The Study On Crack Pattern Of Prestressed Concrete Berthing Pile Under Dynamic Load

Pile is a very important foundation style in engineering constrution and whichwould accounted for1/4of the total constrution cost. In port engineering,the bertingpiles were been settled usually,for decrease the impact force from ship and prolongingthe service life of the wharf.Berthing pile is a straight pile which was driving into theground in front of the wharf,to withstand the huge impact energy from ships by usingelastic deformation from itself and rubber pad which settled on the top of the pile.Prestressed concrete berthing pile usually works with cracks which caused by thehuge and repeated impact force from ships.The cracks issue was a engineering difficultywhich would caused corrosion and durability problem to concrete pile.Not only affectedappearance of the pile but also caused psychological panic to users by cracks.Especiallyfor hydralic renforced concrete structure,many components in contact with water. Thepresence of cracks easily lead to corrosion of steel member, also seriously affect thecarrying capacity, durability of structures and components, as well as the impermeability,frost resistance.For the crack question of reinforced concrete structure under external loads, peopleoften focus on3issues commonly. The first one was cracking load and thecorresponding size of the cracking moment.The second one was the development anddistribution of the cracks.The third one was the issue of crack width.Up tonow,researchs on prestressed concrete berthing pile is little both at home and abroad,andthe crack question about concrete berthing under ship dynamic loads is almost a blankstate.Based on the basic theory of cracks in reinforced concrete structure and principles ofsimulation analysis of reinforced concrete, by takine use of contact-collision theory,motivation theory of large deformation,material nonlinearity theory which are involvedin the research, this paper puts forward a element deletion method to simulate the cracksin the prestressed concrete berthing pile in crack under load, and then propose thespecific steps to implement the element deletion and the calculation method of crackwidth,as well as take comparative analysis between the numerical simulation results andexperimental results.Finally, it proves that the element deletion method can not onlysimulate the crack load, position, development, distribution and morphology with trueimage of the berthing pile specimen cracks under the loads, but also it obtains the width sizes of cracks under different loads.After comparison,it’s very suitable for thesimulation of plasticities and viscous properties of concrete materials under dynamicloads,and of the deformation and damage of concrete materials at large strain, highstrain rate and high pressure by using the JHC model as the constitutive model ofconcrete materials.Based on the theory of fracture toughness，optimization design was carring out forthe prestressed concrete berthing pile.And results shows that the new design couldsignificantly improve the cracking load,greatly reduce the crack width,and make thecracks smaller and distribution more uniform by using a higher concrete strength(C80),ahigher pretension force(1.4times the original value) and a higher reinforcementratio(p=1.151%) with larger diameter of rebar(d=21.6mm).This is very favorable forwaterproof and antirust to hydraulic structure,also provide reference for the design forprestressed concrete berthing pile.