SHRINKAGE AND CREEP EFFECT ANALYSES OF DOUBLE COMPOSITE CONTINUOUS BOX-GIRDER BRIDGE CONSTRUCTED BY PRE-JACKING METHOD

Abstract

Continuous double steel and concrete composite beam is a new structural system developed on the basis of common steel and concrete composite beam. Controlling concrete slab crack width in a continuous double composite beam is a significant content in the bridge construction process. Jacking-up and landing bearing supports method is applied to a double composite girder bridge construction and its structural mechanical behaviors in the whole process will be simulated. By using of User Programmable Features and ANSYS Parametric Design Language, the commercial FEM software ANSYS was further developed. The exponential model of concrete creep and the implicit solution of concrete creep equation under the action of variable stress were introduced into ANSYS, to realize the concrete shrinkage and creep effect analysis of double composite continuous box-girder bridges constructed by pre-jacking method. The results show that it is improved that the stress state of the top concrete slab in the negative moment regions by pre-jacking method. Due to the effect of concrete creep, the concrete creep will cause tensile stress in the negative moment regions of the composite beam, which will reduce the compressive stress in the top concrete slab. The effect of prestressing is greatly affected by pre-jacking value, and the creep of the concrete also causes the stress redistribution of the concrete and the steel beam.