Beam String Structure (BSS) is composed of upper structural member, lower string and struts, which is a new type of long-span hybrid structure. As is shown in Figure 1, the upper structural member may be beam, arch, plane truss and solid truss and so on. BSS is semi-rigid structure, which has many advantages such as high supporting capacity, small deformation, self-balancing function, strong structural stability, convenience of construction and transportation, and so on. Figure 2 shows that the prestress of the cable make midspan bending moment of the beam decrease to 1/4 of the maximum bending moment of simple beam.
