This educational application supplements, but does not replace, the official AASHTO LRFD Bridge Design Specifications, applicable state DOT manuals, project specifications, and professional engineering judgment.

Bridge Engineering
& Design
Master Bridge Design Using AASHTO LRFD
The most comprehensive interactive textbook for bridge engineering. Learn with real-world case studies, worked examples, design tools, and professional engineering workflows — from load definitions through capstone design.
Platform Capabilities
One integrated engineering ecosystem
Every chapter combines lecture, code interpretation, transparent calculation, interactive exploration, and assessment — the workflow real bridge engineers use.
Complete Chapters
22 graduate chapters from load definitions through capstone design.
Worked Examples
13-step calculation format with intermediate results and unit checks.
Interactive Calculators
Transparent HL-93, distribution factor, prestress, bearing, and scour tools.
Design Challenges
Open-ended problems that mirror real bridge design assignments.
Engineering Stories
Francis Scott Key, I-35W, Silver, Tacoma — real cases, real lessons.
Chapter Quizzes
Auto-graded numerical + multiple-choice with per-question feedback.
Curriculum
Your learning path
Nine stages from statics fundamentals to a complete capstone design.
- 1
Foundation
Ch 1–2
- 2
Loads
Ch 3
- 3
Analysis
Ch 4
- 4
Superstructure
Ch 5–7
- 5
Substructure
Ch 8–9
- 6
Bearings & Joints
Ch 10–12
- 7
Foundations
Ch 13
- 8
Extreme Events
Ch 14–16
- 9
Capstone
Ch 17–22
Published
Chapters available now
18 chapters live · 3 in development
Introduction to Bridge Engineering
Bridge functions, classifications, systems, and the design–build–inspect lifecycle. Overview of AASHTO LRFD, engineering ethics, and how bridges fit into the transportation network.
LRFD Philosophy, Reliability, and Limit States
Evolution from ASD to LFD to LRFD. Reliability, load and resistance factors, ductility, redundancy, operational importance, and the four AASHTO limit states.
Bridge Loads and Load Combinations
Permanent and transient loads, HL-93 live loading, dynamic load allowance, multiple-presence factors, braking and centrifugal effects, and Strength / Service / Fatigue / Extreme-Event combinations. Includes a full three-span Mid-Atlantic bridge worked example.
Bridge Analysis and Structural Modeling
Load paths, influence lines and surfaces, live-load distribution factors, approximate methods vs. refined analysis, grillage and finite-element models, and validation.
Bridge Deck Analysis and Design
AASHTO equivalent-strip method, empirical design, minimum reinforcement and cover, distribution steel, crack control, and Extreme Event II overhang design. Complete concrete-deck worked example plus a full steel orthotropic-deck example with the three stress systems (local, panel, global) and rib-to-deck weld fatigue check.
Reinforced-Concrete Bridge Superstructures
Solid slab, T-beam, and RC box-girder bridge design. Effective flange width, Whitney stress block flexural design, AASHTO simplified sectional shear method, torsion in boxes, and detailing. Includes a full T-beam worked example (flexure + shear + fatigue + deflection) and a solid slab bridge example, plus a two-span continuous T-beam design challenge.
Prestressed-Concrete Girder Bridges
Pre-tensioned and post-tensioned girder design. Losses, transfer and service stresses, flexural and shear strength (§5.7, §5.8, §5.9), harped and debonded strand layouts, end-zone anchorage-zone design, deflection and camber. Includes a full AASHTO Type-VI girder worked example, a spliced post-tensioned example, and a mini design challenge.
Steel I-Girder and Plate-Girder Bridges
Rolled and welded plate composite steel girders. Section classification, plastic and yield-moment resistance, LTB, shear with tension-field action, shear stud design, and Category-C fatigue. Includes a full 2×140-ft continuous composite plate-girder worked example and a curved-girder mini design challenge.
Piers, Columns, and Bent-Cap Design
Pier and bent classification, load path from superstructure to foundation, slenderness and moment magnification, biaxial P–M interaction for RC columns, bent-cap flexure and shear, and seismic detailing. Includes a full multi-column bent worked example, a hammerhead pier example, and a bent design challenge.
