American Association of State Highway and Transportation Officials 444 North Capitol Street, NW Suite 249 Washington, DC 20001 202-624-5800 phone/202-624-5806 fax www.transportation.org © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law ISBN: 978-1-56051-451-0 Pub Code: LRFDUS-5 © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law PREFACE AND ABBREVIATED TABLE OF CONTENTS The AASHTO LRFD Bridge Design Specifications, Fifth Edition contains the following 14 sections and an index: 10 11 12 13 14 Introduction General Design and Location Features Loads and Load Factors Structural Analysis and Evaluation Concrete Structures Steel Structures Aluminum Structures Wood Structures Decks and Deck Systems Foundations Abutments, Piers, and Walls Buried Structures and Tunnel Liners Railings Joints and Bearings Index Detailed Tables of Contents precede each section The last article each section is a list of references, listed alphabetically by author Figures, tables, and equations are denoted by their home article number and an extension, for example 1.2.3.4.5-1 wherever they are cited In previous editions, when they were referenced in their home article or its commentary, these objects were identified only by the extension For example, in Article 1.2.3.4.5, Eq 1.2.3.4.5-2 would simply have been called “Eq 2.” The same convention applies to figures and tables Starting with this edition, these objects are identified by their whole nomenclature throughout the text, even within their home articles This change was to increase the speed and accuracy of CD production with regard to linking citations to objects Please note that the AASHTO materials specifications (starting with M or T) cited throughout the LRFD Specifications can be found in Standard Specifications for Transportation Materials and Methods of Sampling and Testing, adopted by the AASHTO Highway Subcommittee on Materials Unless otherwise indicated, these citations refer to the current 29th edition ASTM materials specifications are also cited and have been updated to reflect ASTM’s revised coding system, e.g., spaces removed between the letter and number viii © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law SECTION 1: INTRODUCTION TABLE OF CONTENTS 1.1—SCOPE OF THE SPECIFICATIONS 1-1 1.2—DEFINITIONS 1-2 1.3—DESIGN PHILOSOPHY 1-3 1.3.1—General 1-3 1.3.2—Limit States 1-3 1.3.2.1—General 1-3 1.3.2.2—Service Limit State 1-4 1.3.2.3—Fatigue and Fracture Limit State 1-4 1.3.2.4—Strength Limit State 1-4 1.3.2.5—Extreme Event Limit States 1-5 1.3.3—Ductility 1-5 1.3.4—Redundancy 1-6 1.3.5—Operational Importance 1-6 1.4—REFERENCES 1-7 1-i © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law SECTION INTRODUCTION 1.1—SCOPE OF THE SPECIFICATIONS C1.1 The provisions of these Specifications are intended for the design, evaluation, and rehabilitation of both fixed and movable highway bridges Mechanical, electrical, and special vehicular and pedestrian safety aspects of movable bridges, however, are not covered Provisions are not included for bridges used solely for railway, rail-transit, or public utilities For bridges not fully covered herein, the provisions of these Specifications may be applied, as augmented with additional design criteria where required These Specifications are not intended to supplant proper training or the exercise of judgment by the Designer, and state only the minimum requirements necessary to provide for public safety The Owner or the Designer may require the sophistication of design or the quality of materials and construction to be higher than the minimum requirements The concepts of safety through redundancy and ductility and of protection against scour and collision are emphasized The design provisions of these Specifications employ the Load and Resistance Factor Design (LRFD) methodology The factors have been developed from the theory of reliability based on current statistical knowledge of loads and structural performance Methods of analysis other than those included in previous Specifications and the modeling techniques inherent in them are included, and their use is encouraged Seismic design shall be in accordance with either the provisions in these Specifications or those given in the AASHTO Guide Specifications for LRFD Seismic Bridge Design The commentary is not intended to provide a complete historical background concerning the development of these or previous Specifications, nor is it intended to provide a detailed summary of the studies and research data reviewed in formulating the provisions of the Specifications However, references to some of the research data are provided for those who wish to study the background material in