Loads

Loads can be defined and applied to the model graphically or from within the spreadsheets. There are a number of different Load Types that may used when loading the model. For more information about the application of each Load Type (Deck Load, Area Load, Line Load, and Point Load), see Loads - Load Types.

As you define the loads in the model, you will notice that each Load Type (deck load, area load, line load, and point load) is broken down into several pre-defined Load Cases such as pre-composite dead load, post-composite dead load, non-reducible live load, reducible live load, and such. These 'Load Cases' are the building blocks upon which the more general Load Categories are based. Please note that these 'Load Cases' are automatically assigned to 'Load Categories'. You will then use these Load Categories to define the various Load Combinations that you wish to solve. See Loads - Load Combinations for more information.

You may view the loads on your model for each load category or load combination. This is an excellent way to verify the loads applied to the model. See Model Display Options – Loads to learn more about displaying loads in model views.

Self Weight (Gravity Load)

The Self Weight of beams, columns, and walls is automatically calculated and included as part of the Pre-Composite Dead Load Category (DLPre). The Deck/Slab Self Weight, is likewise calculated. However, to give users more control over this value, the calculation is reported on the Loads tab of the Deck Definitions Spreadsheet and may be adjusted using the SuperDL load entry given on that same spreadsheet. See Deck Properties - Loads for more information.

The 'Self Weight' is applied as a uniform distributed load along each beam, column, or wall and as an area load for the deck/slab. The magnitude of the beam and column loads is the cross sectional area times the material weight density. The magnitude of the wall load is wall thickness times the height of the wall times material density.

Load Cases

As you apply your loads, you will notice that each load is broken down into several pre-defined Load Cases such as pre-composite dead load, post-composite dead load, non-reducible live load, and reducible live load. These loads are the building blocks of the loads applied to the structure upon which the more general Load Categories and Load Combinations will be based.

Point Loads, Line Loads, and Area Loads are applied using the following possible Load Cases:

Load Case	Abbreviation	Description
Self Weight	SW	Weight of Columns, Beams, Walls. Calculated based on Density defined in Materials spreadsheet.
Pre-composite Dead Load	PreDL	Superimposed Dead Load existing prior to concrete deck hardening.
Post-composite Dead Load	PostDL	Superimposed Dead Load existing after concrete deck hardening.
Live Loads	LL-Non	Non-Reducible Live Load
	LL-Reduce	Reducible Live Load
	LLS-Non	Non-Reducible Live Load for garages, public assembly areas, live load magnitudes > 100psf
	LLS-Reduce	Reducible Live Load for garages, public assembly areas, live load magnitudes > 100psf
	RLL-Non	Non-Reducible Roof Live Load
	RLL-Reduce	Reducible Roof Live Load
	SL	Snow Load
	SLN	Non-Shedding Snow Load
	RL	Rain Load
Other Loads	OL1	Other Load 1
	OL2	Other Load 2
	OL3	Other Load 3
	OL4	Other Load 4
Dynamic	Dyn Mass	Seismically Participating Load (for RISA-3D seismic weight calculations). This number should typically be greater than or equal to PostDL.
Vibration Live Load	VL	Realistic Live Load (for floor vibration checks). Often much less than live load for strength design (LL).

The 'Loads Cases' that are specific to decks or slabs are defined within the Deck Definitions Spreadsheet. These load cases are described in the table below:

Load Case	Abbreviation	Description
Deck / Slab	Deck SW	Deck or Slab Self Weight (auto-calculated based on Deck Material Type)
Construction Dead Load	Const DL	Comparable to PreDL, but a property of the deck instead of an applied load.
Construction Live Load	Const LL	Live load present prior to concrete deck hardening.
Superimposed Dead Load	Super DL	Comparable to PostDL, but a property of the deck instead of an applied load. Often used to account for flooring materials, fireproofing.

Load Categories

The 'Load Cases' listed above are automatically assigned to one or more of the Load Categories described below. At solution time, the model will be solved against Load Combinations that are built from the following Load Categories. The load categories and descriptions below are based on the definitions and load combinations listed in various building codes.

Load Category	Includes Addition of Load Cases	Sloped Members Load Direction
DLPre	SW + Deck SW + Const DL + PreDL+ Super DL	Y
LLConst	Const LL	PY
DLConst	Const DL	Y
DL	SW + Deck SW + PreDL + PostDL+ Super DL	Y
LL	LL-Non + LL-Reduce	PY
LLS	LLS-Non + LLS-Reduce	PY
RLL	RLL-Non + RLL-Reduce	PY
SL	SL	PY
SLN	SLN	PY
RL	RL	PY
OL1	OL1	Y,PY,y
OL2	OL2	Y,PY,y
OL3	OL3	Y,PY,y
OL4	OL4	Y,PY,y

Modifying Loads

Modifying point loads, line loads, and tapered area loads can be done from within their respective spreadsheets. Typically, the modification of load geometry and magnitude may be performed in this way. Select Loads from the Spreadsheets Menu and then choose the spreadsheet that you wish to modify. You may then move through different Floors using the drop down list in the spreadsheet.You may use spreadsheet operations to help you modify the loads. See Spreadsheet Operations for more information.

Modifying area loads (non-tapered) can be done graphically. Click the Draw Area Loads tool from the Drawing Toolbar and select the Modify Area Loads tab.

Deleting Loads

Deleting loads may be done manually within the spreadsheets or graphically using the Delete

button on the Drawing Toolbar. Select Loads from the Spreadsheets Menu and then choose the spreadsheet that you wish to modify or delete. You may then move through different Floors using the drop down list on the in the spreadsheet. You may use spreadsheet operations to help you modify or delete the loads. See Spreadsheet Operations for more information.

Load Direction

The load direction indicates how the distributed loads are applied to the sloped members.

Keep in mind that global loads are applied without being modified for projection. For example, a full length Y direction load of 1 kip/foot applied to a 10 foot member inclined at 45 degrees generates a total force of 10 kips. Projected loads, on the other hand, are applied in the global directions but their actual magnitude is influenced by the member's orientation. The load is applied to the "projection" of the member perpendicular to the direction of the load. For example, a "PY" direction load is a projected load applied in the global Y direction. The actual magnitude of the load is the user entered magnitudes reduced by the ratio L/Projected length.

So the total load generated is equal to the input magnitudes applied along the projected length. This generated force is distributed along the full member length, so the applied magnitudes are reduced accordingly.

Y-	Loads applied in the global Y-axis
PY-	Projected load in the global Y-axis
y-	Load applied in the local y-axis