| With the implementation of several environmental protection measures,such as energy conservation and emission reduction for sustainable development,engineering technology has also been upgraded constantly.In Wuhan City,the “Assembly” Project of Huoshenshan Hospital has been completed in just 10 days and such a fabricated structure has now become a development trend in the building industry.However,due to its various defects including great self-weight,poor cracking resistance and mobility,normal concrete has limited application in prefabricated construction.Hence,in order to conform to the trend of the times,developing such concrete that is lightweight with good cracking resistance and mobility has become inevitable.Fiber reinforced self-compacting lightweight aggregate concrete(FSLC)is a kind of brand-new concrete that is lightweight and high-strength with excellent cracking resistance performance.However,as the mechanical properties of its materials and components haven’t been systematically mastered,it’s not yet applied in projects on a large scale,even though it has the various advantages as mentioned above.As the premise enabling FSLC to work with steel bars,good viscosity is also the most important problem that must be solved when FSLC should be applied to concrete construction.However,till now,not a systematic study about this has been reported.In view of this,an in-depth study was made in this thesis about the bond-slip between steel bar and concrete by integrating experimental study and theoretical analysis with numerical modeling,so as to provide the theoretical foundation for the application of FSLC in engineering.The main contents and conclusions of this thesis were as follows:(1)A pull-out test was conducted to study the influence of fiber volume content(0%,0.25%,0.5% 0.75% and 1%),matrix strength of FSLC(LC45,LC55 and LC65),bar dimensions(12 mm,14 mm and 16 mm),relative anchorage length(4 ds,5 ds and 6 ds,ds represents bar dimensions)and the types of steel bars(plain round bars and ribbed bars)on the bond performance of FSLC.By analyzing the failure mode of the bond,the mechanism of bond damage on the surface between steel bar and FSLC was revealed.(2)Based on analysis of the influence of different factors on the bonding strength of FSLC through the response surface method,a bonding strength calculation method under multiple influences was proposed in this thesis.It was found that in terms of influence degree,different factors affecting bond performance can be ranked in order from the greatest to the least: matrix strength of concrete > fiber volume content > bar dimension.(3)According to data from the strain gage within the steel bar and based on the midpoint bond stress method and midpoint stress interpolation method,the intensity and distribution of full cross-sectional bond stress were obtained.The calculation results showed that with the increase in fiber content,the difference in various bond stress peaks was reduced,and thus the bond stress distribution curve became smooth gradually.(4)Based on the elastic-plastic theory and the experimental results,the FSLC bond stressslip constitutive relationship was established.Also,based on the steel bar-FSLC bonding strength calculation model and the test result theory,a calculation formula for the anchorage length of steel bar within FSLC was proposed.(5)Based on the numerical simulation software ABAQUS,a meso-scale finite element model conforming to the experimental results was constructed and its effectiveness was also verified.Then,the revised finite element model was used to track the formation and the evolution rule of the fractures on the surface between the steel bar and FSLC.By doing so,the validity of the established meso-scale finite element model was also verified.Meanwhile,based on the analysis of the acoustic emission signal and the analysis of the signal source location,the bond damage mechanism for the surface between steel bar and FSLC was revealed. |
