Station Cable Machine Base Arch Board Arch Structure, Shrinkage And Creep Performance Pilot Study

For a long time, the Arch structure is one main style of the long-span bridge. Arches concrete bridges are usually statically indeterminate structures, because concrete shrinkage,creep and thermal change can cause second order internal force in structures, the whole bridge 's force state will be very complex. So if we want to know the force state, it is very important to do experimental studying to internal force redistribution which caused by the shrinkage,creep of Arches concrete bridge and to the concrete shrinkage,creep itself. This article refers to long-term monitoring of left riverside cable machine foundation arch bridge construction in Yunnan xiao wan hydroelectric power station, and doing spot research to the shrinkage,creep of plate-form arches concrete bridge.After tow year's monitoring and researching to the shrinkage,creep of arches concrete bridge, the conclusions as follows:1) The concrete time-strain curves is coincide to the time-thermal curves, so temperature make obvious influences in strain of concrete2) Observing the measured creep curves, we can find that the creep changes very quickly during the early days and then slow down after three months. After six-hundred days, the creep trends to immovable. The creep coefficient of arch ring sections are form l.55to 1．69, the district is tiny, on the average of 1．624．According to Mode specification CEB-FIP MC90, the creep coefficient is 1．59, which is near to the measured coefficient, so it is suitable to use Mode specification CEB-FIP MC90．3) Shrinkage and creep will cause obvious stress redistribution to concrete arch ring sections, which reduce the concrete compressing stress and increase steel tensile stress. The concrete redistributed stress value arrange from 34% to 40% of elastic stress value on the self-reconfigurable load of bridge. The steel redistributed stress value arrange from 157% to 197% of elastic stress value. It must be considered when designed.4) Redistributed stress direction of concrete arch ring caused by thermal change is just opposite to redistributed stress direction caused by concrete shrinkage,creep, which increase the concrete compressing stress and reduce steel tensile stress. The concrete redistributed stress value arrange from 18% to 26% of elastic stress value on the self-reconfigurable load of bridge. The steel redistributed stress value arrange from 81% to 122% of elastic stress value. It also must be considered when designed.5) Stress redistribution caused by shrinkage and creep increase the stress of steel and concrete of middle-span section, reduce the stress of other sections. Additional stress of steel and concrete caused by stress redistribution both arrange from-57% to 41% of elastic stress value on the self-reconfigurable load of bridge. So arch structures stress redistribution must be considered when designed.