depth The commentary directs attention to other documents that provide suggestions for carrying out the requirements and intent of these Specifications However, those documents and this commentary are not intended to be a part of these Specifications Construction specifications consistent with these design specifications are the AASHTO LRFD Bridge Construction Specifications Unless otherwise specified, the Materials Specifications referenced herein are the AASHTO Standard Specifications for Transportation Materials and Methods of Sampling and Testing The term “notional” is often used in these Specifications to indicate an idealization of a physical phenomenon, as in “notional load” or “notional resistance.” Use of this term strengthens the separation of an engineer's “notion” or perception of the physical world in the context of design from the physical reality itself The term “shall” denotes a requirement for compliance with these Specifications The term “should” indicates a strong preference for a given criterion The term “may” indicates a criterion that is usable, but other local and suitably documented, verified, and approved criterion may also be used in a manner consistent with the LRFD approach to bridge design 1-1 © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law 1-2 AASHTO LRFD BRIDGE DESIGN SPECIFICATIONS 1.2—DEFINITIONS Bridge—Any structure having an opening not less than 20.0 ft that forms part of a highway or that is located over or under a highway Collapse—A major change in the geometry of the bridge rendering it unfit for use Component—Either a discrete element of the bridge or a combination of elements requiring individual design consideration Design—Proportioning and detailing the components and connections of a bridge Design Life—Period of time on which the statistical derivation of transient loads is based: 75 yr for these Specifications Ductility—Property of a component or connection that allows inelastic response Engineer—Person responsible for the design of the bridge and/or review of design-related field submittals such as erection plans Evaluation—Determination of load-carrying capacity of an existing bridge Extreme Event Limit States—Limit states relating to events such as earthquakes, ice load, and vehicle and vessel collision, with return periods in excess of the design life of the bridge Factored Load—The nominal loads multiplied by the appropriate load factors specified for the load combination under consideration Factored Resistance—The nominal resistance multiplied by a resistance factor Fixed Bridge—A bridge with a fixed vehicular or navigational clearance Force Effect—A deformation, stress, or stress resultant (i.e., axial force, shear force, torsional, or flexural moment) caused by applied loads, imposed deformations, or volumetric changes Limit State—A condition beyond which the bridge or component ceases to satisfy the provisions for which it was designed Load and Resistance Factor Design (LRFD)—A reliability-based design methodology in which force effects caused by factored loads are not permitted to exceed the factored resistance of the components Load Factor—A statistically-based multiplier applied to force effects accounting primarily for the variability of loads, the lack of accuracy in analysis, and the probability of simultaneous occurrence of different loads, but also related to the statistics of the resistance through the calibration process Load Modifier—A factor accounting for ductility, redundancy, and the operational classification of the bridge Model—An idealization of a structure for the purpose of analysis Movable Bridge—A bridge with a variable vehicular or navigational clearance Multiple-Load-Path Structure—A structure capable of supporting the specified loads following loss of a main loadcarrying component or connection Nominal Resistance—Resistance of a component or connection to force effects, as indicated by the dimensions specified in the contract documents and by permissible stresses, deformations, or specified strength of materials Owner—Person or agency having jurisdiction over the bridge © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law SECTION 1: INTRODUCTION 1-3 Regular Service—Condition excluding the presence of special permit vehicles, wind exceeding 55 mph, and extreme events, including scour Rehabilitation—A process in which the resistance of the bridge is either restored or increased Resistance Factor—A statistically-based multiplier applied to nominal resistance accounting primarily for variability of material properties, structural dimensions and workmanship, and uncertainty in the prediction of resistance, but also related to the statistics