Strength Analysis And Experimental Study Of Corrugated Steel-Concrete Composite Structure

Marine engineering equipment is the way and means how we march to the ocean.With the development of science and technology,these engineering equipments are no longer confined to simple ship engineering,but have been extended to all fields involved in marine engineering.Structural design and component design are important links to ensure the normal service of marine engineering equipments.Any marine engineering equipments need to have sufficient strength,stiffness and stability.At present,corrugated steel structure have been widely used in structural engineering,such as pipeline,culvert engineering,corrugated steel web and so on.Because of the corrugated surface of the structure,the stability and stiffness of the corrugated steel can be improved,and the maximum bearing capacity can be guaranteed with the least material.In view of the present submarine pipeline takes steel pipe as the main force-bearing body,the increase of pipe diameter must increase the thickness of the pipe wall to ensure the stability of the pipeline.Therefore,it is proposed that the corrugated steel ? concrete composite pipe should be applied to the submarine pipeline to overcome the limitation of the diameter of the existing submarine pipeline.In addition,the corrugated steel ? concrete composite platform structure has better fire resistance,durability and higher stiffness,which can provide maximum span and stiffness with the least material,and this platform is an universal structure.Therefore,it is proposed that the corrugated steel ? concrete composite platform be used in the platform plate of ocean engineering structures,such as floating island,artificial island,seacrossing bridge and other platforms of human living and traveling structures in the ocean.These two kinds of composite structures are new structures proposed on the basis of many years' application of other structures,which have been used in engineering at present,but its mechanical mechanism and strength analysis need to be further explored.Therefore,these two kinds of structures,corrugated steel-concrete composite pipeline and platform,were selected for strength analysis and experimental study in this paper.The mechanical properties and load-bearing capacity calculation methods of corrugated steel ? concrete composite pipes and platforms were studied based on laboratory tests.Laboratory tests of corrugated steel ? concrete composite pipes were carried out for the first time.The effects of load-carrying capacity and stiffness of composite pipelines with different internal pipes,deterioration degree of RC pipes,grout strength and eccentricity of internal pipes on mechanical performance of corrugated steel ? concrete composite pipes were studied.The calculation method of load-carrying capacity and load distribution mechanism of corrugated steel ? concrete composite pipes were proposed.Combined with the current design method of submarine pipeline,the in-situ strength calculation method of corrugated steel and its composite pipes applied to submarine pipelines was proposed either.The stress distribution and bending capacity of corrugated steel ? concrete composite slabs were studied by numerical analysis method.The calculation method and reasonable section of the bending capacity of corrugated steel ? concrete composite slabs were proposed.The local buckling of corrugated steel was studied by bending test for the first time,and the calculation method of the local buckling of corrugated steel was proposed.For the corrugated steel ? concrete composite platform,the calculation method of the local buckling of corrugated steel was proposed.It provides theoretical support for the design of corrugated steel-concrete composite platform.The main conclusions are as follows:If the corrugated steel pipe is used as the submarine pipeline and the diameter of the pipeline is less than 7.7m,the design resistance of the corrugated steel pipe can be calculated by the AISI(American Iron and Steel Institute)design method.If the span of the corrugated steel pipe is large,the section of the structure is non-circular or the corrugated steel pipe is buried under the seabed,the design resistance of the corrugated steel pipe can be calculated by the CHBDC(Canadian Highway Bridge Design Code)design method.The composite pipe with corrugated steel pipe liner has higher bearing capacity and stiffness than the composite pipes with steel pipe lines and HDPE(High Density Polyethylene)pipe liner,and the composite pipe have higher load-carrying capacity and stiffness than each single pipe liner,and the durability and local stability of the corrugated steel pipes can be improved by using RC pipes as outer pipes.Composite pipe exhibited the mechanical properties of "casing"(pipe in pipe)under two-point loading.Its load-carrying capacity depends on the single-pipes that make up the composite pipe,and the distribution of axial force and bending moment in each pipe depends on EA/D(rigidity coefficient)and ring stiffness.The ultimate load-carrying capacity of composite pipe mainly depends on RC pipe and grout,while the corrugated steel pipe plays a very small role.The damaged degree of RC pipe has little infect on composite pipeline,as long as the RC pipe has not been completely damaged,the loadcarrying capacity of its composite pipe is similar to that of the composite pipe with undamaged RC pipe.The load-carrying capacity calculation methods for the eccentric and concentric composite pipeline.The error between the calculation results proposed in this paper and the experimental results of the composite pipes were mostly less than 20%,whereas the error of the composite pipeline used mortar as the grout was 30%.However,the calculation results were the lower limit of the experimental results,which is beneficial to the engineering design.When calculating pipeline strength,internal pressure and external pressure should be considered separately to obtain more conservative wall thickness and corrugation of the corrugated steel pipes;when designing the cross section of the composite pipeline,design values of internal and external pressure should be allocated to different pipe materials according to EA/D,and then whether they meet their respective design strength should be checked separately;the unbalanced moment caused by earth pressure or by other factors should be allocated to different pipe materials according to the ring stiffness of each pipe rings(these pipe rings formed the composite pipe),and then whether they meet their respective design strength be checked separately;the durability design of the corrugated steel pipes can refer to the anticorrosion treatment methods summarized in this paper,and combined with the current anticorrosion treatment measures of submarine pipelines,the durability of corrugated steel pipe and its composite submarine pipelines can be ensured.Corrugated steel ? concrete composite slabs only suffer from suitable reinforcement failure,i.e.ductile failure;the load ? displacement curve was basically straight before yielding,and the slab could continue to carry loads after yielding due to the slab entered the strengthening stage;Corrugated steel ? concrete composite slabs should be designed as the first kind of section;Correspondingly,the width of bottom slab of the Corrugated Steel Slabs should be increased,whereas the width of roof slab of the Corrugated Steel Slabs should be reduced;on the premise of keeping the cross-section area of the Corrugated Steel Slabs unchanged,the width of oblique webs should be reduced and the bending angle should be increased as far as possible;The reasonable section of the corrugated steel slabs is that the height of compression zone is equal to the thickness of concrete on the top of the roof,that is,the neutral axis is located at the edge of the roof.The local buckling calculation model proposed in this paper can be used to check whether local buckling occurs in the corrugated steel,which decomposes the local buckling of corrugated steel plate into: local buckling of the roof and local buckling of the web,and the buckling correlation of these three should be considered.When choosing the section of corrugated steel slab,if the corrugation and plate thickness are known,the critical loads of corrugated steel slab can be determined,and then the bending carrying capacity of corrugated steel slab can be determined and the local instability of corrugated steel slab can be judged.