WELCOME TO MY

PRESENTATION

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

 

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

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

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

Literature Study

Design Configuration

Modeling for Analysis

Construction Methods and Procedures

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

Component Parts of Cable-Stayed Bridge

1. Cables

2. Cable System

3. Pylon

4. Stiffening girder or Truss

5. Cable anchorage and Connection

Types of cables

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.

New Parallel Wire Strand

Locked coil Strand Helical Strand Bar Bundle

Seven Wire Strand

Cable SystemThree basic arrangements have been developed for the longitudinal

layout of the stay cables. They are

Radial System

Harp System

Fan System

Number of Cable PlanesThe three basic transverse cable of configurations are following;

(a) Single Plane

(b) Double Plane

(c) Triple Plane

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

Tower configurations for single-plane cable

Tower configurations in the case of the high installation position for girder

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.

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 are1. Warren truss2. Pure warren truss 3. Pratt truss

(a) (b)Warren truss

Pratt trussPure warren truss

Figure; Relevant Bracing Systems for the Main Trusses

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 - 7̋=ΦParallel Wire Strands

Cable System - Fan type

Traffic (live loading) - HS-20-44 (AASHTO)

Height of Truss - 3 m

Stringer Spacing - 5.87̋5 m c/c

Design Procedure

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

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

THANK YOUFOR YOUR

ATTENTION