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Ansys Numerical Simulation on Mechanical Behavior of the Reactive Powder Concrete

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Tutor: DuYingJi
School: Northwest University of Science and Technology
Course: Hydraulic Structure Engineering
Keywords: RPC,nano-SiO2,mechanical properties,ANSYS,random steel fiber model,numerical sim
CLC: TU528
Type: Master's thesis
Year:  2013
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RPC is a kind of new material which has high compressive strength, favorabledurability, high toughness and good volume stability. It has a broad application prospect andbecome a new hot spot in the field of international engineering material. At present, the studyof the RPC gives priorities to macro test which is mainly concentrated on the preparationtechnology and mechanical properties while lack of mesoscopic level research. In order tograsp the concrete damage rule, it must start with material’s mesoscopic structure to get itsmechanical performance and failure process. In present work, a new method of studying onmechanical properties of the RPC is provided based on experimental study and numericalsimulation method.At first, a mechanical properties test with a series of13which has39RPCspecimens is conducted, and analysis the material’s flexural strength, compressive strengthand the change rule of splitting tensile strength. Then separate finite element model insoftware ANSYS is adopted to establish the random steel fiber model to simulate material’scrack formation and propagation under uniaxial load. After computing the macroscopicmechanical index of the RPC is obtained. Through those researches in this issue, thefollowing conclusion can be get:(1) After analyzing on test data of RPC specimen’s flexural strength, compressivestrength and splitting tensile strength, the results showed, the fluidity of mixing contentincreased gradually as water/cement ratio increased gradually when the dosage of siliconpowder remain unchanged; the7d and28d compressive strength, flexural strength andsplitting tensile strength of the RPC decrease as the water/cement ratio increased from0.22to0.22; the RPC fluidity significantly decreased evidently with the increase of dosage ofsilicon powder when water-binder ratio remain unchanged. The larger of water/cement ratio,the steeper of the curve and the more obvious of fluidity decrease trend.(2) With the increase of nano-SiO2content, the RPC fluidity increases at first, butthen decreases. The RPC fluidity gets its top with the nano-SiO2content of0.5%. With theincrease of nano-SiO2content, the flexural strength of RPC value, compressive strength andsplitting tensile strength values all increases firstly, but then decreases. (3) Through the prism compressive strength of RPC experiment, the result is: withthe increase of nano-SiO2content, the prism compressive strength value of the RPC firstincreases at first, but then decreases. The law of elastic modulus has the same law, but is notproportional to the compressive strength. Content changes of the Nano-SiO2have no effect onPoisson ratio; its value has certain discreteness.(4) Use the random aggregate model for reference, the random model of steel fiberstatistically similar to the RPC structure has established.(5) Computer simulation uniaxial compression and uniaxial tension is conduced onthe RPC specimen’s model and its compressive strength, tensile strength and the macroscopicstress strain curve are gained by computing. The fitting degree between rising segment ofpressure curve Gained by simulation and experimental is higher. The results showed that thecorresponding relation of numerical simulation and actual test is fitting well.(6) After damage process simulation of the specimen under loading, it shows thatthe damage units are usually produced in the RPC interface transition zone where the internalstrength is relatively low.(7) The direction of the tiny crack in uniaxial tensile is generally perpendicular tothe loading direction, namely it cracks along the horizontal direction, then micro cracks beginto extend to the mortar unit near the interface. With increasing of displacement load, severalcracks extend along the interface area and interconnected by mortar, macroscopic crack isformed within the specimen, until the whole specimen is cut through. Smaller vertical cracksappear during compression and new cracks appear with the increase of load, crackpropagation speed too, most extend quickly to the crack width direction. With thecontinuously produce of damage units, many cracks connect each other, until the wholespecimen is cut through.(8) The constitutive equation has deduced by the RPC compression and tensileconstitutive relation combined with existing concrete constitutive relation model.(9) The numerical simulation results show that numerical simulation can betterpredict the various macroscopic mechanical properties of concrete by some test data so that toreduce the workload of experimental study and has good economic value.
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