Wall Analysis (LRFD)

How it calculates

Wall Analysis (LRFD) shows how the loads on top of a wall reach the members below it. The wall is modeled in-plane as a member spanning along its length. Every load is factored with ASCE 7 LRFD strength combinations, and the factored reaction at each support is reported.

Structural model

The wall is analyzed along its total length L, using the beam solver that also runs Beam Analysis with Load Combinations. You enter an in-plane bending stiffness EI and an axial stiffness EA for the wall. Supports sit along the bottom of the wall in two forms:

• Supporting members perpendicular to the wall, such as floor joists. Enter each location and support type (fixed, pinned, roller or rotation), or generate them from a first location and a spacing.
• Continuous supports parallel to the wall, such as a beam, a lintel or another wall directly below. Each runs between a start and end location as an axial spring, lateral spring, rigid pin or rigid roller.

Auto-generated supports cannot be combined with continuous supports in the same calculation.

Loads at the top of the wall

Loads are entered as unfactored values at any position along the wall:

• Distributed loads in psf, multiplied by a start and end tributary width to give a line load
• Line loads in plf, constant or varying along their length
• Point loads as vertical loads, and moment loads

A rectangular wall adds its self-weight as a dead load: self-weight per area times wall height. Openings split that self-weight along the wall. A door carries no self-weight, and a window carries the wall below it plus the window self-weight per area. A gable wall instead adds a triangular self-weight that peaks at the ridge.

Eight presets cover interior and exterior walls on lower and top floors, walls under lintels, railings and gable walls. Each preset takes the wall height from your project defaults.

Load types

Each load carries magnitudes by type: dead (D), live (L), roof live (Lr), snow (S), rain (R), wind down (W,dn), wind up (W,up), vertical earthquake (Ev) and horizontal earthquake (Eh). Wind is entered at strength level. Under IBC 2012 to 2018, the calculator flags distributed roof live loads over 20 psf. These should be entered as live load instead.

LRFD load combinations

By default the calculator runs these 16 strength combinations, read from your project defaults:

• 1.4D
• 1.2D + 1.6L + 0.5Lr, with S or R in place of Lr
• 1.2D + 1.6Lr + f1L and 1.2D + 1.6Lr + 0.5W (down), with S or R in place of Lr
• 1.2D + 1.0W + f1L + 0.5Lr (wind down), with S or R in place of Lr
• 1.2D + 1.0Ev + 1.0Eh + f1L + 0.2S
• 0.9D + 1.0W (up)
• 0.9D - 1.0Ev + 1.0Eh

You choose whether the reduced companion live load applies. If it does, f1 = 0.5; otherwise f1 = 1.0, the default. Wall self-weight is a dead load, so it enters every combination. Serviceability cases (L + Lr, S, and 0.42W down or up) and a long-term case can be graphed for review.

Reaction outputs

• Ru - the maximum bearing demand, with the load combination that governs it
• Support demands - the position and reaction of each support
• Strength load combinations - the total reaction and maximum reaction for each combination
• Unfactored loads - the total load and maximum reaction for each load type

A load and support diagram and a free body diagram plot any strength, serviceability or unfactored case you choose. The calculator reports reactions only: it does not check the wall's own capacity.

Linking loads in and out

Reactions from beams, joists and walls above can be linked into the wall's point load and line load tables. The wall's support reactions link out the same way. Point reactions feed US wood, steel and cold-formed steel column calculators, spread, pier and combined footings, and beam calculators. Reactions along continuous supports feed beam calculators as line loads. Each link keeps the load types, so the receiving calculator applies its own combinations and updates when the wall loads change.