BEHAVIORS OF SLIP-CRITICAL BOLTS IN COMBINATION WITH FILLET WELDS

Abstract

According to the Specification for Structural Steel Buildings (AISC 2010), slip-critical bolts can only share load with longitudinal welds in a joint. Moreover, the bolt available strength shall not be taken greater than 50% of the bearing-type. This paper presents the result of a series of joint tests verifying the specification. The joints were tested in a manner similar to previous work (e.g. Manuel and Kulak 2000). The slip strength values of JIS F10T and F14T bolts were tested and compared. Transverse and longitudinal fillet welds with a leg size of 12 mm and the same amount of weld material were adopted and tested respectively. The strength ratio between bolts and welds changes from 5/8 to 6/9 in the combination joints. The result shows that in the combination with longitudinal welds, the bolts tend to slip and contact the plates, developing greater bearing strength. In the combination with transverse welds, the bolts slip and the pretension decreases greatly. But the combination also causes the fracture surfaces of transverse welds to change, providing additional strength to compensate the decrease in bolt slip strength. The combination joints therefore can develop strength greater than the sum of slip strength and fracture strength.