Serviceability of continuous box-girder concrete bridges made by the progressive cantilever construction procedure

Continuous segmental bridge construction is relatively new to the Sri Lankan bridge industry. Progressive cantilever method of construction is one method employed for continuous box-girder bridges. This technique is competitive for spans between 30 - 50 m. This construction procedure has several advantages. There is no consideration of balancing cantilevers and provides easy access through parts already constructed. Also horizontal curved shapes can be easily accommodated. From a structural sense progressive placement method is advantageous in substructure design where bearings can be placed immediately. The main disadvantage arising from cantilever action is very high bending stresses. This can be minimized by introducing temporary cables or intermediate supports. The other disadvantages are slow progress and that the superstructure undergoes stress reversal. Often other construction methods may be necessary for the first span