Research On The Shear Performance Of Self-drilling Screw Double-sided Shear Connections

The self-drilling screws,which have the features of good economical efficiency,convenient construction and high bearing capacity,have been widely used in coldformed thin-walled steel constructions.Current research on the shear performance of screw connections has focused on the shear performance of single or multiple screw shear connections.However,little research has been reported on the shear performance of double-sided shear connections of screws,and the effect of different parameters on the shear capacity of the screw double-sided shear connections has not been reported.In response to the shortcomings of the current studies,the failure modes and shear resistance of 139 groups of screw double-sided shear connections specimens and 27 groups of screw single-sided shear connections specimens are discussed in this study by using ABAQUS software.Moreover,the effect of different parameters on the shear resistance of the screw group double-sided shear connections is also discussed in this work.The main conclusions are as follows.(1)The finite element(FE)results indicated that the failure modes of the screw double-sided shear connections can be divided into three categaries: bearing failure,shear-compression failure and shear failure.(2)The results of the parametric analysis showed that: for the screw double-sided shear connection members,when the steel plate thickness is less than 3.0mm,the shear capacity increases with the increase of the steel strength and the steel plate thickness,and tends to stabilise when the steel plate thickness exceeds 3.0mm.In addition,the shear capacity of specimens rises with the increase of the screw diameter.The influence of screw diameter on the shear capacity of specimens progressively increases as the steel strength increases within a certain range.Moreover,the shear capacity can also be significantly increased by increasing the middle steel plate thickness in a certain range.The shear capacity of the screw double-sides shear connections is dramatically higher than that of the screw single-sides shear connections.(3)The shear resistances of single and double-sided shear connections of screws obtained from the numerical simulation were compared with the calculated values of the Chinese,American and European standards.The results showed that when bearing failure occurs on the screw double-sided shear connection specimens,the calculated values of the Chinese,European,American AISI and AISC standard formulas are insecure.When shear failure occurs on the screw double-sided shear connection specimens,the American AISI,Chinese and European specifications are conservative.The calculated values of the American AISC standard formula are in good agreement with the FE values.For screw single-sided shear connection specimens,the Chinese,American and European standards are conservative when specimens occur failure.(4)The FE results show that the failure modes of the screw group double-sided shear connections include bearing failure and compression-shear failure.(5)The effect of different parameters on the shear resistance of the screw group double-sided shear connections was discussed.The results showed that when the steel plate thickness is less than 3.0 mm,increasing the number of screws has a slight effect on the shear capacity of the screw group connections,when the steel plate thickness is3.0 mm,the number of screws increases from 2 to 3,the shear capacity of the screw group connections increases significantly.However,when the number of screws is increased from 3 to 5,the shear capacity of the screw group connections is almost unchanged.As the number of screws increases,the effect of screw spacing on the shear capacity of the screw group connections decreases.Changing the screw arrangement has almost no effect on the shear capacity of the screw group connections.As the thickness of the steel plate increases,the shear capacity of the screw group connections increases almost linearly.(6)When bearing failure occurs on the specimen,the shear capacity of the screw group connections calculated using the existing formula is unsafe;when shearcompression failure occurs on the specimen,the shear capacity of the screw group connection calculated using the current formula is conservative.