of the loads through the calibration process Service Life—The period of time that the bridge is expected to be in operation Service Limit States—Limit states relating to stress, deformation, and cracking under regular operating conditions Strength Limit States—Limit states relating to strength and stability during the design life 1.3—DESIGN PHILOSOPHY 1.3.1—General C1.3.1 Bridges shall be designed for specified limit states to achieve the objectives of constructibility, safety, and serviceability, with due regard to issues of inspectability, economy, and aesthetics, as specified in Article 2.5 Regardless of the type of analysis used, Eq 1.3.2.1-1 shall be satisfied for all specified force effects and combinations thereof The limit states specified herein are intended to provide for a buildable, serviceable bridge, capable of safely carrying design loads for a specified lifetime The resistance of components and connections is determined, in many cases, on the basis of inelastic behavior, although the force effects are determined by using elastic analysis This inconsistency is common to most current bridge specifications as a result of incomplete knowledge of inelastic structural action 1.3.2—Limit States 1.3.2.1—General C1.3.2.1 Each component and connection shall satisfy Eq 1.3.2.1-1 for each limit state, unless otherwise specified For service and extreme event limit states, resistance factors shall be taken as 1.0, except for bolts, for which the provisions of Article 6.5.5 shall apply, and for concrete columns in Seismic Zones 2, 3, and 4, for which the provisions of Articles 5.10.11.3 and 5.10.11.4.1b shall apply All limit states shall be considered of equal importance ∑ ηi γ i Qi ≤ φRn = Rr (1.3.2.1-1) in which: For loads for which a maximum value of γi is appropriate: ηi = ηD ηR ηI ≥ 0.95 (1.3.2.1-2) For loads for which a minimum value of γi is appropriate: ηi = ≤ 1.0 η D ηR ηI Eq 1.3.2.1-1 is the basis of LRFD methodology Assigning resistance factor φ = 1.0 to all nonstrength limit states is a default, and may be over-ridden by provisions in other Sections Ductility, redundancy, and operational classification are considered in the load modifier η Whereas the first two directly relate to physical strength, the last concerns the consequences of the bridge being out of service The grouping of these aspects on the load side of Eq 1.3.2.1-1 is, therefore, arbitrary However, it constitutes a first effort at codification In the absence of more precise information, each effect, except that for fatigue and fracture, is estimated as ±5 percent, accumulated geometrically, a clearly subjective approach With time, improved quantification of ductility, redundancy, and operational classification, and their interaction with system reliability, may be attained, possibly leading to a rearrangement of Eq 1.3.2.1-1, in which these effects may appear on either side of the equation or on both sides (1.3.2.1-3) © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law 1-4 AASHTO LRFD BRIDGE DESIGN SPECIFICATIONS where: γi = load factor: a statistically based multiplier applied to force effects φ = resistance factor: a statistically based multiplier applied to nominal resistance, as specified in Sections 5, 6, 7, 8, 10, 11, and 12 ηi = load modifier: a factor relating to ductility, redundancy, and operational classification ηD = a factor relating to ductility, as specified in Article 1.3.3 ηR = a factor relating to redundancy as specified in Article 1.3.4 ηI a factor relating to operational classification as specified in Article 1.3.5 = Qi = force effect Rn = nominal resistance Rr = The influence of η on the girder reliability index, β, can be estimated by observing its effect on the minimum values of β calculated in a database of girder-type bridges Cellular structures and foundations were not a part of the database; only individual member reliability was considered For discussion purposes, the girder bridge data used in the calibration of these Specifications was modified by multiplying the total factored loads by η = 0.95, 1.0, 1.05, and 1.10 The resulting minimum values of β for 95 combinations of span, spacing, and type of construction were determined to be approximately 3.0, 3.5, 3.8, and 4.0, respectively In other words, using η > 1.0 relates to a β higher than 3.5 A further approximate representation of the effect of η values can be obtained by considering the percent of random normal data less than or equal to the mean value plus λ σ, where λ is a multiplier, and σ is the standard deviation of the data If λ is taken as 3.0, 3.5, 3.8, and 4.0, the percent of values less than or equal to the mean value plus λ σ would be about 99.865 