Yingdi Liao

Corrosion Activity on CFRP-Strengthened RC Piles of High-Pile Wharf in a Simulated Marine Environment

We report test results from an experimental study to investigate the effectiveness of carbon fiber-reinforced polymer (CFRP) against reinforcing steel bar corrosion. Twelve reinforced-concrete pile specimens of 180 mm square by 1,600 mm long were cast. Three pile specimens were corroded to 5% steel mass loss and then strengthened with CFRP sheets; four specimens were strengthened by using CFRP sheets, whereas the remaining five specimens were not strengthened. The specimens were placed in a simulated marine environment, and corrosion was induced by an impressed current technique. At different theoretical corrosion degrees, nondestructive tests were performed to investigate the corrosion activity of the pile specimens, and destructive tests were performed to determine reinforcing steel bar mass loss. Based on the findings, the effectiveness of the CFRP-strengthened RC piles under aggressive marine environmental conditions was established.

The mechanical properties of coastal soil treated with cement

The influences of cement type, cement content, and curing time on the unconfined compression strength (UCS) of soil-cement were investigated. The influence of groundwater on UCS of soil-cement was also studied. The experimental results indicate that the soil treated with high grade cement presents a higher UCS. Additionally, the UCS of soil-cement presents linearly increased with the cement content. A logarithm correlation between UCS and curing time presents to forecast the strength development. Compared with the UCS of samples immersed in distilled water, those immersed in groundwater present a higher value.

Degradation of mechanical properties of cementitious materials exposed to wet-dry cycles of sulphate solution

Abstract In order to study sulphate attack effects on the mechanical behaviour of cementitious materials, the compressive behaviour of such materials subjected to wet–dry cycles of sulphate solution was investigated. Then, their variation of mass was recorded. According to the experimental results, it was observed that the mortars subjected to wet–dry cycles of sulphate attack were more severely damaged than ones immersed in a sulphate solution. In addition, these experimental results showed that the ultimate strength, elastic moduli and mass of samples initially increased with the number of wet–dry cycles and then declined after a certain number of wet–dry cycles. However, the peak strain corresponding to the compressive strength presented a decrease in the initial stage and then increased with the number of wet–dry cycles. Finally, the relationships between the mechanical behaviours and mass increment of such materials were analysed and qualitatively established.

Dynamic response and mooring optimization of spar-type substructure under combined action of wind, wave, and current

Floating wind turbines (FWTs) have become the preferred structures to exploit offshore winds since a large part of the offshore wind resource is located in deep water zones. In the harsh marine environment, a spar-type substructure is the most promising substructure for FWTs with good structure stability and economic advantages. In this study, the surge, heave, and pitch motions of the spar-type substructure under combined action of wind, wave, and current are analyzed by using the AQWA module of ANSYS. Besides, the effects of different parameters, namely, the mooring line distribution form, fairlead position, and line number of mooring systems, on the spar-type substructure motion response are also investigated. Based on the calculation results, a new spar-type substructure with an optimized mooring system is put forward and analyzed. It can be found that both the dynamic response and the mooring tension of the new spar-type substructure are significantly improved relative to the non-optimized structure....

Experimental study of cement strength grade and mixing ratio to cement-soil mechanical properties

Cement-soil mixing method is commonly used in strengthening soft soil foundation, the choice of cement strength grade and mixing ratio influence cement-soil strength and cost of engineering sales. Based on the characteristics of China southeast coastal silt soil, mechanical properties of cement-soil was studied in the condition of different strength grade. In addition, a function was proposed to predict cement quantity for different strength grade in the same ground compressive strength requirement, it has important significance to optimal proportioning and control engineering cost.