Hybrid frp-concrete-steel double-skin tubular beams and hybrid dstb/slab units using the beams

Abstract

This invention relates to a novel hybrid FRP-concrete-steel double-skin tubular beam and a hybrid beam/slab unit which employs the hybrid tubular beam. The hybrid double-skin tubular beam consists of an outer FRP tube, an inner steel tube, and concrete filled between the outer FRP tube and the inner steel tube, and the inner steel tube is provided with a plurality of shear connectors on its side engaged with concrete. The inner steel tube is located eccentrically relative to the outer FRP tube towards the side of the hybrid tubular beam to be tensed. The inventive hybrid beam/slab unit is a slab-on-girder system which is comprised of the hybrid double-skin tubular beam and the lightweight slab of good corrosion resistance (such as a FRP slab or an aluminum slab) that is provided thereon, or a deck or floor system which is comprised of the hybrid double-skin tubular beam and a FRP-rib reinforced concrete slab and in which the upper portion of the hybrid double-skin tubular beam is engaged with the bottom of the FRP-rib reinforced concrete slab thereinside so as to form an integrated body. The inventive hybrid tubular beam features an excellent resistance against corrosion, a good ductility and cost-effectiveness. and is lightweight, while at the same time allows for easy construction and connection with other members.

1 . A hybrid double-skin tubular beam, characterized in that, the hybrid double-skin tubular beam consists of an outer FRP tube, an inner steel tube, and concrete filled between the outer FRP tube and the inner steel tube, and the inner steel tube is provided with a plurality of shear connectors on its side engaged with concrete so as to ensure the inner steel tube and the concrete to work together. 
     
     
         2 . The hybrid double-skin tubular beam as claimed in  claim 1 , characterized in that, the plurality of shear connectors are distributed along the circumferential and longitudinal directions of the inner steel tube. 
     
     
         3 . The hybrid double-skin tubular beam as claimed in  claim 1 , characterized in that, the inner steel tube is located eccentrically relative to the outer FRP tube towards the side of the hybrid tubular beam to be tensed. 
     
     
         4 . The hybrid double-skin tubular beam as claimed in  claim 1 , characterized in that, the cross sectional shape of the hybrid double-skin tubular beam is an arbitrary combination of an outer FRP tube of circular, square, rectangular or any other suitable shapes and an inner steel tube of circular, square, rectangular or any other suitable shapes. 
     
     
         5 . The hybrid double-skin tubular beam as claimed in  claim 4 , characterized in that, the cross sectional shape of the hybrid double-skin tubular beam is identical along the longitudinal direction. 
     
     
         6 . The hybrid double-skin tubular beam as claimed in  claim 4 , characterized in that, the inner steel tube is located inclinedly relative to the outer FRP tube along the longitudinal direction in such a way that the inner steel tube is closer to the lower portion of the cross section in the region of positive bending moments and is closer to the upper portion of the cross section in the region of negative bending moments. 
     
     
         7 . The hybrid double-skin tubular beam as claimed in  claim 1 , characterized in that, the outer FRP tube is manufactured by means of a winding moulding process, and fibers of the outer FRP tube are mainly wound along the circumferential direction or substantially along the circumferential direction. 
     
     
         8 . A hybrid beam/slab unit, which consists of a beam and a slab provided thereon, characterized in that, the beam is a hybrid double-skin tubular beam, including an outer FRP tube, an inner steel tube and concrete filled therebetween; and the inner steel tube is provided with a plurality of shear connectors on its side engaged with concrete to ensure the inner steel tube to work together with the concrete. 
     
     
         9 . A hybrid beam/slab unit, characterized in that, the hybrid unit consists of a hybrid double-skin tubular beam and an FRP-rib reinforced concrete slab; the upper portion of the hybrid double-skin tubular beam is engaged with the bottom of the FRP-rib reinforced concrete slab thereinside so as to form an integrated body; the hybrid double-skin tubular beam is comprised of an outer FRP tube, an inner steel tube and concrete filled therebetween; and the inner steel tube is provided with a plurality of shear connectors on its side engaged with concrete to ensure the inner steel tube to work together with the concrete. 
     
     
         10 . The hybrid beam/slab unit as claimed in  claim 9 , characterized in that, the hybrid double-skin tubular beam is embedded with a reinforcement rib in the upper portion thereof; the reinforcement rib penetrates through the outer FRP tube, and is connected with the bottom FRP ribs of the FRP-rib reinforced concrete slab so as to integrate the hybrid double-skin tubular beam and the FRP-rib reinforced concrete slab.