Three-tower Suspension Bridge Research Articles

Numerical Simulation of Ultimate of Slings for Three-Tower and Four-Span Suspension Bridge under Tanker Fire

Three-dimensional finite element model of Yingwuzhou Yangtze river bridge was established by using the finite element software ANSYS. Since the characteristics of bridge fire differed much from that of buildings, Heating curve HCinc was selected as heating curve caused by tanker fire. Heat loading was imposed on the middle of main span where the tanker fire had taken place of three-tower and four-span suspension bridge . The temperature field and stress, modulus of elasticity, strength of sling changing with time caused by tanker burning in midspan were systematically investigated to obtain the failure time of the sling. The calculation also compared the above results of HCinc curve with that of ISO834 curve. This research can provide some references to fire risk prevention measures of bridge during its service life.

Selection of a Structural System for a Three-Tower Suspension Bridge of Maanshan Yangtze River Highway Bridge

A three-tower suspension bridge has an additional middle tower and a main span when compared to the conventional two-tower suspension bridge. Restriction between main cable and middle tower top is weaker, and the force difference in the main cables on the two sides of the middle tower is large when one main span is fully loaded and the other one is not loaded. The main structure of the Maanshan Yangtze River High way Bridge over the left branch is a three-tower suspension bridge with main span arrangement of 2 × 1080 m. Four different structural systems could be chosen for a three-tower suspension bridge, which are: girder integral with the tower, girder pinned at the tower, half float system and full float system. The slip resistance stability of main cable, whole bridge structure stiffness, middle tower strength, stiffening girder internal forces, cable internal forces, reactions at the bearings, capabilities of resisting wind and earthquake, and so on are compared for these four structural systems. Results show that the girder integral with the tower is better than other structural systems and therefore is adopted for the Maanshan Yangtze River Highway Bridge.

Key Technology of Construction for Middle Tower of Three-Tower and Two-Span Suspension Bridge

Tai-Zhou Bridge, which has a three-tower and two-span, is 1080 meters long and 2 meters wide. The middle tower is a huge caisson foundation and chevron steel tower structure. It is important to make some effective technical measures to control the processes of caisson foundation’s installation, such as floating, orientation, implantation and final sunk, especially in complex conditions. Eroding model tests for the caisson foundation’s floating phase and sunken phase play an important role in the prophase installation. Information control technology could exactly guidance the sunk of cession. Finally, the linkage control of steel tower’s manufacture and operation is necessary for the precision of installation.

Geometrical Nonlinear Analysis on Three-Tower Suspension Bridges under Live Load

Anti-slipping safety factor between the main cable and saddle, deflection-to-span ratio of main girder and force in the mid-tower, which are not important factors in two-tower suspension bridge design, yet becoming dominant ones in three-tower. Moreover, these factors are all controlled by live load. Thus geometrical nonlinearity under live load for three-tower suspension bridge becomes even more significant. This paper takes Taizhou Yangtze River Bridge as the study object, and uses linear deflection theory, incremental UL formulation and total CR formulation to study the geometrical nonlinearity of various key responses of the structure under live load. It is concluded that accuracy and efficiency of total CR formulation is the highest among the three as well as the maximum error of incremental UL formulation is no more than 0.3%; however, the error of widely used linear deflection theory is 6.6%, 4.5% and -2.64% respectively, which is conservative and can not meet the requirements of sophisticated analysis.

Static and Dynamic Behaviours of Three-Tower Suspension Bridges and the Structure Selection of the Mid-Tower

In order to discuss the mechanical behaviour differences between the two-tower and three-tower suspension bridges, based on the Taizhou Yangtze River Bridge, three dimensional space finite element models of two-tower, three-tower with concrete mid-tower and with steel mid-tower were constructed. Through the comprehensive analysis, main conclusions are got as follows: due to the mid-tower lack of effective restraint from side cable, compared with two-tower suspension bridges, three-tower suspension bridges have lower total stiffness and natural frequency, with larger deflection-to-span ratio of main girder. So, some factors such as anti-slipping safety factor between the main cable and saddle, deflection-to-span ratio of main girder and force in mid-tower, which are not important in two-tower design, become controlling ones in three-tower suspension bridges. These factors are related to anti-pushing rigidity of mid-tower, but in contradictory demanding for the rigidity of mid-tower. After comprehensive analysis, steel tower with shape of upside-down ‘Y’ meets all demands, and then, was selected as appropriate structure for the mid-tower.

Research on Mechanical Behaviours of Three-Tower Suspension Bridges from the Perspective of Influence Line

Mechanical behaviours of three-tower suspension bridges from perspective of influence line help insight into mechanical behaviour nature, and grasp the differences between two-tower and three-tower suspension bridges in Static and dynamic behaviours. Based on the Taizhou Yangtze River Bridge, three dimensional space finite element models of two-tower, three-tower with floating system and three-tower with elastic cables between mid-tower and the girder were constructed. Through analysis of influence lines characteristics of different key effects and effect envelop under vehicular load, main conclusions are got as follows: Some factors such as deflection-to-span ratio of girder, anti-slipping safety factor between the main cable and saddle of the mid-tower and force in the mid-tower, horizontal displacement at the end of girder, which are not important in two-tower design, become controlling ones in three-tower suspension bridges and effects under vehicular load is the most important. When live load acts on all or part of one main span, the four control factors reach the worst case, but in very low probability. Code restriction on deflection-to-span ratio of girder can be flexible to relax restriction to 1/220, and riding comfort is still guaranteed. Stresses of mid-tower under vehicular load plus dead load are in a state of compressive stress in the majority of operating conditions and fatigue problem is not obvious.

Study of structural parameters on the aerodynamic stability of three-tower suspension bridge

In comparison with the common two-tower suspension bridge, due to the lack of effective longitudinal restraint of the center tower, the three-tower suspension bridge becomes a structural system with greater flexibility, and more susceptible to the wind action. By taking a three-tower suspension bridge-the Taizhou Bridge over the Yangtze River with two main spans of 1080 m as example, effects of structural parameters including the cable sag to span ratio, the side to main span ratio, the deck's dead load, the deck's bearing system, longitudinal structural form of the center tower and the cable system on the aerodynamic stability of the bridge are investigated numerically by 3D nonlinear aerodynamic stability analysis, the favorable structural system of three-tower suspension bridge with good wind stability is discussed. The results show that good aerodynamic stability can be obtained for three-tower suspension bridge as the cable sag to span ratio is assumed ranging from 1/10 to 1/11, the central buckle are provided between main cables and the deck at midpoint of main spans, the longitudinal bending stiffness of the center tower is strengthened, and the spatial cable system or double cable system is employed.

Wind stability of three-tower suspension bridges

Wind stability of three-tower suspension bridges