Chaotianmen Bridge Chaina ppt about construction

this is a ppt about the construction of a steel bridge

1. Chaotianmen Bridge Chongqing, China Presented BY : Nabeel Asif Shaikh Sem : 05 Roll No. : 23 Sub : THeory Of Structures Smt K.l Tiwari COA

2. Beginning of works: December 2004 Completion: 30 April 2009 Structure: Through arch bridgeTruss arch bridge Function / usage: Railroad (railway) bridgeRoad bridge Material: Steel bridge Designer China Communications Construction Company About Structure

3. About The Structure The Chaotianmen Bridge is a road-rail bridge over the Yangtze River in the city of Chongqing , China. The bridge, which opened on 29 April 2009, is the world's longest through arch bridge . The Chaotianmen Bridge is a major engineering feat spanning the Yangtze and Jialing Rivers with a total length of 1,741 meters and a main span of 552 meters. The bridge supports Chongqing's rapid urbanization and economic growth, while also attracting tourists. Its construction required advanced techniques to address geographical and structural challenges, ensuring stability and durability in a seismically active region. Chaotianmen Bridge is divided into upper and lower decks. The upper deck is two-way six-lane highway with the deck width of 31 meters. The middle deck is a two-way light rail track with vehicle lanes on both sides. With the main span of 552 meters, it is the largest arch bridge in the world at present.

4. LOCATION

5. Construction Design Phase: Conceptualized the bridge's structure, span length, load-bearing capacity, and aesthetic appeal. Site Preparation: Cleared the construction area, leveled the ground, and ensured a stable foundation. Foundation Work: Used deep foundations like piles or caissons to anchor bridge supports securely into the riverbed. Tower Construction: Built the main tower using reinforced concrete or steel to support the bridge deck and withstand lateral forces.

6. Construction Bridge Deck Assembly: Constructed the bridge deck separately and then assembled it on-site, ensuring proper alignment and structural integrity. Cable Installation: Installed tensioned cables connecting the deck to the main tower, a distinctive feature of cable-stayed bridges. Finishing Touches: Added road surfacing, lighting, and safety features to complete the bridge's functionality and aesthetics.

7. The force in the main truss rods on the steel truss girder (arch) has the significant difference during the construction and service state. In order to make sure of the structure safety, the high strength steel was used to reduce the cross section of the truss rod, as well as the different cross section (changed height, 2 different width) of the truss rod was used based on the loading.The assemble nodes were used except the nodes at the middle support to reduce the fabrication difficulty and the cost.The double-level truss balance along with the bridge thrust was used at the main span to simplify the load transfer between the truss components. The double-level truss consisted of steel plates. The change of the part level theory linear system was used to resolve the secondary stress in the truss. The pin support (14500t, largest pin support in the world) was used at the main truss nodes. Orthotropic steel bridge decks were used at the upper and the lower bridge level, while the parts of the deck were connected by truss. 01 — Roxborough House, 1997

8. Installation Starting Point for Superstructure Side Support as Starting Point: Initial work platform and lifting equipment set up at the side piers (sections #1 and #2, 24m in length). Features: Small torque at the side pier next to the tower crane (900t.m). One crane required at the side and middle arch cantilever. Three temporary piers needed at the side span. Difficult positioning of the middle support. Long installation period. Middle Support as Starting Point: At least one truss section (16m) installed as the girder installation platform on each side of the middle support. Features: Short installation period. Easy precise positioning. Two temporary piers for side span cantilever installation. Large torque at the side pier next to the tower crane (2800t.m). One crane needed at both side and middle spans.

9. Middle Span Closure Mode Selection Simultaneous Closure of Truss Arch and Steel Tie Bar: Features: Quick system transfer from cantilever to truss arch. Short construction period. Large self-weight and high overturning moment (570000t/m per truss). Difficult control of cantilever end displacement before closure. High wind resistance risk and overall instability. Sequential Closure with Temporary Truss Installation: Features: Smaller self-weight and lower overturning moment (418000t/m per truss). Easier control of cantilever end displacement. Good wind resistance and stability. Required temporary truss for system transfer after truss arch closure. Long construction period due to complex temporary truss control.

10. General Construction Plan Steel truss components were manufactured to non-stress length, assembled, and shipped to the site for pre-assembly with the front node plate. Three temporary pier supports were used for cantilever installation to the mid-span to form the truss arch. Large cantilever installations by crane with temporary pressure weight and cable-stayed suspender system were conducted in three stages to form the middle span steel truss beam. Side span deck and truss arch were installed simultaneously. The main structure loading system was transformed after steel truss closure, followed by the installation of the middle span bridge deck by crane.

