English：

In order to solve the problem that the free-support steel bar truss laminated concrete slab floorin construction stage is easy to crack and needs a lot of vertical support, a free support measure usingtriangular section steel is proposed. Static tests are carried out on the free-support steel bar trusslaminated concrete slab floor in construction stage. The effect of free support measure and slab span isconsidered. The failure phenomenon and curves between load and mid-span deflection are obtained, andthe change law of the strain between the slab-bottom longitudinal bar and the triangular section steel isanalyzed. Test results show that the adoption of free support measure can obviously improve the stiffnessof floor deck and decrease the strain of steel bar at the bottom of slab, and when the slab span and thefree support measure are adaptive, there is no crack at the bottom of slab and the mid-span deflection isless than the limit, indicating that the free support measure has good application effect. The slab-bottomlongitudinal bar and the triangular section steel are in tension and compression respectively, and the bothdo not yield in construction stage. As the slab span increasing, the strain of the slab-bottom longitudinalbar and the triangular section steel increases.