percent, 99.977 percent, 99.993 percent, and 99.997 percent, respectively factored resistance: φRn 1.3.2.2—Service Limit State The service limit state shall be taken as restrictions on stress, deformation, and crack width under regular service conditions 1.3.2.3—Fatigue and Fracture Limit State The fatigue limit state shall be taken as restrictions on stress range as a result of a single design truck occurring at the number of expected stress range cycles The fracture limit state shall be taken as a set of material toughness requirements of the AASHTO Materials Specifications 1.3.2.4—Strength Limit State Strength limit state shall be taken to ensure that strength and stability, both local and global, are provided to resist the specified statistically significant load combinations that a bridge is expected to experience in its design life C1.3.2.2 The service limit state provides certain experiencerelated provisions that cannot always be derived solely from strength or statistical considerations C1.3.2.3 The fatigue limit state is intended to limit crack growth under repetitive loads to prevent fracture during the design life of the bridge C1.3.2.4 The strength limit state considers stability or yielding of each structural element If the resistance of any element, including splices and connections, is exceeded, it is assumed that the bridge resistance has been exceeded In fact, in multigirder cross-sections there is significant elastic reserve capacity in almost all such bridges beyond such a load level The live load cannot be positioned to maximize the force effects on all parts of the cross-section simultaneously Thus, the flexural resistance of the bridge cross-section typically exceeds the resistance required for the total live load that can be applied in the number of lanes available Extensive distress and structural damage may occur under strength limit state, but overall structural integrity is expected to be maintained © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law SECTION 1: INTRODUCTION 1-5 1.3.2.5—Extreme Event Limit States C1.3.2.5 The extreme event limit state shall be taken to ensure the structural survival of a bridge during a major earthquake or flood, or when collided by a vessel, vehicle, or ice flow, possibly under scoured conditions Extreme event limit states are considered to be unique occurrences whose return period may be significantly greater than the design life of the bridge 1.3.3—Ductility C1.3.3 The structural system of a bridge shall be proportioned and detailed to ensure the development of significant and visible inelastic deformations at the strength and extreme event limit states before failure Energy-dissipating devices may be substituted for conventional ductile earthquake resisting systems and the associated methodology addressed in these Specifications or in the AASHTO Guide Specifications for Seismic Design of Bridges For the strength limit state: The response of structural components or connections beyond the elastic limit can be characterized by either brittle or ductile behavior Brittle behavior is undesirable because it implies the sudden loss of load-carrying capacity immediately when the elastic limit is exceeded Ductile behavior is characterized by significant inelastic deformations before any loss of load-carrying capacity occurs Ductile behavior provides warning of structural failure by large inelastic deformations Under repeated seismic loading, large reversed cycles of inelastic deformation dissipate energy and have a beneficial effect on structural survival If, by means of confinement or other measures, a structural component or connection made of brittle materials can sustain inelastic deformations without significant loss of load-carrying capacity, this component can be considered ductile Such ductile performance shall be verified by testing In order to achieve adequate inelastic behavior the system should have a sufficient number of ductile members and either: ηD ≥ 1.05 for nonductile components and connections = 1.00 for conventional designs and details complying with these Specifications ≥ 0.95 for components and connections for which additional ductility-enhancing measures have been specified beyond those required by these Specifications For all other limit states: ηD = • Joints and connections that are also ductile and can provide energy dissipation without loss of capacity; or • Joints and connections that have sufficient excess strength so as to assure that the inelastic response occurs at the locations designed to provide ductile, energy absorbing response 1.00 Statically ductile, but dynamically nonductile response characteristics should be avoided