Abstract: In practice, the carrying-capacity of beam-slab members is usually enhanced by membrane effect, which results in the change of failure pattern. In order to reveal the influences of membrane effect on the loading process and the ultimate capacity of beam structures, blast-resistance tests of HFR-LWC beam (hybrid fiber reinforced-lightweight aggregate concrete) are performed. The overpressure history, mid-span displacement and failure mode of HFR-LWC beam are obtained. The carrying-capacity and failure pattern of HFR-LWC beams are discussed based on measured data and theoretical analysis. Results show that the membrane behavior on beams during blast loading is reasonably simulated in the test, which provides a reliable tool to quantitatively evaluate the contribution of in-plane force. The existing of membrane effect can effectively avoid the steel yielding, fully use the compressive strength of concrete, prevent the crack propagations, and reduce the mid-span displacement of HFR-LWC beams; thus, the blast-resistance of HFR-LWC beams is improved greatly by membrane effect.