Simplified Calculation of Flow Resistance of Suspension Bridge Main Cable Dehumidification System

To calculate the flow resistance of a main cable dehumidification system,this study considers the air flow in the main cable as the flow in a porous medium,and adopts the Hagen–Poiseuille equation by using average hydraulic radius and capillary bundle models.A mathematical derivation is combined with an experimental study to obtain a semi-empirical flow resistance formula.Additionally,Fluent software is used to simulate the flow resistance across the main cable relative to the experimental values.Based on the actual measured results for a Yangtze River bridge,this study verifies the semi-empirical formula,and indicates that it can be applied in actual engineering.

Study for reasonable value of friction coefficient between main cable and saddle

The value of friction coefficient between the main cable and saddle, relates to not only the anti-slippage stability of three-tower suspension bridge, but also the reasonable stiffness of the middle tower and the magnitude of rigidity of the whole bridge. First, the paper does some comparative studies about the relevant provisions of international norms, and then, summarizes the relevant load test results both at home and abroad. Finally, the paper draws the appropriate anti-slippage safety factor for the most unfavorable load in accordance with international load standards, and discusses the rationality and feasibility of the friction coefficient of 0.2 between main cable and saddle.

Energy conservation research of dehumidification system for main cable anticorrosion of suspension bridge

The necessity of the main cable anticorrosion for suspension bridge is described, and operating principles and composition of main cable dehumidification system are analyzed. An idea using the waste heat of high temperature outlet air of dehumidification system to heat up regeneration air of rotary-type dehumidifier is put forward in this paper. The concrete scheme is to install a heat exchanger on air-out pipeline of roots blower and air-in pipeline of regeneration electric heater of rotary dehumidifier. Air preheated by the heat exchanger enters regeneration electric heater of rotary-type dehumidifier. Energy conservation of main cable dehumidification system for the Yangtze River highway bridge is calculated, and the results show that energy conservation rate can reach 44 %.

Construction techniques of super-length main cable of Taizhou Bridge

Taizhou Bridge is a highway three-pylon two-span bridge with span arrangement of 1 080 m + 1 080 m and the length of the main cable is more than 3 100 m. It is the longest cable in China. As the erection of the main cable needs to cross over three towers and the cables undulate acutely, general problems like the twist, spread and swell of strands and shedding of the zinc coating are prone to arise, which make it difficult to guarantee the quantity of cable traction construction. In this paper, the hauling, shaping and saddling of strands and sag adjusting are illustrated in detail and how to execute the refined construction control to guarantee the erection quality is also covered.

Parameters of static response of carbon fiber reinforced polymer(CFRP) suspension cables

The feasibility of longer spans relies on the successful implementation of new high-strength light weight materials such as carbon fiber reinforced polymer(CFRP). First, a dimensionless equilibrium equation and the corresponding compatibility equation are established to develop the cable force equation and cable displacement governing equation for suspension cables, respectively. Subsequently, the inextensible cable case is introduced. The formula of the Irvine parameter is considered and its physical interpretation as well as its relationship with the chord gravity stiffness is presented. The influences on the increment of cable force and displacement by λ2 and load ratio p′ are analyzed, respectively. Based on these assumptions and the analytical formulations, a 2000 m span suspension cable is utilized as an example to verify the proposed formulation and the responses of the relative increment of cable force and cable displacement under symmetrical and asymmetrical loads are studied and presented. In each case, the deflections resulting from elastic elongation or solely due to geometrical displacement are analyzed for the lower elastic modulus CFRP. Finally, in comparison with steel cables, the influences on the cable force equation and the governing displacement equation by span and rise span ratio are analyzed. Moreover, the influences on the static performance of suspension bridge by span and sag ratios are also analyzed. The substantive characteristics of the static performance of super span CFRP suspension bridges are clarified and the superiority and the characteristics of CFRP cable structure are demonstrated analytically.

Research on key technologies in design of middle pylon of Taizhou Bridge

At the middle pylon of a three-pylon two-span suspension bridge, the effect of unbalanced loads on the adjacent spans may result in a series of technical bottlenecks in design, such as stability and anti-slippage between saddles and main cables. This article presents the researches conducted on structure selection and behavior characteristics of middle pylon, interaction mechanism between main cables and saddles and their anti-slippage safety performance, elastic and plastic stability analysis and safety assessment of steel middle pylon, and fatigue design load and method for steel pylon of Taizhou Bridge. According to the research results, a longitudinal inverted Y shape steel middle pylon is used in design, effectively solving many technical difficulties, and this type of pylon has become a suitable middle pylon structural form for many three-ovlon two-soan susoension bridges.

Tribo-corrosion interaction of the parallel steel wires in the suspension bridges

The effect of contact load and relative displacement on tribo-corrosion interaction of parallel steel wires of main cable in the suspension bridge was investigated in this study.A self-made tribo-corrosion test bench was employed to conduct tribo-corrosion tests of parallel steel wires in 3.5%(wt%)NaCl solution and deionized water under different contact loads and different relative displacements.The friction coefficient and wear coefficient of wires were presented.Electrochemical corrosion behavior(Tafel polarization curves,Nyquist diagram,and equivalent circuit diagram)was characterized by electrochemical analyzer.Wear morphology was observed by scanning electron microscope.Wear volume loss and corrosion‒wear interaction were quantitatively demonstrated by high-precision weighing balance.The results show that the electrochemical corrosion ability of the steel wires increases with the increase of the contact load or relative displacement.The increased contact load or relative displacement increases the volume loss of corrosion‒wear and pure wear,but decreases the wear coefficient.The wear mechanisms in 3.5%NaCl solution are adhesive wear,abrasive wear,and corrosive wear as compared to adhesive wear and abrasive wear in deionized water under different contact loads.The wear mechanisms of parallel steel wires are slightly different under different relative displacements.But the main wear mechanisms are similar to that under different contact loads.The interaction effects of corrosion and wear produced by the contact load and relative displacement are all the synergistic effects.