Examples of this behavior are shear and bond failures in concrete members and loss of composite action in flexural components Past experience indicates that typical components designed in accordance with these provisions generally exhibit adequate ductility Connection and joints require special attention to detailing and the provision of load paths The Owner may specify a minimum ductility factor as an assurance that ductile failure modes will be obtained The factor may be defined as: μ= Δu Δy © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law (C1.3.3-1) 1-6 AASHTO LRFD BRIDGE DESIGN SPECIFICATIONS where: Δu = deformation at ultimate Δy = deformation at the elastic limit The ductility capacity of structural components or connections may either be established by full- or largescale testing or with analytical models based on documented material behavior The ductility capacity for a structural system may be determined by integrating local deformations over the entire structural system The special requirements for energy dissipating devices are imposed because of the rigorous demands placed on these components 1.3.4—Redundancy C1.3.4 Multiple-load-path and continuous structures should be used unless there are compelling reasons not to use them For the strength limit state: For each load combination and limit state under consideration, member redundancy classification (redundant or nonredundant) should be based upon the member contribution to the bridge safety Several redundancy measures have been proposed (Frangopol and Nakib, 1991) Single-cell boxes and single-column bents may be considered nonredundant at the Owner’s discretion For prestressed concrete boxes, the number of tendons in each web should be taken into consideration For steel crosssections and fracture-critical considerations, see Section The Manual for Bridge Evaluation (2008) defines bridge redundancy as “the capability of a bridge structural system to carry loads after damage to or the failure of one or more of its members.” System factors are provided for post-tensioned segmental concrete box girder bridges in Appendix E of the Guide Manual System reliability encompasses redundancy by considering the system of interconnected components and members Rupture or yielding of an individual component may or may not mean collapse or failure of the whole structure or system (Nowak, 2000) Reliability indices for entire systems are a subject of ongoing research and are anticipated to encompass ductility, redundancy, and member correlation ηR ≥ 1.05 for nonredundant members = 1.00 for conventional levels of redundancy, foundation elements where φ already accounts for redundancy as specified in Article 10.5 ≥ 0.95 for exceptional levels of redundancy beyond girder continuity and a torsionally-closed crosssection For all other limit states: ηR = 1.00 1.3.5—Operational Importance C1.3.5 This Article shall apply to the strength and extreme event limit states only The Owner may declare a bridge or any structural component and connection thereof to be of operational priority Such classification should be done by personnel responsible for the affected transportation network and knowledgeable of its operational needs The definition of operational priority may differ from Owner to Owner and network to network Guidelines for classifying critical or essential bridges are as follows: © 2010 by the American Association of State Highway and Transportation Officials All rights reserved Duplication is a violation of applicable law Index Terms Links Splices of bar reinforcement (Cont.) mechanical connections or welded splices in tension 5-176 reinforcement in tension 5-175 tension tie members 5-176 welded splices 5-175 Splices of welded wire fabric deformed wire in tension 5-178 smooth wire in tension 5-178 Spread footings 10-52 anchorage of inclined footings 10-54 bearing depth 10-52 bearing resistance at the service limit state 10-65 bearing stress distributions 10-53 eccentric load limitations 10-79 effective footing dimensions 10-53 extreme event limit state 10-81 failure by sliding 10-80 groundwater 10-54 loads 10-55 nearby structures 10-54 overall stability 10-65 resistance factors 10-38 service limit state 10-54 settlement on cohesionless soils 10-56 settlement on cohesive soils 10-59 settlement on rock 10-64 strength limit state 10-38 structural design 10-82 tolerable movements 10-54 uplift 10-54 10-52 10-67 St Venant torsion aluminum 7-46 Stability buried structures 12-17 elastomeric bearings 14-63 14-76 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Stability (Cont.) MSE walls 11-45 static analysis 11-48 4-72 Stainless steel 6-28 Static analysis analysis for temperature