Study On The Properties Of The Light-gauge Steel Truss Girder-OSB Composite Floor

Nested light-gauge steel truss girder-OSB composite floor is composed of OSBslab and the basic truss element of Nested Light Steel Residential System. In actualcases, gaps exist between OSB slabs which connect with each other to form the deck ofcomposite floor. In addition, screw connections of the compromise boundary betweenOSB and the truss girder have fixed and great space. The actual application shows thiskind of composite floor has low stiffness and bearing capacity.Based on the problems which occur in this composite floor, the shear-slipexperiments of the screw connections were conducted to investigate the shear-slipperformance of OSB-steel and OSB-OSB screw connection which has different OSBthickness and orientation. The tests results shows that different screw connection havesimilar feature, and shear slip process can be divided into three steps: elastic range,plastic range and platform range; OSB orientation, thickness and the different materialshave distinct impact on the shear slip performance of the screw connection; simplifiedelastic-plastic model is established to describe the shear slip performance of differentscrew connections.Differential equation of composite floor slippage is established and solved basedon the slippage theory of composite beam. Compared with the past test results of lightsteel truss girder-OSB composite floor, analytical solution of the equation shows thegreat impact on the stiffness of the floor. In addition, the performance of compositefloors which have full screw connection are calculated and the stiffness and bearingcapacity data are obtained. The calculation results show that slip of composite floor willlead to an additional deflection and decrease the stiffness of the floor; when theconnection degree increases the slip and additional deflection will decrease; OSB havegreat impact on the performance of composite floor.For different screw connections have different performance, it is inappropriate toadopt fixed screw distance in actual floor. The negative impact of slippage on thecompromise boundary shows that the screw distance is too big to make the compositefloor produce the best possible results. Based on the conclusion we make, the staticexperiments of light gauge steel truss girder-OSB composite floor are conducted. Thetest results shows that with certain OSB thickness, the screw connection degree is themain impact factor of the performance of composite floor, and when the connection degree is1, the slippage can be obviously limited; the promotion of connection degreeand OSB thickness lead to rational force distribution of the light steel truss girder andimprove the stiffness and bearing capacity of the composite floor. The double OSBinterlaced by screws improve the integrity of OSB and stiffness in service, while theOSB orientation has no impact on the performance of composite floor. Compared withthe experimental results, the calculation results are conservative and the calculations canbe used in actual application.