逆対称曲げを受けるアンボンドPC梁の耐力・変形評価 : アンボゾドPC部材の構造特性に関する研究(その1)

Abstract

Tests and analytical study were carried out for the purpose of applying unbonded prestressed concrete members to seismic resistant structures. The aim of the tests was to examine the structural behaviors of unbonded prestressed beams. Test parameters were reinforcing steel ratio, distribution of tendon and shear span ratio. Authors have developed an analytical method for estimating the relationship between the load and the deformation of unbonded prestressed concrete members. In this study, a method to evaluate the plastic rotation at the beam end taking account of the plastic hinging and the slip of reinforcing bars at the anchor zone is proposed. The main results are summarized as follows ; 1. When the stresses in reinforcing bars are smaller than the yield stress, the behaviors of unbonded prestressed concrete members can be estimated by using the formula for reinforced concrete members with axial stresses, substituting the prestresses for the axial stresses. 2. The tendon forces of unbonded prestressed concrete members at their ultimate resistant moment are larger than those caluculated by using the formula in A.I.J. Recommendations for prestressed reinforced (partially prestressed) concrete members. This fact affects the ultimate strength of members. 3. The relationship between the load and the deformation of unbonded prestressed concrete members subjected to antisymmetric moments can be roughly estimated by this method.