gradient 4-73 approximate methods 4-20 axial pile resistance in compression influence of plan geometry 10-98 4-17 redistribution of negative moments in continuous beam bridges 4-72 refined methods 4-66 stability 4-72 Stay-in-place formwork concrete 9-13 deck overhangs 9-5 steel 9-13 Steel basic steps for steel bridge superstructures coefficient of thermal expansion 6-294 6-22 minimum mechanical properties by shape, strength, and thickness 6-24 modulus of elasticity 6-22 thickness of metal 6-22 Steel box-section flexural members access and drainage access holes 6-173 6-179 6-58 bearings 6-178 compact sections 6-189 constructibility 6-181 cross-section proportion limits 6-179 fatigue and fracture limit state 6-185 flange-to-web connections 6-178 flexural resistance—sections in negative flexure 6-191 This page has been reformatted by Knovel to provide easier navigation 11-69 11-71 Index Terms Links Steel box-section (Cont.) flexural resistance—sections in positive flexure 6-189 noncompact sections 6-189 service limit state 6-184 shear connectors 6-197 shear resistance 6-196 stiffeners 6-198 strength limit state 6-187 stress determination 6-173 Steel dimension and detail requirements dead load camber 6-52 diaphragms and cross-frames 6-55 effective length of span 6-52 heat-curved rolled beams and welded plate girders 6-66 lateral bracing 6-60 minimum thickness of steel 6-54 pins 6-64 Steel I-girders See: Steel I-section flexural members Steel I-section flexural members compact sections 6-136 composite sections 6-100 constructibility 6-119 cover plates 6-171 cross-section proportion limits 6-117 diaphragms or cross-frames 6-141 6-55 ductility requirement 6-140 fatigue and fracture limit state 6-129 flange-strength reduction factors 6-112 flange stresses and member bending moments 6-104 flexural resistance 6-137 6-140 flexural resistance—composite sections in negative flexure and noncomposite sections 6-141 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Steel I-section (Cont.) flexural resistance—composite sections in positive flexure 6-136 flowcharts for design 6-299 fundamental calculations 6-312 hybrid sections 6-102 lateral bracing 6-60 minimum negative flexure concrete deck reinforcement 6-107 moment redistribution from interior-pier I sections in straight continuousspan bridges 6-281 net section fracture 6-108 noncompact sections 6-139 noncomposite sections 6-102 service limit state 6-126 shear connectors 6-155 shear resistance 6-151 stiffeners 6-162 stiffness 6-104 strength limit state 6-130 variable web depth members 6-103 web bend-buckling resistance 6-109 wind effect on flanges 6-140 4-59 Steel I-section proportioning flange proportions 6-118 web proportions 6-117 Steel orthotropic decks See: Orthotropic steel decks Steel piles 6-257 axial compression 6-258 buckling 6-258 combined axial compression and flexure 6-258 compressive resistance 6-258 maximum permissible driving stresses 6-259 structural resistance 6-257 10-119 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Steel tension members 6-67 builtup members 6-74 eyebars 6-75 limiting slenderness ratio 6-74 net area 6-73 pin-connected plates 6-75 tensile resistance 6-68 Steel tunnel liner plate 12-83 buckling 12-85 construction stiffness 12-85 earth loads 12-84 flexibility limits and construction stiffness 12-11 grouting pressure 12-85 live loads 12-85 loading 12-84 safety against structural failure 12-85 seam strength 12-85 section properties 12-85 wall area 12-85 Stiffened webs nominal resistance 6-153 Stiffeners See also: Longitudinal stiffeners, Transverse intermediate stiffeners bearing stiffeners 6-166 design of 7-42 longitudinal compression-flange 6-198 web 6-198 Stirrups See: Transverse reinforcement Stream pressure lateral 3-37 longitudinal 3-35 Strength limit states 1-4 abutments and retaining walls 11-7 aluminum structures 11-15 7-10 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Strength limit states (Cont.) bridges composed of simple span precast girders made continuous buried structures 5-211 12-8 combined flexure and axial load concrete structures 6-202 5-25 decks 9-6 drilled shafts 10-132 flexure 6-132 6-187 foundations 10-29 10-38 interior-pier I-sections in straight continuous-span bridges 6-287 modular bridge joint systems 14-28 railings 13-5 resistance factors 5-26 6-30 shear 6-136 6-188 6-202 shear connectors 6-136 6-159 6-188 spread footings 10-67 stability 5-29 steel box-section flexural members 6-187 steel structures 6-30 wood structures 6-202 8-30 Stress analyses and design bursting forces 5-144 compressive stresses 5-142 edge tension forces 5-145 limitations of application 5-141 Stress laminated decks 9-29 camber 8-37 deck