The Elastic Analysis Of Prestressed Concrete Frame Joints With Spread-ended Beam

In practical application, circumstances are that the layout of anchorage of prestressing tendons is too complicated that they cannot get through the joint core and be anchored due to functional requirement for the prestressed concrete frame structures. As a solution, a spread-ended beam is utilized to make it possible for the tendons to get through. In this way, the design method of this new type of joint is urgent to be focused on.In this paper, the previous research work at home and abroad are summarized on the loading mechanisms and the performance of the joints with spread-ended beam. The proposed design methods of prestressed concrete frame joints in different countries are also introduced. Meanwhile, the basic principle and the numerical simulation of prestressed concrete frame structures by using ANSYS are described.The prestressing tendons in joints with spread-ended beam are partially spatially curved, while according to the Chinese design codes of concrete structures, only frictional loss calculation formula for 2D curve tendons is given. In this paper, a frictional loss calculation formula for 3D curve tendons is developed. The results of the new formula are much larger compared with those calculated following the formula in the design codes. So in the design of this type of joints, the formula for3D curved tendons should be employed to avoid the overestimate of the effective load due to prestressing.In this article, two prestressed joints with spread-ended beam and a normal prestressed joint are analyzed by using ANSYS. The differences in the trajectories and in the distribution of the principle stresses are compared. Nine prestressed joints with spread-ended beam were analyzed through the orthogonal test design method. The effects of factors (including the length of the spread-end, the width of the spread-end, the value of the load, the distribution of the prestressing tendons) are investigated, thus a further insight is obtained on the performance of this type of joints and on providing references in design.