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1、Bridge Design Manual December 2001 by Texas Department of Transportation (512) 416-2055 all rights reserved Manual Notice 2001-1 To:Districts, Divisions and Offices From:Steven E. Simmons, P.E. Deputy Executive Director Manual:Bridge Design Manual Effective Date:December 1, 2001 Purpose This manual
2、provides policies and guidelines set forth by TxDOT regarding the design of bridges. It has been developed to help bridge designers working on TxDOT projects. Instructions This is a new manual containing new and significantly reorganized material. It supersedes the 1990 Bridge Design Guide and the 1
3、990 Bridge Design Examples, both first editions. Contents The manual contains ten chapters Organizational Overview, TxDOT and Bridge Design, Design Specifications, Geometric Restraints, Preliminary Considerations, General Design Controls, Superstructure Design, Substructure Design, Special Designs,
4、and Foundation Design. The manual also has four appendices. Contact For more information regarding any chapter or section in this manual, please contact the Design Section of the Bridge Division. Bridge Design Manual1-1TxDOT 12/2001 Chapter 1 Organizational Overview Contents: Section 1 This Manual .
5、1-2 Section 2 Evolution of the TxDOT Bridge Division .1-4 Chapter 1 Organizational OverviewSection 1 This Manual Bridge Design Manual1-2TxDOT 12/2001 Section 1 This Manual Overview This manual was developed to provide bridge designers working on Texas Department of Transportation (TxDOT) projects wi
6、th the policies and guidelines set forth by TxDOT regarding the design of bridges. Its purpose is to improve the bridge design and detailing process by promoting uniformity among bridge designers working on TxDOT projects. This manual is subject to revision as conditions, experience, or research dat
7、a warrant. Changes will be issued by Manual Notice. Changes may be in the form of new sheets to be added, revised sheets to replace superceded ones, or sheets to be deleted. The manual is not intended to be a complete substitute for engineering experience, knowledge, or judgment. Special situations
8、may arise that appear to call for variation from the policy requirements herein. Such variation will be subject to approval of the administration of the TxDOT Bridge Division. Direct any questions or comments on the content of the manual to the Director of the Design Section of the Bridge Division,
9、Texas Department of Transportation. Bridge Design Manual Format The manual begins with this overview of the manual and a description of the evolution of the TxDOT Bridge Division. The chapters that follow include information on TxDOT Divisions/Sections, design specifications, geometric restraints, p
10、reliminary considerations, general design controls, superstructure design, substructure design, special designs, and foundation design. The following paragraphs briefly discuss these chapters: Chapter 2 presents a description of the TxDOT Divisions/Sections primarily involved in bridge design, plann
11、ing, construction, and maintenance and provides descriptions of the responsibilities of the TxDOT Bridge Divisions Bridge Design Section. Chapter 3 lists and briefly describes the governing design specifications, or “Rule Books,” involved in bridge design. The chapter includes information on mandato
12、ry specifications, guide specifications, and industry recommendations. Chapter 4 discusses the common roadway geometric restraints inherent in bridge design. Bridge widths, span lengths, clearances, and alignment are discussed. A section on the constraints involved during stage construction is also
13、included. Chapter 5 presents some common aspects a designer/planner must consider during the preliminary planning and design process. These aspects include materials, structure type, Chapter 1 Organizational OverviewSection 1 This Manual Bridge Design Manual1-3TxDOT 12/2001 economics, and aesthetics
14、. A discussion on bridge railing and use of corrosion protection is also included. Chapter 6 discusses in greater detail some of the more common design specifications involved during the design of a bridge, giving the designer additional information on the application and usage of common design spec
15、ifications and criteria. Chapter 7 presents design criteria and design guidance for the most commonly used superstructure types, including cast-in-place, precast, and steel superstructures. Background information on the development of each superstructure type is also included. Chapter 8 presents des
16、ign criteria and design guidance for the most commonly used substructure items, including caps, columns, and foundations. Background information on the development of some of these items is also included. Chapter 9 presents design criteria and design guidance for designs that inherently involve uniq
17、ue aspects, culverts and drainage, bridge appurtenances, sign bridges, and some common bridge items. Background information on the development of some of these designs is also included. Chapter 10 discusses in greater detail the relationship between structural design and geotechnical design. Some gu
