摘要：【中文】本发明提供了一种预应力型钢梁，包括长条形型钢、设置于所述型钢长度方向上中部的第一限位部、以及沿所述型钢长度方向设置的至少一条与所述第一限位部连接的抗拉件；所述第一限位部设置于靠近所述型钢承受拉应力的一侧；所述抗拉件上至少存在一点到所述型钢承受拉应力的一侧的距离大于所述型钢中心线到所述型钢承受拉应力的一侧的距离；所述抗拉件处于张紧状态，以沿着所述抗拉件长度方向产生拉应力；所述第一限位部用于将所述抗拉件产生的拉应力的合力或分力作用于所述型钢，以抵消一部分所述型钢承受的压力。此外，本发明还提供了一种超薄夹层楼盖。 【EN】The invention provides a prestressed section steel beam which comprises strip-shaped section steel, a first limiting part arranged in the middle of the section steel in the length direction, and at least one tensile piece connected with the first limiting part and arranged along the length direction of the section steel; the first limiting part is arranged at one side close to the section steel bearing tensile stress; the distance from at least one point on the tensile piece to the side of the section steel bearing the tensile stress is larger than the distance from the center line of the section steel to the side of the section steel bearing the tensile stress; the tensile piece is in a tensioning state so as to generate tensile stress along the length direction of the tensile piece; the first limiting part is used for enabling resultant force or component force of tensile stress generated by the tensile piece to act on the section steel so as to offset pressure born by a part of the section steel. In addition, the invention also provides an ultrathin sandwich floor system.