tie-downs 9-28 holes in lamination 9-30 nailing 9-30 staggered butt joints 9-30 stressing 9-31 Stressing corrosion protection 9-34 design requirements 9-33 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Stressing (Cont.) prestressing materials 9-33 prestressing system 9-31 railings 9-34 Structural analysis 4-1 acceptable methods 4-9 dynamic 4-74 mathematical modeling 4-10 by physical models 4-88 static analysis 4-17 Structural material behavior elastic behavior 4-11 elastic versus inelastic behavior 4-11 inelastic behavior 4-11 Structural plate box structures 12-39 concrete relieving slabs 12-45 construction and installation 12-47 crown soil cover factor 12-44 footing reactions 12-44 loading 12-40 moments due to factored loads 12-41 plastic moment resistance 12-43 safety against structural failure 12-40 service limit state 12-40 Strut-and-tie model crack control reinforcement general zone 5-35 5-136 proportioning of compressive struts 5-31 proportioning of node regions 5-35 proportioning of tension ties 5-34 structural modeling 5-30 Substructures construction load combinations 5-236 design 5-236 longitudinal reinforcement of hollow rectangular precast segmental piers vessel collisions 5-237 2-5 3-156 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Superimposed deformations creep 3-135 design thermal movements 3-133 differential shrinkage 3-135 settlement 3-135 temperature gradient 3-133 uniform temperature 3-130 Superstructure design 5-238 Surcharge loads live load surcharge 3-126 point line and strip loads 3-121 reduction of surcharge 3-127 strip loads—flexible walls 3-124 uniform surcharge 3-120 Suspension bridges refined analysis 4-72 T Temperature gradients 3-133 4-73 Temporary stresses before losses compression stresses tension stresses 5-98 5-100 Tendon confinement effects of curved tendons 5-119 wobble effect in slabs 5-119 Tensile resistance aluminum 7-23 combined tension and flexure 6-72 fatigue resistance 6-230 MSE walls 11-63 nominal 6-229 prying action 7-30 6-230 reduction factor 6-69 Tension-flange flexural resistance 6-196 Tension members aluminum 7-23 concrete 5-58 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Tension members (Cont.) splices 7-54 Tension ties anchorage of tie 5-34 proportioning 5-33 strength of tie 5-33 Test piles 10-125 Thermal forces temperature gradient 3-133 temperature range for procedure A 3-130 temperature range for procedure B 3-131 uniform temperature 3-130 Thermoplastic pipes 12-73 bending strain 12-82 buckling 12-78 chemical and mechanical requirements 12-74 combined strain 12-81 flexibility limits and construction stiffness 12-11 handling and installation requirements 12-83 idealized wall profile 12-79 materials 12-6 resistance to local buckling of pipe wall 12-79 safety against structural failure 12-73 section properties 12-73 service limit state 12-73 slenderness and effective width 12-80 thrust 12-74 wall resistance 12-78 Through-girder spans 6-250 Timber See: Wood Timber floors See: Wood decks and deck systems Time-history analysis method 4-83 Tire contact area 3-24 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Torsion See: Shear and torsion Traffic railings 13-5 application of previously tested systems 13-8 approach railings 13-6 design forces 13-16 end treatment 13-6 height of traffic parapet or railing 13-9 new systems 13-8 railing design 13-8 railing system 13-5 separation of rail elements 13-14 test level selection criteria 13-7 Traffic safety geometric standards 2-5 protection of structures 2-4 protection of users 2-5 road surfaces 2-5 vessel collisions 2-5 Transverse intermediate stiffeners moment of inertia 6-163 projecting width 6-163 Transverse reinforcement compression members 5-62 concrete 5-62 drilled shafts flexural members 5-64 10-145 5-124 Truss bridges refined analysis Trusses 4-72 6-251 bracing 8-36 camber 6-251 8-37 6-60 6-251 diaphragms factored resistance 6-253 gusset plates 6-253 half-through 6-252 lateral bracing 6-60 This page has been reformatted by Knovel to provide easier navigation 5-79 5-122 Index Terms Links Trusses (Cont.) load distribution 4-47 portal and sway bracing 6-252 secondary stresses 6-251 truss members 6-251 working lines and gravity axes 7-56 6-252 Tub-section members lateral bracing 6-61 U Unfilled grid decks composite with reinforced concrete slabs design 9-19 fatigue limit state 9-19 Unstiffened webs nominal resistance 6-152 Uplift aluminum 7-19 buried structures 12-17 drilled shafts 10-128 load test 10-144 pile group uplift resistance 10-113 piles penetrating expansive soil 10-144 10-79 resistance 10-143 single-pile uplift resistance 10-113 spread footings 10-54 Vehicle-induced vibration 4-76 V Vehicular