Behavior of lapped connected Z cold formed purlins

Cold-formed steel Z sections are widely used in modem roof systems aspurlins .To maintain their continuity, these sections might be overlappedover their interior supports. The overlapping operation introduces cross-sectional changes which would affect the structural behavior of the purlinsupon loading. In this study, many parameters that affect the structuralbehavior of Z purlins are introduced.The finite element teclmique was used to simulate the structuralbehavior of lapped connections over the internal supports in multi span cold-formed stiffened steel Z purlin systems. The considered beams had spanlengths of 500,600,700 and 800 cm with nominal web depths of 20.0 cm. andthickness 2.0 mm. The work program includes modeling of a single Z sectionbeam with lap lengths 50,100,125,150 and 175 cm. The considered lap modelsare of two typical connection configurations, a) Free ends considering thefriction only between the two lapped Z sections in addition to self-drillingscrews by which the corrugated sheets are connected to the Z top flange.b) Connected ends using web bolts at the lap ends plus self-drilling screws atthe top flange. The case of simply supported Z purl ins is also considered in thework for comparison.Based on this analysis using the (ABAQUS 6.8) stresses and deflectionsof lapped beams of stiffened Z sections are studied and presented. Empiricalequations were derived to predict the deflection of lapped beams. Acomparative study is presented between the results obtained from the derivedequations and those from experimental works.