STUDY ON VARIATION OF JOINT FORCES IN STIFFENING TRUSS OF CABLE-STAYED BRIDGE

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STUDY ON VARIATION OF JOINT FORCES IN STIFFENING TRUSS OF CABLE-STAYED BRIDGE

  1. 1. YANGON TECHNOLOGICAL UNIVERSITY DEPARTMENT OF CIVIL ENGINEERING STUDY ON VARIATION OF JOINT FORCES IN STIFFENING TRUSS OF CABLE-STAYED BRIDGE SUPERVISOR STUDENTDR.NYAN MYINT KYAW MA YEE MON KHAINGPROFESSOR AND HEAD ROLL NO. C-28DEPARTMENT OF CIVIL ENGINEERING M.E. THESIS
  2. 2. Outlines of the First Seminar Objectives of the study Scopes of the study Flow chart of the study Component parts of the cable-stayed bridge Design procedure Implementation program Expected outcomes
  3. 3. Objectives of the study To get knowledge on design and analysis of a superstructure of cable-stayed highway bridge To know the components of cable-stayed bridge To have some knowledge of the design specifications for highway bridge published by American Association of State Highway and Transportation Officials (AASHTO) specifications To get better knowledge on practices and standards in bridge design To get detail information on the variation of joint forces in stiffening truss of cable- stayed bridge To be skillful for the way how to use STAAD-Pro software
  4. 4. Scope of the study Only superstructure of cable-stayed bridge will be designed AASHTO design specifications and HS 20-44 loading will be used The preliminary design and joint design will be done by STAAD-Pro software The effect of thermal change, wind force and earthquake effect will be considered The variation of joint forces in stiffening truss which mainly supports the floor of cable-stayed bridge are determined Anchorage, substructure and construction methods are not involved in this study
  5. 5. Literature Study Construction Methods and Procedures Design Configuration Modeling for Analysis Analysis and Design Final Design and Result Joint Detail Design of Stiffening TrussVariation of Joints forces in Stiffening truss Fig. Flow chart of the study
  6. 6. Component Parts of Cable-Stayed Bridge1. Cables2. Cable System3. Pylon4. Stiffening girder or Truss5. Cable anchorage and Connection
  7. 7. Cables Cables are the most important elements of a cable-stayed bridge. They carry the load of the girder and transfer it to the tower and the back-stay cable anchorage. Cables are tension members.Types of cables Locked coil Strand Helical Strand Bar Bundle New Parallel Wire Strand Seven Wire Strand
  8. 8. Cable System Three basic arrangements have been developed for the longitudinallayout of the stay cables. They are Radial System Harp System Fan System
  9. 9. Number of Cable Planes The three basic transverse cable of configurations are following; (a) Single Plane (b) Double Plane (c) Triple Plane
  10. 10. Pylon or Tower The design of the pylon must adapt to the various stay cable layouts. The primary function of the pylon is to transmit the force arising from anchoring the stays and these forces will dominate the design of cables. Tower configurations for single-plane cable
  11. 11. Tower configurations for single-plane cableTower configurations in the case of the high installation position for girder
  12. 12. Stiffening Girder The role of the stiffening girder is to transfer the applied loads, self weight as well as traffic load, into the cable system. The traffic load is acting on the deck of the girder, and both the dead load and wind area in most cases are larger for the girder than for the cable system. Stiffening girders may be I girders, trusses and box girders. The stiffening truss will be made as a space truss comprising four chords connected by four diagonal bracings, two vertical and two horizontal.
  13. 13. Bracing System  The bracing system used in stiffening trusses are generally the same as found in the other trusses with constant depth.  Three types of bracing system for the vertical main trusses . They are 1. Warren truss 2. Pure warren truss 3. Pratt truss (a) Warren truss (b) Pure warren truss Pratt truss Figure; Relevant Bracing Systems for the Main Trusses
  14. 14. Design Procedure Bridge Type - Cable-Stayed Bridge Total Length of Bridge - 240 m Span Arrangement - 3 spans arrangement Main Span - 130 m Side Span - 55 m (each) Clear width - 22 m (six lanes) Side Walk Width - 1.5 m (each) Pylon (or) Tower - H Type Truss Type - Warren Truss Type Cable type - 7̋ΦParallel Wire Strands Cable System - Fan type Traffic (live loading) - HS-20-44 (AASHTO) Height of Truss -3m Stringer Spacing - 5.875 m c/c
  15. 15. Implementation ProgramLiterature study on proposed bridgeConfiguration of proposed bridgePreparation for analysis of bridgeModeling analysis of bridge using STAAD-Pro softwareDesign of main structural componentsDetail for joints of stiffening truss of bridge
  16. 16. Expected outcomes Achieve knowledge and skill in design of a cable-stayed bridge Provide complete joint design data for construction of a cable-stayed bridge

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