load” page.

Line Loads-

  1. Create-Click Loading > Line Loads and then the “Create” button to display the “Add Line Load” window. Select the load case from drop down (as shown in the snap below, loadcase S11 is being selected) , under which this loading is going to be added. Enter the value of the uniformly distributed load. Click “Create” to execute the operation.

  1. Assignment- Line load can be assigned in three different ways, By Line, By Circle or By polygon.

 

  1. By Line- click Loading > Line Loads and then the” Assign” button to display above three options. Click “By Line” icon to display “Assign Line Load” window. Select the load case and the line load from Load Item, by expanding drop down icons (as shown in the snap below, Load case S11 is selected and load item LL3 is picked up), then enter the coordinates of the start and end points of the line on the mat on which the load is to be applied. You may also select two points on the mat by mouse click to draw a line, and the start and end coordinates will be automatically updated. Now click the “Assign” button to finish the assignment.

 

Alternatively, in the Project Explorer tree, select the line load you want to assign to open the “Properties- Line Load” window. Click “New” > “Assign” to display the “Assign Line Load” window. Select “Assign by Line” radio button. There are two ways to assign the load: you can either select the start and end points of the line on the mat or enter the start and end point coordinates in the table available. If you graphically pick up start and end points, then the coordinates will also be automatically updated by the program. Click “Assign” to apply the load along the desired line. If a construction line is present in a file, then the last option (Assign to Construction Objects) will be enabled. Click this option first, then the construction line on the schematic followed by the “Assign” button to assign the line load to the construction line.

  1. By Circle- click Loading > Line Loads and then the” Assign” button to display above three options. Click “By Circle” icon to display “Assign Line Load” window. Select the load case and the line load from Load Item, by expanding drop down icons, then enter the coordinates of the centre and enter the diameter and no of facets of the circular line. You may also select centre point on the mat by mouse, and the coordinates will be automatically updated. Now click the “Assign” button to finish the assignment.

 

Alternatively, in the Project Explorer tree, select the line load you want to assign to open the “Properties- Line Load” window. Then click “New” > “Assign” > Select “Assign by Circle” radio button,  to display the “Assign Line Load” window. There are two ways to assign the load: you can either select the centre on the mat or enter the coordinates in the table available. If you graphically pick up centre point, then the coordinates will also be automatically updated by the program. Provide diameter of the circle and no of facets in the form. Click “Assign” to apply the load along the desired line.

 

  1. By Polygon- click Loading > Line Loads and then the” Assign” button to display above three options. Click “By Polygon” icon to display “Assign Line Load” window. Select the load case and the line load from Load Item, by expanding drop down icons then enter the coordinates of the lines of the polygon and hit enter after input of each node.  Node list would be automatically updated by SFA. Otherwise, you can pick up the points on the mat by mouse click and the coordinates and node list will be automatically updated. Now click the “Assign” button to finish the assignment.

 

Alternatively, in the Project Explorer tree, select the line load you want to assign to open the “Properties- Line Load” window. Then click New > Assign  > Select “Assign by Polygon” radio button, to display the “Assign line Load” window. The next process is same as above.

Area Loads-

  1. Create- Click Loading > Area Loads and then then the “Create” button to display the “Add Area Load”. Select the load case from drop down menu and enter the area load. Click “Create” to execute the operation.

 

  1. Assign- Area load can be assigned in four ways—By Polygon, By Circle, By Object and By Table.

 

  1. By Polygon- click Loading > Area Loads and then the” Assign” button to display above four options. Click “By Polygon” icon to display “Assign Area Load” window. Select the load case and the line load from Load Item; by expanding drop down icons then enter the coordinates of the nodes of the polygon and hit enter after input of each node.  Node list would be automatically updated by SFA. Otherwise, you can pick up the points on the mat by mouse click and the coordinates and node list will be automatically updated (Please refer the snap below). Now click the “Assign” button to finish the assignment.

 

  1. By Circle- click Loading > Area Loads and then the” Assign” button to display above four options. Click “By Circle” icon to display “Assign Area Load” window. Select the load case and the Area load from Load Item, by expanding drop down icons, then enter the coordinates of the centre and enter the diameter and no of facets of the circular line covering the circular area. You may also select centre point on the mat by mouse, and the coordinates will be automatically updated. Now click the “Assign” button to finish the assignment.

 

  1. By Object - Click the “By Object” button to display the “Assign Area Load” window, select the load case and load item then the object (mat/region) in the schematic. If regions are modelled in the mat, you can exclude some of them. When your selection is final, click “Assign” to execute the assignment. The objects already selected are shown in “Selected Object(s)”. If you want to exclude some (just like want to include a mat but want to exclude the regions), click “Select” beside “Exclude Entities” and exclude sub objects by selecting them graphically.

Excluding Objects-

To exclude one or more objects before assignment, click “Select” beside Exclude Entities field. A window opens with a list of all the entities that can be excluded. Check or uncheck per requirements and click OK. Then click the Assign button to complete the assignment.

  1. By Table- Click the “By Table” button to display the Table of Vertices to “Create Area” window, select the load case and load item and enter the coordinates of the vertices of a closed polygon in the table. You can add more rows by pressing down arrow key. When your input is final, click “Assign” to execute the assignment.

 

Assignment of Area Load from Project Explorer-As in contact area loads and line loads, area loads can also be assigned from Project Explorer in the same manner. Click the area load in the Project Explorer tree to open the Properties-Pressure Load window, then click Assignments > New > Assign to open the Assign Area Load window with five options- Assignment by Polygon, by Circle, by Object, by Table and by Construction Object. The downstream process is already explained above.

 

View-

View gives only one option- “Hide Loads” If any load is already displayed in view area and user don’t want to keep the loads in display, just click “Hide Loads” icon to hide all Loads.

Tables-

Click “Tables” icon to expand a list of two items- Load case and Load Combination. Tick or untick to activate the respective tables on your screen.