CELE Structural Theory & Analysis — Loads and Load Combinations (NSCP)Concept Map

Concept

Load Types

Sub Concepts

• Dead Load (D)
• Live Load (L)
• Roof Live Load (Lr)
• Wind Load (W)
• Earthquake Load (E)
• Rain Load (R)

Relationship To Central

Foundation — identifies what forces act on structures

Concept

Load Distribution

Sub Concepts

• Tributary Area
• Tributary Width
• Line Load Calculation
• Axial Load Calculation

Relationship To Central

Method — converts area loads to member forces

Concept

LRFD Design Philosophy

Sub Concepts

• Gravity Combinations
• Wind/Seismic Combinations
• Uplift Combinations
• Resistance Factor φ

Relationship To Central

Primary approach — ultimate strength with load factors

Concept

ASD Design Philosophy

Sub Concepts

• Service Load Combinations
• Wind/Seismic Combinations
• Safety Factor Method
• Companion Live Load Factor f₁

Relationship To Central

Alternative approach — allowable stress with reduction factors

Concept

Code Provisions

Sub Concepts

• Load Case Selection
• Factor Application
• Minimum Load Values
• Occupancy Classification

Relationship To Central

Regulatory framework — NSCP 2015 requirements

Concept

Application & Analysis

Sub Concepts

• Beam Design Loads
• Column Axial Loads
• Design Moment Calculation
• Governing Combination Selection

Relationship To Central

Execution — determination of design loads for members

To

Load Distribution

From

Load Types

Strength

strong

Relationship

Load types (D, L, W, E) are the inputs; distribution (tributary area) routes them to members

To

LRFD Design Philosophy

From

Load Distribution

Strength

strong

Relationship

Distributed member loads are factored using LRFD multipliers to obtain ultimate design forces

To

ASD Design Philosophy

From

Load Distribution

Strength

strong

Relationship

Distributed member loads remain at service level and are combined per ASD rules

To

Calculation Methods

From

LRFD Design Philosophy

Strength

strong

Relationship

LRFD factored loads are used to compute design moment, shear, and axial forces (Mu, Vu, Pu)

To

Calculation Methods

From

ASD Design Philosophy

Strength

strong

Relationship

ASD service loads are used to compute service moment, shear, and axial forces (M, V, P)

To

Code Provisions

From

Calculation Methods

Strength

strong

Relationship

Design forces are checked against NSCP 2015 member strength (LRFD) or allowable stress (ASD)

To

ASD Design Philosophy

From

LRFD Design Philosophy

Strength

moderate

Relationship

Both are acceptable; must be chosen at project start and applied consistently; LRFD is preferred in modern practice

To

Load Types

From

Code Provisions

Strength

moderate

Relationship

NSCP 2015 tabulates minimum load values (kPa) for each occupancy type (residential, commercial, educational, etc.)

To

Line Load Calculation

From

Tributary Area Concept

Strength

strong

Relationship

Tributary width is the spacing between adjacent beams; multiplied by slab load (kPa) to get line load (kN/m)

To

Axial Load Calculation

From

Tributary Area Concept

Strength

strong

Relationship

Tributary area is the region closer to a column than to adjacent columns; multiplied by slab load to get column axial load (kN)

To

Gravity Combinations

From

Load Factors

Strength

strong

Relationship

Factors 1.2 on D and 1.6 on L are applied in the primary LRFD gravity combo 1.2D + 1.6L

To

Uplift Combos

From

Load Factors

Strength

moderate

Relationship

The 0.9 factor on D in combos 0.9D + 1.0W and 0.9D + 1.0E captures uplift/overturning when dead load resists lateral forces

To

Wind & Seismic (LRFD)

From

Wind Load W

Strength

strong

Relationship

Wind load W is factored by 1.0 in combo 1.2D + 1.0W + 1.0L; also appears in uplift combo 0.9D + 1.0W

To

Wind & Seismic (LRFD)

From

Earthquake Load E

Strength

strong

Relationship

Seismic load E is factored by 1.0 in combo 1.2D + 1.0E + 1.0L; critical in seismic PH; also in uplift combo 0.9D + 1.0E

To

Load Types

From

NSCP 2015 Requirements

Strength

strong

Relationship

NSCP Section 202 defines load categories and minimum values for D, L, Lr, W, E, R based on occupancy and location

To

Calculation Methods

From

Design Philosophy Selection

Strength

strong

Relationship

Choice of LRFD or ASD determines how loads are factored and how forces are calculated and compared to capacity

To

Design Moment Calculation

From

Simply Supported Beam

Strength

strong

Relationship

For a simply supported beam of span L under UDL w, the maximum moment is M = wL²/8; basis for many exam problems

To

Multi-Story Stacking

From

Column Axial Load

Strength

moderate

Relationship

Column loads accumulate from story to story; roof column carries roof + one floor; lower columns carry more stories

To

Load Types

From

Occupancy Classification

Strength

strong

Relationship

Occupancy type (residential, office, assembly, etc.) determines the minimum live load L to be applied per NSCP Table

To

ASD Design Philosophy

From

Companion Live Load Factor f₁

Strength

moderate

Relationship

In ASD, f₁ = 1.0 for assembly/garage or L > 4.8 kPa; f₁ = 0.5 for residential/office; reduces combined-load combos to account for low probability of simultaneous max occupancy and wind/seismic