Study On The Influencing Factors Of PBH Steel Concrete Composite Shear Connection Structure Fatigue Life

The Steel box-concrete composite structure is a new-type composite structure under the background of arch bridge,our research group designs a new shear connector—A new Perfobond Hoop.According to this composite structure,which is applied to plenty of bridges.The group has conducted a deeper research regarding to the static behavior of the PBH,so this paper studies on the fatigue life and its factors of the PBH to get the fatigue mechanical properties of the PBH with the aid of the National Natural Science Foundation of China--Study on the fatigue property and the load transfer mechanism of the PBH shear connector in the Steel box-concrete composite structure(51308571),the main contents are as follows:1 The static push-out test has been done,the aperture's diameter of stiffening ribs are 30mm.40mm and 50mm.The tests show that all of the failure modes of the specimens present interface cracks and cracks growth from the ends to the middle,the concrete is crushed and the rebars shear yielding locally at the ultimate load,The load-deformation whole process curve of the static push-out test of the PBH contains three parts:the elastic stage,the elastic-plastic stage and the drooping stage.2 The fatigue push-out test has been done.The tests indicate that,it's similar to the static failure mode,fatigue failure mode contains concrete crushing locally,rebars shear yielding.And the cumulative fatigue damage rule of the PBH has three stages:beginning stage of fatigue damage,developmental stage,and the failure stage of the fatigue.Among the three stages,the speed of the rigidity deterioration is faster in the third stages,while slower in the first two stages.3 finite element modelling about the static push-out test by ABAQUS was deen Constructed;After making comparison with the tset date,we use the finite element model to make some parameter analysis of the static mechanical behaviors,such as the aperture's diameter of stiffening ribs,rebars' diameter,and concrete strength.The results show that the influence factors on the bearing capacity of the PBH are different,the concrete strength is the largest,the aperture's diameter of stiffening ribs is the second,and the rebars' diameter is the least.4.Based on the static model,we do fatigue calculations of the PBH by fe-safe;After doing comparison with the fatigue tset date,we make some analysis of the fatigue influence factors of PBH by making use of this software,the main conclusions are as follows:? when the loading ratio ?=0.25,the larger the aperture's diameter is,the larger fatigue strength is;In the same maximum punishing stress,the fatigue life increases with the increasing of the the aperture's diameter.Under the same conditions,the fatigue life of the fatigue life decreases with the increasing of the maximum fatigue failure stress.? the larger the rebars diameter is,the larger fatigue strength is;In the same maximum punishing stress,the larger the rebars diameter is,the larger fatigue strength is.Under the same conditions,the fatigue life is greatly affected by the diameter of the steel penetration.? the larger the concrete strength is,the larger fatigue strength is;In the same maximum punishing stress,the larger the concrete strength is,the larger fatigue strength is.Under the same conditions,the fatigue life of the fatigue life decreases with the increasing of the maximum fatigue failure stress.? After comparing the influence degree of the three parameters,we can conclude that the most influential factor on the fatigue life of the PBH is the rebars'diameter.