장스팬에 적합한 합성보 개발을 위한 연구

This study aims at developing a new composite beam system suitable for long span and reduction of story height, for which the existing composite beams available in literature were investigated to take advantage of merits and strengthen weakness of existing system. Based on this result, this research proposed a prestressed composite beam with corrugated webs. The proposed composite beam has many merits comparing to the existing composite beams; It has great resistance against non-symmetric construction load due to its strong out-of-plane shear strength. The corrugated webs also make accordion effect, which introduce larger prestressing force, and the upward prestresing force causes camber reducing the member deflection. The form work is not required in the new system due to wide bottom flange, and the member strength also increases by the tendon provided. The effective prestressing force transferred to steel beam in the corrugated beam was estimated using a finite element analysis and compared to that in ordinary I-shaped beam. The strengths of the proposed composite beams were calculated considering composite effect based on the existing method such as shear-bond stress mode and bearing stress caused by the corrugated web. The corrugated beam had greater effective prestressing stress over 15 % than the I-shaped beam, and the composite effects between concrete and steel beam were greatly improved in the proposed beam by the corrugated web. The results also indicate that the prestressed tendons can efficiently increase the flexural strength as well as stiffness of the proposed composite beam with relatively small member height, and that the new composite system has good constructability and economic efficiency by removing/minimizing form work.