18、idance on bridge foundation designs and retaining wall designs is included, as well as background information on the development of some of these items. Chapter 1 Organizational Overview Section 2 Evolution of the TxDOT Bridge Division Bridge Design Manual1-4TxDOT 12/2001 Section 2 Evolution of the
19、TxDOT Bridge Division Origin of the TxDOT Bridge Division The Texas Highway Department was established in 1917 and is responsible to the Governor of Texas to design, construct, and maintain an adequate system of highways in the state. In 1918, a Bridge Office was created with the primary responsibil
20、ity of preparing standard designs and drawings in an attempt to bring some uniformity to the bridges being constructed by the counties. The Bridge Division appeared in 1928, retaining bridge design as a big part of its mission. The Bridge Division continued to maintain standards and design non-stand
21、ard bridges. In time, advance planning, railroad negotiations, and plan review capabilities were developed. Construction management was provided for some of the more complicated structures. 1940s and 1950s Activities were curtailed during the war years, but in the late 1940s and 1950s increased dema
22、nd for improved infrastructure produced a large volume of expressways, for which special design offices were established in the affected cities. Some of the groups adopted their own design and detailing standards. When welding began to replace rivets for field splices in steel beams and girders in t
23、he early 1950s, the Bridge Division sent qualified welders to the larger projects to help with quality assurance and quality control. In the middle 1950s the Bridge Division, with the cooperation of precast manufacturers, developed a group of standard pretensioned concrete beams, which quickly prove
24、d to be the most economical way to construct medium-span length bridges. When the Interstate Highway System was inaugurated in the middle 1950s, the design workload increased dramatically and has remained generally good to date. Between the expressway offices, district design groups, and the Bridge
25、Division, plan preparation was handled for several years with a minimum of help from consulting engineers. Recent Years In the early 1980s, consulting engineers began to do a significant portion of the highway plans and a somewhat smaller portion of the bridge plans. After a period of reduced activi
26、ty, consulting engineers are now preparing a significant portion of highway and bridge plans. Meanwhile, the use of TxDOT “bridge standards” has become more uniform, as many district design groups have abandoned their own plan preparation activities. Currently, the Chapter 1 Organizational Overview
27、Section 2 Evolution of the TxDOT Bridge Division Bridge Design Manual1-5TxDOT 12/2001 Bridge Division continues to prepare its share of structure plans while attending to a growing number of non-engineering responsibilities. Bridge Design Manual2-1TxDOT 12/2001 Chapter 2 TxDOT and Bridge Design Cont
28、ents: Section 1 Coordinating with TxDOT Divisions and Sections.2-2 Section 2 Primary Responsibilities of the Bridge Design Section.2-3 Section 3 Coordination Responsibilities of the Bridge Design Section.2-7 Section 4 Contractive Responsibilities of the Bridge Design Section.2-10 Chapter 2 TxDOT and
29、 Bridge Design Section 1 Coordinating with TxDOT Divisions and Sections Bridge Design Manual2-2TxDOT 12/2001 Section 1 Coordinating with TxDOT Divisions and Sections Overview Before a bridge is designed, critical preliminary functions described in the Bridge Project Development Manual must be comple
30、ted. The planning and design of a bridge project involves several divisions and sections within the Texas Department of Transportation (TxDOT). Some of the contributing entities are: Bridge Division Design Division, Field Coordination Section Transportation Planning and Programming Division Traffic
31、Operations Division, Railroad Section Environmental Affairs Division Construction Division, Materials Section Maintenance Division, Maintenance Operations Section Within the Bridge Division, the Bridge Design Section is responsible for functions that include engineering and non-engineering aspects o
32、f bridge design. These responsibilities are discussed in this chapter. Chapter 2 TxDOT and Bridge Design Section 2 Primary Responsibilities of the Bridge Design Section Bridge Design Manual2-3TxDOT 12/2001 Section 2 Primary Responsibilities of the Bridge Design Section Overview The primary responsib
33、ilities of the Bridge Design Section are structural design and the preparation of working drawings or plans. These primary responsibilities involve a procedure that begins with a concept to construct a highway facility and concludes with the submission of finalized plans, specifications, and estimat
