Precise Approach to Calculate Elastic Behavior of Prestressed Concrete Bridges

摘要

Based on the unified method to calculate stress distribution along the prestressed steel just after anchorage set up in prestressed concrete bridges, a novel approach to compute elastic response caused by tensioning steel both in static and hyperstatic systems is present by introducing finite element method using established built-up element, which considers the effects of concrete, time-variable modulus of concrete, non-prestressed steel and prestressed steel. The approach can analyze easily and precisely each tensioned prestressed steel's contribution to behavior of bridge including the effect due to creep and shrinkage between tensioning different groups of prestressed steel if their interval of working time should be considered, this is the base to predict exactly the long-term behavior of prestressed concrete bridges for some important bridges or deflection-controlled bridges, for all of which affects the relaxation of prestressed steel and functions of creep and shrinkage. The established formulae are easy to be extended to analyze time-dependent effect due to creep and shrinkage if step-up method is introduced. Discussion shows that this approach bears much higher precision than the nowadays commonly used methods while comparing the theoretical values with test resultants.