Chapter index

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.

AASHTO LRFD §1 — Introduction · §2 — General Design and Location Features

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.

§1.3 — Design Philosophy · §3.4 — Load Factors and Combinations

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.

§3.3 — Notation & Load Definitions · §3.4 — Load Factors and Combinations

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.

§4.6 — Static Analysis · §4.6.2 — Approximate Methods of Analysis

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.

§4.6.2.1 — Equivalent Strip Method · §5.6, §5.10 — Concrete Design & Cover

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.

§4.6.2.6 — Effective Flange Width · §5.6.2, §5.6.3 — Flexural Design

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.

§5.4.4 — Prestressing Strand · §5.9 — Prestress Losses

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.

§6.10.1 — I-Section Flexural Members · §6.10.6 — Strength Limit State (Composite Sections)

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.

§5.6 — Concrete Flexure and Axial Loads · §5.6.4 — Compression Members

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.

§14.5 — Bridge Joints · §14.6 — Requirements for Bearings

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.

§6.13.1 — Connection Overview · §6.13.2 — Bolted Connections

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.

§3.11 — Earth Pressure · §3.11.6.4 — Live-Load Surcharge

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.

§10.5 — Limit States and Resistance Factors · §10.6 — Spread Footings

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.

§3.10 — Earthquake Effects · §4.7.4 — Dynamic Analysis for Seismic

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.

§3.8 — Wind Loads (WS, WL) · §3.8.3 — Aeroelastic Instability

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.

AASHTO LRFD §3.4.2 — Load Factors for Construction · AASHTO LRFD §5.14.2 — Segmental Concrete Bridges

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.

23 CFR 650 Subpart C — NBIS · FHWA Recording & Coding Guide (NBI Items 58/59/60)

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.

AASHTO MBE §7 — Rehabilitation · ACI 440.2R — FRP for RC Strengthening