Bearings, Expansion Joints, and Restraint Systems
Bearing families (elastomeric, pot, disc, spherical), Method-A design of a steel-reinforced elastomeric pad, joint movement from thermal + shrinkage + creep, and joint-family selection (strip-seal, modular, finger). Full worked examples for an elastomeric bearing pad and a strip-seal joint plus a curved-bridge design challenge.
Connections, Splices, Cross-Frames, and Bracing
High-strength bolted and welded connections per AASHTO §6.13. Bolted field splices (75 %-of-yield rule, flange direct force, web elastic-vector), cross-frame families and spacing, top-flange lateral bracing during construction, and gusset-plate design. Worked examples for a bolted flange splice and a cross-frame diagonal plus a 3-span composite design challenge.
Abutments, Wingwalls, and Retaining Components
Abutment families (stub, seat, cantilever, MSE), Rankine active earth pressure, live-load surcharge, and stability checks for sliding, overturning, and bearing. Cantilever stem/toe/heel design, wingwalls, approach slabs, and integral abutment thermal demand. Two worked examples plus a river-crossing design challenge.
Bridge Foundations
Spread footings, driven piles, drilled shafts, and micropiles per AASHTO §10. Meyerhof bearing capacity, α/β pile methods, O'Neill–Reese rock socket, p-y lateral analysis, group efficiency, and downdrag. Full worked examples for a spread footing and a driven pile group plus a river-crossing drilled-shaft design challenge.
Seismic Design of Bridges
AASHTO seismic hazard, design response spectrum, single-mode SDOF analysis, response modification factor R, plastic-hinge detailing and spiral confinement, capacity-design hierarchy, and seismic isolation. Two worked examples (design base shear and plastic-hinge confinement) plus a four-span SDC-D design challenge.
Wind, Collision, Extreme Events, and Resilience
AASHTO §3.8 wind pressure and aeroelastic screening (buffeting, vortex shedding, flutter), §3.14 vessel-impact Method II, §3.6.5 vehicular collision, §3.9 ice loads, Extreme Event I/II combinations, and multi-hazard resilience framing. Two worked examples (wind pressure and barge impact) plus a cable-stayed multi-hazard design challenge.
Bridge Construction Engineering
Construction engineering for bridges — erection schemes (span-by-span, balanced cantilever, incremental launching, cable-stayed cantilever), formwork and falsework, camber, temporary works, construction loads and combinations, and rigging/lifting. Two worked examples (falsework check + segmental balanced-cantilever unbalanced moment) and a full girder-erection design challenge.
Bridge Inspection, Evaluation, and Load Rating
NBIS 23 CFR 650 inspection program (routine, in-depth, fracture-critical, underwater, damage, special), FHWA NBI condition ratings 0–9, common deterioration mechanisms and NDT toolbox, and AASHTO MBE §6A Load and Resistance Factor Rating — Design (Inventory + Operating), Legal, and Permit — with a worked example on a deteriorated composite plate girder and a full 3-span river-crossing evaluation design challenge.
Bridge Rehabilitation, Preservation, and Life-Cycle Design
FHWA intervention hierarchy (preservation · rehabilitation · replacement), deck treatments (crack seal, thin polymer, LMC, HMA + membrane), superstructure retrofits (FRP confinement per ACI 440.2R, external post-tensioning, drill-stop + bolted splice for fatigue), substructure jacketing, and life-cycle cost analysis at real discount rates. Full external-PT worked example, a 3-span overpass rehab design challenge, and a PE-format graded quiz.
Engineering Stories
Every failure taught us something
Real bridges. Real consequences. Every lesson embedded in the curriculum.
Design Studio
Professional-grade calculators, in the browser
The AASHTO Design Studio turns every chapter's equations into transparent, editable calculators. Adjust inputs; watch demands, capacities, and safety margins update live — with the code reference beside every number.
Ready to design your first bridge?
Start with Chapter 1, or jump directly into the featured Chapter 3 — Bridge Loads — and follow a full three-span Mid-Atlantic worked example.