Steel Beam Design

Simple-span rolled steel beam bridges, composite or noncomposite, to the AASHTO LRFD Specifications (10th Edition). Lays out the cross section, finds the lightest W-shapes that pass, and checks the one you pick for Strength I/II at every unbraced segment, the deck pour, Service II, fatigue, shear, deflection and the shear studs. Results update as you type.

Bridge

Type

Span, L

Roadway widthCurb to curb

Barrier widthEach side

Number of girders

Girder spacingOverhang follows from the widths

Beam

W-shapeOr pick from the lightest list

Yield, F_y

ksi

Misc. steelCross-frames, connections

Composite deck

Deck f'c

ksi

Structural deck

Sacrificial layerWeight only

HaunchTop of web to bottom of deck

Stay-in-place forms

SIP form weight

psf

SIP flute depthNo strength, half weight

Stud diameter

Stud F_u

ksi

Noncomposite deck

Deck typeSets the distribution factors

Deck and fill weight

psf

Loads on the critical girder

Barrier weightEach

lb/ft

Share of one barrier

Added DC1Utilities, build-ups

lb/ft

Share of added DC1

Added DC2On the finished bridge

lb/ft

Share of added DC2

Wearing surfaceOver the roadway, shared

psf

Bracing & construction

Cross-framesft from the left bearing, e.g. 20, 35

Flange braced for the pour?

Flange braced in service?

Moment gradient, C_b

Appendix A6For the compression flange

Overhang load, wAt the deck edge, on the brackets

lb/ft

Overhang load, PFinishing machine

Construction load, wVertical, on the girder

lb/ft

Construction load, PVertical, at the section

Fatigue

(ADTT)_SLSingle lane

trucks

Design life

User-defined truck (Strength II)

Include

Axleskips@spacing to the next axle (ft)

Load factor

—

Impact factor1 + IM

—

Add lane load

Distribution

Limits & search

Live load deflection, L /

—

Maximum L/d

—

Shallowest W

Deepest W

W40 and W44

Accepted ratio

—

Bearing lengthWeb yielding and crippling