Flexural and Shear Performance of Angle Truss Composite Beams

Abstract

There is a lot of welcome for the precast construction method to reduce the labor in the field and to make it in the factory by upgrading the technology at the construction site and increasing the labor cost. As a structural member, various attempts have been made to increase the efficiency by using steel instead of using only conventional reinforcing bars and concrete which are conventionally used. This is a kind of encased composite beams that are used to construct a truss by using bending angle bent steel plates and casting a U-shaped precast on the bottom. Lower precast concrete replaces formwork to reduce field labor. It is then transported to the site and placed on a column, which is then integrated with the cast concrete. This system is economical because the effective depth of the cross section is deepened due to the existence of the inner angle truss, so that the amount of precast concrete can be drastically reduced. Also, it has the merit that it can add convenience with light weight during construction. The structural performance was verified through the bending and shear tests of the developed angle truss composite beams and compared with the predicted strength values of the existing design standards. In the bending test of the angle truss composite beams, it was found that it was well fitted when the design was made by the existing method which evaluated the bond strength, and the design bending strength was also obtained. However, excessive slippage occurred due to slip of the bolt in the proposed cross section. Further research is needed in this area. In the shear test, the web material of the angle truss embedded was calculated by shear reinforcement of ordinary reinforced concrete, and the experimental results were slightly less than or better than expected strength. The fracture modes of the specimens which were lower than the expected strength were different from diagonal tensile fracture. It was analyzed by the shear failure at the interface between upper and lower concrete of angle truss. In the case where adhesion failure does not occur, it is confirmed that the inner abdominal members are all surrendered, so that consideration can be given to the calculation of the shear strength. However, since the abdomen of the truss is connected by bolts, the upper limit of the shear strength is the bolt shear strength. Through the evaluation of the structural performance, the flexural performance and the structural performance of a kind of embedded composite beam were confirmed, and it was concluded that the contribution of the internal steel to the shear strength of the embedded composite beam can be added.