Experimental Investigation On Anchorage Zone Capacity Of Post-tensioned Reactive Powder Concrete

Prestressed reactive powder concrete structure is a combination of prestressingand reactive powder concrete having ultra-high strength and high durabilityproperties. As the compression surfaces of structural components bear the largeconcentrated loads produced by prestressed force, distribution of the stresses inlocal zone under the bearing plates of anchors is complex. Because the reactivepowder concrete without coarse aggregates is different from conventional concretein microstructure and macroscopic mechanical properties, the entire nonlinearprocess of internal micro-cracking, external cracking and the final destruction hasits own characteristics, and the serviceability and ultimate limit states of local zoneof post-tensioned reactive powder concrete are affected directly. Therefore, thereare important theoretical significance and value in engineering to reveal localcompression mechanism of reactive powder concrete under post-tensioned anchorsof tendons (bundles), to propose the design method of local bearing capacity.Under the same conditions for prestressed reinforcement, we can select asmaller cross-section for prestressed reactive powder concrete structures than forconventional prestressed structures, so the ducts may have a more significant impacton local compression zone of reactive powder concrete, the first key issue should tobe resolved is to analyse the influence of ducts on local compression zone, especialythe influence of the diameter of ducts on local compression failure mechanism andlocal bearing capacity. Local compression experiments on18model specimens withone duct setting the duct diameter d, local compression zone ratio Ab/Aland theamount of steel fiber as the basic parameters are completed, data such as failureprocess and modes of specimens, characteristics of crack distribution, features ofthe compression surface and wedges, load-deformation curves are got. We willreveal the working mechanism and failure mechanism of reactive powder concretespecimens with one duct, analyse the influence of the three key parameters on theenhancement coefficient of concrete strength for local compression, bring forwardthe calculation formula for local compression bearing capacity.Grid net indirect reinforcements which can be applied to local compressionzone of reactive powder concrete is a major configuration form used in local compression concrete zone of conventional concrete. The second key issue shouldto be resolved is to explore the force characteristics of local compression zone ofreactive powder concrete with grid net indirect reinforcements, especialy the entirenonlinear process from crack to the destruction, to explore the failure mechanism, toexplore the influence of grid net indirect reinforcements on local bearing capacity ofreactive powder concrete on the basis of research results of plain reactive powderconcrete. Local compression experiments on24model specimens with grid netindirect reinforcements and a reserved duct setting local compression zone ratioAb/Al, inner edge size lcorof reinforcements and the amount of steel fiber as the basicparameters are completed, data such as failure process and modes of specimens,characteristics of crack distribution, features of the compression surface and wedges,load-deformation curves and especialy the strain distribution of indirectreinforcements are got. We will reveal the working mechanism and failuremechanism of reactive powder concrete specimens with grid net indirectreinforcements, analyse the influence of the three key parameters on theenhancement coefficient of concrete strength for local compression, bring forwardthe calculation formula for local compression bearing capacity.Spiral indirect reinforcements is another major configuration form used inlocal compression concrete zone of conventional concrete, and it’s obvious thatspiral reinforcements made of bended high-strength steel bars can confine reactivepowder concrete having high strength effectively. The third key issue should to beresolved is to explore the force characteristics of local compression zone of reactivepowder concrete with high strength spiral indirect reinforcements, to explore thefailure mechanism, to explore the influence of grid net indirect reinforcements onlocal bearing capacity of reactive powder concrete on the basis of research results ofplain reactive powder concrete. Local compression experiments on24modelspecimens with spiral indirect reinforcements and a reserved duct setting localcompression zone ratio Ab/Al, inner edge size dcorof reinforcements and the amountof steel fiber as the basic parameters are completed, data such as failure process andmodes of specimens, characteristics of crack distribution, features of thecompression surface and wedges, load-deformation curves and especialy the straindistribution of indirect reinforcements are got. We will reveal the workingmechanism and failure mechanism of reactive powder concrete specimens with spiral indirect reinforcements, analyse the influence of the three key parameters onthe enhancement coefficient of concrete strength for local compression, bringforward the calculation formula for local compression bearing capacity.