Overview of Connection Detailing for Post-tensioned Dissipative Timber Frames

摘要

The concept of post-tensioned rocking structures was successfully applied to timber in 2005, in prestressed laminated timber (Pres-Lam) technology. When applied to moment-resisting frames, the technology relies on unbonded post-tensioning tendons passing through hollow beams and the supporting column to provide beam-column connections with moment capacity. Supplemental dissipation devices can be included in the design, resulting in a recentring/dissipative system. Since seismic movements are accommodated through a control rocking mechanism between the beam and the column, the detailing of the beam-column joint can significantly affect the seismic performance of the structure. Among the main concerns, the shear transfer system should be able to transfer shear forces without interfering with the rocking motion, and ignoring the face friction and joint deformation should not compromise the drift activation of the gap opening. Attention should also be paid to minimizing post-tensioning losses while providing access for potential retensioning. As a result of the continuous and rapid development of Pres-Lam frame systems, a wide range of alternative solutions for connection detailing has been tested in the laboratory or implemented in existing buildings. This paper presents an overview of the beam-column detailing implemented in the five Pres-Lam frame buildings currently operative in New Zealand.