New dehumidification system design and dehumidification test for the main cable of suspension bridge

To solve the problems of insufficient dry air coverage of the external dry air supply dehumidification system commonly used in the main cable of the suspension bridge, a new dehumidification system is proposed to dehumidify the main cable by delivering dry air from inside the main cable. The new dehumidification system changes the dry air delivery method of the traditional dehumidification system, and the dry air is delivered from the center of the main cable section, which can effectively solve insufficient dry air coverage in the main cable. Based on the 1560 m long-span suspension bridge of Longtan Yangtze River Bridge, the overall design of the new dehumidification system for the main cable is carried out. The composite air supply conduit is designed to meet the internal compressive strength requirements and adapt to the longitudinal deformation of the main cable. A dehumidification test is carried out to verify the feasibility of the new dehumidification system and evaluate its dehumidification effect. The results show that the composite air supply conduit composed of high-strength steel wire spring and corrugated pipe can withstand the radial compressive stress of 13.4 MPa and meet the compressive strength requirement inside the main cable. Therefore, it can be used as the dry air delivery conduit of the new dehumidification system for the main cable. The dry air of the new dehumidification system can achieve full coverage of the cross-section of the main cable, and the relative humidity of each position in the main cable can be reduced to below the critical humidity (RH = 60%) for the high-strength steel wire corrosion. That is, the entire main cable can be better protected against corrosion. Thus, the new dehumidification system can provide a new effective anti-corrosion measure for the main cable of the large-span suspension bridge.