Experimental Research On Axial Compression Bearing Capacity Of Marine Concrete Pier Column Under Wave Loading

In recent years,the economic development of coastal cities is relatively rapid,but complicated marine environment could intensify the degradation of bearing capacity of marine concrete pier column,seriously affecting the safety of the superstructure.Therefore it is a great practical significance to carry out the experimental study about the bearing capacity of marine concrete pier column.With the support of the national nature fund project about research on dynamic damage experiment of marine concrete structure under wave action,related experimental study is conducted,the main contents are as follows:(1)Based on morison equation,wave loading is simulated as sinusoidal fatigue loading satisfying certain conditions including wave length,wave height,water depth in front of the building and water depth over the foundation bed.(2)Through the electrified accelerated corrosion test under continuous loading,and,the following fatigue test and the axial compression test,development rule of corrosion current density of rebar,variation of residual strain and crack width of concrete and bearing capacity degradation rule are analyzed.Results show that the quality corrosion rate is lower than the theoretical corrosion rate;during the fatigue process,degradation rule of residual strain and crack width are very close;the corrosion rate has a great influence on both of them.When the target corrosion rate comes to 10%,fatigue loading frequency almost has no effect on both.During the pressing process,the failure pattern of the pier is brittle.The corrosion rate severely affects the capacity of the pier,ultimate strain and poisson ratio,but the fatigue loading frequency has little effect on the three ones above.(3)Based on the code for design of concrete structures,steel bar fatigue S-N logarithmic curves,P-M linear cumulative damage theory and equations proposed by some scholars about the degradation of reinforced steel yield strength,the reinforced concrete cooperative working coefficient,the relationship between quality corrosion rate and section corrosion rate.The formula for calculating the bearing capacity of corroded reinforced concrete piers under axial compression and fatigue load is presented.The experimental values of this paper and some scholars~′are basically consistent with the theoretical values calculated by the formula.The influence coefficient of steel corrosion is proposed to correct the calculation formula of bearing capacity.(4)Based on a chemical factory frame column reinforcement repair case in Taizhou,some parameters in the bearing capacity formula proposed in this paper are adjusted.The bearing capacity of the middle column at each stage in the framework is calculated.Compared to the estimated results about the capacity of corroded reinforced concrete columns,it is found that the bearing capacity of the other stages is quite close except for the deviation of the bearing capacity of the column in the frame after reinforcement.(5)Based on relevant detection and analysis of berth 69 of Lianyungang port,the calculation formula of reinforcement stress under wave load is presented.The variation range of corrosion rate and crack width are enlarged,and the bearing capacity of Lianyungang pier in 2008 and 2019 is estimated.Some techniques about the pier monitoring and protecting are introduced.