Research On Mechanical Property Of Concrete Filled Steel Tubular Short Column Subjected To Freeze-thaw Cycle And Salt Spray Corrosion

Concrete filled steel tubular(CFST)has been widely used in the construction field by now and been regarded as a kind of excellent structures for its superb mechanical property and economy.With being used more and more extensively,the durability of CFST has been an urgent issue that researchers have to consider.Nowadays,With the increase of the age of the early CFST constructions,accidents caused by the lack of durability of CFST have been gradually drawing public attention,therefore,it is becoming more and more urgent to do research on the durability of concrete.However,up to now,there are relatively few researches on the durability of CFST under the various environments.In this paper.Both experience and theoretical analysis have been done for the research on the change law of mechanical property of CFST short column separately and simultaneously suffered to the salt spray corrosion and freeze-thaw cycle.The main work is as follow:(1)The tests of CFST exposed to salt spray corrosion,freeze-thaw cycle respectively and both two conditions simultaneously were finished.12 CFST short columns,18 CFST short columns,and 24 CFST short columns were respectively exposed to the three conditions mentioned above,8 CFST columns were not exposed to any condition,62 specimens in total.(2)According to the analysis on the results of tensile test of standard material specimens,the change law of two kinds of steel with different corrosion rates are obtained,including yield strength,ultimate strength,elongation and modulus of elasticity.(3)According to the analysis on the results of CFST specimens subjected to axial compressive loading and the failure mode after axial compressive loading test,bearing capacity-displacement curves are depicted.The change law of different mechanical properties of CFST specimens is summarized,including ductility and rigidity.(4)The finite element method is applied to simulate the CFST short columns under freeze-thaw cycle and salt spray corrosion.A simplified model of CFST short columns under both freeze-thaw cycle and salt spray corrosion is proposed and compared with the test results,and its reliability is proved by comparing with test results.(5)Based on the test results and the simplified model proposed in the finite element simulation,the formula for calculating the ultimate bearing capacity of CFST short columns under freeze-thaw cycle and spray corrosion conditions is proposed by introducing two parameters,including the number of freeze-thaw cycles and the weight loss rate,and its reliability is proved by comparing with test results.