Flexural Behavior of Reinforced Concrete Beams Superposing with Partial Steel Fiber Reinforced Full-lightweight Concrete

To improve the flexural properties and lighten the weight of ordinary reinforced concrete beam (RCB), a new type of superposed RCB is developed with partially steel fiber reinforced full-lightweight concrete (SFRFLC) in tensile zone. 10 beams with different height of SFRFLC were designed. Their flexural behaviors were measured including the concrete strain at mid-span cross section, the load vs. deflection curve, the cracking load and the ultimate load. It may be concluded that the test beams damage in ductile, the concrete strains at mid-span cross section basically fit the assumption of plain cross section, the variations of load vs. deflection curves are similar with obvious changes at the points of the cracking of concrete and the yield of tensile reinforcements, the cracking loads are almost equal, and the ultimate loads tends to decrease with the increasing height of SFRFLC. The SFRFLC and ordinary concrete work well together, there is the suitable height of SFRFLC.