Study On Shear Behavior Of High-Strength Bolt Using For Connecting Steel-Concrete Composite Member

High-strength bolts using for connecting steel-concrete composite members has been applied for dry-connection of all fabricated shear walls,split bolts in reinforcement and concrete-steel composite structures.Shear capability of high-strength bolts have a great impact on integration of members,but seldom researches were carried out.Formulations in steel structure standard are using for designing High-strength bolt using for connecting steel-concrete composite members because its force mechanism and complete loading-displacement curve are unknown.The key problems of interconnection technology using high-strength bolt which applied for prefabricated concrete structure,engineering reinforcement and concrete-steel composite structure will be introduced in this article.Theoretical and experimental basis will be established yet.Eighteen specimens in eight groups were carried out monotonic loading test and two specimens were carried out low-frequency cyclic loading test.Failure mode and eight influence factors which include core board filled with concrete,diameter of bolt,pretension of bolt,concrete aperture,concrete strength,concrete thickness,core board thickness and cover board thickness were analyzed.The conclusion shows that high-strength bolts using for connecting steel-concrete composite members occur three failure modes which include bolt hole bearing failure,bolt bar shearing failure and steel net section.Core board filled with concrete makes bolt bar bend and it will improve its bearing capacity prominently.The increase of diameter of bolt,concrete strength,concrete thickness,core board thickness can improve bearing capacity of specimens,but they have few influence to sliding bearing capacity.The increase of bolt pretension can improve sliding bearing capacity,but it has no influence to bearing capacity.Four influence factors including bolt pretension,concrete strength,concrete thickness and steel board thickness were analyzed by finite element software ABAQUS.The conclusion shows that bolt pretension is proportion to sliding bearing capacity.Concrete strength has an effect on stiffness and bearing capacity and steel plate thickness effects on bearing capacity and failure mode of specimens.Force-transferring mechanism of high-strength bolt using for connecting steel-concrete composite members was analyzed.The conclusion shows that the mechanical behavior of bolt under shearing force divides into five stages which includes friction phase,sliding phase,bearing phase,hardening phase and failure phase.The simplified shear behavior model and calculation formulas of five feature points are proposed.Through experimental study the feasibility of the model is validated.The results show that the simplified shear behavior model provides theoretical basis for the future engineering applications.