Experimental Study On Tensile And Shear Properties Of Blind-Bolt Joints Under Impact Loading

In recent years,the bolt systems which are used to connect steel pipes unilaterally have been developed.The blind bolt can realize the function of single-side installation and tightening,so there is no need to process the mounting hole,and the bolt connection function can be completed without destroying other parts of the steel pipe.Besides,other advantages,including construction and labor costs saving,the simple and convenient construction on site,the extremely small welding quantity are all founded.Moreover,under the same conditions,the blind bolt can achieve the same mechanical properties of the traditional high-strength bolt,and satisfactorily meet the connection requirements of the steel pipe and the steel tube concrete structure.These features of blind bolts can be used in the field of structural engineering and have great application prospects.At present,the related researches on blind bolt system at home and abroad are mainly limited to its static performance and corresponding connected nodes.However,there is limited research on the tensile and shear mechanical properties of blind bolts under impact loading.Therefore,this paper mainly examines the dynamical response of blind bolts,and the main contents are as follows:(1)The load-displacement curves of the blind bolt and the improved blind bolt were obtained through the static tensile test,and then the tensile properties such as the strength,stiffness and ductility of the blind bolt were compared.The tensile properties of the blind bolt were evaluated.(2)The dynamic impact tensile test was carried out on blind bolts,modified blind bolts and high-strength bolts,respectively.Considering the anchoring effect with or without concrete bonding,the time histories of force and displacement and impact force-displacement curves under different impact energies were obtained.Besides,the dynamic tensile properties of different bolt types were analyzed,and the dynamic test results were compared with the static test results to investigate the relationship between the strain rate and the dynamic amplification factor(DIF).(3)The shear performance test of blind bolts under static and dynamic impact was carried out.The time history curve of force and displacement,and impact forcedisplacement curve were obtained.Moreover,the influence laws of impact energy,shear plate thickNess and single or double shear test parameters on the shear performance of blind bolts were analyzed.Finally,the dynamic test results were compared with the static test results to examine the relationship between the strain rate and the dynamic amplification factor(DIF).