collision force protection of structures 3-34 vehicle collision with barriers 3-35 Vehicular live load multiple presence of live load 3-18 number of design lanes 3-17 Vertical wind pressure Vessel collisions 3-42 3-136 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Vessel collisions (Cont.) annual frequency of collapse 3-138 barge bow damage length 3-153 barge collision force on pier 3-152 damage at extreme limit state 3-154 design collision velocity 3-148 design vessel 3-138 impact force 3-154 impact force, substructure design 3-154 impact force, superstructure design 3-156 importance categories 3-138 owner’s responsibility 3-138 protection against 2-5 protection of substructures 3-156 ship bow damage length 3-151 ship collision force on pier 3-149 ship collision force on superstructure 3-151 ship collision with bow 3-151 ship collision with deck house 3-151 ship collision with mast 3-152 vessel collision energy 3-148 W Warping torsion 7-47 Washers 6-220 materials 6-26 Water loads buoyancy 3-35 drag coefficient 3-35 scour 3-38 static pressure 3-35 stream pressure 3-35 wave load 3-38 Wearing surface chip seal 9-37 orthotropic steel decks 9-20 plant mix asphalt 9-37 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Wearing surface (Cont.) wood decks 9-36 Web bend-buckling resistance webs with longitudinal stiffeners 6-94 webs without longitudinal stiffeners 6-93 Web crippling aluminum 7-9 steel 6-321 Web local yielding 6-320 Web plastification factors compact web sections 6-272 noncompact web sections 6-272 Web proportions webs with longitudinal stiffeners 6-117 6-179 webs without longitudinal stiffeners 6-117 6-179 Webs nominal resistance of stiffened webs 6-153 nominal resistance of unstiffened webs 6-152 Welded connections 6-232 complete penetration groove-welded connections 6-232 effective area 6-234 factored resistance 6-232 fillet weld end returns 6-235 fillet-welded 6-233 minimum effective length of fillet welds 6-235 partial penetration groove-welded connections 6-233 seal welds 6-235 size of fillet welds 6-234 Welded wire fabric deformed 5-177 plain 5-178 quadrant mat reinforcement 12-66 Welding procedures for aluminum 7-18 requirements for aluminum 7-18 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Welding (Cont.) splices 7-55 weld metal 6-27 Wheel loads corrugated metal decks 9-26 decks 4-24 distribution through earth fills 3-25 modular bridge joint systems 14-27 orthotropic steel decks 9-20 Widening exterior beams 2-14 substructure 2-14 Wind-induced vibration 4-77 Wind load aeroelastic instability 3-42 horizontal wind pressure 3-38 multibeam bridges 4-59 vertical wind pressure 3-42 Wind pressure on structures 3-39 box sections 4-61 construction 4-61 I-sections 4-59 loads from superstructures 3-40 substructure forces 3-40 Wind pressure on vehicles 3-41 Wood bracing 8-36 camber 8-37 components in combined flexure and axial loading 8-35 components in compression 8-33 components in flexure 8-31 components in tension parallel to grain 8-35 components under shear 8-33 connection design 8-37 deck factor 8-29 flat-use factor 8-28 This page has been reformatted by Knovel to provide easier navigation Index Terms Links Wood (Cont.) format conversion factor 8-25 glued laminated timber 8-12 incising factor 8-29 metal fasteners and hardware 8-21 preservative treatment 8-21 sawn lumber 8-5 wet service factor 8-26 Wood barriers railing design 13-23 Wood decks and deck systems 9-27 deck tie-downs 9-28 deformation 9-28 design requirements 9-27 glued laminated decks 9-28 interconnected decks 9-29 load distribution 9-27 noninterconnected decks 9-29 plank decks 9-36 shear design 9-27 skewed decks 9-28 spike laminated decks 9-35 stress laminated decks 9-29 thermal expansion 9-28 wearing surfaces 9-28 9-35 9-36 Wood piles base resistance and modulus of elasticity structural resistance 8-14 10-120 Y Yield lines 4-78 Yield moment 6-314 composite sections in negative flexure 6-16 composite sections in positive flexure 6-315 noncomposite sections 6-314 sections with cover plates 6-316 This page has been reformatted by Knovel to 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American Association of State Highway and Transportation Officials, Washington, DC AASHTO 2002 Roadside Design Guide, RSDG-3 American Association of State Highway and Transportation Officials, . ..American Association of State Highway and Transportation Officials 444 North Capitol Street, NW Suite 249 Washington, DC 20001 202-624-5800 phone/202-624-5806 fax www .transportation. org... AASHTO 2009 Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 29th Edition, HM-29 American Association of State Highway and Transportation Officials, Washington,