11. 01 — Roxborough House, 1997 Simulation Analysis of the Global Construction Control Model

12. TEMPORARY PIER SETUP AT SIDE SPAN, INSTALLATION OF STEEL GIRDER, L-R 01 — Roxborough House, 1997 02 — Opera House, 1685 Temporary Pier Setup temporary piers were setup as the supplementary support when the steel girder was installed at side-span . The temporary pier was Q235Φ800×16mm Steel tube lattice column. The distribution beam at the top was the welded box girder with simply supported boundary condition. The temporary pier was designed the reaction force based on that the supported steel truss girder was simply supported cantilever beam with the maximum arm.

13. TEMPORARY PIER SETUP AT SIDE SPAN, INSTALLATION OF STEEL GIRDER, L-R 01 — Roxborough House, 1997 02 — Opera House, 1685 Installation of the Steel Girder In order to install the steel girder at the side span, in addition to the 3 temporary piers was setup as the secondary support; the temporary nodes were setup outside the side span for the temporary weight. The falsework was setup between the 1＃ temporary pier and the side pier. 1000t.m crane was used on the 1#、2# truss node on the falsework. As the installation and adjustment girder crane platform, the girder crane cantilever assembly was used to install the remaining internodes at side span. In order to meet the requirement of the closure without stress arch mid-span as well as the location of the north middle support precisely, the side support was moved down 2.3m before the installation of the truss girder at side span. The installation starting point at south side span moved to the mid-span 65cm. The initial installation tilt angle was 1.138°.

14. TEMPORARY PIER SETUP AT SIDE SPAN, INSTALLATION OF STEEL GIRDER, L-R 01 — Roxborough House, 1997 02 — Opera House, 1685 Temporary Pier Setup temporary piers were setup as the supplementary support when the steel girder was installed at side-span . The temporary pier was Q235Φ800×16mm Steel tube lattice column. The distribution beam at the top was the welded box girder with simply supported boundary condition. The temporary pier was designed the reaction force based on that the supported steel truss girder was simply supported cantilever beam with the maximum arm.

15. Arrangement of Chaotianmen Yangtze River Bridge

16. Cross section of bridge

17. In the past, the traditional steel truss is usually designed with one single material and the same width of each chord member. To adapt the large inner force variety of the chord during construction and service (from 89,520kN to 2,290kN), the main chord is fabricated with three type of steels, Q345qD, Q370qD and Q420qD, with maximum thickness of 50 mm. Q420qD is the first time used in large quantities on steel bridge; and the height and width of chord member sections are variable correspondingly; the section width has two types: 1200mm and 1600mm. The members are spliced at four sides; with uniform height and width at splicing joints to make the splicing convenient. For a member, the height and width not vary at the same section, the web members adopt “H” or “王” shaped sections MAIN TRUSS DESIGN

18. MAIN TRUSS DESIGN Section of main truss members (unit: mm) : (a) “H” shape section, (b) “王”shape section.

19. MAIN TRUSS DESIGN Lower Bracing Member Section and Anchorage Detail of Assistant Cable (a) Lower bracing member section, (b) Anchorage detail of assistant cable.

20. Upper and lower decks of Main Bridge Connection configuration

21. JOINTS DESIGN The joint system for the main truss included the upper and lower longitudinal plane joint systems for the arch ribs and the lower deck longitudinal joint system. The main truss width is larger than panel length, so the upper and lower plane longitudinal bracing adopt diamond type, and the stiffened chord’s plane bracing adopts “K” shaped type. Because of some inclination existing between the adjacent plane bracing, the gusset plate should be bended to adjust it. At the figure center of “米” shaped plane longitudinal bracing, a truss transversal bracing is set for each two panels of main arch rib, hence it enhances space rigidity of arch rib, and reduces the calculated free length of diagonal rod. At the zone of stiffened leg, one truss transversal bracing is also arranged for each panel.

22. STEEL GIRDER INSTALLATION AND DESIGN The bridge construction uses a three-span continuous hinge bearing support system with temporary piers at both ends. End spans are built using a cantilever method, starting with steel trusses installed on trestles and progressing with an erection gantry and balanced weights for stability. The mid-span is constructed with a symmetric full cantilever method supported by a 100m high sling pylon system. After closing the arch rib truss, a temporary tie ensures stability. A deck crane completes the remaining installations from mid-span backward. Construction began in September 2006, with the arch ribs closing in January 2008 and the tied chord in May 2008, successfully following the design without modifications.

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