Analysis Of Thermal Effects,Shrinkage And Creep Effects,and Construction Control Of Concrete Main Tower Of Long-span Suspension Bridge

Concrete main tower is constructed for all long-span suspension bridges in China at present. Actions on concrete main tower generally include load direct action (including permanent load and variable load) and non-load indirect action (including thermal effects,shrinkage and creep effects).During the construction of suspension bridge's uper structure, load direct action ,espacially the load from cables,varies and affects tower's safety. To ensure the main tower's satisfactory status,it is necessary to analyze its structural response and its control measure. Thermal effects,shrinkage and creep effects also influence concrete main tower's structural condition,so analysis of thermal effects,shrinkage and creep effects is essential. Taking the Siduhe Bridge as an example, analysis of thermal effects,shrinkage and creep effects,and construction control on concrete main tower of long-span suspension bridge is completed. The main investigations are summarized as follows:1. The main tower's forced state in the construction of the Siduhe Bridge's uper structure is analyzed,and it indicates that the greatest change of the horizontal component force on the tower appears in the floor system construction stage,so special attention should be given to this stage.2. The construction of suspension bridge's uper structure is divided into stages and saddle pushing is seted.The caculating result shows that the division of the construction stages and the saddle pushing setting, which would provide consults for the construction and its control ,can make tower stress close to perfect state.3. The review of mechanism of shrinkage and creep effects and the common prediction models is presented. The analytical results without shrinkage and creep effects disagree with reality.The results calculated by the refined method based on the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts of China (JTG D62-2004) showed better agreement with measured results. The JTG D62-2004 model is suggested to analyze the shrinkage and creep effects of concrete main tower of long-span suspension bridge.4.Temperature field and temperature difference stess influenced by temperature difference between inner surface and outer surface , sunshine temperature difference and annual temperature variation are calculated. The stress condition in every part of the main tower is set out,and some suggestions would provide consults for the design and construction control of the concrete main tower.