34、es (PS otherwise they are called underpasses. Railroad Underpasses. Railroad underpasses are where a highway passes under an intersecting railroad. Design is under strict control by the railroad companies. Miscellaneous Structures. Miscellaneous structures include sign bridges, illumination poles, t
35、raffic signal supports, pedestrian overpasses, utility bridges, movable bridges, fender systems, ferry boat landings, and radio towers. Chapter 2 TxDOT and Bridge Design Section 2 Primary Responsibilities of the Bridge Design Section Bridge Design Manual2-5TxDOT 12/2001 Culverts and End Treatment. C
36、ulverts carry storm water under highways. The larger of these culverts are reinforced concrete boxes. Most culverts are constructed from standard drawings. Under some conditions Safety-End Treatment is required to protect errant vehicles. These conditions are outlined in the TxDOT Roadway Design Man
37、ual. Retaining Walls. Some types of retaining walls require structural design. Mechanically stabilized earth (MSE) wall designs require mostly geotechnical considerations. Detailed plans for MSE walls are prepared by the successful wall supplier. Geotechnical Design. A special group within the Bridg
38、e Technical Services Section performs geotechnical design. Preparation and Approval of Working Drawings Preparation and approval of working drawings involve assuring that the various requirements of the design are shown on plan-size (22 x 34 in.) or half-size (11 x 17 in.) drawings as completely and
39、 accurately as necessary to allow the structure to be built according to the design. Half-size sheets are preferred by the department. The use of full- size sheets is being phased out. Bridge Plans. Drawings for construction projects must contain accurate quantities of the various items of work so t
40、hat the contractor can be adequately reimbursed according to the unit bid prices. Bridge Standards. Bridge standards are maintained by the Bridge Standards Branch of the Technical Services Section. Standard drawings contain often-used systems and details that can be used in bridge plans without modi
41、fication. Standards are indexed on the main TxDOT website under Business/TxDOT CAD Standard Plan Files. (See http:/www.dot.state.tx.us/insdtdot/orgchart/cmd/cserve/standard/disclaim.htm.) The website contains instructions about the use of the graphics files. Preliminary Bridge Layouts. Preliminary b
42、ridge layouts are reviewed and approved by the Bridge Design Section. Layouts are initiated by the district, sometimes with assistance by a consulting engineer. See the Bridge Project Development Manual for the submittal process. Note: For major structures, coordinate with the Bridge Design Section
43、through the project development manager as early as possible. PS the purpose being to discourage an accumulation of drift on the piers. There are no warrants for determining the length of this span; it is a matter of engineering judgment. Marine Bridges Intracoastal canal and international shipping
44、lane main spans are subject to U.S. Coast Guard regulations. Approach spans are determined by economics and/or aesthetics. Navigable rivers as determined by the Federal Highway Administration (FHWA) are also subject to U.S. Coast Guard Regulations. Chapter 4 Geometric RestraintsSection 3 Horizontal
45、and Vertical Clearances Bridge Design Manual4-5TxDOT 12/2001 Section 3 Horizontal and Vertical Clearances Overview Clearances are established by AASHTO, American Railway Engineering and Maintenance- of-Way Association (AREMA), FHWA, U.S. Army Corps of Engineers, U.S. Coast Guard and, to some extent,
46、 local authorities. Minimum horizontal and vertical clearances for highway bridges are established in the TxDOT Roadway Design Manual, repeated in the TxDOT Bridge Project Development Manual, and tabulated here for ready reference. Clearances to railroads are specified by AREMA. Intracoastal canal c
47、learances are determined by the U.S. Army Corps of Engineers. International shipping lane clearances must be negotiated with the U.S. Coast Guard. Highway Grade Separations Clearance measurements for highway grade separations are depicted in Figure 4-2. For a complete listing of horizontal and verti
48、cal clearances for specific highway functional classifications, see the Roadway Design Manual. Highway Grade Separation Clearances Vertical14-6“ (4.42 m)Absolute minimum 16-6“ (5.03 m)To be provided over all roadways if possible and mandatory for new construction over interstate highways Horizontal1
49、-6“ (0.46 m)Absolute minimum from face of curb or barrier 10-0“ (3.05 m)From edge of travel lane on low-speed, low- volume roadways 16-0“ (4.88 m)From edge of travel lane on medium-volume roadways and freeway ramps 30-0“ (9.14 m)From edge of travel lane on high-volume roadways and all freeway main lanes Note: Special conditions that would severely increase structure cost may justify negotiation of these clearances with the TxDOT Bridge Division. Stream Crossings Stream Crossing Clearances Vertical2-0“ (0.61 m)Desired, above
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