Abstract

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Title:: Degradation Characteristics of Flexural Fatigue Property of Prestressed Concrete Beam with Corroded Steel Strand

Author(s):: LI Fu-min; YANG Jun; SHI Xiao-fei; Jiangsu Key Laboratory of Environmental Impact and Structural Safety in Engineering, China University of Mining and Technology

Keywords:: prestressed concrete beam; steel strand; durability; chloride environment; corrosion; fatigue; flexural rigidit

Abstract:: The accelerated corrosion method of mixing salt into concrete which had a similar corrosion result with the situation of actual chloride environment was used. Four prestressed concrete beams with steel strands and different salt contents were fabricated and placed for 90 d to achieve different corrosion degrees. Then the corroded specimens were loaded in fatigue until to failure with one steel wire fracturing, and a static loading test was executed after every 1×10⁵ times fatigue loading. Based on the experiment, the characteristics of fatigue failure, fatigue life degradation and flexural rigidity degradation were studied. The results show that the steel strands are corroded in typical pitting appearance. Multiple fatigue cracks appear on the pitting corroded wires under the action of fatigue, and one of them develops to fracture ultimately and marks the failure state. The fatigue fractures of wires show typical macrobrittle characteristic. The pitting corrosion region, fatigue fracture region and final fracture region are presented clearly in the fatigue fractures. The fatigue life degenerates in the exponential function law with the increase of salt content. For the influence of fatigue action, the loaddeflection curve of corroded beam is changed to be composed with two approximate straight lines with different slopes. The stronger the chloride action and fatigue action are, the more prominent the rigidity of the beam degenerates.