Numerical Analysis On Bearing Capacity Of Headed Studs Under The Effect Of Edge Distance

Concrete prefabricated parts can't be manufactured and lifted without inserts.At present,there are a wide range of embedded hanging parts in the engineering application,which have different force transmission route and stress characteristic,and we have no relative standard for guiding their designing,constructing,testing processing.The complicated boundary condition often appear when inserts are used.For example,the bearing capacity will decrease result from edge effect.The edge distance effect on bearing capacity of embedded hanging parts are complicate,lead to we can't finish all of the research through the experimental way.Because experimental research will consume a lot of humans and material resources,which has no enough necessity and feasibility.Therefore,it's necessary to research the influence of edge distance for bearing capacity of inserts.Main research content of this paper as follows:According to the Mechanical characteristics,inserts be divided into three classes:headed and steel welding,other flat steel.This paper mainly researches the influence of edge distance for bearing capacity of headed stud.Through clearing up the computational formula about tensile,shear capacity and failure mode in domestic specification Technical specification for post-installed fastenings in concrete structures and American specification ACI318,England specification CEN/TR 15728,compare their difference and similarity.In order to study the feasibility of the finite element analysis,the author simulates the preliminary experimental study,including three modes with different buried depth,the relative error between finite element analysis and experimental study stable at around 9%.So finite element simulation can be used to study the bearing capacity related problems of headed stud.Concrete strength C20 and C30,C40 model group be established through ABAQUS finite element analysis software.Each model groups including six models,which edge distance range from 100 mm to 150 mm.Result shows that three model groups occurred concrete conical failure,tensile bearing capacity increases with edge distance,when margins reach to 140 mm,the tensile bearing capacity tends to be stable.Which keep the same with provision that critical edge distance is 1.5 times effective depth in domestic and international norms.In order to explore the influence tendency of edge distance for shear capacity,author also establishes C20 and C30,C40model groups,which edge distance range from 70mm to 120mm.Each model occurred concrete wedge failure.Shear capacity increases with edge distance increases.The trend is same as curve of edge distance-shear capacity from domestic and international standard.When edge distance remain the same,Finite element analysis result less than specification calculated value from ACI318,more than specification calculated value from Technical specification for post-installed fastenings in concrete structures.This paper takes an example of three headed stud inserts from two series of enterprise M,comparing the production capacity and recommended formula calculated value in domestic and international norms,and analyzing the safety degree of each specification for calculating concrete conical failure capacity.Result shows that the safety degree of the calculated value from domestic and foreign norms are different,and it's possible that the ratio of experimental average value and current specification design value less than safety factor specified in the specification.The innovations in this paper as follows:concrete conical failure capacity calculated formula always use concrete compressive strength relevant factor,result in calculated value higher with high strength concrete.The reason for conical failure is that conical surface concrete reach its tensile limit.So,the research improve the calculated formula that use the concrete tensile strength standard value instead of compressive strength relevant factor.Through analyzing the force situation of conical failure and researching the conical surface,deduce the calculated formula for conical failure.Result shows that derivation formula calculated value close the result from England specification CEN/TR 15728,and critical edge distance is also 1.5 times effective depth.