| Because of the shortage of river sand and the pursuit of economic interests,untreated sea sand is misused to build reinforced concrete (RC) structures at thecoastal areas in China. The steel bars in these structures are corroded early todamage. In addition, under the impact of long-term exposed to the marineenvironment, de-icing salts and atmospheric environment, the steel bars in theordinary reinforced concrete (RC) structures will also be corroded with theincreasing of the service life. Reinforcement corrosion leads to concrete covercracking, the decrease of steel bars’ sectional area, and the reducing of bondstrength. This may bring great hidden danger for the earthquake resistance anddisaster mitigation.However, there are no research reports in terms of the seismic performance of thecorroded RC short columns. This paper studied the seismic performance of corrodedRC short columns and the improvement effectiveness of strengthening by carbonfibre reinforced plastics (CFRP). The paper carried out pseudo static tests for oneuncorroded river sand RC short column, seven corroded river sand RC shortcolumns，two corroded sea sand RC short columns, three corroded river sand RCshort columns strengthened by CFRP, one corroded river sand RC short columnstrengthened by CFRP. The influence law was analyzed on the rebar corrosion rate,the axial compression ratio, shear span ratio and the layers of wrapping CFRP to thefailure mode, the shear capacity, stiffness, ductility and hysteretic characteristics ofcorroded RC short columns. Results show that:(1) Reinforcement corrosion has a small influence on the shear capacity of RCshort column, but has a great influence on the limit deformation capacity and energydissipation capacity. The shear capacity of slightly corroded (corrosion rate less than5%) RC short column increases by3.6%, the limit displacement decreases by27.3%,the cumulative hysteretic energy consumption decreases by28%. The shear capacityof seriously corroded (corrosion rate more than10%) RC short column decreasesby4.6%to7.8%, the limit displacement decreases by17.4%to45.4%, thecumulative hysteretic energy consumption decreases by18%to33%.The failuremode of RC short columns with reinforcement corroded and uncorroded, with strengthened and unstrengthened by CFRP, are brittle shear failure. The difference ofthe seismic performance of sea sand concrete corroded short column and river sandconcrete corroded short column is not obvious.(2) Axial compression ratio has a great influence on the shear capacity, stiffness,ductility, energy dissipation capacity of corroded RC short columns. With theincrease of axial compression ratio, the shear capacity and stiffness of corroded RCshort column increases, but the increasement of shear capacity is limited. Whileductility, energy dissipation capacity are decreased with the increase of axialcompression ratio. As axial compression ratio increases from0.1to0.2, thenincreases to0.3, the shear capacity respectively increases by14.7%and24.4%.Shear span ratio also has a great influence on the shear capacity, energy dissipationcapacity of corroded RC short column. With the increase of shear span ratio, theshear capacity and stiffness of corroded RC short column decreases. Under the samedisplacement angle, as the shear span ratio is higher, energy consumption capacity isstronger. The ductility of short column improved significantly by increasing theshear span ratio. As shear span ratio increases from1.5to1.75, then increases to2.0,the shear capacity respectively decreases by16.3%and27.3%.(3) Wrapping CFRP strengthening will not significantly increase the shearcapacity and the stiffness, but can significantly improve the ductility, energydissipation capacity of corroded RC short column. With the increase of wrappingcarbon fiber cloth layer, the increasement of shear bearing capacity is limited, lessthan10%, but the deformation capacity and energy dissipation capacity improvesignificantly. The corroded RC short columns respectively are strengthened bywrapping1,1.5, and2layers of CFRP, the cumulative hysteretic energy dissipationare1.2times,2.2times,3.1times that of unstrengthened corroded RC short columns,the displacement ductility coefficient increased respectively by23.4%,19.9%and47.4%, the shear capacity is increased respectively by8.9%,7.7%and9.7%.(4) A calculation formula for the shear capacity of corroded RC short column issuggested, which can be referenced for structure safety identification. A correction toPark damage model is proposed, and the corresponding damage evaluation criterionis established to evaluate the seismic damage of corroded RC short column. |
PDF Full Text Request