Cyclic Pull-out Strength of Screwed Connections in Steel Roof and Wall Cladding Systems Using Thin Steel Battens

When crest-fixed thin steel roof and wall cladding systems are subjected to wind uplift or suction loading, local pull-through or pull-out failures occur prematurely at their screwed connections. During high wind events such as storms and hurricanes these localised failures then lead to severe damage to buildings and their contents. In recent times, the use of thin steel battens/purlins has increased considerably. This has made the pull-out failures more critical in the design of steel cladding systems. Recent research has developed a design formula for the static pull-out strength of screwed connections in steel cladding systems. However, the effects of fluctuating wind uplift or suction loading that occurs during high wind events are not known. Therefore a series of cyclic wind uplift/suction tests has been undertaken on connections between thin steel battens made of different thicknesses and steel grades, and screw fasteners with varying diameter and pitch. Tests revealed a significant reduction to pull-out strength caused by fluctuating wind loading. Simple design equations and suitable recommendations were developed to take into account this strength reduction. This paper presents the details of the cyclic tests and the results.