This document outlines the first seminar for a study on the variation of joint forces in the stiffening truss of a cable-stayed bridge. It discusses the objectives, scope, flow chart, component parts, design procedure, implementation program, and expected outcomes of the study. The study will analyze and design the superstructure of a 3-span cable-stayed highway bridge using STAAD-Pro software, with a focus on determining the variation of joint forces in the stiffening truss.

2. YANGON TECHNOLOGICAL UNIVERSITY
DEPARTMENT OF CIVIL ENGINEERING
STUDY ON VARIATION OF JOINT FORCES IN
STIFFENING TRUSS OF CABLE-STAYED BRIDGE
SUPERVISOR STUDENT
DR.NYAN MYINT KYAW MA YEE MON KHAING
PROFESSOR AND HEAD ROLL NO. C-28
DEPARTMENT OF CIVIL ENGINEERING M.E. THESIS

3. 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

4. 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

5. 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

6. Literature Study
Construction Methods and Procedures
Design Configuration
Modeling for Analysis
Analysis and Design
Final Design and Result
Joint Detail Design of Stiffening Truss
Variation of Joints forces in Stiffening truss
Fig. Flow chart of the study

7. Component Parts of Cable-Stayed Bridge
1. Cables
2. Cable System
3. Pylon
4. Stiffening girder or Truss
5. Cable anchorage and Connection

8. 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

9. Cable System
Three basic arrangements have been developed for the longitudinal
layout of the stay cables. They are
 Radial System
 Harp System
 Fan System

10. Number of Cable Planes
The three basic transverse cable of configurations are following;
(a) Single Plane
(b) Double Plane
(c) Triple Plane

11. 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

12. Tower configurations for single-plane cable
Tower configurations in the case of the high installation position for girder

13. 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.

14. 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

15. 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

16. Implementation Program
Literature study on proposed bridge
Configuration of proposed bridge
Preparation for analysis of bridge
Modeling analysis of bridge using STAAD-Pro software
Design of main structural components
Detail for joints of stiffening truss of bridge

17. 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