# Steel Joist Analysis Calculator

For Steel Joists Considered as Simple-Span Beams

Subjected to Non-Standard Loads

#### Input Data

#### Results of Joist Analysis:

Note: this worksheet can be used to determine the

total equivalent uniform load required to size a joist

for non-standard loads. The user can input all the

new, non-standard loads beginning at Row #35, and

then full uniform load at Cell B17 can be iterated

until both the stress ratios for shear and moment

are <= 1.0 everywhere the along the entire span.

Ix = 26.767*W(LL)*(L-0.33)^3/1000000

where: W(LL) = uniform live load based on deflection of

1/360 of span from Joist Load Table (plf)

L = joist span from center to center of supports (ft.)

(Note: joist design span = L-0.33'.)

usually includes the self-weight of the joist.

usually includes the self-weight of the joist.

These loads may be full or partial in

length and may be varying in value

(triangular or trapezoidal).

Do not use "Space Bar" to clear contents of unused cells.

"Highlight" those cells which are to be cleared

and click on the Right Mouse

Button and select "Clear Contents".

joist to the beginning (left side)

of the distributed load.

See Nomenclature illustration above.

at the beginning (left side) of the load.

See Nomenclature illustration above.

joist to the end (right side) of

the distributed load.

See Nomenclature illustration above..

at the end (right side) of the load.

See Nomenclature illustration above.

Do not use "Space Bar" to clear contents of unused cells.

"Highlight" those cells which are to be cleared and click

on the Right Mouse Button and select

"Clear Contents".

end of the joist to the point load.

See Nomenclature illustration above.

downward and negative (-) upward.

See Nomenclature illustration above.

Do not use "Space Bar" to clear

contents of unused cells.

"Highlight" those cells which are to be cleared and

click on the Right Mouse Button and select "Clear Contents".

the joist to the applied moment.

See Nomenclature illustration above

counterclockwise and negative (-) clockwise.

See Nomenclature illustration above.

Sign convention: positive (+) = upward.

= 25% of maximum end reaction for K-series and

LH-series joists

= 50% of maximum end reaction for H-series joists

Positive (+) moment = tension in bottom of joist.

Negative (-) moment = tension in top of joist.

Negative deflection is in downward direction.

Note: original calculated deflections were increased by

15% to more closely match actual test results by SJI.

Positive deflection is in upward direction.

Note: original calculated deflections were

increased by 15% to more closely match actual test results by SJI.

ratio and is calculated as follows:

D(ratio) = L/n where: n = L*12/ABS(D(max))

Sign convention: positive (+) = upward.

moment from left end of joist.

moment from left end of joist.

deflection from left end of joist.

deflection from left end of joist.

shear stress ratio from left end of joist.

moment stress ratio from left end of joist.

Sign convention: positive (+) = upward.

Note: Per SJI Spec's. for K-series and LH-series joists,

the minimum design web shear = 25% of the maximum joist end reaction.

(Value is 50% for older H-series joists.)

Sign convention: positive (+) = tension in bottom of joist.

Sign convention: positive (+) = counterclockwise.

Note: original calculated slopes (rotations)

were increased by 15% to more closely

match actual test results by SJI.

Sign convention: positive (+) = upward.

Note: original calculated deflections were increased

by 15% to more closely match actual test results by SJI.

Sign convention: positive (+) = upward.

Note: Per SJI Spec's. for K-series and LH-series

joists, the minimum design web shear = 25%

of the maximum joist end reaction.

(Value is 50% for older H-series joists.)

Sign convention: positive (+) = tension in bottom of joist

Sign convention: positive (+) = counterclockwise.

Note: original calculated slopes (rotations) were

increased by 15% to more closely match actual test results by SJI.

Sign convention: positive (+) = upward.

Note: original calculated deflections were

increased by 15% to more closely match actual test results by SJI.

Sign convention: positive (+) = upward.

Sign convention: positive (+) = tension in bottom of joist.

Sign convention: positive (+) = counterclockwise.

Note: original calculated slopes (rotations)

were increased by 15% to more closely match actual test results by SJI.

Sign convention: positive (+) = upward.

increased by 15% to more closely match actual test results by SJI.

Sign convention: positive (+) = upward.

Sign convention: positive (+) = tension in bottom of joist.

Sign convention: positive (+) = counterclockwise.

were increased by 15% to more closely match actual test results by SJI.

Sign convention: positive (+) = upward.

increased by 15% to more closely match actual test results by SJI.

stress ratio from left end of joist.

stress ratio from left end of joist.

stress ratio from left end of joist.

stress ratio from left end of joist.

**Disclaimer: **This calculator is not intended to be used for the design of actual structures, but only for schematic (preliminary) understanding of structural design principals. For the design of an actual structure, a competent professional should be consulted.

‘Calculations courtesy of Alex Tomanovich, PE ’